Posted by Dennis Lee on October 15, 2000 at 17:22:05:
In Reply to: Re: Focus problem on Century Graphic posted by Alec on October 14, 2000 at 21:12:22:
Alec, thanks for the response.
I'm going to try the 'fence' shot soon as I get a chance.
To answer your other questions: I do have a rangefinder with focus
scale, it's close but not completely accurate to the GG.
I played with the back last night and although I didn't check this
specifically I think all the springs and clasps are in good
shape.
I have a cheap caliper which I used to check the distance between
the front of the GG holder and where the front of the gla-s would
be. I measured in the corners because the front of the back tapers
towards the middle (it's the snap in Graflok back). I figure the
image focuses on the matte portion of the gla-s, so that I
shouldn't have to take the thickness of the gla-s into account.
Right?
I then compared this to the measurement of the back while open and
carrier out. Measuring from the front of the back (the part that
rests on the camera, same in the case of the GG) to the film guide
rails on the inside.
Although the caliper is pretty cheap, the measurements have come
out very close.
I don't really want to get into the rangefinder until I can get a
sharp image off the ground gla-s, right?
I'm going to do another test, the 'fence' shot as you all
propose, and I'm going to use a cable release along with a few
frames on faster speeds (maybe more depending on the light).
I'll use a wider aperature to eliminate too much 'depth.'
I keep wondering if when I set my infinity marks I might have used
a range that wasn't quite far enough away.
I reviewed some recent film that I shot with this camera, a medium
close up, also at a small aperature, it definately had sharp
areas.
This is what keeps troubling me: at f16 or f22, even if my focus
isn't quite at infinity, shouldn't depth of field cover it? Because
I know from the gla-s that I'm definately very close to infinity if
not dead on it.
I'm still in the larger format learning curve here, but shouldn't
depth of field reciprocate to the rear of the lens also? ie help
the film plane even if it is a little off?
Alright, I need to do another film test before I go any
further.
thanks again to all of you for your help and interest.
DL