PDA

View Full Version : Apo-Ronar shims--one, two, or none?



CreationBear
8-May-2019, 07:00
I'm trying to get a feel for lenses available in the 360mm range and am finding that the Apo-Ronar and Apo-Artar's are ticking a lot of boxes. Complicating matters for me, though, is understanding the whole shim business--I get that shims are used for optimizing performance at distance, but assuming I'm looking at an Apo-Ronar in a modern, black Copal 3:

1.) Is there any way to tell I'm looking at a factory-installed shutter, or whether someone has done the job with "aftermarket" parts?

2.) How many shims should a 360mm have? I've seen sellers' descriptions of Apo-Ronars in Copal 3's as having one, two, or in the case of shorter lenses, no shims at all. Should a single shim ring be a danger sign?

3.) As of yet, all of the conversations I've seen about shims have been about Rodenstock lenses--do Apo-Artar's use them as well? Also, I've noticed the in-shutter Schneider's seem to sell for a bit more than do the Apo-Ronar's, which was surprising to me given the latter can have more modern lens coatings. Are there simply fewer Apo-Artar's out there, or is there a "pixie dust":) reputation to consider?

Any insights appreciated!:)

Leigh
8-May-2019, 07:54
All manufactured part dimensions have tolerances. That includes lens thickness and surface curvature, spacer lengths, etc.

Shims are used to optimize the spacing of the cells to compensate for these tolerances to the greatest extent possible.

So the number of shims required will vary from one individual lens to another.
Determining the required shim(s) if any requires an optical test bench or fixture.

- Leigh

Bernice Loui
8-May-2019, 08:00
Shims are specific to one individual lens cell set in the case of Rodenstock. Rodenstock calibrated each shim for each lens cell set and and shim position. They are NOT interchangeable, not universal and not to be discarded as these shims will affect optical performance of that specific lens. It is also possible for a used lens these shims have been removed, discarded or lost since a given APO Ronar has been purchased new. There are some APO Ronars that have no shims, many do.

Goerz APO Artar, Red Dot Artar, Dagor and .... have lens barrels that have been individually adjusted (length overall and distance between iris to lens cell) to the specific lens cell set. This method is more involved and requires each individual lens to be tested then the lens barrel or lens cell mounting rings precision machined to match the optical requirements of the specific lens cell set.

Goerz lens cells are not interchangeable between Goerz lens barrels without very specific modifications. Rodenstock APO Ronar lens cells can be interchanged IF the lens cell set specific shim accompanies the revised mounting.

360mm APO Ronar comes in a #3 shutter, Goerz 14" APO Artar_Red Dot Artar was originally supplied often in a Ilex#4 shutter. Optical performance wise, they are both remarkably similar multicoated or single coated depending on optical condition of a specific lens. Some are excellent, some have been whacked over their course of their history resulting in less than original optical performance.


Bernice

Tin Can
8-May-2019, 08:02
Another question is how do we make and use a DIY Optical Bench.

Luis-F-S
8-May-2019, 08:04
If it’s a black Copal 3 it’s probably newer than the lens so not original. Only way to tell if the spacing is correct is on an optical bench. If it was installed correctly they would have transferred the spacing from the barrel.

Bernice Loui
8-May-2019, 08:14
After Goerz was purchased by Schneider, Schneider offered the same Goerz APO Artar in Copal, Compur, Prontor shutters, Sinar offered both APO Ronar and Schneider APO Artar in DB & DBM mounts they were "multi coated".

The modern Copal shutter has a non-round iris, the older Ilex and similar shutters have a nice round iris. If the Ilex or older shutter is in good condition, there is no functional advantage to the Copal shutter, chrome or black. IMO, the chrome shutter speed ring Copals are made a bit nicer as the black ones appear to be cost-reduction_ed.

Lesser known detail, f9 Goerz APO Artars (Red Dot or Schneider Artar) are optimized at f16. Rodenstock f9 APO Ronar are optimized at f22. Theoretically the Goerz has better optical performance at f16 than the Rodenstock.


Bernice

CreationBear
8-May-2019, 08:52
Henry Ford wept...:)

Thanks so much for the replies--very much appreciated!

Pere Casals
8-May-2019, 09:21
Lesser known detail, f9 Goerz APO Artars (Red Dot or Schneider Artar) are optimized at f16. Rodenstock f9 APO Ronar are optimized at f22.

Bernice, you may check Arne Croell and C. Pérez tests. The Ronars perform exceptionally well at f/16, and in both cases (Pérez-Croell) the ronars show better performance at f/16 than at f/22.

For example Pérez metered for a 1970s APO Ronar 240mm:

f/11 76 68 38
f/16 68 48 54
f/22 60 42 48

76Lp/mm at f/11 in the center is a nice rate for a 1970s glass !

For that sample, if DOF not counting and not having important stuff in the corners then best aperture is f/11. Also perfect corners at f/16, and we may stop further if wanting DOF.

As always this was a practical test at contrast extintion, not a lab test, but to say 76 or 54 he had to see a certain group.element !

Probably the optimal aperture depends on the particular sample, but from the numbers it looks that nobody would guess the aperture from the image quality, beyond DOF...

Mark Sampson
8-May-2019, 09:33
Well, we're talking Rolls-Royces here, not Model Ts. Not to disparage Mr. Ford's fine cars, but these lenses were limited-production items, hand-made to extremely tight specifications... and very expensive when new. The professionals who bought them new were happy to pay to get the best quality (on which their livelihood depended).
If you want the best performance from your lens (don't we all?) the methods outlined above are what it takes. There ain't no free lunch!

Bernice Loui
8-May-2019, 09:49
Absurd (Those ??? LPM numbers again) to apply test from a single lens sample to the entire production of any lens. That individual lens test is a specific isolated test example.

This entire family of Dialyte lens formulations can be exception in optical performance, their trade off is smaller (about 45 degrees) image circle than other optical formulations that offer much larger image circles of good optical performance. Beyond Rodenstock APO Ronar and Goerz APO Artar, there is APO Nikkor, 203mm f7.7 Kodak Ektar, Zeiss Jena APO Germinar and a host of other Dialyte lens formulations that were produce for the process camera and color separation printing industry back in the day. Any of these that are any good have been individually hand tweaked to achieve ideal performance for a given set of lens performance demands and specifications. These needs are often FAR more demanding than any normal photographic needs.

Majority of these Dialyte lens formulations are in barrel as they were most common on process cameras. They are a lot less expensive in barrel to due the lack of a shutter which is easily resolved with a Sinar shutter or similar.

Been using this family of lenses since the 1980's with excellent results for any image needs with a taking aperture of f16 to f45 and longer than normal focal lengths.


Bernice

Pere Casals
8-May-2019, 10:10
Another question is how do we make and use a DIY Optical Bench.

