Focus screen foulup - I think

[Bob McCarthy]

Just located and purchased a technika 2000. It was advertised to come with a beattie screen. Price was Ok and it was advertised to be like new. Got the camera and it was pretty much as advertized.

Made a new friend who has offered to help get me started. Wonderful gentleman who is very generous with information and advice. On our first meeting face to face, he handed me a new fuji 180 (on board) so I could try out the camera. Thats rare in today society

I am minimally familiar with LF, but have extensive experience in photography (both 35mm and MF). Something with the screen is wrong. The screen appears to bow with any pressure(from placing loupe). On closer examination, there is only one screen, it is brightish on one side, somewhat frosty with grid on the other. Using a soft cleaning cloth, I can feel a very fine fresnel on the rear surface facing me. The film plane is obviously not accurate as it is bowed in normal position and is flexable. All that is in the camera is the plastic screen. Am I missing the ground glass screen? Seems so but I don't have any experience with LF viewing systems.

There are two silver hold down clips on each side of the current gg (?) , unused at present. What do I need to do to get the situation repaired?

No wonder the guy sold the camera, lousy focus. may be a blessing is disguise.

Thanks for any advice,

Bob

[robc]

take a look at this thread

http://www.largeformatphotography.in...ight=linhof+gg

it sounds like the GG has been replaced with a fresnel.

The GG should be where your fresnel is and the fresnel fitted on the outside under the clips. The frosted side of the gg should be on the lens side.

[Capocheny]

Bob,

From what I can remember of the Master Technika I had awhile back... the screen definitely did NOT bow when a focusing loupe was put onto it.

IMHO, it does sound like you're missing the ground glass... and if that's what it is, then it won't cost you all that much to get a replacement. I'd think it would be readily available from the distributor.

I'm sure if Bob S. is around... he'll most likely wade in on your question.

.

Rob,

Even if the ground glass has been replaced with a fresnel screen... are they THAT flexible such that it'll bow when you try to focus on it? I could be mistaken but I wouldn't think so. :>|

I have a fresnel on my Sinar and it's quite stiff... no bowing whatsoever.

Cheers

[Bill_1856]

The plastic screen should have been backed with a plain (or grid) piece of glass, which is apparently missing on yours. Get one from Beattie. Also, the plastic focusing/fresnel screen should have been shimmed to match the depth of 4x5 cut film holders. You may need to have that done by an expert (Marflex, Grimes, Ritter, etc). Hang in there -- it's a wonderful camera.

[Michael S. Briggs]

I've never had one, but from reading other postings, I think that the Beattie screen is an integral screen that combines a frosted surface and Fresnel lens into one piece of plastic. or maybe with a protective clear plastic overlay. This seems to match your description of the screen on your camera. So you are probably not missing anything. But it is a problem if your screen is not flat by more than a several thounsandths of an inch when you focus.

The two holding clips in the center are for attaching accesories such as a viewing bellows. The long metal clips are what holds the screen in place, with four screws holding the clips in place. There is nothing wrong with the two clips in the center flopping about.

Since the screen is bent, you might want to replace it with a conventional ground glass, or a ground glass plus plastic Fresnel combination. The Linhof-brand ground glass isn't outragously priced, or you can purchase some other brand. I prefer to use just a ground glass, but many photographers like to add a Fresnel. In my opinion the best way to install a ground glass plus Fresnel is ground glass towards lens, Fresnel closer to photographer. If the frosted surface if your current screen is laying on the positioning shims, and since your describe the Fresnel as closer to the photographer, you should be able to just install a plain ground glass by laying it onto the positioning shims, frosted surface towards the lens. But its probably an excellent idea to test the focus afterwards, or perhaps have the workd done by a repair placed (listed by Bill G.) in case the focus is somehow misadjusted.

