Though not the original commenter, I wanted to just offer some reply to HermitIbis on EVF vs OVF with regard to BIFs of all types. First off, I've been a long-time BIF shooter, with both DSLRs and mirrorless - many times I've gone out with BOTH types, and switched from OVF to EVF throughout the day. I will say that EVFs in general can be just as good as OVF, once you've become accustomed to them, with the caveat that not all EVFs are equal.
Generally, the best EVFs are going to be the ones that offer a true live refresh or 'live view' mode, where there's minimal delay that's approximately the same as the shutter blackout on an OVF, that allows you to easily acquire a distant subject and maintain it in the finder while panning and shooting. Older EVFs usually would display a 'slideshow' effect, where what you were seeing while shooting a burst of photos was a succession of the last shot taken - which meant you were always at least 1 full frame behind the action. Not bad with a big, slow bird moving consistently, but not good for small distant birds, erratic and fast birds. Newer EVFs have solved that issue with real-time display up to certain burst speeds.
Other factors include refresh rates and frame rates - newer EVFs have significantly improved the refresh speeds, and also allow up to 120fps on the EVFs making them much more accurate, no staggering or stutter, etc.
Setting up the EVF properly can help, and also setting up the camera properly for best BIF shooting. Of course, some people may have trouble adapting to EVFs in general, even good ones, if they've spent their whole lives with OVFs...but as someone who shot OVFs since 1977, and EVFs since 1997, I've been able to adapt to both -and also watched the EVFs get significantly better along the way. I'd suggest on the RX10IV, if shooting action/BIF, to switch the 'display quality' setting to 'high' - which should increase the screen refresh from 60fps to 120fps, for smoother and better panning. Next, I'd recommend turning OFF the 'pre-AF' in the menu. This will essentially make the camera behave a bit more like a DSLR...pre-AF has the autofocus constantly working on the camera, even when you're not half-pressing the shutter, which sometimes means strange hunting or catching up when you try to acquire a distant subject. Turning off pre-AF means it won't make any attempt to adjust focus until you tell it to - so even if you were just shooting a macro from 4 feet, and now want to shoot a distant bird, the EVF will be complete blur (just like an OVF would be at minimum focus distance if you tried to look at a subject 200 yards away)...and when you half-press, the focus will go into its highest speed mode to try to acquire the subject...I find it acquires distant subjects much more quickly this way. The one thing missing on the RX10IV's viewfinder is the specialized 'live view' mode as on the A6300 and 6500, or the even better blackout-free mode as on the A9. So there will always be a slight lag in the finder, whether in 10fps mode where you get a very-quickly-refreshing slideshow effect (about .10 sec behind), or a continuous video feed at 24fps, but with the video delayed by about .10 to .15). This can generally be overcome once you get used to these systems, though might present a challenge if shooting something like martins, swifts, or swallows in full swoop from 30 feet, with their erratic movements.
) but it seems this darn expensive all-in-one p+s is capable enough. I think that I, too, have to check the Sony against my combo Canon 7DII+100-400LII.
