Bogdan Karasek wrote: > Hello, > > I was just cruising the darkroom section on ebay and came across this > " Kodak Gray Negative Contact Screen" (#160722629230). I did a > Google search and basically I was informed that it is used for making > "contact prints" which is what I assumed. But what exactly does it > do? nothing. Talk of lines per inch but that doesn't tell me > anything. > > Can anybody here give an explanation as to why one would want to use > such a beast? It does serve a purpose.... > I happen to detest contact screens, but that is because I prefer sealed glass crossline screens for half-tone work. They are much more practical and give better results iff you understand how they really work and take the trouble to learn to use them. But if you cannot be bothered, a contact screen is OK for quick work where quality is not too important. In the simple case, you can photograph a continuous tone subject and make a negative image that is strictly black or strictly clear, but divided up into a lot of little dots whose diameter (if the dots are round) is proportional to the density that would have been produced without the screen. The reason the image is black or white is that litho film is used. In the past I have posted pretty well how a glass sealed screen works, so you will have to look it up. It is described in a few books, but most of the books have it wrong. As far as I know, the only book that has it right is "The Autobiography of an Amateur Inventor" by Frederick E. Ives. But that was privately printed and difficult to find. -- .~. Jean-David Beyer Registered Linux User 85642. /V\ PGP-Key: 9A2FC99A Registered Machine 241939. /( )\ Shrewsbury, New Jersey http://counter.li.org ^^-^^ 18:10:01 up 2 days, 8:39, 3 users, load average: 4.97, 5.09, 4.96 ============================================================================================================= 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.