It’s been cold and raining here in Michigan for several days and it’s getting to me so I started searching for information about Diffraction and our Q. After searching this forum and doing a lot of reading on the Cambridge in Color Web pages on diffraction I find myself still somewhat confused.
Per the Cambridge in Color site for our beloved Q the range of diffraction onset is from f2.4 to f3.6. This is assuming a "
perfect lens" per the site. I know my lenses are far from perfect so what does this mean to me. I did a test photographing a resolution chart with all the lenses I adapted on my Q. Shooting from wide open to f8 assuming f8 to be in full diffraction on my Q. All lenses tested on my Q on a tripod and using a 10sec. timer to trip the shutter. Here is what I found to be the sharpest aperture for my lenses
SMC-A 28 f2.8 is sharpest at f5.6
DA 35mm f2.4 is sharpest at f4
SMC-A 50mm f1.7 is sharpest at f4
SMC-M 135 f3.5 is sharpest at f5.6
SMC Pentax 200 f4 is sharpest at f5.6
Tamron 70-300 f4-5.8 shot at 300 is sharpest at f5.6
DAL 55-300 is sharpest at f5.6
I guess this means my lenses are far from perfect and the 35 & 50 are my sharpest lenses as they are is diffraction limited at the lowest aperture. They are also rated highest for IQ for all my lenses in PF lens reviews
Hans
Last edited by hnikesch; 12-26-2012 at 02:08 PM.