Best aperture for Leica Minilux's 40 mm f/2.4 SUMMARIT

[rolpahof leikonblad]

Usually the best aperture for a lens is f/11. However, it seems to me

that my Leica Minilux's 40 mm f/2.4 SUMMARIT performs best at larger

aperture, somewhere at f/5.6 and f/4. I wonder if other Minilux

owners have this impression? Does Leica's designers optimize the

performance of the lens at larger aperture?

[Rob F.]

Dave: You undoubtedly got it right. Yes, Leica does optimize for wide apertures. Also, most any lens of that focal length will probably peak at an aperture no smaller than f/8. This is due to diffraction limiting, the tendency of light to bend as it passes the diaphragm blades. It sounds quite plausible that your lens peaks between f/4 and f/5.6. You must have done some very competent testing.

[shambrick007]

"Usually the best aperture for a lens is f/11"....according to who/what?

[rolpahof leikonblad]

To Sheldon Hambrick:

 

According to, say, The magazines of Popular Photography and Modern Photography.

 

* * * *

 

To Rob F.:

 

"It sounds quite plausible that your lens peaks between f/4 and f/5.6. You must have done some very competent testing."

 

In fact, it is only my IMPRESSION after having taken several hundreds photos. There is no scientific merits in my statement. I hope I have not given any misinformation to any one, especially Minilux owners.

[chi_huang]

Done some testing before, most impressive to me is very little degradation at wideset aperture. But my impression is stopping down still increase the performance. So my guess is that Leica designed it to highest performance at all aperture and not at any particular end.

 

I can't think of any advantage to optimize at wider aperture for any lens. And the physical design limit should be most dificult at both end and I think that's what most lens are.

 

Best, Chi

[travis1]

The best aperture would be the aperture needed for the right exposure at the selected speed.