[LargeFormat] Ground Glass Focusing

[Clive Warren]

Thought I would share an experience with you.....

Whilst visiting relatives over the holidays, took the 4x5 large 
format rig into a local cathedral for a few atmospheric architectural 
shots using a new to me 90mm Super Angulon. Having set up and paid a 
small suggested fee for the privilege of taking photos (use of video 
cameras was three times the cost!), started to focus the rather dim 
scene on the GG. It was a difficult scene to focus as the light was 
so dim.

After 5 minutes of trying to focus under the darkcloth I decided that 
there was something wrong with either the lens or the camera, but 
couldn't for the life of me work out what it was. It was just not 
possible to get near infinity focus on some organ pipes at the far 
end of the building that were fairly small on the GG.

After having taken the lens off the camera and generally poking 
around, put all back together and tried again - same results, no 
sharp focus possible on the GG.

Stood back and looked at the camera, the organ pipes, my watch, and 
wondered if the pubs were open.  Then glanced again at the GG - hang 
on it was in focus now! Got closer to the GG and tried to fine tune a 
little before getting out the loupe - all out of focus again. A 
lightning bolt of inspiration - head out from under the darkcloth and 
held finger in front of eyes same distance as I was from the GG - it 
was out of focus .. doh!

Cheers,
        Clive