Gigabitfilm

Tom Stanworth said:

If you are using a 35mm lens at f22 for a landcsape, diffraction will limit your resolution somewhat.

Click to expand...

I have never seen a 35mm lens - we ARE talking about true focal length - not "retro" - that would stop down to f/22 ... that is a *very* small - in terms of physical aperture - diameter. Lens makers do not *WANT* to have their product subjected to the possibility of degradation by diffraction.... so f/16 is the lower limit.

Ed,

look at the new 35mm pancake lens voightlander put out
http://www.cameraquest.com/voigtpma2004.htm

it seems it stops to f22

being an m mount lens, I doubt that it is retro focus...
I havent seen the other lenses yet, but I could swear I had seen a 35mm that stoped down that far.

it seems that their color skopar 35mm stops down to f22 as well

http://www.cameraquest.com/inventor.htm

And I have a 21mm Zeiss Biogon (Contax G2) that stops down to f22. This thread seems to have wandered out into the weeds.

The only way to resolve this would be an analysis of the lens design... noting the true aperture - to - film plane distance, and actual aperture diameter. I refuse to extrapolate - but I would *suspect* a retrofocus design.

Yes, the f number is the ratio of the lens aperture diameter to the focal plane distance. As a consequence, the effective f number varies as the on-film magnification varies. The f numbers engraved on a lens are typically the f number for the lens when it is focused at infinity.

The Zeiss Biogons and Hologons are not retrofocus designs.

The 16mm Hologon is a fixed aperture (f8 at infinity) WA lens that provides nearly rectilinear coverage of the 35mm format.