Randy, this is straight... My bench is my Norma "optical bench" with also a lens board in the back standard, I've two special lens boards, one has an F mount bayonet on it to attach a dslr (without the dslr lens,projwecting on the sensor), the other one has an x20 eyepiece. This isn't a pro bench becuase it's not precise enough to account for the field curvature, but with shifts/rise it allows to reach the circle boundaries, if checking focus again for each time we move the position then we have good information, good enough to check the best shimming.

The shim is calculated by counting the tours we unscreew until the optimal position, and then we multilpy by the thread pitch. It requires some work because we need to balance the effect in the center vs corner.

A dslr may have 250 pix per mm, so some 125 "pixel pairs" per mm, this may be good enough for this optimization work, or even we may use other (cheaper) cameras with a very small sensor having a higher pixel density, like an old smartphone with its lens removed, this is a nice solution because we see the screen in the other side, and we operate the camera from that screen, or with a regular mouse attached to the usb with an OTG adapter. I had used the mouse to remove vibrations.

I made tests with a Sony Z2 that has the lens broken, sensor is 1/2.3 diagonal having 5248 pix in 6.17mm, so 850pix/mm, so a trash Z2 with the lens broken, glued on a sinar lensboard and with a PC mouse OTG connected... this is actually a high precision instrument for DIY optics!

Pere Casals
8-May-2019, 10:13
Absurd (Those ??? LPM numbers again) to apply test from a single lens sample to the entire production of any lens. That individual lens test is a specific isolated test example

Not absurd, Mr Perez and Mr Croell did something interesting in photography, this is testing, rather than eating commercial information and repeating urban legends.

From the several croell/perez tests it looks that APO Ronar is not optimized for f/22, this looks it was a urban legend that had been repeated around.

CreationBear
8-May-2019, 10:21
There ain't no free lunch!

Ha, very true--though after the better part of century, trying to sift happenstance and accident from (intelligent ) Design can be a little nerve wracking!:)

Bob Salomon
8-May-2019, 10:34
Not absurd, Mr Perez and Mr Croell did something interesting in photography, this is testing, rather than eating commercial information and repeating urban legends.

...but from the several croell/perez tests it looks that APO Ronar is not optimized for f/22, and that this looks it was a urban legend that had been repeated around.

Nonsense! This test is unrepeatable and extremely variable. Just how fresh or fatigued one’s see is will skew the results!
Not to mention atmospheric conditions, emulsion, processing, etc.. plus he apparently tested used lenses so previipus handling (has it been dropped), etc. enters into the results.

It is simply stuff and nonsense!

Dan Fromm
8-May-2019, 11:08
Bob, on the one hand misinformation is worse than none.

On the other, we all do informal acceptance tests, if only because no two lenses of the same make and model perform exactly alike. There's no substitute for asking the lens in hand whether it meets my needs (not necessarily your needs, and even if your needs are mine you don't have my lens).

Tin Can
8-May-2019, 11:09
As I have a Horseman Optical-Bench Modular Camera (https://www.butkus.org/chinon/horseman/horseman_optical-bench_modular/horseman_optical-bench_modular.htm) I will copy your lead.

Thank you



Randy, this is straight... My bench is my Norma "optical bench" with also a lens board in the back standard, I've two special lens boards, one has an F mount bayonet on it to attach a dslr (without the dslr lens,projwecting on the sensor), the other one has an x20 eyepiece. This isn't a pro bench becuase it's not precise enough to account for the field curvature, but with shifts/rise it allows to reach the circle boundaries, if checking focus again for each time we move the position then we have good information, good enough to check the best shimming.

The shim is calculated by counting the tours we unscreew until the optimal position, and then we multilpy by the thread pitch. It requires some work because we need to balance the effect in the center vs corner.

A dslr may have 250 pix per mm, so some 125 "pixel pairs" per mm, this may be good enough for this optimization work, or even we may use other (cheaper) cameras with a very small sensor having a higher pixel density, like an old smartphone with its lens removed, this is a nice solution because we see the screen in the other side, and we operate the camera from that screen, or with a regular mouse attached to the usb with an OTG adapter. I had used the mouse to remove vibrations.

I made tests with a Sony Z2 that has the lens broken, sensor is 1/2.3 diagonal having 5248 pix in 6.17mm, so 850pix/mm, so a trash Z2 with the lens broken, glued on a sinar lensboard and with a PC mouse OTG connected... this is actually a high precision instrument for DIY optics!

Pere Casals
8-May-2019, 11:26
Nonsense! This test is unrepeatable and extremely variable. Just how fresh or fatigued one’s see is will skew the results!
Not to mention atmospheric conditions, emulsion, processing, etc.. plus he apparently tested used lenses so previipus handling (has it been dropped), etc. enters into the results.
It is simply stuff and nonsense!

Bob, those tests (Perez-Croell) are of extreme value, if undertanding the limitations of a practical tests.

Of course it is possible that some of the tested samples are flawed lenses or bad tests, and many fetures of lenses are not evaluated, but if Christopher Perez say that the APO Ronar he tested resolved 76lp/mm in the center at f/11 then I know for sure that he discerned lines of the 1.6 Element in a 1:20 magnification shot. I've no doubt.

So perhaps that APO Ronar was better than 76 if he did not adjust focus well... but it's for sure that it is not worse.

Beyond that Arne Croell tested 5 APO Ronar samples: http://www.arnecroell.com/lenstests.pdf

In this case (Croell) Cycles are checked at 50% and 10% Modulation Transfer, so to me there is no doubt about how APO Ronars behave versus aperture in the 45 frame and under the reported test conditions. No doubt, Ronars are not better at f/22 than at f/16, as Ronars are very fine lenses.

We have two independent tests of the 240mm showing better performance at larger apertures, additionally Croell tested a 300mm that was also better at f/16 and three 360mm that were poorer performers but mostly equal at f/16 than at f/22.


In both (pérez-croell) tests (1:20, 6m) atmospheric conditions are irrelevant, in both cases they used TMX 4x5 sheets... both men are very skilled technicians. Well, having 6 Ronars tested, in this case, something can be concluded, isn't it?

Bernice Loui
8-May-2019, 11:33
The troll to be entertained....

NO monorail view camera can equal a proper optical table to be set up for proper optics testing as it begins with a device like this:
https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=5930

Then there are precision optical fix'ens required to do a test set up. This does not include the MTF testing instrumentation.

As for "counting turns of threads" to determine shim thickness, you're dealing in fractions of 0.001" or 0.01mm which is easily the slop in any threaded system. This does not account for change in metal dimensions due to compression from tightening threaded parts or changes in parts due to changes in temperatures. Know the world of optical stuff works in wavelenght of light and very precise mechanical dimensions. Optical designs can be done to accomodate mechanical and optical tolerances, to achieve a real world-physical lens that can approach the calculated-therotical design all optical and mechanical aspects of the design must be accounted for, then tested with extreme precision and experienced expertise.

-What are YOUR qualifications to do any of this?

