View Full Version : Process lenses

Michael Wellman
1-Jun-2018, 20:00
As I understand it process lenses were primarily designed for graphic reproduction work but they can be used in LF photography. Has anyone actually used a processed lens? If so, what were your thoughts on it? The good, bad and ugly. thanks

Mark Sampson
1-Jun-2018, 20:52
'Process' lenses were designed for use in copying and reproduction work. Most of them were symmetrical designs, so although meant to be used around 1:1 ratio, also perform well at or near infinity (where most LF photographers work today). The trade-off is the relatively narrow angle of view such lenses tend to have- which means that LF photographers then to use process lenses with focal lengths longer than 'normal' for their film format. A classic example of this would be using a 12"(300mm) process lens as a long lens for 4x5. Of course they perform very well for close-up work- what they were designed for. Most are 'apochromatic', which essentially means fully color-corrected.
Perhaps the most famous 'process' lens is the Goerz 'Red Dot' Artar, but most lens makers offered their own process lenses, such as Rodenstock's Apo-Ronar, Kodak's Copying Ektanon, Schneider's Repro-Claron, various Nikkors, and many, many more.
The only downsides that I can see are that they tend to have small max apertures (f/9-f/11) and often are not mounted in shutters. They have always been widely used and well-respected, as a class of optics. Other people will have more (and varying) information, but I think that is a good general overview.

neil poulsen
1-Jun-2018, 23:40
I have one process lens that might serve as an example. It's a 610mm Repro Claron that Mark includes in his list. Fortunately it's mounted in it's original Ilex 5 shutter. (I think it's the original shutter.:confused:)

It's true that this lens has a narrow angle of view of about 47 degrees. (Data found online from an unknown source.) But, given its extremely long focal length, it has about a 520mm image circle. This is more than enough image circle for 8x10.

So, I would draw these conclusions about my use of process lenses.

> When they're used, they're usually used as longer focal-lenses. In this way, the narrow angle of view doesn't get in the way.

> They're usually optimized for distances less than infinity. This can be overcome on some examples by stopping down the lens.

> It's true that they have a smaller maximum aperture. But this can be an advantage, in that they're smaller, more compact, and lighter. Of course, the longer focal length examples can still be quite heavy. Mines a little heavy. But, I can't imagine the weight, if it had an f5.6 maximum aperture.

> They can require large filters. But being used on larger cameras, it's not likely that the negative will be enlarged (assuming traditional b&w images). But if it's enlarged (e.g. 8x10 neg on 8x10 enlarger), it won't be by much. So, you can get away with using Kodak Wratten gelatin 4in square filters (also available in acetate) with a Lee adapter or Lee compendium lens hood. Lee adapters to fasten these to the front of the lens come in quite large sizes.

My Repro-Claron is not a very good example for the last bullet above. It's filter thread is only 82mm, and it's easy to find 82mm filters. None the less, I've standardized on 77mm diameter glass filters for my large format lenses and so will use my Lee lenshood (that accepts 4" square acetate or Kodak gelatin filters) for the 610mm Repro Claron. I do have a separate 82mm polarizing filter for this lens.

Dan Fromm
2-Jun-2018, 09:02
I've updated the list to include a discussion of process lenses for general photography.

OP, the list is here: http://www.largeformatphotography.info/forum/showthread.php?138978-Where-to-look-for-information-on-LF-(mainly)-lenses

2-Jun-2018, 12:10

I have been using the 610 and 760mm apo-Nikkors on my Toyo 810 MII field camera focusing at infinity. Examples of prints made with both lens can be seen in my last postings in "The KallitypeThread" on this forum. As you can see they are extremely sharp and contrasty. The only "downside" is that they are somewhat pricey when you factor in the shutter and mounting cost but are well worth the extra cost. While both lenses are mounted in an Ilex #5 shutter, they are reasonably compact and will probably "fold-up" with the MII but I always pack them in the pack. The front element is threaded for 95 mm and I bought 95mm adopter ring and step-up ring for the OK in Zpro filter holder so that I can use all of my 4" filters with both lens.
The Toyo Pro Compendium hood will work with those lenses. The main thing is to get a lens in good optical condition and, likewise, shutters in good condition. Owning and using the 610 and 760, I can vouch for them and if I had choose between the two, would go for the 610 as it seems to be mg most used focal length.

