Gigabitfilm

[Ed Sukach]

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

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.

 

[Foto Ludens]

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.

 

[Foto Ludens]

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

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

 

[Tom Hoskinson]

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

 

[Ed Sukach]

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.

 

[Tom Hoskinson]

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.