Process lenses

[lenser]

Am I correct that other than the lack of a shutter and the fact that they are flat field, process lenses from a newspaper or print shop style copy camera will work just fine for traditional large format shooting? Please share your experience and knowledge of any draw backs.

[desertrat]

I have a couple of process lenses, but am hardly an expert. Many use process lenses when they want a longer than normal focal length for their format. Most process lenses have a fairly narrow field of view, so they may not cover the format at a "normal" focal length. A bit longer than normal is usually OK. There are some "wide field" process lenses out there, but I have no experience with those.

[Ken Lee]

You may find this short article helpful: Process Lenses (http://www.kennethleegallery.com/html/lenses/#Process)

These (http://www.kennethleegallery.com/html/artar/) photos were made with a 10 3/4 inch Apochromat Artar.
These (http://www.kennethleegallery.com/html/aponikkor150/index.php) photos were made with a 150mm APO Nikkor.
These (http://www.kennethleegallery.com/html/aponikkor240/index.php) photos were made with a 240mm APO Nikkor.
These (http://www.kennethleegallery.com/html/aponikkor610/index.php) photos were made with a 610mm APO Nikkor and here (http://www.kennethleegallery.com/html/aponikkor610/Nikkor610Test.php) is a resolution test of the 610mm APO Nikkor at infinity distance.

[Vaughn]

I use several of them (8x10 and 11x14).

Their main lack is the lack of a shutter...which for using in the redwoods is not a problem (all exposures are >1 second). Some may not be threaded for filters -- I do not have any handy to check. Coverage may be less relative to 'regular' lenses of the same focal length -- their coverage specs are usually stated at 1:1 rather than at infinity, so one needs to be aware of that.

One advantage is that they weigh less than a shuttered version.

Over-all, I have am quite pleased with the images taken with process lenses. I have particularily pleased with the performance of my two Red Dot Artars (19" and 24"). I believe the red dot signifies that they are optimized for less than 1:1 use (ie landscapes). I also have a Graphic Raptar 210mm that covers 8x10 -- small and sharp. It does not see as much use since I got a Fuji W 250/6.7 (shuttered).

[Michael Jones]

Tim:

As a general rule, yes. Your run of the mill Artars (red dot or not), Ronars, Browns, etc are standard fare for many 8x10 and up format users. I have at least three I use regularly with no issues whatsoever; I have had Steve & Adam at SK Grimes remount into shutter, but all you really need is a lens cap as your "shutter." Most barrel mounts have multi leaf apertures which many portrait photographers prefer over the more modern 5 leaf version in most shutters. These lenses tend to have slightly less coverage than a similar length plasmat, but the coverage tends to enlarge as they are stopped down.

All that said, be careful with some wide field precess lenses; any tended to be used for close-up work and do not behave well if used otherwise. I had a 240 Wide Field G Claron. Aside from being the coolest looking lens with a big hemispherical rear element, it was worthless for landscape or portrait use.

Take a look at the posts in the ULF & lens sub-forums for many threads on process lenses.

Mike

[Jim Fitzgerald]

I use process lenses all the time. My go to lens on my 8x20 is a 360mm Rodenstock Gerogon process lens. 90% of my 8x20 work is shot with this lens. 77mm filter threads which is great!

[Mark Sawyer]

Am I correct that other than the lack of a shutter and the fact that they are flat field...

Nearly all lenses of the past century are flat field, and many process lenses will screw into a shutter without modification other than perhaps correcting the aperture scale. I've used process lenses quite a bit, especially around 1:1 (where they're optimized) with no complaints. All I've tried at distance (admittedly not very many) have done well too.

[John Kasaian]

I have found a 240mm G Claron, 14" APO & 19" Red Dot Artars useful additions to my collection. Additionally a 229mm Process Paragon rides on the snout of the Elwood Enlarger. As Michael Jones mentioned above, not all process lenses are created equal, but the useful ones for LF photography are well documented both here and elsewhere.
I keep an empty Copal at the ready to shelter any homeless, shutterless G Claron that might come my way.

[Paul Kinzer]

I am only dipping my toes into the possibility of ULF, but after looking around a bit about lenses (okay, more than a bit!), I bought a 19-inch Apochromat Artar on eBay, for $45*! It has not even arrived yet, but when I saw the ad, it seemed to beg me to go for it. I don't really believe in omens, but if I did, this would tell me to do more than dip in my toes. This lens has a big image circle; folks use it for 12x20! (Uh oh, those seem to be red dot Artars; this one is not. Does that matter?)

