Iris

Curt · Apr 25, 2007

I contacted SK Grimes about a new iris scale for my Schneider Symmar 210 in Copal #1. I asked them about a convertible scale for the shutter. They didn't have any notes on the 210 as a conversion lens. What dates were the Symmar 210 listed or made as a convertible lens. I may have to do some testing to make my own scale.

paul ewins · Apr 25, 2007

Here's the scale on my Linhof version of the 210/370 convertible. In this shot the aperture arm is at full travel. At f32 on the 210 (black) scale the apparent aperture size is 12.5mm while at f32 on the 370 (green) scale the apparent aperture size is 5.5mm. At f5.6/f12 the aperture is wide open.

Hope this helps,
Paul

Bandicoot · Apr 25, 2007

Not an answer, but maybe helpful

I don't have the information you asked for - hopefully someone else can supply it. But I do have that lens, mine in a Synchro-Compur 1, with a convertible scale on it. If you can't get the information you want, let me know and I can see about sending you a picture of the aperture scale, which might help a bit.

Peter

Curt · Apr 25, 2007

Paul, thank you for the picture and Peter, Grimes asked me if the lens had a previous shutter or if it was from a barrel. It came in a Copal #1 and I think it was just intended to be used as a single focal length lens but because of the design I found I can use it as a convertible. What I was interested in is what if any design changes were made and when. The Linhof 210/370 looks a bit older and the one in a Synchro-Compur 1 is probably older. I have a lens in a Synchro-Compur, it's a very fine shutter by the way. The Linhof lens looks like it is in excellent condition also. Have you used these lenses in the 370mm conversion?

Thanks,
Curt

Ole · Apr 26, 2007

All the "plain" Symmar 210mm's were sold as convertibles, as far as I know. The very early Dagor-types were even sold as triple convertibles; the later Plasmats "only" convertible. The "convertibility" was only dropped when the Symmar got additional letters - Symmar-S.

A Symmar in a Copal shutter is remounted. They came in Compur or Pronto shutters from the factory.

I use converted Symmars quite a bit, but I haven't used the 210 this way yet. Only the 150, the 180, the 240 and the 300...

Curt · Apr 26, 2007

Do you ever write a well thought out note then the server drops out? It happens every evening on Verizon and is driving me crazy.

Anyway.

Thanks Ole I didn't know the history of the Symmar-S lenses. Grimes did say something about the original mount or shutter. I was confused because I bought it new in a Copal #1 and never knew of the Compur shutters or even convertibles. I will have to try it out. Mine is an early '80s model. I don't remember where I bought it, maybe B&H.

I had to resort to cut and paste. What does UNKNOWN ZONE mean?

Curt

Ole · Apr 26, 2007

Curt, a Symmar-S might be in an original Copal shutter.

The pfd from 1980 on http://www.schneiderkreuznach.com/archiv/archiv.htm lists Symmar-S only, and both Compur, Prontor and Copal shutters.

The Symmar-S was not marketed as a convertible, but it is rumored that this is the only difference between the -S and the "plain Symmar" - the lenses are identical, but the -S was not marketed as convertible. I'm sure that SK Grimes could put a "plain" convertible aperture scale on it, and that it would be indistinguishable fro the "convertible" in practical use.

Curt · Apr 26, 2007

Thanks Ole, I am getting an education here, sometimes you never know what you have until something comes up. You are right, they said to send in the works and they will figure it out.

Curt

Dan Fromm · Apr 26, 2007

Um, Ole, if you look closely at the Symmar (http://www.schneiderkreuznach.com/archiv/pdf/sr_5.6_a.pdf) and Symmar-S (http://www.schneiderkreuznach.com/archiv/pdf/symmar_s_73.pdf) documentation, you'll see that there has to have been a redesign. The Symmar-S cross section shows a less symmetrical lens -- front cell palpably larger than rear -- than does the Symmar cross section.

