View Full Version : Turner Reich Triple Convertible ? ? ? ?

Dan Dozer
23-Jul-2005, 19:06
I'm just beginning to get into 8 x 10 work, and I've recently picked up a Turner Reich lens for next to nothing to start to try things with. It's a Turner Reich Triple Convertible Series II NO. 5 (12" / 21" / 28"). I've never worked with triple convertable lenses before, so this is my first. The front and rear lens cells both have the same serial number on them - 117424, so I assume that the lens is as it was manufactured at the factory (and not two mis-matched cells). When focusing at infinity, the combination cells look to be 12", the rear cell looks to be 21", however, the front cell focuses at only about 22" instead of 28". So using either the front or rear cell really isn't much different in terms of focal length. The "infinity" I focused at was quite a long distance away - 400 yards. Is it common for these type of lenses to be that far off on the focal distance? Could this have just been a quality control issue at the factory.

I wasn't necessarily planning on using the front cell only, because from what I've read, it's not supposed to be as sharp . However, I am curious that it seems to be so far off.

Richard Schlesinger
23-Jul-2005, 19:42
I can't help with the discrepancy you describe - if the serial numbers match it doesn't compute. However I had the idential lens some years ago and made some lovely images with it in the 12" mode; 21" and 28" were soft and a bother (adding a rail and bellows to the Sinar Norma) so I didn't do it much after finding out how soft it was. I wish Istill had the lens!

Dave Moeller
23-Jul-2005, 19:52
Since the serial numbers match I can't imagine that you've got anything other than the proper lens cells in your hand. Since the combined cells focus at 12", then it seems likely that the other cells must be the correct 21" and 28" cells.

I think 400 yards might be conservative for infinity on an 8x10 camera It's pretty far out there, but the first thing I'd try is to find a subject that's significantly further away to test the infinity focus (from my back yard I can see a radio tower that's about five miles away; as long as the air is reasonalby clear I find it a great way to test infinity focus).

Finally, the performance of the individual cells will improve if you use strong filters (yellow being an old favorite), as chromatic problems seem to be the overwhelming problems with the individual cells. Make most of the light that's getting through one color, and a lot of chromatic issues disappear. (This assumes, of course, that you're shooting B&W. I suspect the lens would be pretty awful for color use unless you used both cells, and even then would be borderline.)

Best of luck to you.

Vick Vickery
23-Jul-2005, 20:24
Like the others, I can't add anything about the 3rd focal length that doesn't appear correct other than to remind you that you should switch the front group to the rear when using it. Whether this would affect the focal length as you measure it by bellows draw, I don't know but it should affect the bellows length needed by and inch or so anyway since the front element is closer to the glass when used in the back.

The softness Richard described could well have been due to a focus shift after stopping down the lens when using only one group. Triple-convertibles are noted for this and I find that my Turner-Reich (6 1/4"-11"-14") does exhibit this problem. The cure is simple: refocus after stopping down to the stop at which you will shoot, but this can be a little bit of a problem in dim light. You can experiment in bright light or by focusing on a particular light source (as a street lamp at night) and measure the focus shift that occurs (how many fractions do you have to move in what direction to correct the focus)...the shift is reported to be consistant, though I've never checked this out. I get pretty good results from single groups in my lens. Remember to shade the lens well...most of these Turner-Reich Lenses are old and uncoated.

Ernest Purdum
23-Jul-2005, 20:52
Are you putting the front cell on the back when used by itself? This is the way it is supposed to be used.

23-Jul-2005, 21:32
Ernest has probably hit the problem. When using a single cell, the nodal point shifts out from the center (diaphram) of the lens/shutter. If you leave the front cell on the front, 21 to 22 inches of bellows is about right for a 28 inch converted lens. Look at the magnification on the GG. There should be a decent bit of difference between the 21 and 28 cells when used alone.

If you're shooting B&W, using a yellow to red filter will greatly sharpen up the single cells. I can't tell the difference oon my T&R between dual or single cells when I use a 23a filter.

And contrary to what many say here, I also can not tell the difference between mounting the cells in front or behind the shutter! If you want to use the front cell by itself, leave it there. It's a whole lot less work and wear on the threads.

DO pay attention to focus shift when using a single cell! Check and re-focus after stopping down...

The 12-21-28 is a great combo. I like it better than the more common 12-19-25...

John Berry ( Roadkill )
24-Jul-2005, 10:15
That was my first lens. You will be very happy with it. I could only use the 20" part with my camera, but didn't have much luck with it. Then again I didn't know about focus shift and such then.

CP Goerz
24-Jul-2005, 11:30
In addition to the advice Ernest gave you try focussing at F22 to avoid much resetting of the focus distance, the wide open image is just too soft to be reliably used as the point of focus.

CP Goerz.

Dan Dozer
24-Jul-2005, 14:57
Thanks to everyone for the help. I've had a second look at the lens and by mounting the front cell on the back of the shutter, I do get the larger focal length. I guess i never read that part of the "Triple Convertable Lens Instruction Manual" and was not aware that this was how the lens was supposed to be used. Thanks to both Ernest and Rich for making that suggestion- now I feel like a real amature.