This post has gotten me to wonder: is the 19-inch Apochromat Artar one of the lenses that can screw directly into a shutter? The serial number on the one I bought seems to suggest it was made in 1926 or after.

*The ad said his is a 'parts' lens because there is a bit of fungus. But the buy-it-now price was $45, so I figured I'd better jump at the chance. I've bought several fungused lenses, and in about half, the fungus -- if I could get at it -- just wiped right off. And on the rest, the fungus just doesn't seem to have an effect on images. I like a challenge, especially a cheap one.

[Daniel Unkefer]

As I've accumulated a nearly full inventory of the Sinar Norma system over 35 years (about almost everything they ever made), I also have a nearly complete set of vintage Rodenstock Apo Ronars. I have them from 150mm to 890mm in barrel mount. I am lacking the REALLY long ones, due to cost and availability. The Sinar mechanical shutter is a good option for faster speeds and operation.

These are great lenses. I use them for from 6x6cm to 8x10".

[Mark Sawyer]

(Uh oh, those seem to be red dot Artars; this one is not. Does that matter?)

The red dot indicates it's coated. Yours probably won't be, and as its dialyte design has eight air-glass surfaces, expect a bit of flare and lower contrast.

[Michael Jones]

Nearly all ... and many process lenses will screw into a shutter without modification other than perhaps correcting the aperture scale...

That has not been my experience except with G-Clarons. While I have been told some Doctor Optic and Kowas are direct screw in to modern Copal shutters (and these are scare lenses), and assuming we are not talking Packard shutters or Sinar DB lens mounts, a machinist will need to both mount the lens in a modern shutter and re-calibrate the aperture. Even the few direct mounts will require the aperture to be re-calibrated (and its not as easy to be accurate).

Mike

[Paul Kinzer]

The red dot indicates it's coated. Yours probably won't be, and as its dialyte design has eight air-glass surfaces, expect a bit of flare and lower contrast.

Thanks, Mark. That's what I thought from some of my reading, but someone else wrote something different that made me wonder. I'm excited! Even if I never get into ULF, it's another lens for 5x7, (and smaller formats) and fills a gap at the long end. And at the price, I can feel justified in knowing I can sell it on if it is not something I decide to keep.

[Dan Fromm]

Tim, your profile says you shoot 4x5 and 8x10. There's no reason to replace any of your 4x5 lenses with a process lens. If you want to extend your reach, well, a long process lens is a good way to do it if you can get the extension needed. Shouldn't be a problem with your Cambo, I have a 900/10 Apo Saphir for mine.

I shoot process lenses up to very long indeed on, mainly, 2x3. I've been happy with most of the ones I've tried out and, of course, with the ones I regard as good enough to use.

FWIW, I'd avoid uncoated dialytes, also Wray Apo-Process Lustrars (all dialytes, I think). Its hard to make a mistake with, in alphabetical order, coated Apo-Artars, dialyte type Apo-Nikkors, Apo-Ronars and Repro-Clarons. Not all Apo-Ronars are equally desirable. My former 600/9 Klimsch Apo-Ronar is a case in point. Mounted in brass, weighed 3.3 kg. I never tried it out, replaced it with a much lighter 610/9 Apo-Nikkor (1.45 kg).

Shutters will indeed be a problem for long process lenses. The longest G-Claron is the 355, whose cells should go into a Compur #3. Apo-Nikkors' cells don't, in general, go directly into shutters. Some Apo-Ronars' cells do, others don't. My 150/9's cells don't fit anything. I'm a partisan of Apo-Saphirs 'cos I got mine for very good prices but if you want to shoot wider than f/16 Apo-Nikkors are better. From f/16 down, it doesn't matter. Boyer claims that Apo-Saphirs' cells (up to and including 480 mm) are direct fits in standard shutters but they lie; none of mine fit standard shutters. Similarly, not all Repro-Clarons' cells will go into standard shutters. I have a small mistake of a 210 ...

I've never looked into using a Packard shutter behind a 4x5 Cambo's front shutter. Doesn't look easy. But adapters to hang a Packard in front of a lens shouldn't be impossibly expensive. Similarly for adapters to hang a Compound or Ilex #5 (both scarce, the Compound probably more expensive) in front a shutter aren't out of sight. Some years back I had Grimes make one to hang a Compound 5 (industrial shutter, no diaphragm, so not too dear) in front of my big Apo-Saphir.

For what I do front mounting (cup shaped adapter that screws into the front of a shutter and accepts a lens) is a good solution for longer lenses. Mechanical vignetting can be a problem with this approach, but think about using a relatively inexpensive Ilex #3 ...

