Making a Ground Glass Focus Screen

NedL

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Aug 23, 2012

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Sonoma County, California

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• Feb 2, 2014

• #51

Thank you very much for these instructions. I made a prototype camera this week and the GG is just a piece of picture frame glass covered neatly with scotch tape. With these instructions, I can make something nice. I've already got the grit ( occasionally run a rock tumbler...

 

GaryFlorida

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Apr 11, 2012

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Venice

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• Apr 1, 2015

• #52

Ian Grant said:

Yes you can go finer, but it's the balance of contrast/brightness and fineness that makes the difference.

There may be some variations in Grit quality but using #400 followed by #600 gives screens that are superior to the standard Graflex screens and many other commercial screens.




No because the grain of the ground glass will be an issue.

Ian

Click to expand...

Thats a great write up. Thanks for that. Well the million dollar question now is. What specific vendor do you order your grit powder from? Thanks.
Gary

** UPDATE **
I just ordred 1/4lb each of 320 and 500 delivered for $10. I hope its enough to make a 6x9, 6x6 and 35mm gg for calibrating my cameras. This will be great if it works!! Think of the possibilities.

 

Last edited by a moderator: Apr 1, 2015

alanrockwood

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Oct 11, 2006

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• Apr 2, 2015

• #53

A couple of quick comments. First, related to safety, make sure you don't breath any of the dust. You don't want to develop silicosis.

Second, if perfect flatness is desired (probably not strictly necessary) you need to grind three pieces of glass together in a sequence where each plate gets ground against every other plate in a repetitive fashion. Grinding two pieces together can produce a curved surface, but three pieces will produce a flat surface.

 

kglack43

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Aug 29, 2015

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8x10 Format

• Aug 29, 2015

• #54

I'm going to attempt to make a couple this weekend. I read comments about how the corners might be a problem... I plan on using larger glass to begin with then cut down to the 8x10 cut cornered piece i need. I'm thinking THAT should solve the problem... I'll be setting the glass to be ground on a sheet of paper with proper crop guides for the dimension I'm going for as a guide and grind past the borders marked out. I'm also going to attempt to add a type of "grid/layout marks to the frosted surface... I'll post some images when I'm done...

Cheers to all.

 

kglack43

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Aug 29, 2015

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8x10 Format

• Aug 29, 2015

• #55

thanks for that insight

 

Louis Nargi

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Sep 4, 2004

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4x5 Format

• Aug 29, 2015

• #56

Thanks I'll try it in 4x5