Testing

To perform the test, I wanted to remove AF performance from the equation. Why?  Because it's almost impossible to recreate the same action sequence multiple times to repeat tests and I wasn't trying to measure lock-on AF performance anyway. This is solely about frame rates.

So the test setup was quite simple: An A7Riii with the new 24-105 "G" lens, set to manual focus on a fixed object and also set to manual exposure of 1/200th shutter (slow for sports, I know, but fast enough that it should not slow down the effective frame rate) and an aperture of f4 (wide open for this lens). Being wide open eliminates the need for the lens to stop down (and perhaps slow down) performance.

Now the Caveats from the Help Guide

The Sony "Help Guide" is full of foot notes and reminders as to which settings affect shooting rate.  I'm going to call them "footnotes" here and will reference them throughout.  Here are the six I found that matter (some are slightly paraphrased):

• Footnote [1]: on [Hi+], if F-value is greater than F8 the focus is locked to the setting in the first shot.
• Footnote [2]: RAW images recorded with this camera have a resolution of 14 bits per pixel. However, resolution is limited to 12 bits in the following shooting modes:[Cont. Shooting] when [RAW File Type] is set to [Compressed]
• Footnote [3]: The shooting speed during continuous shooting becomes slower when [ RAW File Type] is set to [Uncompressed].
• Footnote [4]: The subject is not displayed in real-time on the monitor or viewfinder when shooting in [Continuous Shooting: Hi+] mode
• Footnote [5]: The shooting speed during continuous shooting becomes slower when [e-Front Curtain Shut.] is set to [Off] in [Continuous Shooting: Hi], [Continuous Shooting: Mid] or [Continuous Shooting: Lo] mode.  (Note that Sony does NOT include [Hi+] warning.)
• Footnote [6]: RAW images recorded with this camera have a resolution of 14 bits per pixel. However, resolution is limited to 12 bits in the following shooting modes: [ Long Exposure NR], [BULB], [Cont. Shooting] when [ RAW File Type] is set to [Compressed] 

Granted, I may have missed a relevant one as the manual is 650 pages (If I did, let me know and I'll incorporate it into a revision of this post)

Ok, so what do we have to consider at the [Hi+] continuous setting?  First off, don't shoot smaller than F8 or else focus is locked (Footnote [1]).  Well, I normally shoot close to wide open so this won't be a problem but it is something to keep in mind.

Footnote [2] says the camera will revert to 12-bit image resolution when shooting continuous and compressed. This applies to Hi+ mode (and all others) so if you shoot compressed, you'll get a 12 bit image. I'll do some exploring on this subject to see what the real world effects are of 12-bit.

Footnote [3] says shooting "uncompressed" will affect speed, so I will test for that.

Footnote [4] says the viewfinder won't be realtime. Yikes. For me this is a game stopper in most sports situations and would force me to shoot at [Hi] setting (or 8fps instead of 10). In shooting with the camera the first day, I ran into this and what the camera seems to do is present a "slide show" of just-captured frames, at 10 or less slides per second; but this is NOT a live image of what's going on and it is exceedingly difficult to follow an unpredictable target.  I can see where it would allow you to shoot someone coming straight at you, but if the target dodges and weaves (basketball, soccer, football players for instance) then it is really tough to follow the subject at 10fps.   For this reason, it is probably better to just run at [Hi] mode (8fps) and get a real live view. (See Mark Galer's recommendation in his youtube video referenced above)

Footnote [5] talks about speed slow down if the "e front curtain shutter" is set off, but you'll notice it does NOT apply to [Hi+] mode so it shouldn't apply here.

Test scenarios

For the [Hi+]  test I basically shot in continuous mode three ways 

• e-front curtain shutter off
  
• e-front curtain shutter on
  
• silent mode
  

Within each setting above, I shot with and without image compression resulting in 6 rows of results.

I tried, as best I could, to shoot continuous for 3 seconds but it is VERY difficult to let off the shutter at exactly the 3-second mark. To try and remedy this, I repeated the test about three times each but in the end, it is not exact.  I then took the "frames captured" over three seconds and divided by 3 to get a rough avg fps.  It's not perfect, but for purposes of getting a feel for how the settings affected performance, I think it is "good enough".  In my sports shooting, I don't recall mashing down the shutter release for more than three seconds but I'm sure some people will.  The problem with long continuous runs like that is that the buffer soon fills and you slow down anyway... 

I also included the total time to clear the buffer.  This shows you the affect of running "compressed" (smaller files) vs "uncompressed" (larger files) and it is absolutely significant.  If you are concerned about shooting compressed (and thus 12 bit), you'll have to find some other articles about what you lose at 12-bit, but what you gain at compressed is significantly faster buffer clearing.

