View Full Version : Focusing Problems

Jim Worthington
12-Aug-1998, 10:38
Hey all, I shot with my new used field camera this weekend and as an experienced photogra pher friend of mine said, some funky things are going on with the focus. What s hould I do to verify that this is due to operator error (very likely) and not mi salignment of the lens (also likely as it is about 30 years old)? In other word s, are there test subjects to use? Is polaroid film okay for such tests? Jim Worthington

mike rosenlof
12-Aug-1998, 12:50
I use 4x5 Polaroid film for a lot of things, but judging critical focus and shar pness is not one of them. At least not Polaroid prints. You might use type 55 for this application, I've never used it, but hear that the negatives are quite sharp.

A brick wall is a favorite test target, but you've got to be certain the the cam era is very precisely aligned to that wall. Align the back parallel with the wa ll, and sharpness should be equal in all corners of the neg.

12-Aug-1998, 19:56
Please define "funky".

12-Aug-1998, 22:11
Please explain "funky".

Bruce M. Herman
13-Aug-1998, 03:18
Here are a couple of things to check.

1. Are you sure that both the front and rear standards were locked before you p ut the film holder into the camera? The rear will likely move when you put in a film holder if it isn't locked.

2. Your concern about the age of the camera suggests that some components are lo ose. Is that true? Can you move either of the standards when they are locked?

3. Assuming that they lock tightly, you can verify that they are parallel when y ou want them to be so by using a good quality level. Use the level to position the camera base so that it is horizontal. Check that both standards are now ver tical. Use the level to aim the camera vertically downward. Now verify that bo th standards are horizontal both left to right and top to bottom along the stand ards. If there is play in the system, it should show in this test. Doing these two tests will at least confirm that the standards are positioned where you wou ld place them for a conventional image.

4. Does the camera have a fresnel lens or bright screen? If it isn't correctly installed, your plane of focus won't be coincident with the film plane. I belie ve that there's an article at the View Camera web site that explains this in det ail.

5. I'd be inclined to use T-max for these tests. It's relatively inexpensive.

Good luck, Bruce

Jim Worthington
13-Aug-1998, 21:05
Thanks for the good focusing advice. For your information, the old saying about looking for operator error rather than equipment error is true. I tested the l ens by making sure that the back, the lens, and a brick wall were parallel. The n I carefully focused, processed, and had one really boring but well-focused pic ture. FYI also-- By "funky," I meant the presence of a strange diagonal plane of good focus in the midground with poor focus in the fore- and background. I think I m ade the beginner's mistake of using too many movements at once. Thanks again for all the help Jim Worthington