I realize that cross sections as published aren't that trustworthy, but in addition the [published distances between principal points are quite different. Symmar, all > 0; Symmar-S, all < 0.

Cheers,

Dan

Ole · Apr 26, 2007

Different focal lengths on Symmars have always looked quite different - I believe the 210mm is usually the most "unsymmetrical", necesstiated by the unsymmetric #1 shutter. even so, none of the longer Symmars look particularly symmetrical

Just out of curiosity I've "measured" the focal length of a converted late 165mm Angulon. It matches that of the original description of Angulon as convertible lenses (I can't remember where I found those figures, and I don't have them available right now). Image quality didn't seem to be as good as from a converted Symmar, so I left it at that.

Anyway - if the marked aperture for a converted lens is 1/3 stop off, will that be a problem? If so, it would be better to measure the actual focal length and compute the aperture scale from that (aperture in front of a single cell is the simplest case for calculating apertures - F/#).

paul ewins · Apr 26, 2007

Hi Curt,
I haven't had a chance to use the lens as a 370 yet, so I can't comment about sharpness. My Symmar is assymetrical. The barrel of the rear cell is different in shape to the front and the rear element is slightly smaller than the front element. If they were symmetrical I would expect the lens to be half the focal length of the indivdual cells, i.e. 185mm.

In fact I don't think any of them are symmetrical. I also have a 150/265 and a 300/500 and the rear cells on these are also smaller than the front cells. In that respect I guess they are more like the "triple convertible" lenses, so maybe the front cell of the 210/370 would be 470? (front + rear = 2 x combined????). In any case the front cell is supposed to be less usable than the rear cell so it's purely academic to me.

Curt · Apr 26, 2007

I had a thought and checked the front element and it does come to focus at infinity with about 18 inches of extension from the ground glass. Mind you I was holding it with my hand and not on the camera and the quality of the front element alone, focusing only in front of the shutter, is questionable. I will have to do some work with this. I probably wouldn't use the lens as a convertible but it's nice to see what the lens will do. A triple like my Turner Reich lenses, I don't think so, A convertible in actuality, maybe.

jstraw · Apr 26, 2007

I just shot a test sheet with my 210 Componon-S with the front element removed. I'm not concerned with printing the test so I'll probably scan the film on campus on Monday.

By the way, anyone know anything about a Componon-S taking lens? I can't find anything about it on the Schneider site.

Ole · Apr 27, 2007

Curt said:
I had a thought and checked the front element and it does come to focus at infinity with about 18 inches of extension from the ground glass. Mind you I was holding it with my hand and not on the camera and the quality of the front element alone, focusing only in front of the shutter, is questionable. ...

Use the rear element, if you use one alone. Or if you use the front cell, it should be mounted behind the shutter (a bit difficult with a #1, a lot easier with a #2 or #0).

The extension will NOT be a good indication of focal length: single cells are very unsymmetrical, and extension at infinity focus is often 20% different from true focal length.

argus · Apr 27, 2007

Ole said:
The extension will NOT be a good indication of focal length: single cells are very unsymmetrical, and extension at infinity focus is often 20% different from true focal length.

Ole, that is correct and a real pain:

I can hardly get my 360mm as 640mm focussed at infinity on the 8x10" with 770mm bellows...

G

GeorgesGiralt · Apr 28, 2007

Hello !
I've one Symmar 210 in it's original Compur Electronic shutter.
The iris scale is labeled 5.6 for the 210 lens, and in exact correspondence 12 for the 370 lens.
All markings are lined up all way from 12 to 64. (this left the 2 extreme positions unmatched, I think Schneider thought that going at 90 or 128 with the single cell 370 was not a good idea)
BTW, the scale is with click stops at 1/3 of a stop interval
So the scale reads
5.6 8 11 16 22 32 45 64 for the 210 and
12 16 22 32 45 64 for the 370.
Hope this helps !

Iris

Curt

paul ewins

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