[rollei_list] Re: OT / prove it !
- From: "Austin Franklin" <austin@xxxxxxxxxxxx>
- To: <rollei_list@xxxxxxxxxxxxx>
- Date: Thu, 31 Mar 2005 22:29:18 -0500
Hi Eric,
> > "suffers". Kind of dramatic. 35mm can easily be equally as
> sharp as MF at
> > 5x7 and even up to 8x10 and perhaps beyond. When talking grain
> or tonality,
> > that's a different story, you can still have very sharp prints,
> but start to
> > see grain. Obviously, this is film dependant (film
> > choice/exposure/development/shutter speed/camera shake etc.).
> >
> > If human visual acuity is 1 arc minute (which is the definition of 20/20
> > vision), that corresponds to .0029" at a distance of 10" from
> the eye. That
> > is 6.88 lp/mm. So, the most you can distinguish from an 8x10
> print held 10
> > inches from your face is 175 lp/inch, or 1400 x 1750.
> >
> > To match human visual acuity of an 8x10 at 10" with 35mm, you
> would have to
> > have only recorded 55 lp/mm on the film. Hardly unreasonable
> to do so on
> > 35mm film.
> >
> > So, unless you're a really shaky dude and working from a really
> out of focus
> > image, I can't imagine how you can see any difference in
> sharpness on a 5x7
> > print made from a 35mm vs a 5x7 made from a Rollei.
> >
> > Regards,
> >
> > Austin
>
>
> Hi Austin -
>
> Your imagination aside, we've been through this before... I can
> easily tell
> the difference between a 5 x 7 from a 35 mm neg and one from an MF neg.
Easily? The only imagination necessary would be to believe this! I simply
do not believe this at all that in reality you can do this with a proper
test, and I am more than happy to arrange a proper test.
> Others on the list can, too.
Well, who? And how do you know? What kind of "tests" have you done, or is
this simply in general passing you made this observation?
> I don't know what that does to your calculus,
> but there's life for you. If you can't, then you are blessed with a much
> less demanding personal photographic baseline, and I guess you should be
> grateful as life is simpler for you. 8-)
I'm sure I have at least an equal and perhaps even more "demanding personal
photographic baseline" that you. I evaluate image quality as part of
designing imaging equipment, and having been a professional commercial
photographer.
> And btw 55 lp/mm on a
> piece of neg
> is not a gimme by any stretch of the imagination...
Absolutely agree, but it also is not extraordinary to accomplish. And,
again, that was for 8x10, and you are claiming 5x7, which would make the
requirement closer to 35 lp/mm.
> I suspect it has much to do with the fact that perceived sharpness is not
> solely a function of resolution.
Or, that perceived sharpness isn't all that you are basing your belief on.
Regards,
Austin
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