[Mark Sawyer]

That has not been my experience except with G-Clarons. While I have been told some Doctor Optic and Kowas are direct screw in to modern Copal shutters (and these are scare lenses), and assuming we are not talking Packard shutters or Sinar DB lens mounts, a machinist will need to both mount the lens in a modern shutter and re-calibrate the aperture. Even the few direct mounts will require the aperture to be re-calibrated (and its not as easy to be accurate).

Mike

The Apo-Ronars fit into shutters, as do many of the Wollensak and Ilexes. Here's a long list of process lenses noting which do and don't fit shutters. (BTW, I have a 25-inch Wollensak process lens factory mounted in a shutter which this list says doesn't go in a shutter.) It also notes the 19-inch Red Dot Artar goes in a shutter, so there's at least some hope for Paul Kinzer's pre-Red Dot.

http://www.allenrumme.com/lensdb/Process.html

Regarding the accuracy of the aperture scale, simple measurements are very likely to be more accurate and consistent than the shutter speeds of even modern shutters.

But if one is going to use process or other barrel lenses, perhaps an in-camera shutter like the Sinar or Mentor cameras have is a better solution.

[Michael Jones]

I can only speak from my experiences, and notwithstanding factory mounted process lenses, let me assure you fitting a barrel lens into a shutter and directly screwing its elements into a shutter are very different. I have never seen a barrel mounted 19" Artar that will directly screw into an Ilex 4 (its "usual" factory mount), let alone a Copal 3.

And lenses that list states do not fit into a shutter is not 100% accurate. I have a 42" App Ronar in an Ilex 5 and an 18" Wide Field Ektar in a Copal 3. SK Grimes can work wonders.

Take a look at this page:

http://www.skgrimes.com/lens-mounting/table-of-lenses-fitted-to-shutters

I agree a Sinar shutter or Packard shutter make using a barrel mounted lens much simpler.

Mike

[Dan Fromm]

The Apo-Ronars fit into shutters

My little 150/9 Apo-Ronar regrets to inform you that you are mistaken.

[Drew Wiley]

I have a number of process lenses, mostly Apo Nikkors, and mostly obtained free by cannibalizing retired process cameras. They are optically SUPERB for both enlarger and camera use, with ample image circles. But I haven't mounted any in shutter yet, so have to resort to the lens cap method with long exposures. My ordinary view camera lenses tend to be more compact anyway.

[David Lindquist]

I can only speak from my experiences, and notwithstanding factory mounted process lenses, let me assure you fitting a barrel lens into a shutter and directly screwing its elements into a shutter are very different. I have never seen a barrel mounted 19" Artar that will directly screw into an Ilex 4 (its "usual" factory mount), let alone a Copal 3.

And lenses that list states do not fit into a shutter is not 100% accurate. I have a 42" App Ronar in an Ilex 5 and an 18" Wide Field Ektar in a Copal 3. SK Grimes can work wonders.

Take a look at this page:

http://www.skgrimes.com/lens-mounting/table-of-lenses-fitted-to-shutters

I agree a Sinar shutter or Packard shutter make using a barrel mounted lens much simpler.

Mike

Mike, I think you mis-typed and meant "10" Wide Field Ektar" not "18" Wide Field Ektar". Pretty nice having one of these in a Copal rather than a No. 5 Ilex, I'd think. Does it still have the maximum aperture of f/6.3?
David

[Mark Sawyer]

My little 150/9 Apo-Ronar regrets to inform you that you are mistaken.

Well, some came from the factory in Copal 0 shutters. I guess some do and some don't...

[Dan Fromm]

Well, some came from the factory in Copal 0 shutters. I guess some do and some don't...

Exactly. That's why generalizations are dangerous.

About danger, earlier this year I spotted a 210/9 Repro-Claron in ebay.co.uk for very little money. So I went to the archive.org version of Schneider's old site and downloaded the Repro-Claron brochure. It says that the cells will go in a #0. I bid, won, paid, the lens arrived and guess what? The cells' barrel are huge, won't fit any shutter I have.

[Bernice Loui]

Goerz, Red Dot Artar happened about after serial numbers beginning with 78x xxx... They are coated, but serials numbers in the 77x xxx ... can also be coated. RDA in barrel were more often than not used for process cameras, optimized for near 1:1 or so. Regardless they work fine at infinity.

Trade off being they have smaller image circle of good definition while their circle of illumination is larger than the image circle they can produce. These are most effective as longer than normal focal length lens, aka "Telephoto lens." The other trade off, they have higher definition with low geometric distortion and excellent color rendition. In case of RDA, moderate contrast.


