Here's worst case scenario just to show how bad it can be:
- Little to no light
- Subject speed varies
- Distance to subject varies
- Slow shutter speed
The point of the photo was to get what is sometimes referred to as a "cross pan" or "cross blur" photo, where the front and the back of the car blurs in different directions due to the low shutter speed. Normally with a 28mm equivalent like I used here, I would go to 1/15 to 1/20s, but I had more or less given up when this photo was taken, and increased speed to 1/30s to see if I could get at least a couple of shots with vital parts sharp. Vital parts would be sponsor logo and/or number on the car.
That is not possible without placing the exact point of the car that should be sharp at an exact point in the viewfinder and keep it ther. I use the focus point indicators for that with an SLR camera, and I reduce the number of focus points visible in the viewfinder to make it easier to follow.
When these cars enter the curve, their speed is probably around 100 kilometers per hour, which slows down as the drift starts. 100 kilometers per hour is 28 meters per second or roughly 5 meters per shot at 5fps.
Even the tiniest lag makes it impossible to get a "sharp" shot under these circumstances, since the car will inevitably move around in the viewfinder if I'm late to react, and I am when there's a lag. As stated earlier, the blackout time of a good DSLR is so short that it's hardly noticeable, and it's 100% predictable. Also, it's the same regardless of time of day, weather, temperature and what I had for lunch.
With an SLR, my hit rate for photos like these varies between 1 in 10 to 1 in 25 regardless of light. With a mirrorless camera, the hit rate sinks to something like 1 in 40 to 1 in 60 during daytime and zero at night like here. This in spite of the fact that I mostly use longer shutter times with an SLR. The results for mirrorless cameras actually improves slightly if I follow the subject and take only one shot pre-focused.
I notice that often when this discussion comes up, those who want to prove that mirrorless cameras are suitable for sports, mostly show photos taken in broad daylight of subjects coming straight towards the photographer, move at a slow pace or travel along a more or less straight line at a predictable speed. I can take pan shots with my Nokia under circumstances like that. Then there are the inevitable soccer shots where the superior face detection of mirrorless cameras makes getting the shot very easy.
Which of course means that for some action photography, the best mirrorless cameras can actually be better than a DSLR, if the sensor can render images of the same quality. There was a thread at dpr last year that showed that this wasn't always the case. That discussion was about blown red colours in images showing football players with red jerseys, comparing photos from an E-M1 and a D3. I know from my industrial photos that this is a problem, at least with the Panasonic bodies.
Which brings me back to the start: I need a camera system that I can use for
all kinds of photography and a camera that doesn't come between me and the image. As good as some mirrorless cameras are, they aren't there yet.