Hello, everybody.
Sorry for the delay. I've got problems with my internet connection.
hi antonio
first of all, nice photographs !
are you focusing wth the lens wide open or are you
stopping down a little bit to focus ?
i can't really speak for your problem is it is a hardware-issue ( strange / obscure equipment related issue )
but if it is a learning curve / focusing with a fast lens issue i have a trick for you
( well, its not really a trick, it was included in the instructions for a portrait veritar i have )
wollensak used to suggest to stop the lens down a stop or stop+1/2 to make it easier to focus
i have done that with other fast lenses, and it seems to help a little bit. with fast lenses, ( 4x5 )
the focus is such a "sliver" ( narrow ) that it it isn't easy to see what is in focus ...
maybe stopping down a little will help ?
looking forward to seeing more beautiful portraits !
good luck !
john
Hello, John.
Thank you for your kind words.
I've done what you suggested ... But, no way.
Thank you, regards.
Antonio
It could be that your film plane is at a difference distance than the GG. Have you measured This with calipers?
Hello. Maybe, I've to measured this ...
Thank you !
Regards.
Dear Antonio,
It is also possible you have one or the other of the ground glass and freznel turned the wrong way. You should visit Graflex.org.
Good luck,
Neal Wydra
Dear Neal.
I think this could be the most probable cause … I’m not sure how to check it. Both sides are so similar! I'll check it ;-)
Thank you !
The correct order of assembly is Fresnel with the ribbed side facing the rear of the camera then the ground glass with the ground side facing the fresnel/camera lens.
Is the Fresnel the factory one?
Hello!
I'm not sure if the fresnel is the factory one. I guess is not.
Thank you!
Hi Antonio,
If the actual point of focus is further away than the point on the ground glass, the ground glass is too far from the lens (or, more precisely, further from the lens than the film). If the geometry of that camera assumes the ground glass is on the lens side but is installed the opposite way, that would create this effect.
duane
Couldabin, Pacemaker Graphics delivered with fresnel lenses were designed to have the fresnel between the lens and the GG. The likely but not absolutely certain problem is that the GG is in backwards, with the ground (matte) side facing the photographer, not facing the lens as it should be. This is easy to check for.
Film holders are pretty well standardized and were/are industrial products made fairly well. Every time a question like this one comes up people suggest that the film holder is not to specification. I don't recall an instance that didn't involve an early MPP camera -- these beasties required non-standard film holders -- where a film holder that didn't match the specifications was the problem.
Hello!
Couldabin, as Dan has said, the fresnel of my back is between the lens and the GG.
Dan, I’ve to check if the GG is backwards …
Thank you!!!
If the film focuses behind your GG image (as in your example) the film is too close to the lens. The film either is buckling in the film holder or the ground glass needs to be moved closer to the lens.
You can use the thin lens equation to see how far off you are. Without doing the math it looks like about 0.3mm to just less than 1 mm (assuming 150mm lens).
Hello!
I’ll look for that equation.
“the ground glass needs to be moved closer to the lens” -> What happened if the GG were backwards?
Thank you!!
Regards