Graflex.org

[shutterfreak]

Hey everyone I got my new graphic today and just had a few questions.

When was it made, serial number is 873077. The camera is in great condition. I fell in love with it the moment I picked it up. Great build quality, and very beefy.

Second question. I don't have a ground glass. Is it possible to just make one and how would you do that (sandpaper on the glass???).

Third question, my camera came with the Optar 135 by Wollensak. On the shutter I have speeds like 200, 100, 400, 50 etc and it is completely variable between them (or at least it seems) How do I get 1/3 EV 2/3 EV steps etc. and how do I know that when the arrow is lined up with 100 it is 1/100th?

Thanks everyone!!!

[t.r.sanford]

You raise some interesting questions.

The two traditional ways of producing a ground glass surface were (of course) grinding, with the abrasive on a plane surface and the glass driven across it in random directions, or etching, using hydrofluoric acid.

The right kind of sandpaper might work, but I think it would take a good deal of experimenting to find the correct grit and the most satisfactory technique.

Similarly, hydrofluoric acid is available (it's used for making decorative glass objects), but you'd probably need to conduct a few tests to see just what it does.

You might locate a good local glass supplier and see whether it stocks ground glass of the right thickness. I've done this, with decent results, but it was years and years ago, and glass suppliers nowadays don't seem as complaisant as once they were. The commercial product I got has a coarse surface, which produces a nice snappy image for focusing, but tends of obscure fine detail. It also is too thick to fit into a "Graphic" focusing panel, which did not matter for my application.

The most efficient and, I dare say, cost-effective way would be to buy a replacement focusing screen. Stephen Shuart, who is referenced on the links page of this site, has a wide variety of useful glasses, including "Graphic" focusing screens.

As for the shutter, I have not examined a whole lot of them, but the ones I have looked into have a stepped plate that rotates beneath a follower when you turn the rim. Thus, 1/100 has its own step, and so does 1/200, with a short incline between them. You can't get intermediate speeds with a shutter of this kind -- but you also don't have to use a magnifying glass to make sure the speed setting is precisely aligned with the index mark.

I am not sure the thing is worth trying with any shutter, since actual speeds almost always vary from marked speeds. According to the "Focal Encyclopedia of Photography" (1969, reprinted 1982), the accepted tolerance in effective exposure time for diaphragm shutters is plus or minus 20% for exposure times longer than 1/125 sec., and plus or minus 30% for shorter exposure times. In practice, after the shutter has been out of the factory and in use for awhile, you do well to be within one stop of the marked times at all speeds.

When using slow materials for which very accurate exposures are necessary, it's always a good idea to do a preliminary exposure test to see what the shutter actually is doing, and write down the results. You then can use the diaphragm for precise final adjustment of exposure.

[45PSS]

[ This Message was edited by: 45PSS on 2005-12-25 11:49 ]

[RichS]

little cautionary note just in case you can find true hydroflouric acid. DO NOT!!!!

Commercial glass etching compound can be semi safe. There is no way possible that hydroflouric acid can be. It is by far the most dangerous acid you could handle. No odor, crystal clear, you'd swear it was water. If it comes into contact with your skin, it won't hurt. You won't even feel the skin fall from your body. I would hope this stuff would be difficult to find? But since I used to work with it, I know that it is easily obtainable one way or the other. Don't even go looking for it!!!

That said... If you do a search, there are many articles on the net for making ground glass. I've heard people say not to bother with the over-the-counter glass etchant. I bought a bottle anyway but never did get to try it. The sandpaper method works but I don't think you'll get the surface you'd like. The grinding method is the most popular, very easy and produces the best results (I've read a lot of those articles). And it's easy if you use two sheets of glass. Just search around and try more than one method. Then let us know how it works.

Or, you could find a used GG, most probably the right size or cut it to fit, and it should only cost 10 to 20 bucks...


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"Ya just can't have too many GVIIs"
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[DenisP]

[shutterfreak]

Thanks everyone, I will give it a try will that valve grinding paste, I think it would be interesting to experiment. Does anyone know when my Crown Graphic was made. Serial Number 873077.


Thanks!

[DenisP]

BTW, if anyone's interested, the result can be seen on photo.net - I've just replied to almost the same question, and I attached a photo of my DIY ground glass.
The photo is here

Denis

[glennfromwy]

For downright quick and easy ground glass, use NoVue window spray from the paint or hardware store. It has silica in it and it really works quite well. Spray it on in thin, even coats until you get the desired result. That's provided you can find a piece of glass the proper thickness. Try ultra cheap 4X6 picture frames as a glass source.
When you live 100 miles or more from everything, ya learns a lot!

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Glenn

"Wyoming - Where everybody is somebody else's weirdo"

[shutterfreak]

I don't have a glass cutter so how do you get a 4X6 to work in a 122mm set?

[glennfromwy]

You buy one at the hardware store for 5 bucks or less. They may even cut it for you for a couple of bucks.

_________________
Glenn

"Wyoming - Where everybody is somebody else's weirdo"

[shutterfreak]

Okay everyone, I went to my local glass shop and have them cut me a piece that fits perfectly in my Crown. I am going to southern Utah this weekend to shoot and I didn't have time or money to buy a nice ground glass. Sooooo. . . after reading some of the ideas posted here I thought about putting something "frostlike" onto the glass. I work at a industrial print shop where they print pressure sensitive labels. So I used a substrate as my "ground" part of the nifty glass.

It will work really well for the trip until I get a commercial gg. But it was fun to experiment.