PS: The 760 won't work on the Toyo 810M but will on the MII because the MII's front standard reverses
allowing for the extra bellows draw. Of course that's not an issue on minoraillike the Toyo G.

Drew Wiley
2-Jun-2018, 14:56
There were different quality offerings of process lenses even from major manufacturers. For example, a T-shirt silkscreen shop needed only a bargain lens for a relatively cheap stat camera, while a high end print shop probably wanted only the best. I have a number of modern extremely reputable view camera lenses. But my various 4-element Apo Nikkors (their better ones) exceed all of them not only in apochromatic correction, but in sharpness all the way from close-up to infinity. But by the time you add a shutter, they're bulkier and no longer a steal. They were quite expensive when sold new, but now are abundant and cheap on the used market. The image circles are decent. Anything from 305 up easily handles 8x10, or even 240 if you don't need movements. The published angle of coverage specs are MUCH stricter for repro work than what applies to general photography, so keep that fact in mind.

Michael Wellman
2-Jun-2018, 17:46
Thank for the replies. I'm thinking about getting ULF (8x20 or 11x14) and would like something in the larger focal length ( 24-30"). It seems that you can find a lot of the process lenses out there more than your normal lenses and at a better price. This helps a lot. thanks

Pere Casals
2-Jun-2018, 18:38
I'm thinking about getting ULF (8x20 or 11x14) and would like something in the larger focal length ( 24-30").

In that case I'd recommend you read well this fair information: http://www.angusparkerphoto.com/blog...ndations-14x17 . Thanks again Mr Parker.

A good start point would be the Symmar 360mm convertible to 620mm, you get two focals and probably also a shutter, low cost. I've one and the 620mm conversion is pretty good, just (when used as 620mm) check focus at the aperture
you are to shot, because when you stop the lens the focus may change, this is focus shift. Single problem is that it weights some 2kg, but in the ULF business 2kg is nothing :)

Let me add that a process lens optimizes for focus field flatness and lowest distorsion possible, that's way less important for pictorial photography. Other capabilities are sometimes sacrificed, like coverage angle, to excel better in field flatness.

A process lens may not require an extreme coverage because with near focus you get a large circle. Be aware that process lenses have (usually) the image circle specified for 1:1, not for infinite, so the cricle will be smaller for distant subjects.

Another thing is that a process lens may be optimized for near focus only, so it can be is less optimal for distant subjects. APO Nikkor family is said to work well also for distant subjects.[/QUOTE]

6-Jun-2018, 04:23
I don't think it's very useful to lump all "process lenses" together in this context. Very different lens designs can fall under this term, with very different coverage, size, usability at distance, etc.

* Dagor and Plasmat variations – these are often used as general purpose wides and normals. The normal f/9 G-Clarons are a good example of these. Earlier ones were Dagor type, later ones are Plasmat type. They perform well at distance and are very usable as moderate wides at small apertures. Schneider's estimate of 64 degrees coverage for the Plasmat type G-Clarons seems overly conservative to me, esp. for contact printing.

* Slow, 4-element air-spaced dialytes (Apo-Ronar, Artar, Repro-Claron etc.) - these are narrow-angle lenses of very high quality. Many are highly usable as long lenses for general photography and shutter mounted versions are not uncommon. Barrel variants can be a good candidate for custom mounting into a shutter.

* Tessar derivatives. These can behave similarly to the previous group (high quality over a narrow field of view; e.g. Zeiss Apo-Tessar) but this is a varied group so tread carefully.

* 4-element double Gauss wides, for example the f/11 G-Claron WA models. These have very wide coverage but are not easily mounted in shutters and image quality apparently suffers a lot at distances outside their designed range. Avoid if unsure.

* Special purpose high resolution/ultra flat field/etc. designs – overkill for normal use, usually slow, large and in weird mounts.

Stay away from unusual barrel mounts. Sometimes the barrels use massive brass parts so can be surprisingly heavy – it makes sense to ask about actual weight when purchasing.

6-Jun-2018, 14:45
Hopefully I'm not hijacking this thread, but it seems like a good place to ask this question. I understand that Apo-Tessars have narrow coverage, around 43 degrees IIRC, so the math says a 46cm lens won't cover 7x17, but from practical experience, can anyone tell me if a 46cm f/10 Zeiss Apo-Tessar will cover (even just, without movement) 7x17, assuming f/22 or smaller and subject distances from say, 8 feet to infinity? The negatives would be contact printed. Some light fall off at the extremes would be acceptable.