Short answer: probably.
I ran some tests and found with deconvolution sharpening most of my lenses are as good at f/22 as they are at f/8. I am somewhat nonplussed.
I've been advocating the use of deconvolution sharpening for a long time, and there is a interesting thread with examples
covering that subject on LuLa as well. However, there is something that many people overlook. When looking at the MTF curve of diffraction, it becomes clear that the spatial frequencies near the Nyquist frequency (the highest level of detail that can be reliably reconstructed from discrete samples), will suffer most loss of contrast. That means that when detail already has a low contrast (such as all high spatal frequency already does), it will be reduced to zero much earlier than higher contrast detail with the same spatial frequency. So low contrast microdetail will become unrecoverable, while some of the higher contrast microdetail may still be recoverable by deconvolution (having a low noise image helps to increase the chance of pulling it off).
So yes, you will be able to recover a lot of what seemed to be lost by using high quality deconvolution, but the low contrast micro detail may be lost forever (also in the focus plane, not only at the edges of the DOF zone) when stopping down too far. An aperture of f/22 is guaranteed
to limit your average luminance microcontrast detail to being totally unrecoverable above 90% of your 40Ds maximum resolution! When you limit the narrowest aperture to f/20, then some lower contrast micro detail can theoretically be recovered all the way up to the maximum resolution of your camera (although in practice, the residual lens aberrations will still throw a spanner in the works, but at least you're not throwing away every possibility of recovery).
The challenges with deconvolution are:
- a. Finding the optimal model of the Point spread function (PSF) with which to deconvolve,
- b. Keeping the noise amplification down as much as possible.
I've made available a free tool
to determine point a. for a given camera/lens/aperture combination. That will alow to determine the correct settings for Topaz InFocus (which you apparently used), or other deconvolution tools (e.g. RawTherapee offers Richardson Lucy deconvolution, even when using existing files, not only Raws), much more accurately than we generally can achieve by eye with trial and error. It can also reveal some interesting facts, such as when using tele-extenders or some zoomlenses. My tool will also allow, under its section 4. that operates independently from the 3 prior steps, to figure out what the diffraction limits for certain aperture sensel pitch combinations are.
Good deconvolution also benefits from good tools (preferably with tweakable regularization of noise amplification, and custom PSF input), and high computational accuracy (to avoid round-off errors creeping into the results).