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[OM] Re: Apertures, where is f22 ?

Subject: [OM] Re: Apertures, where is f22 ?
From: Der Eiserne Reiter <ferider@xxxxxxxxx>
Date: Tue, 7 Jun 2005 13:31:32 -0700 (PDT)
Winsor,

this is true for some lenses, but not for others. For example,
the 35/2 peaks at f11 and f16, in Gary's test. Also, I am wondering
if it depends on the shape of the aperture, nr. of blades, etc.
The other day, on *bay, I saw the picture of a Zeiss lens
with a triangular aperture and was wondering what this did to
the picture.

Roland.

--- Winsor Crosby <wincros@xxxxxxxxxxx> wrote:

> 
> In lenses for the 35mm film format you start running into significant  
> softening of the image  by F16 due to diffraction effects of the  
> physical size of the aperture. It just gets worse at F22. In smaller  
> format digital cameras the cutoff is frequently before F8, for the  
> same reason. The newer Sony digital cameras have been roundly  
> criticized because their exposure program goes immediately to a small  
> F stop and has soft images as a result. I think leaving it off is  
> just a recognition that knowledgeable photographers, who seem to be  
> the only people still using lenses with F markings, just don't use  
> F22 because of image quality issues.
> 
> Just for your own information you could check out the lens tests at  
> Gary Reese's web site and see the resolution start to drop at F16 in  
> lens after lens.
> 
> 
> 
> Winsor
> Long Beach, California, USA
> 
> 
> 
> 
> On Jun 7, 2005, at 12:53 PM, Der Eiserne Reiter wrote:
> 
> > List,
> >
> > let me offer a new technical subject:
> >
> > I have often wondered why some lenses in the 28-50mm focal range do
> > not offer an additional f stop. I understand that is is technically
> > difficult to provide both wide and small apertures, and good bokeh,
> > but for landscape photography, f22 is very helpful sometimes.
> >
> > Why do some lenses stop at f16 and others continue to f22 ? Do other
> > people care about f22 ? For instance, the 50/3.5 features f22, while
> > the 1.2, 1.4, 1.8 do not.  Technically it is feasible to get f22 with
> > a wider lens, as was demonstrated by C*non in the 50s with their
> > 50/1.2 lens. Why do the 35/2.8, 28/3.5 and 28/2 not have f22 ?
> >
> > Just wondering,
> >
> > Roland.
> >
> > PS: forgive my English, it's my third language. As our Kahlifonian  
> > governor says:
> >     Q: isn't my English very good - A: yes it isn't ...
> >
> >
> >
> >
> > FeRider (R.)
> >
> >
> >
> > __________________________________
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