focus problems

[rmolson]

Focus


Having a problem with ground glass. Got a fine ground glass for my 4x5 press view. I replaced the old glass which was a coarser grain .But now my images seem ever so slightly soft as though I missed in focusing with my magnifier. Dug out an old micrometer and checked thicknesses. It’s been so long since I worked with a micrometer and I probably have the wrong readings but there is a difference between the glass the old read about .013 and new glass .005. It is only a tiny difference if my measurements make no sense But would it be enough to throw my focus off a hair?
I have a 150mm F/5.6 Topcor which gave me good results on my monorail,but I can't carry that into the field.

 

[Jon Shiu]

Hi, the thickness doesn't really matter, as long as the ground side of the glass is at the same position as before.

Jon

 

[RalphLambrecht]

Focus


Having a problem with ground glass. Got a fine ground glass for my 4x5 press view. I replaced the old glass which was a coarser grain .But now my images seem ever so slightly soft as though I missed in focusing with my magnifier. Dug out an old micrometer and checked thicknesses. It’s been so long since I worked with a micrometer and I probably have the wrong readings but there is a difference between the glass the old read about .013 and new glass .005. It is only a tiny difference if my measurements make no sense But would it be enough to throw my focus off a hair?
I have a 150mm F/5.6 Topcor which gave me good results on my monorail,but I can't carry that into the field.

Jon Shiu is correct. Are you sure you've got it on the right side?

 

[rmolson]

I checked that part ,next I suppose will be to check if the film plane and the ground glass agree.the camera while all metal is 50 years old and I suppose something could have changed since then.

 

[Rick A]

I havent used a LF in some time, but could it be just the difference in contrast between the fine and coarser glass? Just a thought.
Rick