Outback shack methods and ideology can never equal precision designed and made for the needs of optical testing coupled with experienced optical expertise.

Test using film is a combination of lens & image source & film & processing & visual judgement result.. NOT the actual performance of the specific lens under test.

As for APO Ronar not being optimized for f22, Contact Rodenstock direct to discuss this with one of their technical support engineers.



Bernice

Drew Wiley
8-May-2019, 11:35
Bernice - any statistical sample variation between lenses due to alleged quality control issues would be pretty low on my list of things that can be potentially misleading in a situation like this one. A lot of testing methodology is itself suspect. I always laugh when such an such a person's data base is considered trustworthy, yet they probably established it in the first place with either film sagging unevenly in a conventional holder or with fatigued eyes. Percival Lowell was convinced he saw canals on Mars. Well, that's what fatigued eyes do. And, as you just stated, equating monorail cameras to true scientific optical benches is sheer bunk, no matter how they might have been once marketed. But gotta run and do some scouting with my own Norma.

Pere Casals
8-May-2019, 11:48
As for APO Ronar not being optimized for f22, Contact Rodenstock direct to discuss this with one of their technical support engineers.


Arne Croell, he is a member IIRC, he tested 5 APO Ronar samples, at 50% and 10% MTF, in the center/mid/corner, for tangential and for sagital. This is enough for me.

http://www.arnecroell.com/lenstests.pdf

It has to be noted that even in the case that a lens is optimized for best performance possible at f/22 still the lens may still perform better at f/16 than at f/22. This has been a source of controversy...

Perhaps this is the case...


________________


Regarding camera alignment, it should be pointed that a 240mm at (1:20) 6m far and f/16 has 2m DOF for practical photography. A test requires more accuracy.


191110

I guess that both Pérez and Croell could be able to focus/align well enough...


I think it's quite easy to see when focus and alignment is influential in a test, at 6m f/16 it isn't at all, because in this situation the CoC provocated by aligment errors of a good LF camera are lower than the lens performance, also we correct very well the alignment with easy procedures, we can make the calculations if you want:

191115

By imposing a 0.007mm CoC we would have 130mm DOF. By focusing wide open, then aligning the camera to have optimal corners and then stopping there is room to make a perfect test in what the alignment won't be influential.

It is not necessary to adjust the camera controls, just by checking focus (wide open) in the corners we can align the optical axis to be perpendicular to the target, based in the Scheimflug principle, for testing it is not necessary that the camera is extremly well aligned, if we align the optical axis for the film plane then the test is good enough.

With 130mm test DOF at 6m we need an accurate job in the test, but those 130mm allows room enough to make a perfect test.

I made several personal tests and I found that aligment is no problem, also we may focus again for each spot of the circle, making additional shots, to find if the result changes or not.

Today, for personal tests, best if focusing again for each spot (Center-Mid-Corner), using a DSLR body in the back of the LF camera, this removes the field curvature and alignment factor. The lens field curvature of modern lenses may be irrelevant in practical photography, but it's good to remove that factor from a test.

Drew Wiley
9-May-2019, 12:37
Pere - why are you deferring to very superficial web banks of lens data when Rodenstock has already published resolution graphs that factor in tangential as well as axial performance figures as well as how this behaves at different spheres of the image circle? What good is a mere axis reading in view camera work? I have seen Sinar components specially configured for high resolution diagnostic work. But a lot goes into that. All the tolerances have to be tightened to the point it would make them unrealistic for ordinary photography. Then you'd have to precisely collimate the film and lens nodal plane using a series of front surface mirrors etc (I won't go into detail), and finally you'd need some kind of very dimensionally stable beam mount (I know how to make em). Then, of course, you'd either have a very precise vacuum holder or a means to measure the aerial image at multiple positions. And having looked at some of those Perez etc results, I too am convinced that they're often worth LESS than nothing because they're so misleading. The characteristics of Apo Ronars are pretty well understood. For your own objective of just determining shim usage, adapting a DLSR to the rear position in a carefully leveled Norma would probably be sufficient in a practical sense, then comparing the result at different distances from near to infinity. But quantifying that sort of thing is a different story. And it's an utter myth that all view lenses are optimized at f/22. It all depends. A lot of us like to stop down 4x5 work to f/22 or f/32 not only for sake of depth of field, but also to minimize the effect of the film plane inevitably being a little off in the holder. With graphics lenses, the question includes the ability to precisely apochromatically align dots in all three or four color separations clear out to the corners of the recommended field of usage. A copy camera routinely used flat vacuum targets for sake of precision at that end. In that particular industry, f/22 was a convention related to their own kind of application. Ordinary photographic applications are rarely that nitpicky. And as per actual optical quality, as an example, my own Apo Nikkor barrel lenses are superbly sharp from f/11 down - more sharp and better apo corrected than any of the high-reputation regular view camera lenses I own. But all of this is overkill talk. Sometimes convenience is more important, as well as the specific "character"of image rendering you are seeking. I think you're making a mountain out of a mole hill. Just go out and enjoy your lens.

Pere Casals
9-May-2019, 13:57
Pere - why are you deferring to very superficial web banks of lens data when Rodenstock has already published resolution graphs....

You know, there was a sample to sample variation in the production run. Manufacturer graphs show average MTF at low cycles because in that case they can provide consistent information, but peak performance at extintion were never guaranted. They had some product segmentation, the same SCH product could be sold under 4 brands: Linhof, Sinar, Schneider and Calumet, prices were different in each segment, all lenses completely capable but perhaps not the same QC requirements for the Technika or the Calumet stamps, we can guess that from discounts :).




All the tolerances have to be tightened to the point it would make them unrealistic for ordinary photography. Then you'd have to precisely collimate the film and lens nodal plane using a series of front surface mirrors etc (I won't go into detail)....

Drew, even me I can calculate the accurate MTF graph and the extintion cycles with high precision, the "collimation" (aligment in this case) it's very easy to do, you don't require any sort of sofisticated equipment to make very accurate measurements, you only need the knowledge and refined procedures.



And having looked at some of those Perez etc results, I too am convinced that they're often worth LESS than nothing because they're so misleading.

I simply don't agree, it is a test with limitations and some flaws, just read the disclaimer at the bottom of the document, but if understanding the limitations then that test is really a great source of information, see this example:

This is a Symmar 150 convertible:
f/11 42 48 38
f/16 42 48 42
f/22 48 64 42

This is the 265 conversion of the same lens:
f/16 48 48 23
f/22 48 48 33
f/32 42 42 38

This is the 265 conversion with a #15 yellow filter:
f/16 48 48 21
f/22 48 48 32
f/32 30 38 33

This shows a pretty nice consistence in the measurements, it also shows what happens with the conversion in the corners, and it tells that a filter (removing possible chromatic aberration) does not improve the result, pointing that the flaws of the conversion come from the spheric aberration. And the conversion is not bad at all ! Probably the values in blue are inconsistent, because the the filter addition has only an effect at f/32, but if you look at the "general picture" this great information.

