Darkroom oblique

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mtuell
Posts: 289
Joined: Wed May 11, 2016 12:42 pm
Location: Tucson, AZ
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Darkroom oblique

Post by mtuell »

I have no idea if this or the "technical discussion" forum is better for this random topic... :)

I was working in my darkroom and playing around with lithography film, which is high-contrast sheet film. By projecting the normal negative image through this film positive, edges are accentuated just as with oblique or Hoffman. Contrast reversal is common, as well.

First, the whole continuous tone image (enlarged to 5x7 or so), printed on cooltone paper.
Image

Now, a crop of one area, printed on warmtone paper.
Image

Next, it was printed on lith film as a full-size positive.
Image

I could now make contact prints with the lith positive, making a negative image. However, what I did was to leave the negative in place, and with registration, project that image through the lith. This created an oblique look to many aspects of the photo. In this case, I kept the lith positive in contact for the full exposure, so negative and positive have the same exposure time.
Image

Next, I removed the lith film for part of the exposure. In this case, it was a 15 second normal exposure plus 5 seconds through the lith film.
Image

I then did radial shearing by moving the enlarger head up a small amount. Here the normal exposure with no lith film was 15 seconds, plus 15 seconds with the lith in place.
Image

And, finally, the same picture as above, but with "medium backlight compensation" in the scanning.

Image

I realize this may not be the right forum for this, but it seemed you guys may be interested since it looks so similar to some microscopic techniques. :shock:

The full images, at 1/3 resolution are on my site in the Photography Manipulation section.

Mike

Olympusman
Posts: 5090
Joined: Sun Jan 15, 2012 12:31 pm

Masking

Post by Olympusman »

This is a variant on a technique called masking. In color darkroom work, it can be used to control contrast in printing from color slides. When Cibachrome was being used, it was commonly used to print from Kodachrome slides since the combination of the contrast of Kodachrome and the contrast of Cibachrome combined resulted in unbearable contrast. The technique employed a thin black and white mask B&W negative sandwiched with the slide, essentially resulting in localized contrast dodging. The technique could also be used with color negative film to try to salvage a thin negative.
The technique became popularized in those Petersons photography books in the 1970s.

Mike
Michael Reese Much FRMS EMS Bethlehem, Pennsylvania, USA

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