View Full Version : summar convertables 135mm/235mm+180mm/315mm

mark e mark
2-Dec-2006, 10:23
Hi, I have just purchased 2 summar lens, 135mm and a 180mm. After receiving them in the post, I discovered they are convertable (135mm to 235mm and the 180mm to 315mm) -sweet. However, with both front and rear elemets in place the lens are 135 and 180, but do I take the front element group off to get the longer focal length or the rear group? If I take the rear group off, what happens if I leave the rear on and take the front off - a different focal length or not. I have read that the longer focal length is soft - but I take it not to bad. both lenes date from 1968-1971.



Kevin Crisp
2-Dec-2006, 10:49
Mark: Though many eBay sellers state it otherwise, per Schneider you take the front element off for the longer focal length. Stop down a long way when using the back element alone. Whether the quality of the image with one cell is "good enough" for your purposes is something only you can judge. I encourage you to try it. If you don't have enough bellows for for the longer length (and it will take more than 315mm of bellows to shoot the 315 element at infinity) you can use the front element, the f:stop scale is still essentially correct even though the focal length isn't exactly the same. I have has some where front and rear elements were pretty decent used alone. The suggestion is often made to use a strong filter like a yellow when using one element, I have not found that a benefit. The 180 Symmar is one of my favorite lenses, have fun and good luck.

Ole Tjugen
2-Dec-2006, 10:52
Mark, I'll assume that you meant to write Symmar, not "summar"?

You take the front cell off to use the longer focal length. The converted lens is soft in the corners, but quite usable when stopped down to about f:32. In that mode they also need a bit more bellows draw than you would expect - I think you need about 27cm for the 235mm, and about 35cm for the 315mm.

mark e mark
2-Dec-2006, 11:22

Sorry, I did mean Symmar (u next to y on keyboard- but still should have checked before posting).
Thanks for the quick reply. Taking the front element group off is easier - but as the lens info length and f12 was posted on the front element group and no info on the rear group, I was unsure. Looks like I will need to use the triple extension on the MPP.

Many thanks again.



Any other comments on these lens will be appreciated.

Kevin Crisp
2-Dec-2006, 11:45
I knew what you meant. It is counter-intuitive; there is something that makes you not want to expose the shutter internals to the scene, but it is the front element you take off. The older ones had the f:12 in green (matched the slower aperture scale color) on the side of the rear element but Schneider dropped that and so there is confusion. These lenses can build up significant haze inside, usually in a ring internally. If the threads on the elements are not dinged up it is not hard to disassemble one and clean it up. (The SK Grimes wrench is terrific for this.) If somebody has painted the shiny chrome of the threads on the front element black you are done for. Use a lens shade, if you have good samples these are terrific lenses I think you'll really pleased. Even ones much older than yours performed very well.