The Red Dot, Gold dots and gold rim thing with Goerz lenses are more of a marketing thing.


Bernice







(Uh oh, those seem to be red dot Artars; this one is not. Does that matter?)

[Paul Kinzer]

Thanks, Bernice,

After more reading, it seems my original statement, that mine was made 'during or after 1926' was based on misinformation. The serial number is 762650, and according to this source (http://www.largeformatphotography.info/classic-experts.html), it was made between 1937 and 1945, probably closer to the later year.

[Mark Sawyer]

Exactly. That's why generalizations are dangerous...

No, generalizations are never dangerous.

Wait, I meant generalizations are always dangerous.

I mean, oh, never mind...

[Jim Andrada]

The second LF lens I bought for 5 x 7 was a 305mm f/9 Repro Claron in a Copal shutter. Bought it new in 1971, still using it.

[Dan Fromm]

The second LF lens I bought for 5 x 7 was a 305mm f/9 Repro Claron in a Copal shutter. Bought it new in 1971, still using it.

According to the brochure, a #3. Unfortunately my 210 didn't read the brochure and won't go into a #1 as the brochure claims. As I said, generalizations are dangerous. Or, catalogs don't always report every production variation.

[Michael Jones]

Mike, I think you mis-typed and meant "10" Wide Field Ektar" not "18" Wide Field Ektar". Pretty nice having one of these in a Copal rather than a No. 5 Ilex, I'd think. Does it still have the maximum aperture of f/6.3?
David

Nope, no mis-type. It was a Kodak Wide Field Copy lens 18" and f16 max aperture. Adam at SK Grimes mounted in a copal 3. The 10" wide field Ektar is f6.3 and in an Ilex 5.

Mike

Mike

[Michael Jones]

Well, some came from the factory in Copal 0 shutters. I guess some do and some don't...

This is the key; a factory mounted in shutter lens is not necessary the same critter as the process lens. The mounts for the lens elements are sometimes different due to the requirements of mounting in a shutter as are Copal shutter mounts themselves (there are at least 3 different bore diameters for the Copal 3 shutter not including variations in the mounting flange thread).

And you are correct, its the generalizations that can trip us all up.

But for a newbie, buying a lens and thinking it just screws into a shutter can be an expensive failure (been there, done that when I was younger).

Mike

[Bernice Loui]

Most processes lenses in barrel are not direct to shutter compatible. The thread pitch and diameter are often different thread pitch and diameter of shutters.

In the case of Goerz RDA and similar, Goerz shutter mounted lenses have adapter rings to convert their lens cells to shutter diameter and thread pitch. Goerz shutter mounted lenses are optically adjusted to 1:20 > infinity instead of 1:1 or similar as Goerz believed their lenses in shutter will be used for image making on a camera while their barrel process lenses are often used o process cameras back in the days when process camera were an essential part of the printing process.

IMO, if you're serious into barrel lenses, get a Sinar shutter and be done with this. Converting barrel lenses to shutter can be expensive and with more complications than needs to be.



Bernice

[David Lindquist]

Nope, no mis-type. It was a Kodak Wide Field Copy lens 18" and f16 max aperture. Adam at SK Grimes mounted in a copal 3. The 10" wide field Ektar is f6.3 and in an Ilex 5.

Mike

Mike

Ah, Kodak Wide Field Copy lens. Thank you for clarifying.
David

[Pere Casals]

Am I correct that other than the lack of a shutter and the fact that they are flat field, process lenses from a newspaper or print shop style copy camera will work just fine for traditional large format shooting? Please share your experience and knowledge of any draw backs.

My view is that Process Lenses can be pefectly usable, but I see no advantage for a regular LF photography. A process lens may be cheaper, but then you have to find a solution for shutter.

Today LF lenses are very cheap, and I find that a Sironar-N with a working shutter will be a better choice (in "normal" conditions) than dealing with a Process lens.

One important thing is coatings. Modern Photographic lenses have very good multi coatings because scene strong bright points (like sun) can induce flare and ghosts, a process lens may not be multicoated because it simply has less need of it.

Then the process lenses are optimized for near subjects, while (non macro) photography lenses are optimized for perhaps 1:10 or 1:20 to infinity.

So, IMHO, there are some fields where Process lenses are a good choice, like ULF and and perhaps with very long focals, but at current prices I don't see the point of using a 240mm process (celor type) lens instead a Multicoated (plasmat type) Symmar-S (MC), or their Nikon W, Fuji or Rodenstock equivalents. With the Symmar you have no shutter issues, you have multicoating, and you have a lens optimized for common working distances.

