Symmar-S as convertable?

[Ironage]

I have been wanting a 180mm Symmar because it works as a convertible lens. Today I thought about using my existing Symmar-S as a convertible by removing the front element. Will it work? I use the camera for contact prints only, so extreme sharpness is not necessary.

[df cardwell]

Sure. You'll have to estimate the aperture settings, but you can figure out something close enough.

It'll work pretty well for you if you were making enlargements, too.

[paul ewins]

The Symmar-S was reworked to maximize sharpness with both cells in place, so performance with just the rear cell is likely to be worse than in the comparable convertible Symmar. However as you have nothing to lose (except a few sheets of film) go ahead and try as it may well be good enough for your purposes. As a starting point, I would simply double the f-stop when calculating exposure as that is fairly close to the difference with the convertible Symmar. It is worth noting that even though the focal length increases, generally the image circle does not. From memory the convertible Symmars were rated at 70 degrees normally and just 40 degrees when using the rear cell.

[bdial]

I tried this once with my 210 S, my experience was as Paul predicts; sharpness is not so good. Though, if you're only contact printing and shoot well stopped down, it might be ok for your purposes.

[bowzart]

I tried this once with my 210 S, my experience was as Paul predicts; sharpness is not so good. Though, if you're only contact printing and shoot well stopped down, it might be ok for your purposes.

With my 210 symmar, I quickly learned not to use it converted but suspect that in a contact print it could be adequate. But if the S version isn't as good, it's a guess.

[AgX]

Let us look what the industry replied (in 1993) on a letter of mine where I asked why they stopped advocating the convertibility of those lenses and asked about that possibility on their current ones (or so). I translated the letters for you:



Rodenstock:

… Rodenstock once also stated this chance of doubling the focal length. However it works only with symmetrical lenses and even then is coupled to a significant reduction in quality. This is the reason why today we do not longer consider this possibility, as the quality demands claimed to large format photography are no longer fulfilled. Thus we advise our customers to use the lenses only `complete´, in order to yield an optimum image quality and thus making the photograph fulfill the demands toward large format photograph. …




Schneider:

… With the transition of the Symmar-range to the Symmar-S we abondoned the optics feature of being convertible, because the construction of improved high-performance lenses did not permit this anymore.
The optical performance of one of the modules of the Symmar was significantly worse, especially because of the occuring color fringes and diffraction phenomenon of the slower module which had a useful aperture of 22-33.
With the revision of of the Symmar-range towards the Symmar-S an improvement of the central part was realized; with the Apo-Symmar [an improvement of] the outer part in addition to the central part.
With the Super-Symmars HM the outer part was adjusted in a way that an angle of view of 80° was achieved. …

[Ian Grant]

Actually the early Sironar's were designed to split and the were definitely not remote symmetrical, far from it, I have one with the double scale but it's on loan to an Itlaian APUGer or I'd post some images. . But these early Sironar lenses suffered problems with seperation and were re-designed the new ones didn't split.

The early Symmra's were very poor quality when split and I never met anyone who used them separated. The Angulons were marketed as Triple Convertibles too

Ian

[df cardwell]

I have a nice coated Symmar, (still a dagor formula but a triple convertible), and is fine for 4x5. OK, not to count pin needles from a quarter mile, but a very nice lens for portraits and handsome landscapes.

I've used the plasmat Symmar in length from 135 to 360 and like them well.

The 135 Symmar S that lives in the Crown Graphic is fine as a convertible.

So, it isn't so much the lens, perhaps, as your taste. Or my taste. Try the lens and see what you get.

If we shoot at f/22, diffraction eats up most of the differences anyhow.

[epatsellis]

Ian, I had forgotten that the original Angulons were marketed as convertible, I wonder if I have enough bellows to try my 210 Angulon converted?

erie

[paul ewins]

I've got two of the original f6.8 "Doppel Anastigmat" Symmars in shutter and they only have the combined focal length and aperture marked. The Schneider catalogs of the time (pre WWII) do mention that they can be used converted but provide no other information so I guess Schneider weren't too keen on the practice. As far as I can tell the triple convertible version (still f6.8) arrived post-war and has been replaced by the new Plasmat (f5.6) Symmars between 1952 and 1956. What I don't know is whether the cells in the triple convertible Symmars were reworked to provide better focal lengths. I only have two of the triples, a 135/210/260 and a 180/285/355 and haven't been able to find any brochures so how extensive the range was is anybody's guess.