I have no idea why would anyone buy this, what do you get with this system, what are the advantages compared to canon nikon sony, how will panasonic stand out?
ANSWER WHY:
I think 50mp and 6fps with servo focus is a big deal, and hopefully Canon will be able to double its full frame mirrorless frames per second in servo AND double its megapixels simultaneously, but until it does, this is quite a reach above the EOS R - at least for the sorts of things I shoot (reach-limited nature/wildlife).
It seems squelched by thin-aperture lenses with Leica prices, yes, but that gets solved once Sigma releases its L-mount versions, the timing of which I'm slightly more optimistic about than the release of a pro R version.
The S1R + Sigma lenses appears to be the best first-try full frame mirrorless of any vendor to date. You could make a real system out of this thing.
CONS:
The thing I'm skeptical about is the autofocus, which we won't really be able to suss out until it gets into peoples' hands. My impression is that it is attempting to use a deep learning process to enable old-style contrast AF to be able to have the same function as phase-detect AF. That could either work brilliantly, or suck. Early reports are that it sucks, but there isn't a production version being tested yet.
Vlogger reviews seem to get hung up on video disappointments, such as potential overheating issues with 4k 60fps, crop in 4k 60fps, etc., etc., all of which are features not even present the Canon competitor. I'm not a video guy, so I'm sort of ignoring all that, but if I were to care, Canon wouldn't be the alternative.
UPSHOT:
I've been saving up for a mirrorless full frame upgrade, and I'm not entirely positive this slug of capital will go to Canon or Panasonic. Provided the AF is good (significant liability), if the Sigma lenses come out before the Canon pro body, I'll probably give the Panasonic system a go. Sigma is also developing an L-mount camera, but their camera body track record is pretty bad on the factors I care most about (fps, for instance), so I'm assuming I'll be interested only in their lenses, unless they really surprise - and you never know with Sigma. While the Canon R lenses are easily the best launch-with-camera set of lenses ever offered in more than a decade, I still need >3 fps in servo for me to allow the body in the house.
The upshot: if Canon waits a year to launch a pro-performing body, I'll likely be fooling around with a second system by that time. Will still be open minded to selling 2nd system and come back completely to Canon with a deserving pro mirrorless body, but it'll require the new Canon body to outperform the 2nd system, which will probably be coupled with a wide range of Sigma L-mount lenses that are akin in capability to the fast/bright lenses Canon is putting out geared to the short flange distance. In other words, Canon likely won't be able to answer lower-specced body issues with a simple "it's the lenses."
THINGS TO LOOK FOR:
- AF performance of the SR1 (quite unknown now)
- Adapter performance on the L system (not optimistic)
- Sigma lens launch timing