Achieving adequate DOF in 8x10

[Jody_S]

TR triple convertibles are readily available inexpensively now. Some are very good, and some are very bad. They were hand assembled thus proper alignment was a common problem.

I suspect the issue is more that all of them suffered from balsam separation and those with clear glass have been re-cemented. Usually by some joker like myself who doesn't have the proper equipment to ensure the alignment is as good as new, which can be an issue re-cementing a 5-glass block like mine (my pics are quite sharp so I guess I didn't mess up too badly).

It might be a safer bet to go with a Protar VII if you want a vintage triple-convertible.

[jesse1996]

Would anyone recommend certain convertible lenses over buying 3 or 4 individual lenses?

[Pere Casals]

Would anyone recommend certain convertible lenses over buying 3 or 4 individual lenses?

Of course... let me comment on next lens (I've one):



> From Japan, serious people, normally. 100% Positive feedback seller, free shipping. You can make offer... $100 to $125 perhaps.

> It covers 4x5 with movements. https://www.schneideroptics.com/info...5,6-150mm.html

> "Technika Selected". Linhof made an additional QC to their requirements, so perhaps the lower crop of the sample to sample variation is not stamped by them, this is subject to some debate, but I've a Symmar/technika 360 that's razor sharp to my eyes, (I picked it because the 620mm conversion for 8x10).



You wil have a damn sharp 150mm f/5.6. Ken Rockwell says this is "the sharpest lens he owns" http://www.kenrockwell.com/schneider/150.htm. I don't think he is jocking a lot.

Also you have other focals https://www.schneideroptics.com/info...lenses/symmar/ See what schneider says about the conversion.


Drawback:

> It's single coated (not multi coated), so in some situations (framing with sun inside) you will have a bit lower contrast, so a POL filter would be useful.

> Perfect for BW, some would say that they need multicoating for color, I think it's also good for color in most situations.


What happens when using the Conversion?

If you remove the front cell you get the lens converted to 265mm f/12

See again what schneider says about the conversion: https://www.schneideroptics.com/info...lenses/symmar/



But you can have very decent images by stopping to f/22, perhaps a bit softer in the corners.

When converted it has focus shift, this is you frame and focus all open (f/12 in this case), then you stop to f/22 to get a sharper image, and then you need to correct the focus again with lens stopped because when you stop the lens the focus setting varies a bit. So you need a bright point to focus on or a very tight cloth to focus a dim f/22 image on the GG.

(People that don't knew that was saying conversion was very bad, but it's not that bad.)

Note that aperture has two scales, the green one is for the conversion.


With this lens you can shot a lot, learn about its limitations and what you have to learn, and when your LF photography has a flavor then you can pick more expensive lenses that would satisfy the specific needs you will have.

In the future you may want a portrait lens, a lighter lens for landscape/hiking or a heavy glass with large circle/movements for architecture.


So having recently made same path, I'd recommend don't falling in G.A.S. (gear acquisition syndrome), just pick a single lens like that and shot, shot and shot. And learn all in the way, like LF processing.

Later you will have a criterion to acquire the right glassware for you. Then you would sell that lens for mostly the same, or not at all.

An alternative would be picking a Sironar-N, Symmar-S, Ninkon-W, or Fujinon.

At the beginning you don't need a lot of lenses, think that with LF you can shot wider and later you can crop without Image Quality issues, this is not an small format at all.


Caution:

Mechanical shutters have a precission specification of +/- 30%, and old shutters can have big difference about real to marked speed.

So check all speeds. A shutter tester is a good investment, from $15 (PC souncard type) to $100.

Read this: http://www.kenrockwell.com/tech/expo...rge-format.htm


Regards,
Pere

[interneg]

Would anyone recommend certain convertible lenses over buying 3 or 4 individual lenses?

I'd recommend giving some extremely serious thought as to what focal length feels most natural to you in terms of the spatial relationships between objects. You can test this out to a reasonable extent in smaller formats. Buy the lens that matches that. For me, that's a lens in the 210-250mm range on 8x10 (with possible excursions into the 270-305mm range, but generally no longer).

Convertibles are potentially useful if you see yourself needing long focal lengths (with some compromises) at a more reasonable price. They're not a good idea on colour film - most are not fully colour corrected when split, thus the recommendation of a yellow filter.

Try not to repeat the #1 LF newbie mistake & buy lots of extraneous lenses. Buy a good lens in the focal length you want & spend the rest on film. Ignore the fluff about needing multiple lenses. Given the scale of prints you want to make, you'll need every penny you can save.

[LabRat]

Convertible lenses seem like a good idea, but in practice are a PIA...

The jump in FL using the single groups tends to be quite a jump (requiring a lot more bellows extension that you might not have), and require stopping down at least 2 or 3 stops more to get decent definition and correction, so one has the problem of a slow lens and the camera (more extended) mounting more prone to vibration, atmosphere, etc, so can be difficult to find the sweet spot where a single FL (or tele) would do fine...

I have a TR 15/24/36 that my biggest camera can only use the 15" (as my bellows extend about 23"), so the two groups always stay on the lens... And flipping around different cells while shooting seems to be asking for handling trouble... (Crossthreading, dropping!?!!! What could possibly go wrong!?!!!)

