Checking ground glass/film holder tolerances

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sanking

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Can anyone point me to articles on the web or in print that describe practical techniques for testing ground glass/film plane tolerances. I am aware of an article on the subject that appeared in PhotoTechniques in 1999 but would like to know of any others that may be out there, perhaps in View Camera? or in on-line sites.

Sandy King
 

mark

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There was one in VC, or shutterbug, maybe, that described using a tooth pick and a pencil. Pretty informative and it works well. I remember the techniques but not where the article appeared, sorry.
 

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Sorry, no article, but FWIW this works for me: put a post-it pad inside the film holder and peel away sheets until a ruler lies flush across both it and the edge of the film holder. Then put the pad against the inside of the ground glass and see if the depth is the same. Not a perfect system, but pretty good.
 
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sanking

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mark said:
There was one in VC, or shutterbug, maybe, that described using a tooth pick and a pencil. Pretty informative and it works well. I remember the techniques but not where the article appeared, sorry.

Thanks, I believe that is the one in Photo Techniques.

Sandy
 

glbeas

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I've done it using a steel rule from a carpenters square and a caliper with a depth feeler. laid the ruler across the seat area and the caliper against the rule and pushed the feeler down to contact the bed or the glass. It's best to check your filmholder with film in it naturally and careful not to scratch the GG with the feeler. Don't just check one spot but the center and four corners if at all possible.
 
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sanking

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glbeas said:
I've done it using a steel rule from a carpenters square and a caliper with a depth feeler. laid the ruler across the seat area and the caliper against the rule and pushed the feeler down to contact the bed or the glass. It's best to check your filmholder with film in it naturally and careful not to scratch the GG with the feeler. Don't just check one spot but the center and four corners if at all possible.

Yes, ANSI specifications state that the T-dimension should be the same everwhere on the septum 1/4" outside of the film retaining lip.


Sandy
 

DrPhil

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Lambrecht and Woodhouse describe the toothpick method in their book "Way Beyond Monochrome"
 

wfwhitaker

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sanking said:
Can anyone point me to articles on the web or in print that describe practical techniques for testing ground glass/film plane tolerances. ...

Sandy,

It's not clear to me what you're asking. Are you looking for a method to adjust the ground glass to match the film plane of a holder? Or are you asking how to determine what is a realistic tolerance? Or something else?...
 
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sanking

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wfwhitaker said:
Sandy,

It's not clear to me what you're asking. Are you looking for a method to adjust the ground glass to match the film plane of a holder? Or are you asking how to determine what is a realistic tolerance? Or something else?...

Just looking for references to articles that may have been published on the subject. Don't need the how to or tolerances, just references to what others may have already published on the subject, either in print or on the web.

Sandy
 

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I think that falls under "something else". ;-)

Good luck!
 

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cjarvis said:
I think it falls under "potential bibliography".


If this is true, Mr King would you be sure to keep us posted on when the book would be available. I'm sure I'd like to have a copy.
 
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sanking

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cjarvis said:
I think it falls under "potential bibliography".

Well, that too but more importantly I am just trying to get an idea of the kinds of ideas that have been proposed. I am trying to write something on this but I don't want to reinvent the wheel if there is already a better wheel out there than the one I have in mind.


Sandy
 

JHannon

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In Barry Thornton's book "The Edge of Darkness" (P41-48) he describes testing camera focus accuracy using a board with a series of 1cm spaced vertical lines drawn on it. The center line is marked and is the point of focus. Distance is 2 feet from the board and all cameras had full aperture.

Upon developing the film he has several photos showing how far off the focus is for each camera tested. I thought it was an interesting test and I am going to try it. It does involve using rolls of film, developing and printing etc.

I hope this helps.
John
 
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