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David Williams
15-Jul-2017, 17:45
This may be an obvious dumb question, but would 210mm lenses of different brands have the same view? As in could one build a twin lens 4x5 camera and use different makes of lenses for the viewing and taking lenses? I have a Caltar II-E 210.

karl french
15-Jul-2017, 18:03
They are very likely to have slightly different angles of view. Even within the same brand, within the same lens line there can be very slight differences in focal length and thus angle of view. You might not notice the difference though.

Mark Sawyer
15-Jul-2017, 18:27
What Karl said. Process lenses are made to the most exacting specifications, and their smaller maximum apertures forgive a lot of sins, including minor errors in focus. Still, the more conscientious manufacturers engrave each lens with its own individual focal length.

David Williams
15-Jul-2017, 18:49
Thanks for the info! Very helpful!

EdSawyer
15-Jul-2017, 19:22
All the tlr large format cameras I know of (cambo twr, gowland) did use different lenses for viewing and taking, so yes, the idea is valid.

Mark Sawyer
15-Jul-2017, 19:29
What Ed said too. If you have two fairly-well-matched lenses and register the focusing lens to match the shooting lens at the distance you'll be shooting at, yes, very doable. And you'd have to register them anyways. But if you stray too far from the distance you registered them at, you may have some trouble. TLR's aren't for shooting close-ups anyways, though.

Oren Grad
15-Jul-2017, 20:59
In today's market, the 210 Caltar II-E (which is just a private-labeled Rodenstock Geronar) is a very affordable lens. If you like it, why not just get another one? Sure, no guarantees, etc., but the easiest way to maximize the likelihood that the true focal lengths of the actual samples you are using are going to be closely matched is simply to use a pair of modern lenses from a major manufacturer that in principle have been built to exactly the same specification. If you want to be extra picky, you can look for a serial number that's not too far away from yours.

Jac@stafford.net
16-Jul-2017, 06:59
All the tlr large format cameras I know of (cambo twr, gowland) did use different lenses for viewing and taking, so yes, the idea is valid.

Yes, and in MF TLRs the viewing lens has no diaphragm.

Oren Grad
16-Jul-2017, 08:51
Just to clarify, because although the bits needed to understand this are more or less all here, it might be confusing if you don't already understand it:

Lenses with a given marked focal length can and do differ in actual focal length. This can be due to differences in optical design (across different lens models, even within brand) and sample variation (within a given lens model). Even if the lenses differ in actual exact focal length, you can set up the camera so that focus agrees at a single focus distance. That can be fine if, say, you are using the camera in a fixed studio setup. Many large format TLRs were indeed used for studio work or studio-type work in the field. Depending on your working apertures, how far you will be enlarging the pictures and how critical you will be in judging them, depth of field may allow you some wiggle room around the optimal focus distance. On the other hand, if you don't want to be restricted in that way, you'd be better off trying to match the lenses as closely as possible.

In principle you might be able to find different model lenses that have identical or near-identical actual focal lengths; some of the Schneider lens documentation indicated the actual design FL and tolerances as well as the round-number marked FL, though I've never seen this information from other large format lens manufacturers. But in general, if you use different lens models you can expect lots of tinkering to find optimal shimming of the flange-to-film distance for the different lenses and figure out how closely the lenses track across the desired focus range. I just think hassle is most likely to be minimized if you stick with same brand, same model lenses and have to deal only with sample tolerances rather than design differences as well.

I don't know much about the Cambo TLRs. I do know that Peter Gowland sold his early TLRs with Xenar lenses in barrel for viewing and Symmar lenses in shutter for taking. I never asked him about it and have not tested that setup myself, so I don't know whether he was configuring it for optimal results at a set distance or had verified that those two particular lenses track adequately over a broader focus range, and to what standard in judging the results. But a late-model 4x5 Gowlandflex that I owned for a while came with a matched pair of 180mm Sironar-N's in Copal shutter. That could have been because of the benefits of matching, or because in later years it became more of a nuisance to source lenses in barrel so it was easier just to buy a pair of same-model lenses in shutter off the shelf.

Dan Fromm
16-Jul-2017, 17:51
Hmm. If two lenses have the same focal length they may well have different flange-focal distances. This often the case if they're of different designs, e.g., a Symmar and a Xenar. But if they are both set up to be in focus at infinity then both will have to be moved the same distance forwards from the infinity position to focus at any arbitrary nearer distance.

OP, if you can get lenses of the same focal length -- in practice very very close -- and get them in register you'll be fine. If you fail at matching or registration, well ...

Chauncey Walden
17-Jul-2017, 13:46
The Caltar/Geronar is a fine modern triplet with multicoating. They are compact and, as was mentioned, sell for very low amounts relative to their quality. Two of them would make a nifty TLR.

Jac@stafford.net
17-Jul-2017, 16:07
All I read in this thread is what is problematic, and nothing about what will work.
IOW, a lot of technical posturing.
.

Dan Fromm
17-Jul-2017, 17:54
All I read in this thread is what is problematic, and nothing about what will work.
IOW, a lot of technical posturing.
.

Oh, the answer was defined. Lenses of the same focal length both in register.

What wasn't laid out were an easy idiot-proof way to measure focal length and obtain a pair of lenses of the same focal length and an easy idiot-proof way to put two lenses on a TLR's lens board in register.

Let the OP complain for himself.

Jac@stafford.net
17-Jul-2017, 18:01
Oh, the answer was defined. Lenses of the same focal length both in register.

What wasn't laid out were an easy idiot-proof way to measure focal length and obtain a pair of lenses of the same focal length and an easy idiot-proof way to put two lenses on a TLR's lens board in register.

Let the OP complain for himself.

Your attitude is registered, and thank you for the solution to "pair lenses of the same focal length and an easy idiot-proof way to put two lenses on a TLR's lens board in register". Not!

That's my complaint. Deal with it.

David Williams
17-Jul-2017, 19:37
Thanks to everyone who contributed to this thread. Your information was very helpful. I said in the beginning that it may have been an obvious question, but it turns out that is wasn't quite as obvious as I thought. I really didn't need anything idiot-proof. I just don't have that much knowledge of how various brands of the same focal length differ in large format lenses. You all cleared that up. Thanks again! This forum is a wealth of information and experience.