Anyway there is nothing wrong in using process lenses if those advantages are not important for you.

Presently I have a russian LOMO O-2 600mm process lens, it was $50 with shipping, and it was in pristine condition. I had to make a custom lens board, and I've no shutter, so I use the cap.

[Drew Wiley]

Well, for one thing, except for wide bargain versions intended for "stat" cameras, process lenses tend to better apo corrected, are sharper all the way from close-up to infinity, might indeed be multicoated, and might turn up even cheaper. The only real downside is that you still need to add a portable shutter.

[Bernice Loui]

Err, Modern APO process lenses ARE higher definition than the typical modern Plasmat multi coated or not. Trade offs are, smaller image circle of definition compared to a Plasmat with a smaller largest aperture. This makes them smaller for longer focal length lenses which IS an advantage. IMO, too many are obsessed with coverage or image circle and might not consider the other factors in optics performance.

APO process lenses tend to have significantly less geometric distortion and more over the larger image circle Plasmat and they are designed to produce identical sized images for Red, Green, Blue the once mandatory requirement for color separation films used for color printing.

Optics are all a set of trade offs, none are perfect or no single optic will meet all image making requirements.

Me, don't have any modern Plasmats in the optics collection. Gave them up decades ago as there are other optics that have proven to be better in many ways. Yet, the modern Plasmat in a modern predictable-reliable shutter is ideal for those beginning the sheet film journey due to their overall good image capability and essentially problem free shutters. Lens and shutter problems will compound the difficulty with learning how to get film and view camera to produce images in mind.



Bernice





Well, for one thing, except for wide bargain versions intended for "stat" cameras, process lenses tend to better apo corrected, are sharper all the way from close-up to infinity, might indeed be multicoated, and might turn up even cheaper. The only real downside is that you still need to add a portable shutter.

[Paul Kinzer]

For me, it's all about finding something really inexpensive that will do what I'm looking to do. I do not, and never will, have much money for LF. Still, I hope to get into ULF, probably 11x14*, and wanted a lens that is not too heavy, will cover the frame, and that I could afford. It may be that multi-coated Plasmats are cheaper than they once were, but comparing prices --whether here, or on eBay, or other places -- I still see a pretty large difference in price. In fact, part of the reason I am considering going up from 5x7 to ULF is because I found out, through threads just like this, that there are lenses out there that will provide excellent results at a really low price. That, along with X-ray film, has me dreaming. Yes, I'll need to figure out a shutter, but that's part of the fun for me. (How about part of the body of a 3x4 Anniversary Speed Graphic, with its shutter? Newer Speeds only go as low as 1/30, but the Anniversary goes as low as 1/10. A kluge might be made to make this a sort of universal shutter to work with cameras with larger front standards.)

By the way, the 19-inch Apochromat Artar I mentioned upthread arrived today. I paid $45 for it, and it was pretty awful looking when I opened the box (hence the price), but half an hour of disassembly and cleaning brought it back to 90% of new, and that is more than good enough! Though Artars typically seem to cost about as much as more modern lenses in shutters, from what I see, I think much of that is because of the mystique and name recognition. There are other, less known lenses that I'm keeping a look-out for.

(*I'll either wait for a really beat up camera to refurbish, or build my own. Right now, I'm exploring making my own bellows. It looks like the most expensive bit might be the film holders, since making them is, I think, beyond my skill set.)

[Pere Casals]

Well, for one thing, except for wide bargain versions intended for "stat" cameras, process lenses tend to better apo corrected, are sharper all the way from close-up to infinity, might indeed be multicoated, and might turn up even cheaper. The only real downside is that you still need to add a portable shutter.

Hello Drew,

IMHO it should be clarified that the term "Process" is loose... APO-Nikkor and Process-Nikkor refer to similar models, for the Process-Nikkor range Nikon do not claim being APO corrected: http://www.galerie-photo.com/apo-process-nikkors-en.html

In some photoengraving ("Process") works it was not necessary using "colors", by using monochromatic green light they could expose all screens for the 4 or 12 inks used.

For color separation, of course, achromat or apo would be required, depending on the enlarging factor and required IQ.

About long distance subjetcs with process lenses, some ULF photographers do unscreew a bit the front cell (when it is possible) to get best peformance. Distance between cells is a parameter that can be optimized for particular subject distance, and also for corner vs center performance...

