G-claron 240 front and rear group for portraits

[Kevin Crisp]

There are lots of threads suggesting putting the aperture in front of a single cell (cell inside camera) is advantageous. Ron Wisner used to have posted some comments about lens bench testing that showed some performed better on the front, but it has been a long time since I could check on what he said and I'm going from memory. The conventional wisdom is that convertible lenses when used with both elements do better with the longer cell of a so-called "triple convertible" on the front. Wisner's comment may have pertained to using the shorter cell on the front when both are used.

My personal experience is that I've noticed no difference practically speaking with using a single cell on the front rather than the rear and there can be a big advantage in bellows draw. I've also not noticed a practical difference (with B&L protars) in using a yellow filter. I've found single cell use of Zeiss protars basically useless even at small apertures; the sharpness fall off is just too much for me. B&L ones have always been better for me in that regard.

For you? What you're doing seems to be working fine. I'm going to try it.

[Peter De Smidt]

I was just able to do a quick test. With my 240mm G-claron, the mounting threads for the front and rear cells are not the same, and so moving the front to the back isn't an option. Using just the back cell works, and it produces a dim but managable image on my 8x10 ground glass, using the modeling lights of my Speedotron strobes to provide light for focusing. It really isn't that bad. Holding up Fresnel, a cheap whole page magnifier, to the ground glass does usefully lighten up the corners of the glass. Unfortunately, the rear cell protrudes about 2mm too far back to use as-is with my Sinar shutter. I'll have to make a spacer of some type.