[LargeFormat] Ground Glass Thickness

[Clive Warren]

At 07:41 17/04/02 +0100, philip.lambert wrote:
>On a related matter, are all replacement ground-glasses the same
>thickness/register?  I fitted a Boss screen from the Netherlands to
>my Linhof and it was no trouble at all, brighter and virtually grainless. Is
>there an international standard for focussing screens or can you buy glass
>of the wrong thickness? That is, if a screen is right for a Wisner is it
>right for a Sinar/Cambo/DeVere? Philip
>snip

The easy answer here is, probably not.

The thickness of the replacement ground glass does not matter too much as 
long as the ground or etched face of the glass is located at the same 
"plane of focus" position as the original.  If the glass is oversize and 
because of this does not seat correctly, then there will be problems as the 
image focused on the GG will not be accurately focused on the film when the 
film holder is inserted.

There was a thread on this list about the methods for making a ground glass 
using various methods and different types of glass a short while ago. Have 
a quick search through the posts using the search box on the f32.net web 
site and all will be revealed :-)

Cheers,
             Clive