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amateur6 · 02-09-2008, 01:08 PM

Originally Posted by Richard Day

Try your DA* at f4.5 as well. At f22 diffraction is occurring. The sweet spot is usually around f5.6 to f8.0.

Thanks very much Richard! I'm going to do another round of test shots (actually I just did but I'm still getting a wicked back focus to correct). *sigh*

Of course, the diffraction issue begs the question: can Pentax perhaps take a lesson from the elevator industry and please OVER-engineer instead of UNDER-engineering? In other words, if your f22 has issues, well, you shouldn't really have an f22, should you? Especially true of the 100mm Macro example you linked to -- adding f22 and f32 when your f16 has issues -- that's just bad engineering. Or a case of marketing running the show: "See, we have f32 too!"

I'm not quite as bitter as I sound right now, but when my $200 lens is beating the pants of off my $900 (plus the UV filter; $1000) lens, yeah -- I'm gonna be a little upset. Plus, I was really looking forward to the k20d, but if it's just so much hoopla there, too, well -- I may as well sell all of this stuff and join one of the two dark sides. It's been a year, I've just rolled the shot counter (10k shots on my k10d), and I've gotten to the point where I'm thinking... maybe it's NOT just me.

Oh, and -- how about the size difference? Those are identical crops from what are both supposed to be 50mm. Any thoughts?

02-09-2008, 01:08 PM	#42
amateur6 Pentaxian Location: Rhode Island Gallery Photos: 10 Posts: 145	Originally Posted by Richard Day Try your DA* at f4.5 as well. At f22 diffraction is occurring. The sweet spot is usually around f5.6 to f8.0. Thanks very much Richard! I'm going to do another round of test shots (actually I just did but I'm still getting a wicked back focus to correct). sigh Of course, the diffraction issue begs the question: can Pentax perhaps take a lesson from the elevator industry and please OVER-engineer instead of UNDER-engineering? In other words, if your f22 has issues, well, you shouldn't really have an f22, should you? Especially true of the 100mm Macro example you linked to -- adding f22 and f32 when your f16 has issues -- that's just bad engineering. Or a case of marketing running the show: "See, we have f32 too!" I'm not quite as bitter as I sound right now, but when my $200 lens is beating the pants of off my $900 (plus the UV filter; $1000) lens, yeah -- I'm gonna be a little upset. Plus, I was really looking forward to the k20d, but if it's just so much hoopla there, too, well -- I may as well sell all of this stuff and join one of the two dark sides. It's been a year, I've just rolled the shot counter (10k shots on my k10d), and I've gotten to the point where I'm thinking... maybe it's NOT just me. Oh, and -- how about the size difference? Those are identical crops from what are both supposed to be 50mm. Any thoughts?