If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
Contact Printing paper negatives
Here's an odd one, and one I've never heard anyone else mention on all
the sites and archives I've read. I can't seem to get a perfectly sharp all over 8x10 contact print from a paper negative. And this is flat RC to flat RC. I've put glass on the base to get the flattest surface, and a heavier glass on top. I've smoothed the paper out with my hands trying to sqeeze out any air, I've even tried doing wet on wet,with a squeege. There will always remain a circle of fuzz out, edges that get fuzzy, etc. Real shame, because otherwise these can about 96% rival a negative in some cases. |
#3
|
|||
|
|||
Contact Printing paper negatives
"Ken Smith" wrote
Here's an odd one, and one I've never heard anyone else mention on all the sites and archives I've read. I can't seem to get a perfectly sharp all over 8x10 contact print from a paper negative. A paper negative will never be as sharp: the light making the exposure is _very_ diffuse with the paper base acting as a diffuser. The image will undercut (called 'choke' in the graphic arts industry) from light penetrating into the paper at an extreme angle - flying low under the cloud cover of the negative, as it were. The graphic arts industry uses a diffusion screen (sometimes called a 'diffusion foil'), made from a sheet of matte drafting mylar (think onion skin paper) that is placed just above the contacting print frame. In this instance it is used to shrink the size of lithographic dots and to produce fancy graphic effects on lithographic film. The fuzziness, however, should be uniform across the paper. Variable fuzz is an indication of bad contact. Try a real contact printing frame. After that, the next step is a vacuum printing frame: this is made from a plate of glass and a rubber blanket, the materials are placed between the glass and the blanket, the frame is closed up and the air is evacuated between the blanket and the glass - this results in 14 lbs/in^2 clamping force, or about 1/2 a ton for an 8x10 print. Even with this force (an also because of it) it is very hard to get all the air out, a pressure gradient is required to get airbubbles to evacuate. My partner and I were the inventors of Nuarc's nuVac vacuum frame contacting system, U.S. Patent No. 4,935,773. -- Nicholas O. Lindan, Cleveland, Ohio Consulting Engineer: Electronics; Informatics; Photonics. |
#4
|
|||
|
|||
Contact Printing paper negatives
In article t,
"Nicholas O. Lindan" wrote: My partner and I were the inventors of Nuarc's nuVac vacuum frame contacting system, U.S. Patent No. 4,935,773. That's impressive.....and yes I am being serious! -- LF website http://members.bellatlantic.net/~gblank |
#5
|
|||
|
|||
Contact Printing paper negatives
|
#6
|
|||
|
|||
Contact Printing paper negatives
Hi
There is really no need to contact print paper negs. I use 8x10 Color RC paper as negative material in my pinhole camera. After typical 2 minute sunlight exposure using an 85B filter, I process as usual in a roll transport processor. Then I scan the color paper negative on a Epson scanner. Then use photoshop to reverse the image and color correct. I print the results out on 8x10 color dyesub paper. The results look just great and sharp. Larry |
Thread Tools | |
Display Modes | |
|
|