Some Recent History
Sony has been innovating in the full frame camera space for a number of years now. The first was the A7 producing the smallest full-frame camera on the market, this was quickly followed by the A7R the highest resolution full frame camera. Finally the A7S, a camera that could almost see in the dark and did some good video work as well. Since this time they have upgraded these cameras at a rapid rate, the current line up is the A7S II, A7II and the A7RII. All of these cameras are similar in size and much smaller than the equivalent Nikon or Canon Cameras, as you can see from the illustration below.

Curtesy camerasize.com

What was Missing
Sony’s market share has been increasing steadily due to the compact size of the A series and its mirrorless features that DSLR camera simply do not have. The growing high-quality lens stable has also helped to increase the market share and being able to use Nikon and Canon glass on the A7 series has not hurt them either. So what was missing? It has not attracted the sports photographers and others who have similar needs. Sony has decided to close that gap with the introduction of the A9 on April the 20th, 2017. Reviewers are now referring to the A9 Sony has as a “DSLR killer.”
The Sony A9
So why might this camera be a “DSLR killer?” A comparison of specifications with the four flagship cameras will help illustrate why. Here we are looking at the A9 compared to the Nikon’s D810 and D5 and Canon’s 1DX Mark II and 5D Mark IV all DPreview Gold Award winners.

Here are a few key specifications that put this camera out ahead of all of these gold winning cameras:

• Smallest and lightest full frame interchangeable camera on the market.
• World’s First full-frame stacked CMOS sensor, 24.2 MP effective resolution, which allows for 60 autofocus calculations per second.
• Blackout-Free Continuous Shooting at up to 20fps for up to 241 compressed RAW/ 362 JPEG images.
• Silent electronic shutter provides vibration-free shooting at speeds up to 1/32,000 sec. This means you can shoot with absolutely no noise coming from the camera. It also has a much higher speed than DSLR cameras that are limited to 1-8000.
• The electronic viewfinder is 3.6 million pixel providing essentially a 4K view of your shot without any blackout. Sony has added auditory or visual cues you can turn on if you need it.
• The viewfinder is WYSIWYG so you know before the shutter is pressed if the shot is correctly exposed.
• The autofocus also works in much lower light conditions than any other camera.
• The camera has built-in Bluetooth as well as the usual Wifi and NFC. 
• No black out when shooting so you can see that you got the shot.
• It has a tilting articulating LCD screen.

In keeping with the other cameras in this class, the camera also has the following features:

• Extensive professional features including Ethernet port for file transfer, Dual SD card slots and extended battery life.
• Its 24-megapixel resolution provides a pixel pitch similar to the 1DXII and D5.
• It has an ISO range from 100-51,200 equivalent to the 1DXII and well above the D5.
• It is cheaper than the D5 or DXII but more expensive than the 5D IV or D810.

Comparing the Specifications
Clearing the A9 has features that are well above those of the other cameras in the full frame category but how important are these features to a sports, action or wildlife photographer? In reviewing a number of sites it would appear there are some features that are “make or break” features, for sports photographers. Of these features generally, the frames per second appear most important and related to that is the size of the buffer. A close second appears seems to be focus accuracy which has a correlation to focus points. After that, there is not as much consistency in what is important.

	Sony A9	Canon 1DX II	Canon 5D IV	Nikon D810	Nikon  D5
Frames/Second	20	14	7	5	12
Buffer jpegs Fine	362	Unlimited	Unlimited	57	200
Buffer uncompressed RAW	128	Unlimited	19	23	183
focus points	693	61	61	51	153
Battery Life	650	1210	300	1200	3780
Weight	673g	1530g	890g	980g	1415g
DSLR/Mirrorless	Mirrorless	DSLR	DSLR	DSLR	DSLR
Technical Age	Apr 19, 2017	Feb 2, 2016	Aug 25, 2016	Jun 26, 2014	Jan 5, 2016
Effective Pixel Res.	24	18	30	36	21
Pixel Pitch	5.97	6.95	4.13	4.87	6.45
Price Apr. 2017	4500	6000	3500	3300	6500
ISO Range	100-204800	50-409600	50-102400	64-12800	50-3280000
Min/Max Shutter	1/32000	1-8000	1-8000	1/8000	1-8000

Let us look at someone upgrading to full frame sports shooting which of these cameras would meet their needs and which would fall below today’s standards. Given today’s standards, I would suggest somewhere between 8-10 frames per second adds a very useful feature to this sort of photography. So I am going to set the cut off at 10 frames per second which will exclude some cameras but includes enough for a diverse choice. Although this may seem an arbitrary cutoff, given what today’s cameras can do, anything below 10 frames per second seems out of step with the market.
The next decision is around focus, which is a much more difficult as focus points do not tell the whole story. However, given the enormous advances in this area, I am going to suggest a minimum standard of 150 focus points, again this allows for some exclusions but enough cameras fall above this threshold to provide a selection. This would, of course, exclude Canon’s 1DX II, but as this might seem too controversial I will leave it in for the moment.
The hit rate on the Sony with 693 focus points has been reported to be well above that of the D5 at almost 100%. (This was using Sony’s expanded flexible focus.)
If we look at the chart above this has now reduced the selection in the flagship category to the A9, and the D5, and a free pass the Canon’s flagship camera.
APSC and Full Frame Cameras
Sports photographers also use APSC cameras so let’s include them in the discussion. APSC cameras provide a distinct advantage when using the critical sports lenses such as the 200mm f2.8, 300mm 2.8 and other such prime telephoto lenses. Clearly, if you can place you 200mm f2.8 camera on an APSC camera and instantly have a much lighter 300mm equivalent, this is why the APSC cameras need to be considered.

	Sony A6500	Fujifilm X-T2	Sony A9	Sony A99II	Nikon D500	Nikon  D5	Canon 1DX II
Frames/Second	11.11	14	20	11	10.2	12	14
Buffer jpegs Fine	231	42	362	61	200	200	Unlimited
Buffer uncompressed RAW	110	25	128	25	200	183	Unlimited
focus points	425	325	693	399	153	153	61
Battery Life	350	340	650	490	1240	3780	1210
Weight	435g	507g	673g	849g	860g	1415g	1530g
DSLR/Mirrorless	Mirrorless	Mirrorless	Mirrorless	Translucent Mirror	DSLR	DSLR	DSLR
Technical Age	Oct 6, 2016	Jul 7, 2016	Apr 19, 2017	Sep 19, 2016	Jan 5, 2016	Jan 5, 2016	Feb 2, 2016
Effective Pixel Res.	24	24	24	42	21	21	18
Pixel Pitch	3.9	3.9	5.97	4.51	4.2	6.45	6.95
Price Apr. 2017	1400	1600	4500	3200	2000	6500	6000
ISO Range	100-51200	100-51200	100-204800	50-102400	10-1640000	50-3280000	50-409600
Min/Max Shutter	1/4000	1/32000	1/32000	1/8000	1/8000	1-8000	1-8000

If we apply the same minimum criteria to the flagship cameras of both APSC and full frame you get a selection of six cameras. It is probably useful to also see a size comparison between these six cameras.

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