Originally posted by Not a Number Old or cold chemicals could lead to "thick" negatives making them appear under exposed.
I guess I still don't understand what you mean by "thick" negatives. An unexposed frame is clear after development (very thin). A severely overexposed frame is opaque (very thick). Underdeveloped negatives will lack density and/or contrast depending on the film being used and exposure.
I would suggest that the OP compare the camera's meter readings against a known good camera or meter. If the meters agree, the issue is with the processing and/or the scan. It is highly unlikely that there is an issue with the electronic shutter and lenses have been ruled out since it happened with several different lenses. I am assuming that the correct ASA (ISO) film speed was set on the camera.
All that being said, I can relate my personal experience with similar results from a couple of years back. I was having my processing and scanning done with a local minilab (Costco). Everything was great until I got two rolls of film back where the scanned results looked very much like those on the OPs proof sheets. The negatives appeared to have adequate density, but the scanned images sucked. I was able to rule out the camera meter and the film (fresh Ektar 100, processed promptly) and finally came to the conclusion that the processing was primarily at fault with the problem being compounded by poor quality scans. (The minilab scanner attempted to compensate for the bad negative with really nasty results.)
It was that experience that prompted me to switch to a local pro lab exclusively for my C41 processing and to purchase a film scanner to do my own scanning. I have had no problems since. At one point I revisited the two bad rolls using my Nikon scanner and determined from the histogram that the negatives were badly underdeveloped with very poor contrast. Case closed. Regular maintenance, chemical replenishment, and rigorous quality control checks are essential for good results from an automated film processor. Apparently Costco was not adequately diligent.
Steve
Last edited by stevebrot; 01-23-2014 at 01:43 PM.