[Drew Wiley]

Yes, Pere, thank you for pointing that out. I am well my aware of the distinction among Nikkors, and am using the term "process lens" generically. Most barrel Nikkors which appear on eBay are four-element units which were originally expensive. In this country, cheap process lenses tended to come from other sources and be used for silk-screening and sign shops. Serious print operations went only for the best.

[John Kasaian]

FWIW a Goerz 14" APO Artar in a Dial set Compur was my first 8x10 lens and I cannot fault it for general photography. I still have it although these days it rides aboard the snout of a 5x7

[Dan Fromm]

APO-Nikkor and Process-Nikkor refer to similar models

Reread what I wrote. Apo-Nikkors are either dialyte types (symmetrical) or tessar types (asymmetrical). Both are quite good at distance. Process Nikkors are 4/4 double Gauss types and are poor at distance. Not similar at all, unless you regard all lenses with four elements as essentially the same. I don't.

[Drew Wiley]

There were once lots of print shops and pro photo labs around here, but I've never personally encountered a tessar Nikkor. The standard was dialyte Nikkors, and prior to that, Goerz trigors. T-shirt and flyer shops bought cheap stat cameras already equipped with private-label 3-element lenses that look like Rogonar student- quality enlarging lenses. But dialyte Nikkors seem better at infinity than regular view lenses. In fact, a former Celestron dealer known as the local guru on telephotography finally settled on a big solid Toyo G 8X10 with a Nikon on the back and a long Apo Nikkor on the front. It outperformed all his 35mm Nikon teles.

[DG 3313]

I use a Sinar shutter behind the Cooke 6" Anastigmat lens (series 2 not soft) and love it!

[Pere Casals]

Reread what I wrote. Apo-Nikkors are either dialyte types (symmetrical) or tessar types (asymmetrical). Both are quite good at distance. Process Nikkors are 4/4 double Gauss types and are poor at distance. Not similar at all, unless you regard all lenses with four elements as essentially the same. I don't.

Dan, I don't need to reread it, near I can recite your article from memory, it explains it very well. I was pointing external similarity, anyway now there is a (not cheap) Process-Nikkor 210mm at ebay and front element it is way more curved. Well, it covers 74º at f/22, and not 45º like the APO.

171412

[Dan Fromm]

As I said, 4/4 double Gauss type and a lens not to buy or even accept as a gift.

[lenser]

Thank you for all the replies!

[Bernice Loui]

What metric or criteria would be used during the image making process to determine the amount of "unscrewing" the front lens cell to optimize image quality -vs- subject distance?


Bernice




About long distance subjetcs with process lenses, some ULF photographers do unscreew a bit the front cell (when it is possible) to get best peformance. Distance between cells is a parameter that can be optimized for particular subject distance, and also for corner vs center performance...

[Drew Wiley]

A common misunderstanding involves coverage. Published image circles for these kinds of lenses are generally related to precise apochromatic dot reproduction even at the corners of the field - a much stricter standard than what applies to general-purpose taking lenses. An unrelated consideration not mentioned yet is the character of the out-of-focus rendering. For example, I sometimes use a 360 f/9 Zeiss tessar process lens for its lucious bokeh, whereas my Apo-Nikkors render a relatively obnoxious harsh look in this respect.

[Bernice Loui]

Or the mis-understanding of illumination circle -vs- actual image circle of design criterial. More than a few "process" less have a significantly larger circle of illumination with "good enough" definition for photographic image making but not good enough for critical graphics process work.

There was a time not too long ago when precision grid films were made using the photographic process. These high precision grids could be more than a few feet long and high. Grid precision is measured in thousands of an inch from edge to edge and the line width cannot have only minimal geometric distortion and line width variation. Only high quality process lenses were used for this high precision photographic work. Similar would be monolithic semiconductor make making. These mask were once hand cut on rubylith that were up to 4 feet x 8 feet in size, then photographic reduction to produce microscopic sized photographic mask used in the semiconductor making process. Or color separation films of Red, Green, Blue of identical image size to make plates for color printing. These are a few of the extreme demand made on process lenses that are a world apart from the typical photographic image making lens.

Another area where these "process" lenses were commonly used was studio table top images. Rodenstock offerings of APO Ronar (later versions were multicoated) , and Goerz APO Artar and later Schneider APO Artar in shutter were very popular with studio table top image makers for their high definition the common Plasmant cannot match.

Not all "Process" lenses have poor out of focus rendition, it depends on the specific lens design, aperture shape and more.

Point being, there appears to be an obsession with lens image circle coverage while the other lens performance factors are often ignored, not considered or completely forgotten.



