linhof technika ground glass shim

[patrick_5926]

Hi, all

I just bought a used linhof Technika IV 4x5 camera. I did a search on this site for linhof ground glass as the original one is bent. I thus learned that mine is a linhof super screen which tends to bent.

But another thing I found is that my technika does not have the 4 shims in the corner at the ground glass. It seems this causes problems since a rough measure shows about 1/16 inch difference of gg position and a standard 4x5 holder.

Now the question comes, where can I buy these adjustable shims? Or if it is not available, what is suggested to be good replacement for those? If you know any place that can calibrate my linhof, that will be awesome. Any suggestions are welcomed.

Thanks,
Patrick

[Michael S. Briggs]

If you are in the US, the Linhof suggested repair agent is Marflex

(http://www.hpmarketingcorp.com/warrantysvcs.html). In Europe, contact Linhof directly.

[John_4185]

Now I am puzzled. I have a Linhof IV (so-called transitional model?) and a Linhof Color (4-digit serial number). They have the same back. No shims, nor can I see any detent or place intended for shims. Anomaly?

Bent ground-glass? And 1/16 of an inch is a huge error!

Who's messed up here?

[Neal Shields]

I suspect that Bob Solomon will answer this, but as I remember, the shims are for when you don't have the super screen.

There are several ways for ground glasses to be installed on cameras. Ground surface toward the lens, ground surface away from the lens with a fresnel screen against the ground glass surface, frensel screen closest to the lens with the ground glass against the cut surface of the frensel screen. Etc.

As I remember Graflex did it one way and Linhof another. However, all these different spaceing considerations.

I suspect your camera didn't need the shims as currently configured.

[andy bettles]

Patrick,
There are 2 different types of ground glass backs for Technikas, Only the later version has the 4 adjustable shims at each corner which are adjustable (zero-able) enabling the use of non factory ground rangefinder cams( you can tell the difference as they have 4 little grub screws drilled through the frame so you can adjust the shims). The earlier backs were non adjustable and you needed to send the entire lens/camera combination into Linhof to have the cams ground to use the rangefinder accurately.
There are on a Tech.4 (as I recall) two steps or ledges that the ground glass/fresnel sits on.The smaller fresnel on these earlier cameras sits in the lower stepped ledge without affecting the position of the ground glass on the upper one.
I'm sorry I have never used a super screen (or seen one) but if your film plane is that out of sync. with your ground glass, either it is just physically in the wrong place or your measuring is inaccurate.
Maybe try using a standard ground glass (in the correct position) and see if it makes a difference.
Andy

[Michael S. Briggs]

You might want to make some photographic tests to check the focus of your camera. Perhaps it is correct and doesn't need repair. Here is a previous post with suggestions: Ground Glass focusing errors at
http://www.largeformatphotography.info/lfforum/topic/118997.html.

[John_4185]

The old Linhof back was on the bench, so I just measured and...

To affirm and add to Bettle's good information, the second 'ledge' between the ground glass and lens is 1/16" closer to the lens than the installed ground glass.

Patrick if the 1/16" difference you found is closer to the lens, then perhaps you are measuring from the fresnel, or the ground-glass is mounted on the wrong detent. It should be on the ledge furthest from the lens, with the matte surface facing the lens.

Hope this helps.

[Bob Salomon]

Call Marflex for the correct answer.

[patrick_5926]

Thanks all for the information.

Bettle's suggestions are very helpful. Since mine doesn't have '4 little grub screws drilled through the frame' I conclude that it is the model without the adjustable shims.

Also, the back is exactly as jj specified. It has two 'steps' or 'ledges'. The gg fits into the shorter ledges, which is closer to the lens. So maybe the previous owner misplace it. I am going to get a longer gg that will sit onto the second ledge. Anyway, I use GG only for focus. So the cam miss alignment is not that critical. I will take some test shots to verify the focus.

Thanks again for everyone's attention. People on this forum are always helpful.