On Dec 9, 2012, at 4:16 PM, William Robb wrote: > On 09/12/2012 5:07 AM, Larry Colen wrote: > >> In other words, with an AA filter, a 24MP APS-C lens will definitely be >> diffraction limited by f/8.0. Without an AA filter, assuming that the lens >> is sharp enough, diffraction is probably having an effect by f/4 or f/5.6. >> > > Some people treat a diffraction limit as if it's a brick wall. It isn't. > Diffraction has always existed in the photographic world, and is just one of > many things that we juggle, and frankly, I've never felt diffraction was > something that ruined a print. > Lack of depth of field because the lens was too wide open has, at least in my > own work, ruined more images than because the lens was stopped down past the > "diffraction limit".
I understand this. At least one of the sites I found looking while for the diffraction calculators discussed these in some detail. > Shooting 4x5 film, one is often shooting at very small apertures, invariably > smaller than f/22, and most often much smaller than that. > My most used aperture when shooting 4x5 was f/64, which, even with a 150mm > standard lens is well and truly into what computer age photographers would > consider mushville. > It was what I had to do to get the depth of field I needed, it never seemed > to cause me unsharp images. > OTOH, leaving the aperture open too wide was a sure way to ruin a picture. I think that there is always a balance. I also suspect that as we have more processing power to throw at these images, and sensor resolution greatly exceeds the diffraction limit, it might be possible to apply an inverse transform and recover some of the data. If we already know the f/stop, and some characteristics of the lens, we know the airy disk of what a single point of light looks like. I don't think that it would make a lot of difference when the ratio is two or three to one, but if it gets up to 8:1, it might work. I don't know the math, but it might even just be an inverse of the gaussian blur formula. > > Some of us run the numbers and decide something just couldn't possibly have a > chance of working, some of us go out and take pictures. > I suppose trotting out the old adage of bees being aerodynamically unable to > fly, but the bee, knowing nothing of aerodynamics keeps zipping from flower > to flower might be apt here. Kind of like those of us who don't understand that Pentax is a dead brand, and we just keep zipping from flower to flower taking macros? -- Larry Colen [email protected] sent from i4est -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
