Need help with fresnel & ground glass on Charnonix 45n-2

[andre]

So I have an amazing offer for a Charmonix 45n-2 and have it at home for testing.
It seems that the ground glass is not quite sharp compared that of my Sinar F2.
(And I'm not sure if that is even a realistic comparison.)

There's seem to be an air bubble in between.

What's to be done?

Thanks!!

[vinny]

chamonix ground glasses aren't that great but I wouldn't say they're horrible.

as for the "bubble"
take note of it's orientation.
unscrew the screws.
remove the fresnel.
put it back together.
wash if necessary.
put it back together.

[Bob Salomon]

You mean when using a loupe? If so, have you adjusted the eyepiece of your loupe so it is focused on the grain side of your ground glass?

Or, do you mean the grain of the gg is coarser then the grain of the Sinar's?

You are doing this with the same lens of the same subject under the same light?

Or, do you think that something is warped? The fresnel is plastic and so is some gg.

[andre]

Noticed something else...
The lensboard does not sit entirely level and causes maybe a 2 degree shift.
It might be that because the "unsharpness" reminds me off "shift blur".

To answer the other questions:
I don't use a loupe but focus with my eyes alone. (Always had above average eyesight.)
I use the same lens, same subject, same light.

[Bob Salomon]

Noticed something else...
The lensboard does not sit entirely level and causes maybe a 2 degree shift.
It might be that because the "unsharpness" reminds me off "shift blur".

To answer the other questions:
I don't use a loupe but focus with my eyes alone. (Always had above average eyesight.)
I use the same lens, same subject, same light.

Buy a good loupe and focus it on the grain of the gg. No matter how "good" you eyes are a good loupe is always better.

It is doubtful that the board is the problem. You compose on the gg and you adjust your tripod head to level out the scene.
And a tilted board does not have anything to do with your "bubble".