Very interesting, isn't it?

It is possible that some Pérez measurements were flawed and the lens was better, but never worse than what he says, because to say a number he had to see a certain Group/Element. It has to be pointed that Mr Perez made his career in a a prestigious instrumentation company (Tektronix, IIRC), we may guess he knows what accuracy and methodology are.



The characteristics of Apo Ronars are pretty well understood.

Yes, a narrow angle around 48 degrees only, 4 elements only, first-class for all formats whose long side is not larger than half the focal length. Light, compact, affordable and superior in sharpness and similar coverage angle to tele lenses, but requires more bellows than teles....



A lot of us like to stop down 4x5 work to f/22 or f/32

I shooting a lot f/32 we don't need expensive lenses, diffraction limit is 50, so in practice around 45.



Ordinary photographic applications are rarely that nitpicky.

True... in 3D scenes with near subjects the circle of confusion grows easily in the DOF. A distant shot may exploit better the lens performance, another thing is needing that performance overkill or not...



Apo Nikkor barrel lenses are superbly sharp from f/11 down

It is easy making a good lens with with a low angle of coverage (37º to 46º). If the corrections have cover 70º or 100º then we require more elements and a refined design.

Bob Salomon
9-May-2019, 14:10
Pere - why are you deferring to very superficial web banks of lens data when Rodenstock has already published resolution graphs that factor in tangential as well as axial performance figures as well as how this behaves at different spheres of the image circle? What good is a mere axis reading in view camera work? I have seen Sinar components specially configured for high resolution diagnostic work. But a lot goes into that. All the tolerances have to be tightened to the point it would make them unrealistic for ordinary photography. Then you'd have to precisely collimate the film and lens nodal plane using a series of front surface mirrors etc (I won't go into detail), and finally you'd need some kind of very dimensionally stable beam mount (I know how to make em). Then, of course, you'd either have a very precise vacuum holder or a means to measure the aerial image at multiple positions. And having looked at some of those Perez etc results, I too am convinced that they're often worth LESS than nothing because they're so misleading. The characteristics of Apo Ronars are pretty well understood. For your own objective of just determining shim usage, adapting a DLSR to the rear position in a carefully leveled Norma would probably be sufficient in a practical sense, then comparing the result at different distances from near to infinity. But quantifying that sort of thing is a different story. And it's an utter myth that all view lenses are optimized at f/22. It all depends. A lot of us like to stop down 4x5 work to f/22 or f/32 not only for sake of depth of field, but also to minimize the effect of the film plane inevitably being a little off in the holder. With graphics lenses, the question includes the ability to precisely apochromatically align dots in all three or four color separations clear out to the corners of the recommended field of usage. A copy camera routinely used flat vacuum targets for sake of precision at that end. In that particular industry, f/22 was a convention related to their own kind of application. Ordinary photographic applications are rarely that nitpicky. And as per actual optical quality, as an example, my own Apo Nikkor barrel lenses are superbly sharp from f/11 down - more sharp and better apo corrected than any of the high-reputation regular view camera lenses I own. But all of this is overkill talk. Sometimes convenience is more important, as well as the specific "character"of image rendering you are seeking. I think you're making a mountain out of a mole hill. Just go out and enjoy your lens.

Right on!!!

Pere Casals
9-May-2019, 14:32
!!!

Drew Wiley
9-May-2019, 15:55
Pere, ordinarily if an Artar or Apo-Ronar was FACTORY fitted in a conventional shutter like a Copal or Comupur 3 it was intended for general-purpose shooting and will probably be excellent at infinity as is. If it is in barrel only and meant for something like a Compur electronic shutter, then you should just ask Rodenstock or Schneider how to proceed. In all such cases angle of coverage figures can be misleading. No, you won't get as big an angle of coverage as with a plasmat of the same focal length. But the published specs tend to be very conservative because they had repro usage in mind; and besides, in such applications the image circle often became significantly bigger due to close usage, possibly right up to 1:1 magnification. And although a lot of process lenses are on the used market rather affordably at the moment, that certainly doesn't mean they were cheaper than plasmats when new. And as far as Mr Perez goes, why should I trust anyone who does not describe his methodology up front? I'm sure not gonna guess at what he might or might not have done. What I do know, is that, having used certain lenses he lists and knowing their performance quite well, some of his results just don't make sense. Others have noted the same thing. And I'm a bit skeptical about the notion of there being significant lens to lens variation with modern expensive lenses from the "big four" manufacturers. That might have been true at one time, but there are no reasons to suspect it now. The symmetrical elements of Dagors had to be hand tuned; but no dagors have been made for for large format for quite awhile except for a rare Schneider intended for ULF use. Who knows what vintage of lenses Perez tested tended to be. Therefore I place that kind of information in the same category as Ken Rockwell - take it with a grain of salt.

Bob Salomon
9-May-2019, 16:13
Most of the lenses, if not all, tested by Perez were not new!

CreationBear
9-May-2019, 17:56
Pere, ordinarily if an Artar or Apo-Ronar was FACTORY fitted in a conventional shutter like a Copal or Comupur 3 it was intended for general-purpose shooting and will probably be excellent at infinity as is.

OP, here....[waves hands over head]:)--Drew actually raises a question I had earlier: is there any way to tell if an in-shutter lens came from the factory that way (versus having been retrofitted into a modern shutter by some owner down the line?) Coincidently, one of the larger lens vendors currently has an Apo-Ronar 360/9 that's described being factory installed in a Copal 3--whence this confidence?

And, finally, if for some reason I decided that the Apo-Ronar I've bought needs a different set of shims, what resources are available to rectify the issue? Would Rodenstock still have shims on-hand, or would I be looking at a custom-machining job?

Bob Salomon
9-May-2019, 18:24
OP, here....[waves hands over head]:)--Drew actually raises a question I had earlier: is there any way to tell if an in-shutter lens came from the factory that way (versus having been retrofitted into a modern shutter by some owner down the line?) Coincidently, one of the larger lens vendors currently has an Apo-Ronar 360/9 that's described being factory installed in a Copal 3--whence this confidence?

And, finally, if for some reason I decided that the Apo-Ronar I've bought needs a different set of shims, what resources are available to rectify the issue? Would Rodenstock still have shims on-hand, or would I be looking at a custom-machining job?

Rodenstock has shims but they come in different thicknesses. If you really want the lens to be adjusted to factory specs then you would need to send it to them.

Contact Dieter Wenzel here:

http://www.rodenstock-photo.com/service/?lang=en

Pere Casals
9-May-2019, 23:18
Pere, ordinarily if an Artar or Apo-Ronar was FACTORY fitted in a conventional shutter like a Copal or Comupur 3 it was intended for general-purpose shooting and will probably be excellent at infinity as is.

