I've been looking into this problem and running a few experiments. My hunch is that there is something going on at the enlargement stage as I made two prints from the same negative that displayed the same type of pattern but not exactly the same position and density; which could be explained by each print being made in slightly different orientation to the enlarger. I'll print the negatives on a different enlarger and lens for control.
Tom Helge Nareid wrote:
Richard Knoppow wrote:----- Original Message ----- From: "Tom Kershaw" <tom@xxxxxxxxxxxxxx>My posting on APUG hasn't generated anything by way of a response, and as there isn't total overlap between pure-silver and APUG I thought I should post here.http://www.apug.org/forums/forum40/68152-odd-higher-density-marks-ra-4-print-probably-optical-issue.htmland the image links: http://www.tomkershaw.com/apug/rf645_65mm_hair.jpg http://www.tomkershaw.com/apug/strange_mark_kp800.jpgAs the density marks do not appear to be visible in all prints from the RF645 negatives and do not occur with my Bronica SQ negatives, perhaps the hair which is within the lens generates the defect depending on the light direction.TomI think its very unlikely that the mark is caused by the hair. For one thing, even if the lens design was such that the hair was imaged it would leave a dark mark not a light one. Secondly, in most lenses the hair would not be imaged. I have not explaination for the mark, a hair or thread in the path from lens to film would also have left a dark mark. My best guess is that something happened in processing. I wonder if you have examined the negative. If the mark is _not_ on the negative it suggests that there was some problem with the printer at the lab.I will in the main agree with Richard on this one. If it only occurs on a single print or a sequence of images from the same roll, my main culprit would be a hair between the film and paper in the printing process. This can best be determined by looking at the negatives. If it doesn't show on the negatives, it is a printing problem, and simply reprinting the negatives should eliminate the problem. The hair (?) showing in the picture of the lens is highly unlikely to be the problem, since it is likely to be completly out of focus in the image plane - if the lens were stopped down sufficiently to bring it into focus, the hair would be well out of the active aperture. It may be worth checking the relative alignment of the hair and the image artifact. If the artifact shows up on the negatives - particularly across multiple rolls of film - my main candidates would be a light leak or an internalreflection in the optical system. Does this happen with more than one lens?- The Horrible Helge============================================================================================================= To unsubscribe from this list, go to www.freelists.org and logon to your account (the same e-mail address and password you set-up when you subscribed,) and unsubscribe from there.
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