![]() ![]() ![]() The fact that the aperture is not really round but a series of lines and v slots, the light is in wave form and hits in different places and so the the interference can be greater in smaller apertures. The smaller the aperture, the higher the percentage of interference with the bundle of energy. Something like that takes place in the bundle of light entergy as it passes by the lens aperture, the aperture blades cause the energy to be splayed out around, pretty much the same way regardless of the diameter of the aperure. Remember, it is diameter of aperture, not f stop.ĭiffraction is sort of like watering your flowers with a hose, if you just point it, the water come our in the same shape of the hose, if you put your finger into the stream of water it splays out in that direction. In tests for some superb 210mm LF lenses, the film resolution at f32 was always 1/3 as much as at f 5.6, however, the film quality at f32 was such adequate to make mural sized enlargements. In testing lenses for various purposes, there is a tremendous difference between visual resolution and film resolution (much less). If you wish to explore the science, see Dawes and Dawes Limits of resolution. Sharpness related to diffration is related to diameter of aperture (and in the case of DOF, diameter of aperture and distance to the subject). Ignore this statement from the film maker. What they're really saying is, "You gotta be a real man to use Adox CMS 20! Only the best photographers can take advantage of what we're sellling!" Which of course, implies that if you buy some, you'll be the best. Loss of sharpness due to diffraction (or sloppy technique)is visible on practically any film. I wouldn't get too excited over Adox's marketing blurb. The slight loss of sharpness to diffraction at f22 is much preferred to parts of the picture being out of focus. In the real world, you have to balance the "sweet spot" against getting enough depth of field. I determined that diffraction wasn't noticeable (for me, anyway) until I got down to f22. I did this on a Pentax 67 some years ago. Look for tiny details and notice how they vanish at small apertures. You can examine the negatives on a light table with a magnifier. DOF will vary, of course, so be sure to focus on something of interest. Put the camera on a tripod and shoot the same scene at all apertures. It's very easy to determine the sweet spot yourself. Were always told the sweet spot of those lenses was around a 5.6. So I'm wondering, is the sweet spot for all lenses a stop under closed down from wide open? Does itĭepend on the film as well? Different format, but when I used to shoot 16/Super16 with Zeiss lenses, we Speed would force you to stop down too much on a sunny day, letting slip what your lens can actually Up to two hours before sunset will give you something like a 125th or a 250th of a second at F 3,5. Any normal winter day 2 hours after sunrise and This puts you effectively to between F2 and F4. Best lenses are F1,4 high speed high quality lenses like Nikkors, Summiluxes, Rokkors or Canon Otherwise the lens defraction will lower your lenses resolution down to half of what this film canĬapture. If you want high resolution pictures you need to open your lens aperture to one stop below maximum I was reading on last night and caught this bit under the section for Adox CMS 20 film. ![]()
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