The loss of detail to diffraction from 10MP to 2MP was based on my
erroneous assumption that Joel had been using a 4/3 camera at marked
f/11 but more probably about f/16 at close focus for the flower. The 5D
is on the verge of diffraction at f/11 but does not have a problem
there. f/11 is my standard landscape shooting aperture.
But as I said before, if diffraction takes 80% of the detail, it's
immaterial if you resize the image downward to 0.5MP for a web images
since the detail gets thrown out anyhow. Depth of field calculations
also go out the window (meaning greater depth of field) since the CoC
assumptions are based on very fine detail for prints. If the finest
detail is a screen pixel then CoC for depth of field is likely 3-4 times
larger than for a print.
Chuck Norcutt
On 1/31/2012 12:35 AM, Moose wrote:
> On 1/30/2012 7:23 PM, Joel Wilcox wrote:
>> Shallowest I generally go with big flowers is f8 (rarely) with film/FF. F11
>> is barely adequate. I would routinely go
>> with f16. If filling the frame, there is still plenty of bokeh to be had.
>> Bugs me to see a good bit of the flower out
>> of focus.
>
> Although it doesn't agree with Chuck's computations, my experience peering at
> 5D shots at 100% is that f11 doesn't give
> up any sharpness to diffraction. Theory aside, if I can't see it at 100%, it
> isn't a problem.
>
> Diffraction softening does start to become visible at f16, but I don't see it
> as a problem for deep subjects like these,
> if shooting for great DOF. It bugs me too, when important parts aren't in
> focus. I do occasionally go Dawid's way, but
> would prefer it to be by choice, not necessity. :-)
>
> The same thing was clear in the flower buckets Mike posted recently. If you
> want to go beyond what f16 gives, and still
> want overall sharpness, you have to either stack focus or use software.
>
> This is a simple, two shot focus stack, put together by hand in PS.
> <http://galleries.moosemystic.net/GGPark/Flowers/pages/FL27.htm> A couple of
> others in this gallery are also focus
> mixes, including at least one hibiscus. You don't always have to go with
> fancy, deep stacks. It did take some fussing in
> PS to get the transitions clean in this one. They were hand held. Taken with
> a tripod with focusing rail, it would have
> been easier.
>
> Deconvolution software often allows deepening the DOF. Same basic technique
> as in the few images I've posted moving
> focal planes forward or back.
>
> One does need some way of masking and feathering the effect, as what's
> required to bring softer areas into focus will
> generally seriously overcook the areas already in focus. A fair number of
> images I've posted over the last months have
> had that treatment.
>
> Moose
>
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