cannot focus 4x5 B and J pressgreenspun.com : LUSENET : Large format photography : One Thread
I recently purchased a 4 x 5 B and J press camera. Very well made with good front movements. I have taken four photos and all are out of focus even though shart on the ground glass. Any answers?
-- joe zarick (firstname.lastname@example.org), September 27, 2001
If you can see a sharp image on the glass, then what is being transmitted to the film is not what you're seeing. That's not very clear, is it? What I mean is that you should measure and verify that the distance from the film holder face to the film plane is the same dimension (precisely) as the distance from the edge of the gg back to the glass. If it is not, then the image reaching the film will not be in focus. There has been much discussion (and disagreement) on this board regarding the best way to measure this. I suggest searching back through the archives and after reading the various suggested methods, decide for yourself what will work for you.
-- Matt O. (email@example.com), September 27, 2001.
Joe... your ground glass may not be the same distance from the lens as the film plane when the film holder is in use. Or your ground glass may be in backwards. I think those are the 2 most likely causes. Best wishes -Dave
-- Dave Richhart (firstname.lastname@example.org), September 27, 2001.
Joe: This is a poser. How out of focus? What stop are you using? Tell us what the lens is just for background. Even fairly significant registry errors between the film and the ground glass ought to disappear as you stop down. If this is the camera I'm thinking of (black metal, with revolving back, Kalart on the right side) there isn't much that can shift around. If the photos are just slightly out of focus, see if the ground glass is facing the subject or the photographer. It should be on the inside. Make sure the ground glass is properly seated in the frame, with the little metal prong things tight and the glass down in the slots. Maybe it is replacement glass and it doesn't quite fit down in the factory depression? Try putting a row of objects down a fence or on a table, mark one of them, focus down the row on that one and take a picture. See if the one that is in focus is in front or in back of the one you focussed on with the ground glass. If none of the objects are in focus then a loose lens shifting around when you close it back down after focusing. If the lens (according to the film) is focusing in front or in back of the object you focus on with the ground glass, then you have to get the lens to film distance the same as the lens to glass difference. This will be somewhat of a pain to measure on this camera since the back doesn't come off, but with a finely scaled ruler and the front locked down you can measure through the front opening to a piece of scrap film in a holder with the slide removed and compare that to the ground glass. Let me know what you finally work out on this, I'm interested. Oh, by the way, with just a little sanding you can get Zone VI lens boards to fit this camera.
-- Kevin Crisp (KRCrisp@aol.com), September 27, 2001.
Are you using a tripod?
-- Jim (email@example.com), September 27, 2001.
Before you go spend $300 for a dial indicater, do this quick check; Get a carpenters tri-square and with no lensboard in place, loosen the ruler part and slide it in until it touches the ground glass surface, and tighten it up. Now put a film holder with one of your blurry films in it in the camera and put that thing back in. If everythings aligned right it should touch the film with the 90º rest touching at exactly the same place you tightened it down. If it doesn't, you've found the problem. Hope this helps more than confuses. J
-- Jim Galli (firstname.lastname@example.org), September 28, 2001.