Re: Sputnik at f32?

[erker@xxxxxxxxxxxxxx (Greg Erker)]

>Doesn't the fuzziness from being stopped down add
>to the CoCs?  Or are the CoCs enormous compared to
>the fuzziness?  On my SLR I found stopping down
>too far made everything very fuzzy.  This was in
>a real-world situation with lots of depth.  But
>it was a macro situation so that might be different.
>I found the fuzziness was unacceptable so it was
>better to open up a stop to get some resolution
>back and suffer a little loss in DOF.

  Good question. My f32 and smaller experience
is limited but...

1) My Ammarylis Stamens photos was taken with
my Ricohflex at f32 and my Pentax +11 diopter
(achromat) closeup lens. Because of
the high magnification (nearly 1:1) the DOF is
tiny. But the stamens themselves are very sharp
and you can see the pollen grains on them.
MF folio members (and Steve Spicer) who saw this
photo  will attest that it ain't fuzzy.

2) There were some pinecone and seashell photos
in the folio taken at f32 and f45 and they looked
sharp to me. The improved DOF helped the photos
even if the l/mm (at the focal plane) were reduced.

3) Sam has entered folio shots (non-macros)
that were taken at f32. Again, they did not
appear fuzzy in any way.

---
To change over to numbers, using your MAOFD
spreadsheed (80mm lens, anear=2metres, afar=inf)

At f11: geometric res=6.4  and diffraction ltd res=0.26
(minutes of arc I assume)
At f16: geo=4.3  diffr=0.38
At f22: geo=3.1  diffr=0.38
At f32: geo=2.1  diffr=0.77
At f45: geo=1.5  diffr=1.08

  So for a medium format camera with a normal
2 metre to infinity scene the geometric resolution
(at anear and afar) is much worse than the diffraction
limited res (at the focal point of 4m) at almost
all apertures. At f45 they are getting close.

  Assuming they add in quadrature then the resulting
res at anear and afar is 1.85 moa. At f32 the
result would be 2.24 which indicates that the
diffraction isn't making anear and afar much blurier
than they were (2.1). Intermediate points that
aren't so blurry will be more affected by the diffraction
induced blur.

---

  Regarding your 50mm lens that you made waterhouse
stops for. Repeating the above (50mm lens, an=2m, af=inf)

At f11: rg=3.9 rd=.42
At f16: rg=2.7 rd=.61
At f22: rg=1.95 rd=.84
At f32: rg=1.34 rd=1.23
At f45: rg=0.95 rd=1.73

  So here f45 is bad news. F32 isn't great
unless the near object and infinity are the
most important in the scene. F22 looks like
the min aperture to use.

---

  Straighten me out if I'm confused about
what MAOFD is telling me.

Greg