Take Aways using [Hi+]?

First, [Hi+] is of limited use because of the "not real-time" display.  I would recommend [Hi] (8fps) in most action situations even though you lose about 2fps.  [Hi+] may be "OK" if the subject is running at you predictably and in more of a straight line.  This is also the recommendation of Mark Galer on Youtube, a Sony ambassador.

Compression doesn't seem to affect frame rate even though the Help Guide warns it will. I got 10fps (plus or minus 0.5fps) both ways.  Yeah, it came out a hair slower, but there may be user error in that it is almost impossible to release the shutter at the exact moment.  Regardless, I didn't find Compression to slow down frame rate in a meaningful way (buffer clearing is a different story).

Uncompressed does, however, significantly delay buffer clearing times.  Buffer clearing takes about 50% longer uncompressed except for Silent Mode (which captured significantly fewer images and thus less to buffer).

Turning e-front curtain shutter off doesn't seem to slow down Hi+ mode.  And thus, this supports footnote [5]. For some reason, [Hi+] mode operates just about as fast with or without the electronic front shutter.

Silent Shooting Uncompressed was the outlier speed-wise, at 7fps which is a significant penalty vs 10fps. There's probably an explanation for this but I can only guess it has to do with computing time needed to process images while also operating a completely electronic shutter.

Dropping down a notch to [Hi]

So given the "not real-time display" at [Hi+] 10fps, let's drop down to [Hi] mode.  This has been mentioned by some reviewers as the preferred action setting for one key reason:  the EVF/Display become real-time again. 

Also, According to footnote [5], we should see slower speeds with e-front curtain shutter turned off, we'll see.

Observations using continuous [Hi]

Not sure why, but I got just a hair above 8fps. It could be that I just held the trigger a fraction too long, or it could be that the A7Riii operates a hair above 8fps. Either way, that's good news and a very decent frame rate for action.

What's not so good is that the A7Riii slows down considerably when you turn off the e-front curtain shutter in continuous [Hi] to roughly 5 or 5.5 fps.  So keep e-front curtain shutter turned on!

Overall Conclusions: [Hi+] vs [Hi]

So you have an A7Riii and you want to capture action, be it a pet running, a soccer/basketball/baseball game, or an energetic 5 year-old, what continuous settings should you use?

For high frame rate shooting, unless you can live with the "not real-time" display of the [Hi+] 10fps setting, I will personally opt for [Hi] setting and e-front curtain shutter. 8fps is plenty good for me in most situations and I imagine it works for most users, especially shooting a 40+ megapixel sensor.  If I want more than that, I'll consider the A9 which is very similar in its relationship to the A7Riii as my Nikon D5 was to the D810 (or the more current D850).  There's a reason for the A9 (and the D5 and Canon's EOS-1D X Mark II) as pure sports/action beasts, but the A7Riii can comport itself quite well all while providing gorgeous, crop-able 40+mp files.

Can you use [Hi+]?  Yes, of course, if a jogger is running right at you then I can see it, but I prefer the real-time view that I get in [Hi] mode in most circumstances and will sacrifice the 2fps.

Another scenario that works great in  [Hi+]: say you expect an eagle to swoop down and grab a fish stuck on a rock in the middle of a river. You focus on the rock and will remain focused on the rock.  Set the A7Riii for [hi+] 10fps and blast away as the eagle arrives, grabs and departs.  

But if you have to follow a soccer player handheld, moving left/right, fore/aft, the non-realtime display just bugs me and I imagine it will bug others too.

I will also stay away from [Hi] setting on the A7riii and full mechanical shutter (e-front curtain shutter off). It just slows things down too much (e.g. to less than 6fps).

Compression?  The one thing I miss most from Nikon is the lossless Compression mode as it is a no-brainer.  In Sony world, you have to determine if you can live with the much-slower buffer clearing times shooting uncompressed (and the larger files) or live with the image quality differences of lossy compression.  

What are those image quality differences? Well , most importantly is that the bit-depth drops to 12-bit in compressed mode (see Footnote [6] above). That's something you have to consider for yourself.  Most things I've read show  that you cannot see the difference unless pixel peeping at 100% and then only if the image meets certain criteria (high contrast etc). If you'd like to read more on 12-bit vs 14-bit differences, try this article   The thing about Sony is that you have lossy-compression AND 12-bit working against image quality ever so slightly.  For sports/action, that's not an issue for me, but I still wish Sony had a lossless compression option. 

In a nutshell, for action shooting with the A7Riii, I'm shooting [Hi] mode, compressed, with e-front curtain shutter turned on.