Bernice



A common misunderstanding involves coverage. Published image circles for these kinds of lenses are generally related to precise apochromatic dot reproduction even at the corners of the field - a much stricter standard than what applies to general-purpose taking lenses. An unrelated consideration not mentioned yet is the character of the out-of-focus rendering. For example, I sometimes use a 360 f/9 Zeiss tessar process lens for its lucious bokeh, whereas my Apo-Nikkors render a relatively obnoxious harsh look in this respect.

[Drew Wiley]

Even Apo El Nikkors are still being mfg for tech applications, but only in fixed aperture for designated magnifications. It's been about 25 yrs since I've heard of a 360 Apo El being sold for enlarging 8X10 film, and it went for $11,000. Once in awhile a 105 or 210 still turns up, covered for high-end repro of paintings with scanning cameras. But utter overkill for ordinary use. Apo Nikkors are only a stop slower and 1/20th the cost.

[Pere Casals]

What metric or criteria would be used during the image making process to determine the amount of "unscrewing" the front lens cell to optimize image quality -vs- subject distance?

Bernice

Hello Bernice,

For DIY the criterion is empiric, it consists in measuring resolving power at center, corner and mid while you unscreew. It is possible that image on Ground Glass (granularity) does not allow a perfect adjustment (with a magnifier) because GG do not show all possible sharpness. Of course a manufacturer may know a theoric increment in cells best spacing depending on focus plane distance.

Manufacturers like Rodenstock (for some models) were including a shim or more (or none) for some lenses, I guess they used fancy optical equipment to find optimal cell to cell distance for each unit, perhaps they also searched for good combinations of rear and front cells with compensating errors.



In the DIY realm, let me suggest 3 ways:

1)

Attach an eyepiece from a telescope or microscope (I use a x20 nikon eye piece from nikon microscope) in a lensboard, place that lensboard in the camera rear.

Place a USAF 1951 target at the intended distance, 1:30 magnification is good enough for distant subjects, from 1:30 you may not notice a change.

With rise-shift place the eye piece in the center, corner or mid of the image circle. Adjust tripod ball head to see the resolution target.

Check resolving power (group/element) for each half tour increment, check focus (belows extension) each time, as you unscreew you should check focus again.

This test do not check field flatness, as you get optimal focus for each reading, but it overcomes any camera alingment missmatch.

Then, if you know the good number of tours you also can know the shim thickness, just multiply the thread pitch by the number of tours.



2)

Another choice is using a DSLR in the back of view camera. Let me explain how I did some experiments for that.

I attached an extension ring (those for macro) ito a lens board, in that ring I place a Nikon D3300, this is better than a D3200 because the 3300 do not have the optical lowpass filter. A cheap D3300 has a high pixel density around 250 pix/mm IIRC.

Then the routine consists in placing a USAF 1951 target at the intended distance, for infinite distance optimization working at 1:30 magnification is enough. Then you unscreew half tour each time, then you have to measure resolving power (USAF 1951 group/element ) for center, mid and corner, so you use the camera rise/shift to place the camera sensor in each point, you check focus always before taking the digital shot, so you avoid camera alignment issues, as a view camera is not lab equipment. In this way you are not able to measure field flatness... but still you can find the best shim. You have a collection of digital images to find the right cell to cell distance.






3)

Another way, straighter, it consists in just taking series of shots with a sharp film (TMX, CMS 20...) , each with the front lens unscreweed more or less, but here you also have the effect of camera alignment, film flatness and film plane to GG matching.



Regards

[Bernice Loui]

Really, Really......


Bernice



Hello Bernice,

For DIY the criterion is empiric, it consists in measuring resolving power at center, corner and mid while you unscreew. It is possible that image on Ground Glass (granularity) does not allow a perfect adjustment (with a magnifier) because GG do not show all possible sharpness. Of course a manufacturer may know a theoric increment in cells best spacing depending on focus plane distance.

Manufacturers like Rodenstock (for some models) were including a shim or more (or none) for some lenses, I guess they used fancy optical equipment to find optimal cell to cell distance for each unit, perhaps they also searched for good combinations of rear and front cells with compensating errors.



In the DIY realm, let me suggest 3 ways:

1)

Attach an eyepiece from a telescope or microscope (I use a x20 nikon eye piece from nikon microscope) in a lensboard, place that lensboard in the camera rear.

Place a USAF 1951 target at the intended distance, 1:30 magnification is good enough for distant subjects, from 1:30 you may not notice a change.

