Unconvertible lens convertible?

[Tom Perkins]

I am wondering if my 135mm Schnieder Symmar-S would be usable with the front element removed as a longer lens in the manner of the previous convertible lens of similar design. It seems that they probably did not change the design of the lens that much. I am going to go ahead and try it at my first opportunity, but I wonder if anybody has tried this and could tell me how it worked. Thanks. Tom Perkins

 

[avandesande]

Practically any lens can be used this way. How good the element works depends on the lens design. My APO nikkor 360 has a second aperature scale for the rear element, which has a fl of 27 inches. It is really only usable at f64 or higher, but since I make contact prints I can use it. You have to factor in the size of your enlargment as well...

--Aaron

 

[rogein]

I have a friend who uses his 305 G-Claron this way - by unscrewing the front cell and increasing exposure about 2 stops - works in a pinch and plenty sharp for contact printing.

Cheers,
Roger...

 

[jimgalli]

Tom, give it the benefit of the doubt and put an orange filter out in front. That way you won't have different colors landing on different planes and making the image fuzzy. Stop way down.

 

[Claire Senft]

Just a thought. I do not know how this would affect a modern lens that was used with the rear element only but the practice for older lenses when using one cell of a two cell lens was to use, for example a #12 filter, and focus with the filter in place and at the stopped down apertue to eliminat focus shift.

If you have a very bright clear bulb try focussing as described above with say a 7x to 10 x loupe on the filament and then open the aperture all the way and see if it stays in focus. If it goes out of focus then the single cell is giving focus shift when used alone.

 

[MikeS]

It's my understanding that the only reason the Symmar-S lenses weren't marked as convertible was that convertibles were out of fashion by the time they came out, and that they would work fine as convertibles just as the non S Symmars do.

-Mike

 

[MarkS]

Somewhere I *had* the brochure Schneider used when introducing the Symmar-S lenses, from 1972 or so. In it they said, essentially, that they had sacrificed the convertible feature in order to improve the corrections for both halves used together. That still doesn't mean that you couldn't converting a Symmar-S, though.

 

[Ole]

Just about everything can be converted. Symmars, APO-Lanthars, Angulons et cetera.

The sole exception seems to be Tessar-type lenses. Give it a try anyway, just to see why not