How to convert a lens?

[Ed Pierce]

I read somewhere that some lenses can be converted by removing one of the elements. Wondering if I could do this with mine and if so how to go about it. I use both 4x5 and 8x10 with:

Nikkor M 450
G Claron 305
Symmar 210
Super Angulon 120
Rodagon 90

[Gem Singer]

None of the lenses on your list are convertible-type lenses.

Also, you would need two sets of aperture scales on the shutter, if they were.

[Iga]

Hi !
Older Symmar 210 is convertible for sure. Normally it cames in shutters with plate for both focals 210 and 370mm
Best,
Igor.

[Gem Singer]

I stand corrected. Didn't realize that the 210 Symmar was the older type.

[Vick Vickery]

Yep, as Iga and Gem said, the Symmar (but NOT the Symmar-S) would be convertible. If it is the convertible, it probably has two f-stop scales on the face of the shutter, one for 210mm and one for 370mm.

To use the convertible feature you remove the front lens group, focus on your subject, stop down the lens to your desired setting using the upper f-stop scale which starts with the slower f-stop setting, THEN REFOCUS THE LENS!!! I have always suspected that much of the bad press the convertible lenses get is because the focus often shifts when stopped down with only one lens group being used and the photographer neglects to check his focus. Focus shift on convertible lenses when converted is not at all unusual and is no problem as long as you watch for it.

[Iga]

There is some old literature at Schneider site. I have 180/315mm and 210/370mm Symmars. Both come in compur shutters with two scales.
Best,
Igor.

[Dan Fromm]

The G-Claron is also separable whether it is a dagor or plasmat type; remember that there are G-Clarons of both types. All dagor and plasmat type lenses can be separated. With either type a single cell - for most but not all the rear -- will form an image. Whether the image is good enough is an open question. The manufacturers usually say it isn't, some users disagree.

The Nikkor-M is a tessar, not separable.

The Rodagon is a plasmat, separable but not recommended and also probably not that good a taking lens except closeup.