With rise-shift place the eye piece in the center, corner or mid of the image circle. Adjust tripod ball head to see the resolution target.

Check resolving power (group/element) for each half tour increment, check focus (belows extension) each time, as you unscreew you should check focus again.

This test do not check field flatness, as you get optimal focus for each reading, but it overcomes any camera alingment missmatch.

Then, if you know the good number of tours you also can know the shim thickness, just multiply the thread pitch by the number of tours.



2)

Another choice is using a DSLR in the back of view camera. Let me explain how I did some experiments for that.

I attached an extension ring (those for macro) ito a lens board, in that ring I place a Nikon D3300, this is better than a D3200 because the 3300 do not have the optical lowpass filter. A cheap D3300 has a high pixel density around 250 pix/mm IIRC.

Then the routine consists in placing a USAF 1951 target at the intended distance, for infinite distance optimization working at 1:30 magnification is enough. Then you unscreew half tour each time, then you have to measure resolving power (USAF 1951 group/element ) for center, mid and corner, so you use the camera rise/shift to place the camera sensor in each point, you check focus always before taking the digital shot, so you avoid camera alignment issues, as a view camera is not lab equipment. In this way you are not able to measure field flatness... but still you can find the best shim. You have a collection of digital images to find the right cell to cell distance.






3)

Another way, straighter, it consists in just taking series of shots with a sharp film (TMX, CMS 20...) , each with the front lens unscreweed more or less, but here you also have the effect of camera alignment, film flatness and film plane to GG matching.



Regards

[Luis-F-S]

Really, Really......
Bernice

Guess some people have nothing better to do...............

[Drew Wiley]

Variations in film flatness in a typical holder pretty much renders option no.3 unrealistic.

[Bernice Loui]

Real "Process" cameras have precision vacuum film backs to assure that big sheet of film is flat.

Typical view camera film holders can never approach this degree of film flatness... and camera alignment has not been discussed yet.

Real "Process cameras" are very much a different breed of camera.


Bernice



Variations in film flatness in a typical holder pretty much renders option no.3 unrealistic.

[Pere Casals]

Variations in film flatness in a typical holder pretty much renders option no.3 unrealistic.

Hello Drew,

This should be discussed...

I may be unrealistic with diafragm wide open, but if stopping (say to f/16) then DOF in the film plane increases, in the same way that it increases in the scene field, a math formula describes that.

At the end the inter-cell spacing optimization won't be seen if the lens is not working in a sweet aperture point, what I mean is than if the lens has too much diffraction or too much spheric aberration (because too open) then you won't see the inter-cell spacing optimization.

As allways, sharpness can have a number of limitating factors, the one that has more impact it masks the others.

Also for extra film flatness I use a very easy trick, I place a 9x12cm sheet in a 4x5" holder, in this testing holder I sprayed 3M Re Mount glue, so the sheet is pretty adhered to the back. Well, it is not a precission holder, but at least you completely avoid any sheet curvature impact.

At one time I had a box of 912 sheets but I only had 45 holders... so the trick came from that.

Also I checked well my 45 Norma alignment, I've it very tight and lubed. Well, Normas still are precission gear in this 2017. I'd strongly recommend a lube for it: Interflon FoodLube (oil, not grease). Being H2 atoxic grade, it has very high performance for that. Every movement skids like new or better: No real need for geared movements.

Regards

[Drew Wiley]

I use 8X10 adhesive holders for images intended for significant enlargement. For diagnostic testing or critical duplication work I do have an all-metal precision holder. I test camera backs using precision flat stock with a depth micrometer. I took my Norma for a pleasant walk today and noted the need to tighten a couple of tiny set screws. That's a positive feature in my opinion. With the subsequent F-Sinars you have to add or remove shims.

[Drew Wiley]

Forgot to state that my all-metal holder is indeed vacuum.

[Jim Andrada]

Once upon a time I was thinking of getting a real process camera. Can't quite remember why, but I was pretty serious about it. If I hadn't had to move for work I might have done it.

[Pere Casals]

I use 8X10 adhesive holders for images intended for significant enlargement. For diagnostic testing or critical duplication work I do have an all-metal precision holder. I test camera backs using precision flat stock with a depth micrometer. I took my Norma for a pleasant walk today and noted the need to tighten a couple of tiny set screws. That's a positive feature in my opinion. With the subsequent F-Sinars you have to add or remove shims.

Hello Drew,

I did not know that adhesive holders existed... you know, I'm a learner. I feel very lucky to have the chance to comment all that with proficient people, so what my learning is checked. Thanks for it.

Regards,
Pere