Archived posting to the Leica Users Group, 2001/02/07
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At 4:35 PM -0800 2/7/01, Mark Rabiner wrote:
> ><Snip>
>> I suspect that, that is what everyone, using an RF camera, does. For large
>> blow-ups, think f/8, shoot at f/16. With the newer APO & ASPH lenses, this
>> is critical. You can relax this when using older non modern design lenses.
>>
>> Jim
>
>Why is this Jim? I'd think I'd be the opposite!!!
>
>mark rabiner
I'm not Jim, but my reasons are the following:
With the new, very highly corrected lenses, the items in the true
plane of focus are rendered more crisply than with previous lenses.
The sharpest items in a picture set the perceptual standard for
sharpness in that image, so if the standard is very high, the
criteria for what else in the picture is 'sharp enough' also gets
raised.
If your lens is not as sharp at the true plane of focus, and already
has a slight spread, the OOF areas that are just slightly less in
focus will in fact be further away from the true plane of focus.
Therefore, you will put up with a larger COC, and therefore you can
shoot at a wider aperture.
Another interesting item wrt DOF is the fact that when taking
landscape shots in which objects at infinity are supposed to be
sharp, it's necessary to make sure that the your lens is set closer
to infinity than you might suppose. The eye is much more critical of
sharpness of things at infinity than at the near focus point.
- --
* Henning J. Wulff
/|\ Wulff Photography & Design
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