Let me explain how IMHO a bare amateur may tuneup perfectly an Apo-Ronar like if it was "FACTORY fitted" for distant subjects:

191170
https://www.ebay.es/itm/WF30X-30mm-Biologic-Microscope-Eyepiece-Ocular-for-Lab-Metallic-Lens/401717880713?hash=item5d88406789:g:hYkAAOSwtM9cdq~W

$25, free shipping... x30


You place that in the camera back, you may use a lens board for it substituting the GG+Graflock of the monorail, with the APO Ronar in the front: ready for action. Then print a target (http://www.takinami.com/yoshihiko/photo/lens_test/USAF.pdf) and place it far, some 8m to 15m is excellent for a low quality print of the target in the link, depending on the focal and what the printer/paper was able (that pdf has group 7 !!!).

Then unscreew the Ronar's front cell in half turns and focus again, repeat while the thing improves. You are done. Now screew the lens by counting the tours, your shim is the tours multiplied by the thread pitch. You can also repeat for the mid/corner to balance the tuneup.

If our pocket is in shape ($200) we may buy a better ocular, not necessary, but nice:

191171

Or used/good/cheap ($35) microscope/telescope oculars, a x50 would be great for MF and 35mm lenses.


____________________________________________


With that simple gear we may also rate easily any LF lens, without exposing film or making dslr shots: No ALIGNMENT problems, you focus again for each spot in the circle, you navigate in the circle with rise/shift and focus again. Of course you multiply the lp/mm reading (tables here: https://en.wikipedia.org/wiki/1951_USAF_resolution_test_chart) by the magnification, so the single thing you have to calculate accurately is the magification, which is pretty easy, just placing again the GG and using a cheap digital caliper on it....


This kind of measurement is said "in the air", it's the perfect way to compare lenses because we remove the film flatness miss, film resolving power influence, alignments, etc, etc, etc..


This is a simple way in what a bare amateur may make very precise optical ratings at extintion.

Those ratings do not include the filed curvature, wich is irrelevant, but if wanting to measure the field curvature an amateur also has simple ways to do it: You substitute the GG by a clear class, it can be anti-reflective True-Vue, then you align the camera (max aperture) until all corners are perfectly sharp (we need a flat wall) seen with the ocular, then the center may not be in perfect focus, by measuring the camera (tripod) displacement for a perfect center focus we measured the flatness miss, or by measuring the additional bellows draw we have the reading for the film plane so we can calculate the impact in the field.

Substituting the GG by a flat clear glass is also a way to explore the circle with the ocular, instead removing the graflock+GG and replacing it with lensboard+ocular. The naked ocular works better than the GG+loupe, because the GG grain degradates the image, so with GG we cannot see all performance that the film will see.

________

Measurements in the air are perfect for rating glass, but making practical tests by shooting film (like Pérez-Croell) also has sense because we see the practical effect on film after some degradation factors.

________


Of course modern LF lenses also have a remarkable sample to sample variation !!!! which is lower in the last models but it's there. Another thing is when such variability has a practical impact. At f/32 no impact...

If usually shooting at f/22 and beyond we won't see the sample to sample variation because diffraction masks it, at f/32 even we won't see a difference of a 1950s lens vs a 2000s one, coating apart.

Bob Salomon
10-May-2019, 04:51
Suit yourself, you can do it right or your way.

Pere Casals
10-May-2019, 05:07
Suit yourself, you can do it right or your way.

Or... in my way and also absolutely right.

Bob, I'm not alone, many ULF shooters have unscreewed some tours the front cells of process lenses before, with perfect results. Just pointing that with a bare ocular one may make a lab grade optimization. What is not seen with 30x "in the air" it won't be seen in a print.

Of course sending a process lens to the manufacturer is always a good choice, but in many situations this is not possible or feasible. It is nice if Rodenstock still services that.

Bob Salomon
10-May-2019, 05:29
Or... in my way and also absolutely right.

Bob, I'm not alone, many ULF shooters have unscreewed some tours the front cells of process lenses before, with perfect results. Just pointing that with a bare ocular one may make a lab grade optimization. What is not seen with 30x "in the air" it won't be seen in a print.

Of course sending a process lens to the manufacturer is always a good choice, but in many situations this is not possible or feasible. It is nice if Rodenstock still services that.

Whatever floats your boat!

CreationBear
10-May-2019, 05:48
Rodenstock has shims

Excellent, thanks!:)

Tin Can
10-May-2019, 05:50
Custom Round Steel Shims (https://www.phoenixspecialty.com/products/shims?st-t=google-CustomShim&vt-k=custom%20shims&vt-mt=google-e&gclid=EAIaIQobChMIy7PVkfyQ4gIVArjACh2OsQnBEAAYASAAEgJgEvD_BwE)

Sets could be made for our common shutters,

At my last job, the custom division often made 0.001 to 0.005" steel or brass shims for me to shim diesel engine cylinder height to out of spec dimensions.

We made the liner height out of spec on purpose to test our product on Dynamometers. We used USA Made Power Test (https://youtu.be/yCTefZmrQJI).

Then we measured cylinder head movement while running at full power/load with tiny expensive gap sensors. Usually took 3 weeks with 2 shifts to complete a 5 minute test. A short test as the gap sensors were destroyed in less time than that.

My point is, manufacturers do test with many devices unavailable to normal people.

Pere Casals
10-May-2019, 06:33
My point is, manufacturers do test with many devices unavailable to normal people.

Of course...

This is a machine making automatic MTF graphs for smartphone lenses, 600lp/mm, 1% error on axis, a single machine measures 10 million lenses per year. And this is only a QC machine for production, but it determines what optimal tilt some lenses do require on sensor to be acceptable !

https://www.youtube.com/watch?v=VKYEIxTVCGE

But many people inflate the car's tyres... some may prefer that a workshop does it... Personal choices.

Tin Can
10-May-2019, 06:40
I visually check my tires before every drive when approaching the thing.

Then I check pressure on digital readouts after starting the engine.

Then I worry less...

I always carry a good air pump and tools to fix punctures.

I hate flats.





Of course...

This is a machine making automatic MTF graphs for smartphone lenses, 600lp/mm, 1% error on axis, a single machine measures 10 million lenses per year. And this is only a QC machine for production...

https://www.youtube.com/watch?v=VKYEIxTVCGE

But many we inflate the car's tyres... some may prefer that a workshop does it... Personal choices.

Oren Grad
10-May-2019, 09:18
OP, here....[waves hands over head]:)--Drew actually raises a question I had earlier: is there any way to tell if an in-shutter lens came from the factory that way (versus having been retrofitted into a modern shutter by some owner down the line?)

The strongest evidence would be if the lens is supplied with original box with matching serial number, labeling and documentation consistent with the mounting. Even then, a defective shutter could have been swapped for a replacement of identical type at some point, with risk that shims were lost.

