Archived posting to the Leica Users Group, 2001/12/10

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Subject: Re: [Leica] noctilux DOF as compared to other lenses
From: Rei Shinozuka <shino@ubspw.com>
Date: Mon, 10 Dec 2001 13:40:15 -0500 (EST)

i guess it took someone cleverer than me to point this out too!

:-)

- -rei

> From: John Collier <jbcollier@powersurfr.com>
> 
> When you fix the magnification of the final output relative to actual
> subject size, then you are in effect removing focal length and focused
> distance from the equation. The only variable left is aperture. The larger
> aperture yields the smallest DOF. Not particularly useful info in the real
> world mind you. The 75/1.4 and the 90/2 are more difficult to focus when you
> are close and wide open which is what most people will want to know.
> 
> John Collier
> 
> > From: Rei Shinozuka <shino@ubspw.com>
> > 
> > someone cleverer than i pointed out to me that for a GIVEN MAGNIFICATION, the
> > noctilux is still DOF champ.  in other words, you need to scale the distance
> > by the focal length so that a cat or a face would be approximately the
> > same size on the negative for each lens.
> > 
> > using my favorite calculator: http://members.home.net/gillettm/DOF.html
> > we get:
> > 
> > f.l.  f.stop. distance DOF
> > 35     1.4     1.4m    13.1cm
> > 50     1.0     2.0m     9.4cm
> > 75     1.4     3.0m    13.1cm
> > 90     2.0     3.6m    18.7cm
> > 
> > the most surprising is that given these constraints, the 35 lux at 1.4m
> > has the same DOF as the 75 lux at 3.0m!
> >
> >> From: "Steve LeHuray" <icommag@toad.net>
> >> 
> >>> someone sed:
> >>> 
> >>>> Plus, I love the
> >>>> shallow depth of field that the 1.0 lets me use.
> >>> 
> >>> i think someone posted a couple months ago a list of the DOF of various
> >>> leica lenses -- i was suprised to learn that the noctilux wasn't really even
> >>> terribly close to having the shallowest DOF (3rd or 4th if i recall)
> >>> 
> >>> kyle
> >>> --
> >> 3rd, with MORE dof than a 75 or 90. Why is that shocking? The longer the
> >> focal length, the less depth of field.
> >>
> 
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