The advantage of LF is that we can process a single sheet at a time. You might consider a simple test. Two way to do this are as follows.
Use any suitable target, a plane surface with good contrast in fine detail; sometimes a printed sheet, e.g., flattened newspaper taped to a door or wall, is useful. You can also draw sharp, dark, thin X's on printer paper, cut out, and tape to the surface in an X pattern that will occupy 2/3 to 3/4 of the image. Set up the camera with all movements in the zero position (no swings or tilts) and determine that the camera back is vertical (assuming that your target is) and the camera horizontally parallel with the target as well. Make sure all tripods movements are locked in place. Focus carefully, lock down, close the shutter. Set the aperture wide open or perhaps just a half-stop closed (for slightly better optical performance) to minimize depth of field/depth of focus.
If you have a couple of small trays, you can use some print developer, even at 2x the normal dilution, and just develop the film for 2-3 minutes, in total darkness of course, agitating the film gently. If you do this, under-expose your target by about 1 1/2 stops; print developer is active stuff, and we're not looking for beautiful tones, just sharp detail. Rinse the developed neg and then fix for a few minutes and wash in running water for a few more. Squeegee off the water well or pat the neg in paper towels (again, this is just a test) and hang to dry. Examine under a sharp loupe or other magnifier -- you may be able to use your camera lens, pointed backwards at the neg.
The second approach is superior in one way, because, even if you selected plane of focus is not accurate, one will be, and you'll be able to see how sharp you lens is at the selected aperture. In this test, you use a flat plane angled to the camera. You can make one out of stiff cardboard formed into a V, book-like, to stand on a table, with the "front cover" angled at perhaps 35-45 degrees. Something larger than a book makes it easier, maybe 16x 20 inches or so. This time, draw a "ruler" on your target with, say, 7 vertical lines about a 1/4-inch apart, which, at 45 degree, will measure only about 1/8 difference in distance. Mark the middle one clearly with an X. Set your camera with the lens about middle the height of the target, squared up as before, except for the angled target plane. Focus on the X line, and proceed as above. The result wii show whether the X line or one closer or further is the sharpest.
This should give you an idea.
Reply With Quote
Originally Posted by Ulophot
Bookmarks