Re: Interesting Panasonic TZ1 feature

On Jun 29, 10:56 pm, "David J Taylor" <david-tay...@xxxxxxxxxxxxxxx
this-part.nor-this-bit.co.uk> wrote:
Nervous Nickwrote:

[]

That raises an interesting question: Have any *empirical* studies
been done regarding small-sensor cameras (or, rather, very short
focal- length lenses), WRT at what point the lenses become
diffraction- limited? I am relatively new to digital photography,
and initially found it difficult to remember that you just plain
cannot stop a lens down on a digital camera as much as you might
unthinkingly do with a larger format camera.

I do hope someone can answer your question, but knowing the way in which
marketing /can/ drive engineering, I suspect that cameras are already at
or beyond that limit!

So you seem to be saying that most of these lenses would be
diffraction limited when *wide open.* Which makes sense considering
the much smaller scale we are talking about.*

However, as people's expectations may be less with
small-sensor cameras, perhaps it doesn't matter as much if some
diffraction shows. I think it would just be a lack of sharpness rather
than anything unpleasant. To keep noise down, you may stick with ISO 100,
so not having a smaller aperture may not matter as much. In any case, you
already have greater depth-of-field.

See, there is where I got messed up initially; in thinking that you
would get greater depth of field by stopping down, when you already
*have* that greater depth of field inherent to the smaller scales.

Cheers!

--
YOP...

*By "a point where a lens becomes diffraction limited* I mean, the f-
stop past, where if you stop down any further, you get no net gain in
sharpness, and indeed begin to experience loss in sharpness. You can
actually view this phenomenon under an enlarger, for example, if you
carefully look at film grain through your enlarging magnifier while
stopping down the lens. As you stop down, the grain will appear to
become sharper, up to a certain f-stop, past which the sharpness
degenerates. It is at that crucial f-stop that the lens is said to be
"diffraction-limited," as in, for example, "diffraction-limited at f/
11".



.

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