One flag is a mismatch between the serial number / production date of the lens and the vintage of the shutter. Some of those will be obvious - for example, anything that's plainly really old put into a late-model all-black Copal. But often that test will not be conclusive.

Bob Salomon
10-May-2019, 09:47
The strongest evidence would be if the lens is supplied with original box with matching serial number, labeling and documentation consistent with the mounting. Even then, a defective shutter could have been swapped for a replacement of identical type at some point, with risk that shims were lost.

One flag is a mismatch between the serial number / production date of the lens and the vintage of the shutter. Some of those will be obvious - for example, anything that's plainly really old put into a late-model all-black Copal. But often that test will not be conclusive.

The most obvious would be aperture scales that have a different largest aperture then the lens or no scales.

Rodenstock does not put serial number on the box. Just the lens description and the factory catalog number. We opened each box before shipping and put the serial number on the dealer invoice and packing list.

Drew Wiley
10-May-2019, 10:40
Custom shims are easy enough for any serious machine shop in this day and age. Heck, ten minutes from my house is where the correction lenses for the Hubble telescope were made! Or probably some outfit like SK Grimes could do it for you. It's just a question of price and fuss. If it costs more than the shutter itself, that's a pretty stiff penalty for someone seeking a high quality lens at used relatively bargain pricing. I don't think making an analogy to production standards of little BB cell phone lens quality control is quite the same thing because those have extremely little focal length with great depth of field, and so-so final image quality expectations, which is stating it mildly. But Pere's do-it-yourself methodology is probably workable in this case if the lens comes out unharmed. Maybe not ideal; but people can't always afford ideal. I don't know about others, but I almost never take 8x10 pictures wider open than f/22, and more often around f/45. When I use a 360 lens with 4x5 it tends to be around f/22 or f/32, but sometimes f/16, and I even use the same focal length sometimes for 6x9 roll film with excellent results. I admit I don't own any Apo Ronars myself, but have seen a lot of work done by them as well as by Red Dot Artars, and have tested several of my own Apo-Nikkors on the 8X10 camera, though I tend to use them more on enlargers since I have excellent more compact lenses already in shutter in that focal length.

CreationBear
10-May-2019, 11:59
If it costs more than the shutter itself, that's a pretty stiff penalty for someone seeking a high quality lens at used relatively bargain pricing.

Great information, gentlemen, thanks! I was definitely aware of "sample variation" from shooting other, smaller, formats, but it seems as if discretion should be the better part of valour here. (Of course, there's "exposure," and then there's the Fuji A and the Schneider 350/11, where ROI issues start to rear their ugly heads...:))

Drew Wiley
10-May-2019, 12:38
The Fuji 360 A and 355 G-Claron are very similar optically. But the smaller no.1 shutter of the Fuji is a distinct advantage on smaller field cameras due to less weight and potential vibration on the front standard. It's also generally mutlicoated, though the single coating of G-Clarons had never given me a flare issue, and just a tiny bit less contrast. Color rendering is very similar. Both have big image circles, though I wouldn't recommend the Fuji for any format larger than 8x10 with significant tilts due to potential mechanical vignetting of the smaller shutter. And it takes a long time for a big bundle of the necessary dollar bills to pass through that little shutter!

Pere Casals
10-May-2019, 13:41
But Pere's do-it-yourself methodology is probably workable in this case if the lens comes out unharmed. Maybe not ideal; but people can't always afford ideal.

Drew, thanks but I cannot be credited for inventing this method, I learned all here !! For sure it would work very well, because with the x30 ocular we see the image like if it was in a x30 print, so sure we may clearly see the good shimming, but Bob's advice is also wise, nobody better than the manufacturer to adjust gear.

Inspecting the image plane with an ocular is something that it can be recommended also for fun, in special for night landscapes. One realizes what a crazy amount of detail the image plane has, and how damn good are LF lenses.



but I almost never take 8x10 pictures wider open than f/22, and more often around f/45. When I use a 360 lens with 4x5 it tends to be around f/22 or f/32, but sometimes f/16

Beyond technical considerations, this is also in the creative part... A well stopped lens ensures at least a certain amount of image quality that it can be an overkill anyway, as we open we have more risks... but it should also be considered that if stopping a lot then it would be more effective an smaller format for the same image quality, with a shorter focal and shooting with a wider aperture for the same DOF...

Let me point an antique rodenstock brochure:

https://www.pacificrimcamera.com/rl/00817/00817.pdf
https://web.archive.org/web/20171001000000*/https://www.pacificrimcamera.com/rl/00817/00817.pdf

It is an interesting reading, also they recommend f/22 for all except for the imagon(!) and the long ronars (1000 and 1200, f/32).

Bob Salomon
10-May-2019, 13:51
Drew, thanks but I cannot be credited for inventing this method, I learned all here !! For sure it would work very well, because with the x30 ocular we see the image like if it was in a x30 print, so sure we may clearly see the good shimming, but Bob's advice is also wise, nobody better than the manufacturer to adjust gear.

Inspecting the image plane with an ocular is something that it can be recommended also for fun, in special for night landscapes. One realizes what a crazy amount of detail the image plane has, and how damn good are LF lenses.




Beyond technical considerations, this is also in the creative part... A well stopped lens ensures at least a certain amount of image quality that it can be an overkill anyway, as we open we have more risks... but it should also be considered that if stopping a lot then it would be more effective an smaller format for the same image quality, with a shorter focal and shooting with a wider aperture for the same DOF...

Let me point an antique rodenstock brochure:

https://www.pacificrimcamera.com/rl/00817/00817.pdf
https://web.archive.org/web/20171001000000*/https://www.pacificrimcamera.com/rl/00817/00817.pdf

It is an interesting reading, also they recommend f/22 for all except for the imagon(!) and the long ronars (1000 and 1200, f/32).

What you should do is buy a used Rodenstock lens and try to check it your way, make what ever shims you think you need. Then send it to the factory and have them return it to factory spec and see if shims were needed if they are the same as what you found.
Then you could say, if the shims are identical, that your process is accurate to factory spec.

CreationBear
10-May-2019, 13:55
And it takes a long time for a big bundle of the necessary dollar bills to pass through that little shutter!

Ha, I wish this "packable 8x10" fad would pass...though of course, I think the ULF guys might be bidding up the 355 G-Claron as well.:)

One more question as I hijack my own thread: assuming a "man portable" camera, can I conclude that a Copal 1 lens is the limit if you're shooting 120?

Pere Casals
10-May-2019, 15:41
What you should do is buy a used Rodenstock lens and try to check it your way, make what ever shims you think you need. Then send it to the factory and have them return it to factory spec and see if shims were needed if they are the same as what you found.
Then you could say, if the shims are identical, that your process is accurate to factory spec.

