View Full Version : How Do I Use a Schneider Convertable Symmar?

Daryl George
18-May-1998, 12:28
I recently purchased an older Schneider Convertable Symmar lens. It is marked 1 80/5.6 and 315/12. According the the serial number, it was made about 1971 and is all black.

The salesman told me to remove the rear component to use the lens at 315. Anoth er question on this site also references removing the rear component. However, when I called Schneider to get a replacement index screw to engage the slot in m y board (the original was missing and Schneider customer service was super!), I asked about the "conversion". They said to remove the front component, as does Ansel Adams in his book "The Camera".

So I tried both ways. With the rear removed I get an infinity focus at about 10 .5" between the standards (a bit short of 315mm), and with the front removed I c an't get anything to focus. That would appear to agree with the "remove the rea r" recommendation. The complete lens focuses at infinity with about 7" between the standards (seems to agree with 180mm). Removing the rear component does req uire more effort, but it keeps the shutter protected from the elements and retai ns the filter ring---so I actually prefer that arrangement.

What's the correct method to convert a Symmar, and why do some sources say to re move the front component and others the rear? Were these lenses made in two dif ferent configurations?

18-May-1998, 23:09
Removing the front element is the correct configuration for the use of a convert ible lens. It will take more bellows draw if the front element is removed as opp osed to removing the rear. If you are racking the bellows all of the way out and still not getting focus at infinity, your bellows may be to short for a 315mm l ens. The lens to film plane distance is measured from the rear of the lens with the front element removed. That is why prople try to remove the rear element, t o make the bellows draw less. This can lead to a reduced focal length and some f ocusing problems.

To illustrate, I have a 150 convertible Symmar. At 150 mm the lens board to fil m plane distance is 5 1/2 inches, or about 150mm. Converted, by removing the fro nt element. the lens board to film plane distance is 13 inches or 325 mm, approx . The distance from the back of the rear element to the film plane, however, is 11 inches, or close to 265 mm. The lens board to film plane distance is 7 inches or 175mm with the rear element removed, as opposed to the front element. These bellows measurements are based on focusing on an object at 25 feet, not, infinit y.

You can see that the removal of the elemements doesnot result in the same focal length being produced. To address the filter concern, it is normally preferable to place the filter behind the lens, and to focus at the shooting aperature with the filter in place. The use of a filter, generally a yellow or orange is reco mmened to correct for the fact that by removing a lens element the colors of lig ht will not focus on the same plane.

I hope this helps address some of your concerns, I am not an expert by any means , but have used convertibles with some success. These observations have resulted from my reading and practical use of the lenses. Good luck.

Daryl George
21-May-1998, 12:47
Thanks for the help, Marv. Following your advice, I retried removing the front component. As you suggested, I had to extend the bellows much more than I was e xpecting in order to achieve focus. I got an infinity focus with about 15 1/2 i nches between the lens board and the film plane. Subtracting 2 inches for the r ear component extending behing the board gives 13 1/2 inches, which is fairly cl ose to the rated 315mm focal length. There was still enough bellows and rail le ft that I could get a close focus of about 15 feet. The field of view agreed we ll with a 35mm zoom lens set for 90mm (the 35mm equivalent). Now everything see ms to fit.

You mentioned that some people do remove the rear element to reduce the bellows extension. When I tried that, it looked like I was getting the equivalent of ab out a 10 1/2 inch lens. That configuration might work as a portrait lens. A sli ghtly soft image would be a problem. Do you have any information on what the f/ stops would be with the real component removed?

21-May-1998, 22:57
Strictly guessing, I would say to use the same f-stops as when the rear element is removed. I have tried shooting with the front element only on a 12" Turner an d Reich Convertible Triplet, and used the 19" f-stops. It was a little soft, but the exposure was about right. Try experimenting a little, that's half the fun a nyway!!

Franco Rallo
2-Dec-1998, 03:13
In mine opinion the main advantage of removing the front lens is that in this way the diaphragm stays before the lens, so the light travel is: subject-diaphragm-lens-film. It seems that this arrangement corrects aberrations of the single element better than the other pathway (i.e.subject-lens-diaphragm-film).I know that the first lenses used in photography, very simple and poorly corrected for aberration, have been used with the the diaphragm in front of the glass. I tried both the ways with an old Zeiss Protar VII Convertible, using the short-focus group (ca.300 mm focus) placed behind the diaphragm and in front of it, and working in both cases with f/22 on a 13x18 cm film.. In the former arrangement, the picture resulted much more sharp in the borders, while the central parts of the images were in effect equally crisp. I would like to know more about the influence of the diaphragm position in a lens. Thanks, Franco.

Kreig McBride
27-Dec-1998, 03:54
Yes. The correct method is to remove the front element on the Symmar lens. Not mentioned here is a term called focus shift. When using only the rear element the plane of focus will move as the diaphram is closed down. You should focus at the shooting aperture to get a reasonably sharp photo.

26-Jan-2009, 07:28
I am sorry about messing this thread a bit..

But I have convertible Summar 5.6/210 - 12/370mm and it behaviers similary.

The main problem is the focus shift caused by aperture. What is the best way to deal with it especially when I want to maximize depth of field?

When stopped down enough, the image on GG is so dark that it's impossible to correct focus. Especially if I want to check the sharpness of the foreground and background.

