Jeff Kott wrote:
Thanks for the info Juha. I’ll have a lot of testing to do since I have quite a number of M mount lenses from the days when I was adapting to my NEX cameras.
Yes, I've had plenty of fun testing my M-mount lenses (which I also started accumulating after getting NEX-6 back in 2012) with LM-EA9. Now that my A7CII got firmware update 2.0 (including automatic AI subject recognition option), I've started testing with LM-EA9 again. I find that with AI subject recognition, AF sometimes works at wider area than with other modes, but it's not always certain whether accurate focus is achieved correctly even when the focus system indicates it with green box etc.
Recently my strategy has been to get native E-mount CV lenses whenever possible and trade away corresponding VM lenses, and to only keep the interesting M-mount and LTM lenses that are not available in E that also happen to perform decently on Sony stack. I've also been heavily into MS-Optics lenses in the last couple of years (they tend to work relatively well on Sony in general). I've accumulated around 17 unique MS-Optics lenses (that I'm keeping) currently. I still have around 30 other M-mount lenses as well, but not many wides (except for 28mm which is one of my favorite focal lengths).
This weekend I was playing with MS-Optics Vario Petz 57/2 on my LM-EA9. It's a very interesting lens for LM-EA9 testing since it has a control that allows changing the Spherical Aberration correction (by moving the back element of the lens slightly in either direction). With this lens I found LM-EA9 AF to work much better on the maximum under-corrected SA setting (-2). However, with this setting the lens can only focus in close range up to 2.5m by design. When used with maximum over-corrected setting (+2), I was getting very unreliable focus confirmations for example on cars (with AI subject recogntion) where focus was confirmed without hesitation but target was visibly out of focus... I figured that I could not trust AF with +2 setting so I switched to traditional adapter (CV VM-E close focust adapter II) at that point...
Other that that, I've found that LM-EA9 focuses more reliably with wide apertures, and in stopped down shooting where everyhthing is more or less in focus, it may give focus confirmations more easily when the target is not actually in perfect focus. For stopped down shooting / trying to get best corner-to-corner sharpness it's not so easy to rely on it and I often prefer focusing manually, especially with lenses that have some field curvature and would benefit from focusing in the mid-zone rather than central area for balanced results.