300mm f5.6/500mm f12 Convertible Symmar

[Ron Marshall]

Could anyone tell me how sharp this lens is, and it's approximate weight?

Are there any particular downsides to convertible lenses?

[Jim Rhoades]

You just don't know how sharp it will be until you test it. And, acceptable might depend on if you enlarge or contact print. I just ran some tests with a bunch of lenses from 150 to 240 including some big name equipment. My sharpest lens that I use in 5x7 is an old 210mm Caltar S convertible made by Rodenstock. Unlike Schneider, with this lens you remove the rear. As a 210 at infinity it will cut your eye. However doing table top close up it sucks. It converts to 400 and is not bad. I use a 240/420 Schneider for 8x10 and it's fine converted, but 8x10 is contact only.

A Wollensak 13,20,25 is fine for 8x10. I have yet to test it for 4x5 and enlarging at 25".

I think it's 35.2 oz.

[Steve Hamley]

Ron,

http://www.schneideroptics.com/info/vintage_lens_data/large_format_lenses/symmar/data/5,6-300mm.html

Combined it should be quite sharp, but shine a light through it and see if there's any fogging or haze.

Converted, it suffers the same as all convertible lenses because abberations are not as well corrected as with the complete lens. Consequently shooting at small stops is recommended with single cells of convertible lenses.

If you're shooting B&W, many people recommend using a dark yellow or light orange filter on the single cell. B&W contact prints would likely be acceptable, enlarged color prints taken with the single cell, maybe or maybe not depending on enlargement factor.

Steve

[Ron Marshall]

I have no experience with convertibles. Is the longer focal length achieved with the rear element attached?

Are convertibles usually sharper at their longer focal length, or is there no firm rule?

[Ole Tjugen]

1) It might be slightly less sharp at full aperture than a modern aspheric lens, but I doubt you will see any difference in less than 2x2.5m enlargements (10 x) from an 8x10" negative. At f:16 all lenses are basically equal.

2) With all convertible lenses, you remove the front element. If you wish to use the front elment alone this should be placed at the rear of the shutter. However Schneider DID recommend putting the single (rear) element in front IF the camera didn't have sufficient extension to reach focus in the normally recommended way.

"Convertibles" are always a compromise. They are sharpest when complete, but not as theoretically sharp as they could be if the manufacturer decided to drop the "convertibility". In practice here's not a lot of difference.

When converted they are just about as sharp in the center, but the sharpness falls off very dramatically toward the edges. It is often recommended to use a strong monochromatic filter when shooting converted, to alleviate the chromatic aberration. I have photos which show this very clearly - but I also have photos that are tack sharp all over, shot with the rear element of a convertible Symmar, without filters.

BTW; I have used a 150/256 on 4x5 and 5x7", a 240/420 on 5x7 and 18x24cm, and a 300/500 on 4x5 and 18x24cm (so far).

[ronald lamarsh]

My only experience is with my old 135/235 convertible symmar, which was a linhof select in a linhof shutter. I have several good images taken with this lens converted to 235 with a #15 yellow filter and it is plenty sharp for enlarging out to 16x20. Fully assembled it was as sharp as any other lens I have or have owned including my 240mm G-claron.

[Ron Marshall]

Thanks for all of the informative posts. Now I don't feel quite so lost on my ebay quest for a long lens.