Current mirrorless cameras still can not compete with DSLR for sports and safari photography. Other than that I don't see the need to carry such heavy equipment. Currently using Lumix m4/3 but is tempted by Fujifilm X100s.
>Current mirrorless cameras still can not compete with DSLR for sports and safari photography.
You'll be surprised how quickly that changes. A 900$ Sony Alpha 77 shoots at 12fps, and a 6.000$ Nikon D4 does 10fps. The Nikon has a much more expensive autofocus system and yet that system is disabled anytime you take a shot by the mirror lifting while the Sony has it enabled throughout. Mirrorless is a natural evolution for sports and safari because of this. On-sensor autofocus has already been cracked so we should be seeing amazing mirrorless cameras for sports coming out in the next Alpha refresh.
The A-mount Alphas are not mirrorless. They have a semi-transparent, non-moving mirror that steals about 1/3 of a stop to send light to the AF sensor. It gives most of the advantages of the DSLRs (phase-detect AF, but that's creeping into higher-photosite-density mirrorless cameras) while making live view and continuous AF much less complicated.
That's why Sony refers to them as "SLT" cameras and not SLR.
You'd be just as well served by comparing a $900 Nikon (D7[12]00?) or Canon DSLR to the D4. If you can't justify the difference between, let's say, a D600 and a D4, then it's moot anyway. I imagine the D4 compares quite favorably to the HST and Kepler on many axes as well. :-)
Read my comment more closely. My point was that SLT is already a big step towards mirrorless and alpha will be completely mirrorless in the next refresh. This will give you possibilities that haven't before been possible.
As for my example the D7100 you mention has the same 24MP sensor of the A77 and yet can only do 6fps. The point was that a 900$ camera could best a 6000$ one on dimensions that are very important to professional users like fps because of mirrorless technology. Mirrorless will give you some things only the very high-end could do before (or even the high-end couldn't do) at entry-level prices, that's textbook Innovators Dilemma.
I'm not so sure on-sensor autofocus has been cracked for use in wildlife and sports photography just yet -- it's pretty good for slow-moving subjects, but I've not seen an on-sensor autofocus system that can make a 400mm f/2.8 lens keep a jockey's eyes in focus. It's only a matter of time though.
As soon as it is though, I also expect that mirrorless cameras will rapidly infiltrate the pro sports and wildlife market. Burst mode will become as irrelevant as loading film -- sports photographers will simply record full-resolution RAW video and pick out the frame that they want in post.
You're probably thinking of contrast based autofocus, no? The reason I say it's been cracked is that there are now sensors with integrated phase-detection on the sensor itself, so you don't need to split the optical path into a separate sensor. Canon has even announced a sensor where every pixel phase detects. That's even more impressive as you're not limited to a few autofocus points.
The other reason that mirrorless has it easier for autofocus is that the sensors can be always on, unlike a traditional SLR where the mirror is up for the exposure and the autofocus is literally in the dark. Sony's SLT system already solves this by splitting the optical path continuously. Removing the mirror entirely is just the next step. That together with the more precise but slower contrast detection should make autofocus systems much better.
I'm very familiar with phase-detection autofocus on the sensor, and I absolutely agree that this is very likely to be the primary technology in the future, but it's not yet capable of providing the required focusing performance for serious wildlife or sports photography.
All of the systems currently widely available are what are called hybrid systems, because the on-sensor phase detection alone is not sensitive or accurate enough to work on its own in a wide enough range of conditions. They use the phase detection to get the lens roughly in focus, which then allows the contrast detection to work over a very small range of possible values, and allows the combined focusing to be both fast and accurate. (There are various claims online that the 70D, which uses the new sensor you mention, isn't a hybrid system, but Canon's own specs state it still uses some contrast-detection in live view mode[1], so my understanding is that it's simply doing more phase-detection and less contrast-detection than earlier systems, rather than being 100% phase detection)
As an example of how unsuited these systems currently are to sports or wildlife photography, in the Canon 70D, there is no way to enable proper continuous autofocus when using live view to shoot still images. Tracking is only available in movie mode.[2]
The camera can continuously provide a rough focus[3] (which speeds up final focus acquisition, and is also probably the exact same system used for movie focusing -- see below), but this is not accurate enough for reliably in-focus shooting. (Behind the scenes, this will almost certainly be using the on-sensor phase detection only).
Whichever mode you half-press the shutter in, the camera will then perform a precise focus (behind the scenes, it's almost certainly using the phase detection data combined with contrast detection data), but at that point, regardless of which of the modes you are in, the focus is locked -- if your subject moves closer or further away, you will need to release and re-press the shutter to regain accurate focus. I'm sure you'll appreciate that if you gave this system to anyone other than an extreme amateur sports or wildlife photographer, they wouldn't touch it.
(Note that the 70D does include a 'tracking' mode[4] in live view, but this merely uses face detection to ensure that the focus area is constantly over a face in the image, it doesn't cause the focus to adjust should the camera-to-subject distance alter while the shutter is half-pressed)
When you're shooting movies, of course the camera will track focus, but while it does a pretty good job compared to previous systems, it's very easy to see how bad the system would be for still photos. Take a look at this example footage[5], where it's very easy to see that the autofocus system is not performing anywhere near what would be required for action photography -- even at the default Youtube size and resolution (without needing to view it full-screen), the inaccuracy and big jumps are very easy to see, on a subject that is moving very slowly and predictably. And that's in pretty excellent light, not an indoor stadium or under trees in overcast conditions. (Also remember that that video is very clearly out of focus at times at a resolution of just over 2 megapixels, and when you're shooting stills you're expecting it to be sharp at 20 megapixels)
As I say, I think it's very likely that improvements to the on-sensor phase detection, as well as algorithmic improvements to the blending of the phase-detection and contrast-detection data, will mean that this is the future of action photography, but it's not there yet, and personally I'd say we're probably 2-3 generations away from a system that can track action as well as even a low-end DSLR that uses a separate dedicated phase-detection sensor.
>As I say, I think it's very likely that improvements to the on-sensor phase detection, as well as algorithmic improvements to the blending of the phase-detection and contrast-detection data, will mean that this is the future of action photography, but it's not there yet, and personally I'd say we're probably 2-3 generations away from a system that can track action as well as even a low-end DSLR that uses a separate dedicated phase-detection sensor.
Thanks for the detailed post. I haven't tested any of these systems so am going from specs only. It's an exciting time for camera technology indeed.
I recently bought an X100s and it has rejuvenated my photography interest more than just about anything else in the digital age. You can argue specs and image quality and value for money all day, but shooting the X100s is fun and makes me happy in a way no other digital camera has.
