View Full Version : Filter size and screw in front cap for Truner Reich

Mike Troxell
28-Dec-2003, 17:49
I just got a Truner Reich 12"/19"/25" lens as a gift. I already have a 12" lens (well, close enough), a Fuji C 300 that covers 8x10. What I plan to do is use only the seperate 19"/25" configurations of the TR and use the Fuji 300 instead of the 12" settup. Since I will always have the Fuji with me when using 8x10, I would like to carry the TR with the front element removed. Is there a screw-in lens cap that will fit a Turner Reich with the front element removed? If not, is there a screw-in lenscap that I could use with a step up ring and does anyone know what size I would need?

I also need to find what size threaded filter I could use on the read element.

Brian Ellis
29-Dec-2003, 06:17
I'd suggest that rather than looking for a screw in lens cap you look for a yellow or orange filter that will fit. Using a yellow or orange filter will improve the quality of your images (at least they did for me) when you use the two longer focal lengths and will also protect the shutter (which I assume is why you ask about a lens cap). I don't know what size thread you need, I'd suggest asking Steve Grimes' company about that kind of thing. They can make almost anything in any size at reasonable prices. For example, they could make a step up ring in a standard filter size and then you could use a yellow filter on it. Or they could make a screw in lens cap for you if you don't want to use a filter.

Mike Troxell
29-Dec-2003, 07:24

I thought about using a filter on the front to protect the lens where the front element was removed. Someone else had mentioned in another post that the filter whould be used behnd the lens. Thats why I was thinking of a threaded filter for the back and a lenscover for the front. If a front filter would'nt hurt performance then that would be just as good. I'll check on it. Thanks.

Pete Caluori
29-Dec-2003, 08:21

In a discussion with Ken Hough a couple of years ago, he told me that the Turner Reich lenses came supplied with an orange filter. Most of these filters had become lost, or discarded and he had only seen one - I've never seen them. The filter was meant to be used on the rear element and in addition to improving contrast, it would correct focus, when only using a single cell. Ken may have some information on this on his WEB site.

Regards, Pete

Michael A.Smith
29-Dec-2003, 11:30
I think you are going about it all wrong. The TR with both elements is a fine lens. Where it falls down is when used with one element--so why would you want to use it that way?

But if you do, carry it with both elements in place. Then you can decide which one to use when you set up. Sometimes you may want to use one element. Sometimes the other. How can you possibly know ahead of time?

Mike Troxell
29-Dec-2003, 14:26

I was planning to use it that way because I already had a Fuji C300 lens when I got the TR as a gift. Of course, I plan on making an identical exposure with the Fuji and with the TR 12" and compare them. I expect the Fuji to be sharper than the TR with both elements setup as a 12" but if there is no difference in sharpness, then I will probably use the entire TR like you suggest.

While we're on the subject of TR's, I remember Ken Hough saying in a post once that the Turner Reich convertibles originally came with a deep orange rear screw-in filter that compensated for focus shift. Does anyone know what size filter this was? Also, exactly how would a deep orange filter compensate for focus shift? Would it block light wavelenghts that account for the shift or what?

N Dhananjay
29-Dec-2003, 21:17
The orange filter is not to compensate for focus shift but to deal with chromatic abberation. Chromatic abberation deals with the fact that the lens brings light of different colors to focus at different points. The chromatic abberation is corrected by symmetry in the TR lens. When you remove one of the cells, you lose this correction. The way this is dealt with is by using a strong monochromatic filter to restrict the spectrum. Using an orange filter allows only a restricted set of wavelengths through, which can be brought to focus on one spot with somewhat better fidelity.

Focus shift is a somewhat different phenomenon that is caused by uncorrected zonal spherical abberation. Spherical abberation refers to the fact that light from different parts of the lens are brought to a focus at somewhat differnet points resulting in a spread function to a point source (light from the periphery of the lens is brought to a focus at a differnet place than light passing close to the optical axis) - it is again corrected by symmetry. Spherical abberation is reduced by stopping down but the problem is that this can result in the apparent point of best focus changing, the phenomenon known as focus shift. The point of best focus really does not really change - it is our perception of it that does (in that sense, it is a bit of an optical illusion). In my observation, if you judge focus by contrast, you are likely to experience focus shift.

Cheers, DJ

Mike Troxell
30-Dec-2003, 06:53

Thanks for explaining it. I've heard the terms for years but never had a clear understanding of them till now. Thanks.

Jay DeFehr
30-Dec-2003, 13:08
I'm sorry Mike, I'm a little confused. If you intend to use one or the other of the cells, but not both, won't you need to carry them both? If so, why wouldn't you keep them in their respective places until it's time for an exposure? I have a TRT and was thinking about finding a lens shade that would screw into the shutter. I wonder if an old barrel with the elements removed would work?

Mike Troxell
30-Dec-2003, 16:24
Jay, I'm afraid I was a little bit confused too. I hadn't thought it thru completely. I will probably end up carring both cells in their respective places until its time to make an exposure.

I took the TR to a repair shop and had the shutter speed checked today. Everything is accurate up to 1/25 and from there the speeds go up to 1/75 instead of the marked 1/150 (1 sec = 1 sec. 1/5 = 1/5 .....1/25 = 1/25, 1/50 = 1/30, 1/100 = 1/60, 1/150 = 1/75.This is no problem for me since most of my exposures are at 1/60 to 1/30 or more. The repair shop also measured the TR and told me it uses a series 7 filter on the rear element. Now all I need to do is find a source for series 7 filters.

Jay DeFehr
30-Dec-2003, 18:05
I hope you enjoy your lens Mike. I have the 12, 25, 28 version and the two longer FLs are too long for my bellows at portrait distances, so I use it in its combined configuration. It makes a very nice portrait lens that lands conveniently between my Ektanon and Verito on the sharpness/contrast continuum. Here's a link to a self portrait made with my then-new TRT, while investigating a light leak.


Good luck.