Fujinon-C 300mm Lensgreenspun.com : LUSENET : Large format photography : One Thread
I've recently been testing a Fujinon-C 300mm lens in 4x5 format. My test results suggest this lens has some peculiar behavior which suprises me. I'd like to post what I've done, and get some feedback to understand if there are problems with my test methodology. I'd be interested in hearing other people's experience with this lens - in particular people who use it to shoot 8x10.
The test did not involve test charts, but was a subjective empirical test shooting the John Hancock Tower (I. M. Pei) in Boston at infinity. The building has sharp horizontal and vertical lines at every floor which allows direct comparison of sharpness as you go up in height. The camera was an Arca Swiss F (metric) sitting on a Arca Swiss B2 head with Gitzo 410 legs. I tilted the rail 15 degrees to keep both the front and rear standards as solid as possible and allow the required rise without having to reset the basic camera position. The ground glass and lens were set parallel to the building using an accurate external level. The starting position (0 rise) was determined by placing a level between the tops of the standards. Film was Ilford FP4+ in a Grafmatic with good septums. F-stops were between 22 and 22 +1/3. Shutter speed was 1/60. I developed the B&W negs in Rodinal 1:50.
I shot exposures at 0, 70, 100 and 130mm of rise. Since the Fujinon-C 300mm has an advertised image circle of 380mm, you need about 130mm of rise to see to the edge of this field. Examining the negs with both 7x and 10x loupes, I'd say the zone of very-sharp focus falls within about a 230mm image circle. The negative without any rise is incredible - you couldn't ask for a sharper more contrasty image. By the time you reach an image circle of 260mm, there is no question that the image has degraded significantly. Out at 380mm, there is an image, but the sharpness resembles what a near-sighted person with 20-200 vision might see.
I'm guessing there must be some problem with my test. Please comment. Again, I'm very interested in hearing from anyone with direct experience with this lens. Certainly anyone who shoots 8x10 with this lens could easily validate or question my results.
-- Larry Huppert (Larry.Huppert@mail.com), July 24, 2000
If anyone has experience with either the Rodenstock APO Ronar 300 or the Nikkor-M 300 I would also be interested in hearing your results. Since I shoot architecture, the quality of the image within the prescribed image circle is of interest to me.
-- Larry Huppert (Larry.Huppert@mail.com), July 25, 2000.
I bought the Fuji 300 C specifically so that I could use it in both 4x5 and 8x10 formats. I just looked at some of my 8x10 negs and couldn't confirm the phenomenon you observed, but I will do a more rigorous test and report back.
As for possible explanations, did you remember to remove the set-screw before mounting the lens? Forgive me for suggesting that you might have made such a silly mistake, but I did this once! And the result is a lensboard not parallel to the film plane and very poor sharpness away from the
-- Stewart Ethier (email@example.com), July 27, 2000.
Ah yes - that little set screw. I've done that before as well. The screw was removed from this shutter.
-- Larry Huppert (Larry.Huppert@mail.com), July 27, 2000.