Bob, I did something that's equivalent, 4 years ago. I checked the shimming of my Sironar-N 300, it came with a single shim, but as with used lenses one never knows... I used the instructions detailed in a "Internationale Phototechnik" issue, from 1992 or 1993 IIRC. My calibration was 1/8 of tour different than the original shimming, so under 0.1mm, but the real effect was small.

_____


This is, post 9, 1993/8 : https://grossformatfotografie.de/thread/5041-rodenstock-apo-ronar-240-360-485-und-600-brauche-infos/

_____

An interesting effect is that optimal calibration depends a bit on temperature... And I found that we may favor a bit the center or the corner. No doubt that a shimming made by rodenstock would offer an optimal balance, but a DIY procedure can also be very good in practice. Some say that from 0.05mm we may have an small effect...

Tin Can
10-May-2019, 15:46
Didn't Pros used to sample several iterations of the same lens to find the best one? Back in the heyday of Studio LF.

Seems I read that somewhere, here probably .

Pere Casals
10-May-2019, 15:56
Didn't Pros used to sample several iterations of the same lens to find the best one? Back in the heyday of Studio LF.

Seems I read that somewhere, here probably .

Yes, here, wasn't it about Sexton ?

Drew Wiley
10-May-2019, 16:06
Well, that was certainly the case back when Commercial Ektars were sorted out into three levels of quality post-manufacture, in the 60's when my brother sold Linhof and Rollei gear too. And we all know old terms like "Linhof select" or "Sinar Select" in relation to German lenses, some of which were not even well color-corrected at the time. Goerz had a high reputation back then, though some the shutters were not as accurate as later. But Rodenstock and Fuji got a jump on Schneider for awhile, modernizing optical control first, with a high degree of repeatability. At Adolph Gasser in the 70's there were a couple of long-standing salesmen in the view camera dept who really knew their stuff and swore by Fuji quality control as the most reliable brand of all, even though Fuji wasn't at that point as well known among US shooters as well as Schneider and Rodenstock, and was certainly less aggressively marketed in the US. Nikon was a relatively minor player, but by that point outstanding too. This whole question is analogous to the advances being made in pro film quality control over the same decades. You'd buy a box of Ektachrome 64 etc and there were starting filter recommendations stamped on it to balance it to spec. Then, at one point, Fujichrome came out of the gate so precisely coated that there was no longer need to do that, and Kodak followed suit. Now we just take that kind of batch to batch quality control for granted, at least with Kodak and Fuji. Amateur films, however, are rarely stored ideally anyway; so drift in color balance due to heat and aging is just expected, and to a degree engineering into the latitude of the emulsion.

Drew Wiley
10-May-2019, 16:17
Creation Bear - you better not be one of the bears I encounter this summer, or you sure won't be allowed to raid my pack for snacks! I have one of the most "packable" 8x10's ever - the original Phillips, serial number nine (!), and it's quite a bit more solid and vibration-resistant than many view cameras far heavier. Packable is the name of the game for me. Being in the mountains for two weeks or more at a time means that a whole lot of food and gear has to go into that pack besides camera gear. And I ain't young anymore. Haven't quite made up my mind yet for the next trip, but it will probably be an 4X5 Ebony folder. I use my Sinar Norma and Phillips 8x10 more for dayhikes, though I have done many thousands of miles of backpacking with a Sinar back in earlier decades.
I didn't know about petite little Fuji A and C lenses back then, or Nikkor M's, and Schneider G-Clarons, so lugged big clunker plasmats, a 120 Super Angulon, a thick Dagor, etc. Don't regret either the pictures I got or the good workout; but that era is past for me.

CreationBear
10-May-2019, 19:46
Ha, I'm afraid bears are a pretty thick on the ground in these parts, but they're not quite Mensa-level like their Yosemite kin...it would definitely suck to come out at the trailhead and find your quarter panels ripped off.:)

Bernice Loui
11-May-2019, 06:51
0.1mm converts to about 0.004 inch which is HUGE for a lens barrel. Tolerances for lens cell barrels and shutters are typically 0.001 inch range. These numbers are not appreciated unless one does machine work, engineering-technical calculations and similar. For the hobbyist and those with no real world experience doing stuff like this these numbers and their physical dimensions are difficult to relate to or appreciate.

"Oh, I've ripped apart a Philippe Patek watch, put it all back together but for some reasons it is no longer time accurate, it does work, so good enough for me.

As for easy for any "good" machine shop to make shims. Shims less than 0.01 inch thick or 0.254mm are not going to be made on a lathe or similar machine tool process due to the limits of shearing material from bar stock. Parts like this will be made by etched metal process where a mask is applied to a sheet of metal specified fo the part, then etched until the part is cleared. They can also be made by laser cutting or similar. These are not common machine shop machines.

LF has become more of a Foto hobbyist or speciality artist endeavor today due what has happened to the image production universe. There are not similarities to the custom car world or similar and the LF camera world. Not a bad thing if this keeps LF image making alive and well. What can and does happen, the difference between technical excellence and individual projections of what they believe is excellent can become accepted as a standard of excellence disconnected from true technical excellence based on Science, Engineering, and the way Nature is.


Bernice

Pere Casals
11-May-2019, 08:39
I'd like to summarize my findings in lens shimming these years, for the case it can be useful for some, as old&used lenses may have lost their shims.

Why shims ?

Some manufacturers were not usually shimming their lenses, Fuji for example...

Sample to sample variation in LF lenses performance always has been there, over time manufacturers found several ways in the lens assembly to minimize aberrations (sometimes manufacturing engineers were moved to the design department to help designs be easier to manufacture with high quality consistence cand reducing defective products). In some barrels possition for each group can be individually adjusted. Probably a manufacturer would pair the right front and rear cells that do minimize a certain aberration, perhaps another remaning aberration would have a better compensation by adjusting the inter-cell spacing.

Old convertible Symmars (for example) have their cells individually corrected, but in many designs the cells are individually uncorrected, the rear cell compensates a miss of the front in the counter sense, when the amount of the miss reaching the rear cell does depend on the intercell distance then the shim adjusts the amount of the miss, thus the shim allows an adjustment for an optimal compensation.

It is not a trivial compensation, because a shimming may be better for the center and another one for the corner or the mid. Or a different aperture has different optimal shimming. Or a different shimming have better corrections for close or distant subjects...

IMHO the work the shimming makes depends on the design, this is beyond what I may understand... in practice we adjust the shimming for best performance for the particular lens usage.



Problems...

1) We never know if a used lens has the original shims.

2) We may want you optimize a process lens for distant subjects, a common case for ULF people.



Manufacturer's shimming service

This is the best way, an expensive lens (or a lens we love) that has to be used a lot it deserves the manufacturer's care at any cost, if available. As Bob Salomon adviced, on any doubt about the shimming, Rodenstock will make a perfect job, we can guess that they know how to do a perfect job, they have all the shims, they know the design and the assembly procedures, this is a perfect choice, and it is a privilege to still have that service available.



When DIY shimming ?

