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From: jam@ho95b.UUCP (Joe Malecki)
Newsgroups: net.rec.photo
Subject: Re: re: Camera Vibration and Sharpness
Message-ID: <339@ho95b.UUCP>
Date: Fri, 15-Mar-85 09:07:42 EST
Article-I.D.: ho95b.339
Posted: Fri Mar 15 09:07:42 1985
Date-Received: Sat, 16-Mar-85 04:23:21 EST
References: <1253@drusd.UUCP> <330@lcuxc.UUCP>
Organization: AT&T Bell Labs, Holmdel NJ
Lines: 33


	>I've gotten contact
	>sheets back that, when examined on a light table with a magnifying
	>loupe, showed fine detail all the way through.  When enlarged to
	>8 x 10, about 75% of the print--mainly the center--was sharp; but
	>the corners were blurry, thus ruining what otherwise was a really
	>good photo.  I've heard explanations that the enlarger lens was
	>faulty; and I've heard that's impossible in a good commericial
	>shop.  Anyone have any experience with this?

This happens because of carelessness of mounting the negative in the
enlarger. Most negative carriers used to hold the negatives have little
projections which are supposed to keep the negatives flat.  Some don't,
though. If you're at the end of a roll of film, or the negatives were left
too long in a heated film dryer, the negatives can be curled a lot. So when
the enlarger is focused on the center, the edges of the negatives end up
being out of focus because they are at different distances from the enlarger
lens, and hence out of the plane of focus.

The simple cure to this problem is to use little pieces of masking tape on
the edges of a curly negative to make sure it's flat.  I would guess that it
would be too much hassle for most commercial shops to take that much time and
care when they want to keep their costs down.

I would take the unsatisfactory prints back, and demand that they take the
care that is required to make a good print.

Joe Malecki
AT&T Bell Labs
Holmdel, NJ 07733
201-949-4847
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