F/5.6 and be there. Sent from my iPad
Jeffery L. Smith New Orleans, Louisiana USA On Jun 4, 2012, at 19:05, Mark C <pdml-m...@charter.net> wrote: > On 6/4/2012 6:22 PM, Larry Colen wrote: >> I was thinking about my quest for sharpness, and was considering trying to >> do some research into what the aperture "sweet spot" is for each lens, and >> was wondering if anyone had already made a chart of them. >> >> Then I wondered how much it really matters. I've heard "a couple of stops >> down from wide open", "anywhere between f/8 and f/16", and a couple other >> rules of thumb. I do know that on some lenses, particularly the FA50/1.4, >> that stopping it down a couple of stops from wide open, makes a huge >> difference. And I suspect that if you look on an MTF chart, you might be >> able to easily see the difference between f/4 and f/8, but is there a >> practical noticeable difference? >> >> There is also the question of sharpness at the critical focus distance, and >> overall sharpness. That a lens might be sharper at f/4 than f/16 at the >> focal distance, but with a lot more depth of field, more of the photo will >> be sharper at f/16, than at f/64. >> >> I'm primarily interested in answers based on personal, practical experience, >> rather than theory. My hunch is that as long as I'm not too close to wide >> open, or pushing diffraction limits, optimizing aperture for sharpness is >> not the most productive place to spend my time and energy. That I'm >> generally best optimizing the aperture for the picture, and not trying to >> optimize the aperture for MTF. >> >> -- >> Larry Colen l...@red4est.com sent from i4est >> > To a large extent it depends on the lens - I've seen some that benefit hugely > from being stopped down one or two stops and others that show less of an > improvement. My A 50 1.4 benefits form being stopped down, my FA 50 1.7 is > almost as good wide open as it is at f 4 or 5.6. Back when I had the Rikenon > 55MM F1.2 it was noticeably less sharp wide open (and also had a fair bit of > light fall off.) My Tokina 400 f5.6 is not so sharp at f5.6 but improves > tremendously at f8. Most macro lenses I've tried benefit from stopping down > but are very good wide open as well. What it boils down to (for me) - in > theory any lens would benefit from stopping down one or two stops, but unless > I see a difference I don't worry about it. Stopping down = slow shutter speed > or higher ISO, either of which would probably offset the benefit gained by > shooting at the optimum f stop. > > I do notice a loss of sharpness when stopping down to f16 or beyond, I assume > due to diffraction. So, as a general rule of thumb I try to stick with f8 or > at the most f11 . Makes for nicer backgrounds as well. For general shooting I > find f5.6 to usually be fine for DOF. You really just got to try out your > lenses and see what you experience. > > MCC > > -- > PDML Pentax-Discuss Mail List > PDML@pdml.net > http://pdml.net/mailman/listinfo/pdml_pdml.net > to UNSUBSCRIBE from the PDML, please visit the link directly above and follow > the directions. -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