Even it would be helpfull if I would know where to put focus to get hyperfocal... I can build a guide for focusing if I know the focus shift caused by aperture.

Ole Tjugen
26-Jan-2009, 09:01
In my experience, the focus shift with aperture is negligible. Or maybe that's just me accidentally focussing "correctly"?

Anyway if you do see noticeable focus shift, most of the shift will happen as you dust stop down from wide open - from f:12 (wide open, converted) to f:16. If you can tune the focus at f:16, there should be very little focus shift left.

26-Jan-2009, 09:10
Yes, so far I have stopped down from full aperture. I'll check how focus shift behaviers on my lens.

Ole Tjugen
26-Jan-2009, 09:32
I'll check it out tomorrow, using a 300/500mm Symmar on a camera with enough bellows. But I'll have to wait for daylight. :)

Vick Vickery
26-Jan-2009, 12:46
Ole, night is probably the best time to check for focus shift...pick a street light up the way a bit, focus on it wide open, stop down and check the focus. A bright light at night is still easy to focus on as you stop down.

Ole Tjugen
26-Jan-2009, 13:55
"Street light"?

Can't see any from here. :D

Bjorn Nilsson
26-Jan-2009, 14:09
Vick, Ole is in Norway, not Newark. They only have electric streetlights turned on once a year, when they give out the Nobel Peace Price. Else they use lamps filled with whale grease. (Well, crude oil nowadays.) :)
The only possible glimmer of light is when the Polar bears show their teeth, by which I recon it's rather late, if you know what I mean. ;)

//Björn (swedish/norwegian for "Bear")

26-Jan-2009, 14:57
He's probably in the middle of the North Sea :D


26-Jan-2009, 17:06
The removal of the front element is the correct move to get the longer focal length. The aperture settings will not be the same, and there is usually another scale written on the shutter front. My symmar 210 has the larger 370 settings written in green.

Also, the focus shift can be a problem as mentioned, which means when stopped down you'll be examining a very dark image on the ground glass that won't be snapping when you rock back and forth like the f5.6 you've grown fond of. Remember, too, that for the 370mm something like 15" of bellows is needed which some cameras don't have.

For those reasons I've never found the longer focal length useful. After a period of time I went ahead and bought a 300mm and never looked back.


Ole Tjugen
27-Jan-2009, 07:54
I've checked now, and saw no discernible difference on stopping down from f:12 to f:22 with the rear cell of a 360/620mm Symmar convertible on my 24x30cm plate camera - which has the longest bellows of all my cameras. It might be that I could have spotted a slight shift if I had been watching the ground glass through a good loupe while closing the aperture, but my arms are too short to watch the ground glass and change the aperture at the same time with 76cm of bellows extension! :)

Kevin Crisp
27-Jan-2009, 11:18
When I test for this I stop down to f:22 and focus as best I can. There is at that stop typically a zone that seems sharpest, I find the middle of that. Then I open it up all the way and check the ground glass. Is it still the sharpest it can be for wide open? If not, try it a few more times. If you get the same result you have a little focus shift. This can be a dramatic effect with some lenses like a single element protar cell. I have a Wollensak wide angle that has a lot. I have not noticed it with the single cells of Symmars in the 180mm and 210mm convertibles.

Len Eselson
27-Jan-2009, 14:34
Having never run into focus shift caused by changing the f-stop, I would be curious if someone could explain why this happens.
Len Eselson

27-Jan-2009, 14:49
I did some testing against distant street lights.

Yes, the focus shift is much smaller than I remembered. Actuallu it seems to be so small that it does not have any practical meaning, as many of you have already stated :)
I did use 4x loupe, perhaps 8x or 10x would have shown more difference.

The bellow had to extended to the 38cm lenght to get focus at infinity (I measured only the lenght of bellow). The lens was attached to Toyo view camera.

Len, as far as I know, the focus shift is caused by aperture blades and usually it happens when there is no front element or design of front element allows it.

But that is all I know. I have found lot of discussion at the internet where common judgement is that most convertible lenses have remarkable focus shift, including symmars. But as usually, the internet facts turned out to be only rumours.

27-Jan-2009, 14:53

If you go to www.Cameraeccentric.com, scroll down to the Schneider Symmar catalog and click on it. It opens into the pages and gives specific data about using the lens with either element.

Good luck.


Ole Tjugen
27-Jan-2009, 16:22
Focus shift is a result of uncorrected spherical aberration, which is not a major limiting factor in converted Symmars. Chromatic aberration and coma is. ;)

28-Jan-2009, 11:39
Focus shift is a result of uncorrected spherical aberration, which is not a major limiting factor in converted Symmars. Chromatic aberration and coma is. ;)

I know, my coma has been messing me up for a long time.


28-Jan-2009, 18:51
The lens makers' instructions for conversion have varied over the years.
Try removing the front, make a picture then leave the front and remove the back, take a picture, switch front to back and take pictures.. There are lots of possible consequences, and with a good quality optic, most are inconsequential
Focus shift- if there is one, refocus when stopped down
Distortion can occur when the iris is not centered- probly not detectable
Focusing- if you use the rear position the bellows must extend farther than lens in front
Iris protection- if you remove the front element there will be no glass to keep your finger out of the blades
Convertability sometimes requires compromises in some facet of design/manufacture that does not permit each combination to be "perfect" , but nothing ever is
Don't obsess, take pictures and see what happens with YOUR lens