Question re: convertible lens orientation

**Randy H** · 19-Mar-2007, 13:14

I thought I had read somewhere here, but can't find the answer.
When using a triple convertible lens, seems I read that using the rear cell alone, that it should be moved to the front? Or was it when using the front cell alone, it would work better if moved behind the shutter?

I have not shot this lens yet, but as stated, seems I remember a thread about lens orientations. Does it make a significant diff?

(Don't guess it makes any diff, but lens is nameless except for "symmetrical convertible" on the lens, mounted currently in a Conley Safety. FL is approx. 12/18/24 judging from bellows draw on a Conley View. Doesn't cover 8x10 wide open, but covers 5x7 nicely, with room for a little wiggle.)

**Vick Vickery** · 19-Mar-2007, 13:33

I have always read that the single element group should be used behind the shutter and have always done it this way, though I've never run any tests to see if I could see the difference. I currently use two triple convertibles, a Wollensak and a Turner-Reich.

**Ole Tjugen** · 19-Mar-2007, 14:25

Originally Posted by Randy H

II have not shot this lens yet, but as stated, seems I remember a thread about lens orientations. Does it make a significant diff?

(Don't guess it makes any diff, but lens is nameless except for "symmetrical convertible" on the lens, mounted currently in a Conley Safety. FL is approx. 12/18/24 judging from bellows draw on a Conley View. Doesn't cover 8x10 wide open, but covers 5x7 nicely, with room for a little wiggle.)

Always on the back, unless you have a very good reason (like insufficient bellows draw) to put it on the front.

Yes, it does make a difference. Yes, you can very often see the difference by looking at the print, which IMO means it's significant.

Bellows draw with the single cell behind the shutter is significantly longer than the focal length, which is why it's sometimes necessary to "break the rules". Just as long as you know that it makes a difference...

I use convertible Symmars in 180, 210, 240 and 300mm, as well as a convertible Turner-Reich, two Zeiss Serie VII Protars, and a handful of casket sets...