Steve K

[Tobias Key]

There's a lot of good advice on this thread, but one thing no one seems to have mentioned is the effect of the wind on your camera. Large bellows cameras are very susceptible to being shaken by the wind and I imagine it can be pretty breezy at the top of the skyscraper! Of course you can do what you can to shelter the camera, but you might find that you have a minimum shutter speed you cant go below before vibration becomes evident in the final print. So talk of f64 might be academic if you can't get a shutter speed fast enough to keep out any camera shake.

[Pere Casals]

Convertible lenses seem like a good idea, but in practice are a PIA...

Steve K

The non converted focal is very good and /5.6 (with Symmars), no PIA. Just a regular lens.


"Ansel used the 19" (480 mm) component (Cooke TC) for "Aspens, Northern New Mexico," 1958; both components to get 12" (300 mm) for "Clearing Winter Storm, Yosemite National Park," 1940; and the 23" (580 mm) component for "Moonrise, Hernandez, New Mexico," 1941."


The converted option is something that comes as a bonus and can be more or less useful. If one usually shots /5.6 to /8 the conversion is a limitation. If anyway one shots beyond /11 the conversion is no limitation. The additional bellows extension is not very significative compared with 265 focal and extension one needs for near, but this depends on the camera capability if some 2 inches make a difference.

Here Mr Perez shows that he found the 265 conversion of the 150 a bit soft in the corners at f/16:

f/16 48 48 23
f/22 48 48 33
f/32 42 42 38

http://www.hevanet.com/cperez/testing.html.

From those numbers we can conclude that with conversion configuration at f/22 we need a really big print seen at reading distance to really notice a resolving power flaw vs a modern multicoated lens, but only in some situations: Perfect focus, no DOF problem, great scene microcontrast, sharp film, no shake, large aperture (difraction limitation).


Single PIA of the conversion is that you need to focus with a dim image (because some focus shift), this can be solved with a well light tight cloth to the groung glass. Note that the non converted configuration has no focus shift.

Anyway with a non converted lens and for portrait I think important to focus with lens stopped to the shot setting becasue one may want to know how defocus is to work.

Of the convertible Symmar series I've the 150, 2x 210 (for an stereo project) and the 360. I've tested the 150 with CMS 20: it's like a razor. Yes... single coated... this may be a defect (mostly) or even an advantage for a situation.

[Pere Casals]

I'd recommend giving some extremely serious thought as to what focal length feels most natural to you in terms of the spatial relationships between objects. You can test this out to a reasonable extent in smaller formats. Buy the lens that matches that. For me, that's a lens in the 210-250mm range on 8x10

Try not to repeat the #1 LF newbie mistake & buy lots of extraneous lenses. Buy a good lens in the focal length you want & spend the rest on film. Ignore the fluff about needing multiple lenses. Given the scale of prints you want to make, you'll need every penny you can save.

I agree, but for 4x5 this would be 105-125 range. Having a wider focal one can always make crop: Relative size of objects won't change. Anyway IMHO a 150 is better to engage 4x5 because (in general) one has a larger circle that allows a good deal of movements, IMHO, so one can practice that important resource.

Convertibles are potentially useful if you see yourself needing long focal lengths (with some compromises) at a more reasonable price.

Compromises when with the conversion configuration, the non converted configuration is mostly a regular lens of the era.

They're not a good idea on colour film - most are not fully colour corrected when split, thus the recommendation of a yellow filter.

I saw no color fringes with converted version in the GG, given what resolves the converted version in LP/mm terms this is of the film color cloud range so no difference.


My own informal tests are consistent with what it was measured in the Perez Test: No sharpness advantage with yellow filter:


150mm
single element
at 265mm

f/16 48 48 23
f/22 48 48 33
f/32 42 42 38


150mm
single element
at 265mm
with #15 yellow
filter

f/16 48 48 21
f/22 48 48 32
f/32 30 38 33

http://www.hevanet.com/cperez/testing.html


My Velvia tests are done with Sironar-N, still I've not tried with the Symmar Conv. My personal guess is that a difference may be there in case sun is in the framming because flare and parasite light direct sun may deliver, this is something I'll test when I've the chance. Also I thing a POL will conmpensate that, as direct sunlight comes polarized the filter will remove more sun direct rays than the stray light proportion is additionally spreaded by the single coating vs mc.


IMHO in the times of Symmar Convertible it happened marketing poison aganist convertibles.

[Pere Casals]

There's a lot of good advice on this thread, but one thing no one seems to have mentioned is the effect of the wind on your camera. Large bellows cameras are very susceptible to being shaken by the wind and I imagine it can be pretty breezy at the top of the skyscraper! Of course you can do what you can to shelter the camera, but you might find that you have a minimum shutter speed you cant go below before vibration becomes evident in the final print. So talk of f64 might be academic if you can't get a shutter speed fast enough to keep out any camera shake.

IMHO shutter speed is not important to Freeze shake of an LF camera, in most field situations. A perfect shot is done with 1/30000s flash, true.

Tripod does it. You can attach a toy laser pointer to front standard to see vibration projected 20m away. In regular conditions you have no shake, with some wind you use your car or a rock to protect camera from wind. The laser pointer is very, very interesting because it shows the real vibration on the scence itself, so you know very what not will be shaked. After inserting the holder (or removing the slide) it is important to wait some seconds to allow vibrations to stop.

This is a 25" exposure: no shake and there was some wind: https://www.flickr.com/photos/125592...posted-public/

[Jody_S]

Convertible lenses seem like a good idea, but in practice are a PIA...


Steve K

I have a few convertible lenses by T-R and Schneider, many more if you include Dagors and the like. I have never used one in the longer configuration.