I think the latest ones look good Mike. And what about your recent
Educated fleas? That looks excellent to me.
f/16 looks like it is working for you. As you know, I shoot f/45 full frame equivalent for invertebrates. At 1:1 your f/16 is effective f/32, and your f/22 at 1:1 is effective f/45, so we are in the same ballpark, and your latest ones don't look soft to me.
If you are still concerned about sharpness ..... I don't know what processing you are using but based on my recent experience you might want to download a trial copy of Topaz DeNoise AI and try it. (I have incorporated it into my workflow.)
As you know I often use a bridge camera with a very small sensor for invertebrates, but that doesn't provide any additional depth of field. In fact, depending on magnification I can get greater depth of field with any of my interchangeable lens cameras (micro four thirds, APS-C or full frame) than with my small sensor cameras. With a given minimum aperture (e.g. f/22), and
at a given magnification [<correction: when framing the same scene], you can get greater depth of field with APS-C than full frame, and more with micro four thirds than with APS-C. For example you can get roughly twice the depth of field with micro four thirds at f/22 than with full frame at f/22. However, would you really want to go there? f/22 on micro four thirds at 1:1 is effective f/45, and that is f/90 full frame equivalent. OK, you do get more depth of field, but of course you get the additional diffraction effect to go with that. So even though as you know I'm happy using small apertures, I don't think I would want to go that far. Were I using my full frame camera for invertebrates I would be experimenting with up to effective f/45 or so, but I wouldn't be hankering to go further than that (although I'm sure I would try it just to check that I wasn't missing a trick).
As to low hit rates .... I usually have low hit rates, and I don't know but I strongly suspect most people do who photograph active invertebrates like your latest ones above that are easily frightened off and even if not may stick around only briefly. My advice would be to do lots and lots of captures and be prepared to sift through them. If a subject sticks around I'll keep on snapping away, moving in and out, and changing the angle of attack. There are aesthetic considerations involved in both cases, but also practical considerations to do with the impact on cropability (see next paragraph) and the impact of the angle of attack on how the depth of field falls across the subject. There may only be one combination of magnification and angle for which everything falls into place, and if I take half a dozen shots with that combination, only one of them (or none) may have the depth of field falling optimally. (I work hand-held and I get a lot of shot to shot variation in terms of focusing.) You might want to add variation in aperture to the mix so you can explore the depth of field issue with some practical like for like examples of individual subjects to compare and contrast, and help work out what works for you and what doesn't.
Cropping? ..... Yes, that can help, and with your A7rii you should have plenty of scope for cropping. Definitely something to experiment with and see how far you can push it. (One of the reasons I use framing/magnification variations is that how much cropping I can get away with varies from scene to scene, It's not unusual in my experience for a cropped capture from further out/lower magnification to be better than an uncropped capture framed as I want the final image to look. But take that too far and the depth of field advantage gets outweighed by loss of detail and/or increased visibility/impact of noise. I can't work out in the field what will work best for a particular subject; I have to look at and compare candidate captures carefully, and see how they respond to processing, including cropping. Hence my doing capture variation.)
Out in the field I do captures for stacking for flowers etc, but stacking for invertebrates out in the field is a lot more difficult - smaller subjects, and subjects that are liable to move, or have parts that are moving, and time constraints because they may not be there very long. I keep thinking I'll try it more for invertebrates, but when it comes to it I'm thinking that while I trying to get stacking captures I'm going to be missing single shots that may be fine. One thing you might want to try is small stack captures, which can be done quickly, with perhaps as few as two or three captures (maybe few more sometimes if you have time). That is more practical in the field than deep stacks, the type that people do on often mechanised rigs, for tens of captures are used along with sweet spot (quite large) apertures. Out in the field I would try using a middling to small aperture, maybe in the f/8 to f/16 range and take several shots probably using fixed focus and moving the camera a little between shots.
If you are going to try stacking I suggest, if you haven't got some already, getting a trial of some software to help with the stacking, the two specialised stacking applications to try being Zerene Stacker and Helicon Focus. Some of the more general purpose editing applications will do focus stacking, for example the very modestly priced Affinity Photo. The general purpose applications won't provide the degree of control that the specialised stacking applications will, but there are plenty of people who find them suitable for their needs.
