Mounting a Symmar 360mm f5.6 lens

<p>I have recently bought a Symmar 360mm f5.6 convertible lens. minus shutter. I have now discovered that a No.5 Compound shutter will cost around £250 and having it mounted proffessionally will cost around the same.<br>

Whoops!<br>

I already own a Packard type shutter with an aperture of 105mm. I found an iris diaphragm with an aperture of 64mm on Ebay.<br>

I have the machining skills to make the threaded adaptors that I need to mount this lens but how do I determine the spacing between the lens elements?<br>

Can anyone help me?<br>

Thanks, Norman</p>

<p>Norman, hi. It sounds like what you have are the front and back cells from an old Symmar. If this were my problem (don't take offense, please), I would sell them on the hated auction site, and make them somebody else's project.</p>

<p>If you want to be shooting in a week or two, you can get a 360mm plasmat lens in a working shutter for $400 to 600 from KEH.com. You're in the UK, but they ship internationally. If your hobby is photographic machining for it's own sake, that's another matter.</p>

<p>Here's a few thoughts. (I'm no expert. Michael Briggs or Charles Monday may be around.)</p>

<p>(i) You may be able to measure the lens spacing off the barrel mount, but, having said that, it sounds like you don't have the barrel mount and all you have are cells.</p>

<p>(ii) Schneider says this lens was supplied in a '5FS' shutter in one place, and in a 'IV 10/2' shutter in another place (whatever 'IV 10/2' means). J-C Barnoud, on <a href="http://www.largeformatphotography.info/shutters.html">this page</a>, says #5 was a nonstandard size and includes shutters with different specifications.</p>

<p>(iii) For what it's worth, <a href="http://www.sizes.com/tools/shutter_photo.htm">this page</a> says a <em>Prontor </em>#5 has cell spacing of 42mm. I don't know if this is the same as the Compur standard.</p>

<p>(iv) To confirm the spacing is perfect, you may need specialized collimation equipment. Carol Miller, who knows a thing or two about shutters, says <a href="http://www.flutotscamerarepair.com/FAQ.htm#RemoveLens">a critical distance</a> is from the rear element to the iris diaphragm. This is probably important to you, if you're trying to jury-rig a separate diaphragm.</p>

<p>Read my second paragraph again. Good luck, and keep us posted how you get on with this.</p>

<p>Please confirm what you have, cells only or complete barrel lens.</p>

<p><a href="https://www.schneideroptics.com/info/vintage_lens_data/large_format_lenses/symmar/data/5,6-360mm.html">https://www.schneideroptics.com/info/vintage_lens_data/large_format_lenses/symmar/data/5,6-360mm.html</a></p>

<p>principal point seperation may be what you are looking for.</p>

<p>Thanks for your contribution Dave, you are right, the challenge for me is solving the problem. I just have the two cells. I have a data sheet from Schneider (in German) that shows the overall size of the combination but I do not think that is accurate enough. I am not in UK, I am based in the Falkland Islands, so am isolated from direct contact with the rest of the world. But it is a great place for landscape photography.</p>

 

<p>The obvious solution is often best. Schneider is still in business. In the US, look here http://www.schneideroptics.com/ for contact information. For the rest of the world, which includes the Falklands, look here http://www.schneiderkreuznach.com/index_e.htm <strong>Ask</strong> Schneider for the dimension you need.</p>

<p>Or, you could go here http://www.schneiderkreuznach.com/archiv/pdf/sr_5.6_a.pdf . You want dimension "c", should be able to calculate cell spacing from that and the your cells' rim-to-shoulder distances.</p>

<p>Charles, the distance between a lens' principal points is rarely the distance between the ends of the barrel or shutter it fits in.</p>

<p>Norman, if you are happy shooting with a Packard and are up to turning them then by all means make the threaded bushings you need. FWIW, my friend Eric Beltrando, who's written a ray tracing program that he uses to evaluate lens designs, tells me that Plasmats' performance is not particularly affected by small errors (~ 1% of focal length) in cell spacing.</p>

<p>Besides Dave's excellent observations, people think they can simply put the cells into a shutter and call it good. Well, a 135mm lens and 210mm lens in the same shutter will need different calibration (spacing) for the apertures as well. In theory, f/2 on a 100mm lens would be 50mm, while f/2 on a 200mm lens would be 100mm. The shutter might have the same aperture scale, but it is entirely different for every focal length.</p>