This is suitable if we like/enjoy DIY, we want to make the effort and/or manufacturer's service is not available, not feasible or not wanting to spend much money. Or simply we may want to check if our shimming is good.



"Internationale Phototechnik" 8/1993.

In this issue it was described a DIY method to optimize G-Claron and APO Ronar repro glass for distant subjects, this was posted by Peter K in this forum: (https://www.largeformatphotography.info/forum/showthread.php?38401-360mm-f6-8-Symmar-S-MC-Copal&p=369572&viewfull=1#post369572)

"Focus the center of your ground-glass on fine structures in the distance like leafless trees or high grasses with a strong loupe at wide open aperture.

Shift the rear frame of your camera to the left and the front frame to the right up to the point you can see the structures get blurry.

Unscrew the front group of the lens circa 2 mm (1 line or 0.08 inch) from the shutter or barrel and look for the fine structures, twigs or leafs. Adjust the distance between the front group and the shutter up to the point the structures are as sharp as possible without any coma and blur. Refocus if necessary during the adjustment.

Place a steel or brass shim of the determined thickness between shutter and front group. If the thickness of the shim is the correct one there is no difference in image quality between the center and the edge of distant subjects. For close-up work remove the shim or place a much thinner one."




Hr. Dieter Wenzel --Dieter.Wenzel-at-linos.de

https://www.largeformatphotography.info/forum/showthread.php?14422-Apo-Ronar-ad-infinitum!

Hr. Dieter Wenzel says that shimming in APO Ronars makes a difference visible in the periphery, wheras the central parts will be equally sharp at infinity and close-up with either adjustment.



P.Casals contribution to the shimming technology :) (sorry for the self-irony, laughing at myself) :)

> To check performance at different spots in the circle, don't use GG+Loupe , but an Ocular/Eyepiece of 20x to 50x without the GG, the GG won't allow to see many lp/mm, using a simple Ocular substitutes shooting film

> Check different off-axis distances at different apertures

> A cheap ocular is only good in the center, or has curvature, it will work but one has to be aware of that, not difficult to understand that...

> Off-axis we have to tilt-swing the ocular to align it in the rays direction.

> Use a resolution target to have a quantitative reference http://www.takinami.com/yoshihiko/photo/lens_test/USAF.pdf

I'm pretty confident that the x30-x50 ocular is a very good way to see what happens with the shimming, a x30 or x50 enlargement in LF is a lot, I'm pretty sure that what we don't see with the ocular it's impossible to see it in a print, and it's beyond lens and film performance... so an easy/fast way to do it.



Field curvature

The inspection with the Ocular won't account for field curvature. My guess is that shimming won't modify much the field curvature, but the aberrations correction, anyway after adjusting a shimming with an ocular it would be great to spend some sheets on a resolution target to see the practical difference.

Tin Can
11-May-2019, 08:51
Good useful summary, Pere.

I recall a recent LFPF post by I think Bernice that allowed that machining was always done on a shutter and never on the lens halves to make up for too much distance.

It may have been Mark talking about Kodak lenses.

The desire was to make switching to a new shutter easier.

Leigh
11-May-2019, 09:57
The thickness of Copal shutters is as follows:
#0 - 20mm
#1 - 20mm
#3 - 28.6mm

The tolerance on all of those is ±0.025mm (0.001 inch), which is pretty tight.

This info from the respective Copal instruction manuals.

- Leigh

Tin Can
11-May-2019, 10:11
Good data Leigh!

Pere Casals
11-May-2019, 10:15
The tolerance on all of those is ±0.025mm (0.001 inch), which is pretty tight.

Leigh, yes, "but anyhow measured shutters show that practical manufacturing tolerances are much smaller than specs" https://www.largeformatphotography.info/shutters.html

Probably 0.05mm won't make much a difference, the APO Ronar adjustment for long distance may be around 2mm (it looks)... We can guess that newer shutters may have a more accurate manufacturing than the older ones.

Bernice Loui
11-May-2019, 10:33
So tell us all Pere...

*How many lenses have you design that have gone into high volume production?

*What kind of optical test instrumentation have you used and experience with?

*What is your real world machine tool experience with making machined parts?

*How many machined parts have you made, what kind of machine tools are you qualified and skilled at using?


Bernice

Bernice Loui
11-May-2019, 10:36
O.001" is typical of optical world tolerances. Any more will NOT yield production consistency. As to older shutters being lesser tolerance, they are NOT. Having measured un-molested Kodak Ilex, Compur and other older shutters they are remarkably accurate and close toleranced. Fact is, optical folks understood well what the mechanical demands were.


Bernice


The thickness of Copal shutters is as follows:
#0 - 20mm
#1 - 20mm
#3 - 28.6mm

The tolerance on all of those is ±0.025mm (0.001 inch), which is pretty tight.

This info from the respective Copal instruction manuals.

- Leigh

Leigh
11-May-2019, 10:49
O.001" is typical of optical world tolerances. Any more will NOT yield production consistency. As to older shutters being lesser tolerance, they are NOT. Having measured un-molested Kodak Ilex, Compur and other older shutters they are remarkably accurate and close toleranced. Fact is, optical folks understood well what the mechanical demands were.Hi Bernice,

We've been making precision components and assemblies for well over a century.
It's surprisingly easy, even using good manual (not computerized) equipment, depending mostly on mind-set.

I personally am a Tool and Die Maker with more than 50 years' experience in that trade, doing precision work.
I commonly work with tolerances less than .001 inch.

- Leigh

Bernice Loui
11-May-2019, 11:21
Have a 13" lathe and RF45 in the garage with needed tooling, cutting tools and measuring tools from Etalon or Mitutoyo or Kafer (German) or Compac (swiss). At some point these machine tools will be upgrades to a Mori Seiki MS850 or HL460 and Deckel FKP_?

For those who are skilled using good tools, 0.001" is not difficult. Problem is, most folks have no idea the physical aspects of what 0.001" is.
Remember what it was like to learn how to run a lathe or mill trying to make any part?

This is not my day job which has more to do with designing stuff by numbers and similar. The machine tool stuff is a "hobby". As for designing optics, cranking out the math and numbers related to a design is only one aspect, actually producing a real world lens is an entirely different ordeal that I'm not in any way qualified to attempt any lens or optics design even if the math-calculations are not difficult to do.

My machine tool and machine parts history is making microwave bits where 0.0001" is common. Taught how to do machine work by the proto type machinist decades ago initially on a Hardinge HLV and Bridgeport mill. He got tired of me designing parts that are not easy to make and not understanding paper designs -vs- how parts are actually made.


Bernice




Hi Bernice,

We've been making precision components and assemblies for well over a century.
It's surprisingly easy, even using good manual (not computerized) equipment, depending mostly on mind-set.

I personally am a Tool and Die Maker with more than 50 years' experience in that trade, doing precision work.
I commonly work with tolerances less than .001 inch.

- Leigh