> Hello Carlos,
For a single lens reflex, typically there are FIVE things that affect in camera focus: 1) lens to film plane register, 2) lens to film plane parallelism, 3) mirror angle, 4) focusing screen alignment-both distance and attitude, and 5) lens calibration.
Items 1 and 2 will normally last for the life of the camera UNLESS it is subject to misuse, e.g., dropped, mounting a very heavy lens and carrying/holding this combination only by the camera.
Item 3 should last a lifetime as well as the adjustment/alignment is NOT normally requirement.
Item 4 MAY or may not be a problem with Hasselblad interchangeable screens. My dear friend Bill Maxwell (Maxwell Precision Optics - makes custom focusing screens for cameras) once told me that their screen frames have interesting tolerance and that when he makes his custom Hassy screens, he has to precisely set the screen height within the frames. The screen situation doesn't pose a problem UNLESS the camera body has been misused. ALL Hasselblad V series use an solid cast aluminum outer chassis (much like insects with an exo-skeleton). The innards are fabricated with sheet metal. Misusing the body CAN cause the the innards to be misaligned. Some 2000 bodies have its inside loosely 'attached' to the outer casting - you can actually see movements between the mounted lens and the outer body casting.
Item 5 - lens calibration should not be a problem for the life of the lens. Only physical damage will cause focusing problems. Three questions to you:
1. Have you taken anything pictures of infinity subjects WITH THE LENS SET TO INFINITY? The normal average photographer really has no access to test equipment so commonly available subjects and test procedures are use in lieu of shop instruments - most photographers don't know what to do with these even if they have access. If this 'film' test shows that infinity subjects (targets) are in good focus, the chances are that your critical lens flange to film plan register is proper.
2. Have you a Hasselblad focusing screen design to be used with the SWC? With this, you can quick check to see if the lens flange to film plane distance is still OK. Test you camera at INFINITY and DON'T rely on the focus scale on your lens when you do a test of this kind. E.g., positioning your camera at five feet and setting the lens at five feet. The scale is not instrument accurate and in theory and practice, distances are measured from subject to film plane. A 'hairs breath' off on your lens' focus scale (at five feet) can be inches off of the actual subject distance (MUCH, of course is dependent on the focal length of the lens). This test MUST be done with an infinity subject (roughly AT LEAST 1000x the lens' focal length) and that the lens itself be set at infinity. If you see a good focus at infinity, the lens flange/body register should be OK.
2. How old is your 500c/m - has it been serviced by Hasselblad or a competent Hassy technician? Why? If has been serviced properly, your 500c/m mirror's foam cushions should have been replaced. This MAY be your problem. Have the mirror cushions checked out; it may require replacement. Bill Maxwell replaced them on some of my cameras. Unfortunately, Bill NO LONGER repair camera; a pity as he was ONE heck of a camera technician! Faulty or old cushions will affect visual focus ONLY on the focusing screen. Film focus is UNAFFECTED.
Hope I didn't bore you with my verbiage.
Tsun >
