Ouch!! that makes a pristine sensor a precondition for pinhole photography.
Nothing for this neck of the woods, we have open marl and claypits not far from here and three cement works. They produce the finest, greyest, dust you've ever seen - seems to concentrate particularly on the furniture in our front room and on anything even faintly resembling a camera or lens, even when stored in cabinets.:-)
The matter of the aperture blades possibly explains why the Yashica 2.8/55 mm Macro is so good, they offer an almost perfectly round aperture
On 18.07.2012 16:02, Richard Ward wrote:
Less Sharpness @ f32 would be quite likely from Diffraction from the Aperture Blades. - To way over-simplify, at wider apertures the blades bend light nicely like a good lens element, but past a certain opening size (depends on lens design, aperture construction, sensor size etc), the blades progressively become like a mis-having lens element. Coincidentally ;-) The Dust on your sensor suddenly shouting 'Hey, Look at Me!' is caused by the narrow Aperture, too. - At wider apertures, the light rays are coming onto the sensor from a lot of different angles and enough slips under the edges of dust particles to either be invisible or hidden in image details. At narrow aperutres (especially pinhole lenses!) the lightrays have gotten very directionalized to flow in fairly straight lines from the aperture opening sooooo the shadows of the dust bunnies are now sharp and crisp and stand right the heck out in an image. Trust me! My Pinhole Lens arrived and had me going all Mein Got! My sensor is dirty. :-) I'm sure others can give more science-y answers, maybe more accurate too! But mine work for me as functional analogies. RLW _____________________________________ My Sarcasm Fu Is Strong, Proceed With Caution. :-) _____________________________________ On Jul 18, 2012, at 6:23 AM, Douglas Sharp <douglas.sharp@xxxxxx> wrote:Still there after three days http://gallery.leica-users.org/v/DMS/album150/_MG_4312.jpg.html http://gallery.leica-users.org/v/DMS/album150/_MG_4313.jpg.html http://gallery.leica-users.org/v/DMS/album150/_MG_4319.jpg.html http://gallery.leica-users.org/v/DMS/album150/_MG_4324.jpg.html http://gallery.leica-users.org/v/DMS/album150/_MG_4327.jpg.html It actually seems that stopping down as far as f32 reduces the sharpness to some extent and brings out all the gunge and micro-dust on the sensor. Must be something to do with pixel sizes or something else technical that's beyond my comprehension. Any way, these may be only reasonably sharp, but I think the subject is posing very nicely on what's left of its Dahlia:-) Cheers Douglas ------ Unsubscribe or change to/from Digest Mode at: http://www.lrflex.furnfeather.net/ Archives are at: //www.freelists.org/archives/leicareflex/------ Unsubscribe or change to/from Digest Mode at: http://www.lrflex.furnfeather.net/ Archives are at: //www.freelists.org/archives/leicareflex/
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