<p>Hello Norman,<br>

May I chime in ?<br>

As the shutter for this lens was being phased out, Schneider Optics delivered the latest run of this lens in a Compur #3 shutter. but this reduced the effective speed to 6.8 if I'm not mistaken. So you may make a try at a Copal #3 shutter if you've on in hand...<br>

As the overall length of the lens, I've found it to be very precise (but for a Rodenstock lens) and helped me find a bad lensboard mount explaining the poor performance the lens showed. (the lensboard was too thick and preventing the rear cell to sit properly on the shutter, sitting on the board instead ! So increasing the cell spacing and destroying the lens sharpness by a tremendous amount)</p>

<p>"IV 10/2" is probably a compound shutter, which were frequently designated with a roman number. But within each basic size, there were some variations on cell threads and spacings, which the second numbers describe.</p>

<p>The spacing between the cells and the spacing from the aperture are both important. How critical depends on the particular lens design.</p>

<p>One approach: measure the threads on the cells and from this you can probably determine the intended shutter (Compound V, IV). Most likely if you find one of those shutters, it will be good enough. If you are patient, sometimes bargains can be found on eBay, but it will take awhile. But you may have to ask the seller to measure the shutter to make sure that it is the correct variety, and even then there is a risk that you will get the wrong sub-type.</p>

<p>Michael Axel wrote "Besides Dave's excellent observations, people think they can simply put the cells into a shutter and call it good. Well, a 135mm lens and 210mm lens in the same shutter will need different calibration (spacing) for the apertures as well. In theory, f/2 on a 100mm lens would be 50mm, while f/2 on a 200mm lens would be 100mm. The shutter might have the same aperture scale, but it is entirely different for every focal length."</p>

<p>Whether the aperture is scaled correctly or not, stopping down by one stop indicated, e.g., from f/11 marked to f/16 marked, <em>always</em> stops the lens down by one stop. Think about it and you'll understand why.</p>

<p>A practical implication is that a shutter <em>need</em> not be rescaled when the lens it was scaled for is replaced with a different one. One simply has to find the marked aperture at which the diaphragm just starts to cover the lens' entrance pupil. That corresponds to the lens' maximum aperture. Mark that on the scale.</p>

<p>If, however, the diaphragm starts to cover the entrance pupil when the aperture indicator is off the scale or too far to the right, there's no alternative to having the shutter scaled for its "new" lens.</p>

<p>Thank you everybody for your suggestions, yes Dan, I missed the obvious, ask Schneider!<br>

There won't be a problem with the diaphragm, I don't believe it has a scale anyway so I'll just have to make one.<br>

I think that I will go ahead and make the parts but keep my eyes open for a no. 5 Compound shutter which is the one it was originally mounted on. Does anybody have one?<br>

Thank you again everybody. Norman</p>

<p>If I'm not mistaken, the early Componons used the same cell thread, and cell spacing as well. (though I could be wrong..) It would probably be easier to find a junk Componon 360 than a Compound #5. If you have the ability to measure the thread diameter and pitch, I can compare it to my 360 Componon, complete with barrel and tell you the barrel length and aperture location, if that helps.</p>

<p>Erie, I don't have a thread gauge but the pitch appears to be .75mm and the diameter is definitely 68mm.<br>

Norman</p>

<p>You do not need a thread pitch guage to measure the threads. SAE are measured Threads Per Inch and Metric are measured MM Per Thread. Measure from valley to valley or peak to peak. </p>

<p><a href="http://skgrimes.com/adapter/measure.htm">http://skgrimes.com/adapter/measure.htm</a> for more info.</p>

<p>not if your eyesight is not that good!</p>

<p>Dan was correct, Schneider provided the information very quickly. Excellent service for such an old lens!</p>

<p>Dan was correct, Schneider provided the information very quickly. Excellent service for such an old lens!</p>

 

Good thing. I know this is a very old thread, but did you actually succeed in mounting the lens cells? I’m asking because I have a mounted lens with a missing rear cell and I am looking to find one or the set of both. In case you still have it catching dust somewhere drop me a line please :·)