Here are some past discussions: http://www.largeformatphotography.in...ad.php?t=17024, http://www.largeformatphotography.in...ad.php?t=14933, http://www.largeformatphotography.in...ad.php?t=12526 and http://www.largeformatphotography.in...ead.php?t=9396

[Bob McCarthy]

The plastic screen is definately bowed in by maybe 1/8 to 1/4 inch. It is held in (and maybe shimmed?) on the two short dimensions. The long dimension across (landscape) is definately bowed in towards the lens and can be moved more with modest pressure. If it were stacked over a glass GG I would guess it would conform to glass underneath. I'm trying to reach the original owner to see if he recalls anything, the original gg maybe in his possession.

I am concerned about calibration (?), and don't have a clue how to prove up good adjustment.

Thanks for your help.

Bob

[JimL]

As Bill said, you're missing the backing glass which protects the fresnel grooves. It sounds like your screen is either warped or is clamped into the gg frame wrong, causing it to bow. It would be best to remove the screen to see where the warp is coming from or (if you're not comfortable with DIY) send it to a repair person.

[KenM]

Sound like you're describing a Linhof Superscreen - I had one on my Master Tech, and was amazed at how bowed the screen was - I fail to understand why a $4500 camera has a piece of crap plastic GG/fresnel - brutal. In the end, I removed it and replaced it with a Satin Snow GG - it's certainly not as bright, but I at least know it's perfectly flat (checked with a depth gauge).

As was mentioned above, there should have been a gridded glass protector placed over the superscreen - since that's missing, I would either replace it, or get rid of the Superscreen and replace it with a plain GG.

If I were to replace it with a Fresnel-type GG, I would probably go with a Maxwell screen. I'll be sure to have a spare hour or so when I phone in the order

[Brian Ellis]

I had a Beattie screen on my Master Technika for a while. It didn't bow but it wasn't especially good either. Having spent what you must have spent to buy a Master 2000 I'd suggest that you forget the Beattie, spring for another $250 and get a Maxwell. That's what I did. It's a substantial improvement over every other type of screen I've owned (with the possible exception of the BosScreen, it's better than the BosScreen I think but not by as wide a margin as the others)and I've owned most of them at one time or another.

[Michael S. Briggs]

The plastic screen is definately bowed in by maybe 1/8 to 1/4 inch. It is held in (and maybe shimmed?) on the two short dimensions. The long dimension across (landscape) is definately bowed in towards the lens and can be moved more with modest pressure. If it were stacked over a glass GG I would guess it would conform to glass underneath. I'm trying to reach the original owner to see if he recalls anything, the original gg maybe in his possession.

I am concerned about calibration (?), and don't have a clue how to prove up good adjustment.

Thanks for your help.

Bob

If the screen is bowed this much, it needs to be replaced. The mounting method sounds correct. If you remove the clips by removing the four screws, you will find two metal strips which positon the screen. These aren't exactly shims, since the position position is adjusted by turning the screws on which these strips rest. Buy probably this won't be necessary.

Some of the links that I provided in my previous answer suggest photographic tests of the focus accuracy. If you are unsure of your ability to implement these tests, then send the camera to one of the repair places suggested above.

This screen isn't meant to be stacked over a ground glass. The frosted surface is integral to the screen that you have, so it shouldn't be put on top of a ground glass with its own frosted surface. What may be missing is a clear protective sheet that goes between the integral screen, with its combinded frosted surface and Fresnel, and the photographer. At one time the US distributor for Linhof supplied Super Screens for Linhof cameras. I don't think that these were a Linhof factory product -- probably that were Beattie screens. I think I remember previous complaints of them bending.

1/8 inch bow or more is definitely defective. So replace your screen. You can buy a Linhof ground glass from B&H or other suppliers, a Satin Snow, various generies on ebay, and see if you like these. Or you can try the Maxwell. Since the screen you have has its frosted surface facing the lens, probably you can make a straightforward replacement. Just don't make a replacement in which a Fresnel is in front of the frosted surface (this would require adjusting the focus). But without knowing the history of what has been done to the camera and examining the camera, we can't be sure, so either you should test the focus accuracy with your new screen or have a repair person install the new screen or check the camera for you.