Taking pics of dancers in a ballroom

Troilo wrote:

Peter63 and Alastair, many thanks for taking your time to answer. So your recommendations are:

* Either get a modern mirrorless like the M5 / M6, or a DSLR and use the viewfinder. In the last case, any suggestion about the minimum DSLR that will do the job? A 100D, a 750D or do I have to go higher? (the 7D mark II is a bit expensive for me...)

The 7D mark II has sophisticated tracking modes that are overkill for the speed of your subjects. The 100D and 750D will both focus down to -0.5 EV (100D only with the center point), if you move up to an 80D, it will focus down to -3 EV. The -3 figure is near darkness and probably not needed based on the 2 shots posted above, any DSLR will probably be fine.

Back to considering an M for your needs:

If based on the above photos, you have faces with that much light on them that also fill that much screen, any of the M models with DPAF (M100, M5, or M6) will probably work with facial tracking. If they get further away, the face recognition has a harder time. You may have to revert to single point and place the focus point on the face of the dancer you want. As the light drops, the contrast of your target becomes very important, the dancer in the first shot with pale skin and a dark beard should be easy. If you have a face that is relatively far away and lacks contrast, you can try to lock on clothing like the checkered shirt in the second photo. If facial recognition fails and you have to track manually, my choice would be the M5 since you can move the focus point with your thumb on the LCD while your eye is at the EVF.

* Regardless of camera body, use a faster focusing lens. From your recommendations, it would have to be the EF 50 mm 1.8 STM or the EF 85 mm 1.8, since I want to keep at a certain distance from the dancers... (22 mm or 35 mm is too close to them and makes them unconfortable).

Yes, the 50 STM and 85 1.8 will be an improvement, focus should be faster but more importantly, it should be more reliable. Both of them benefit in IQ from stopping down but I am more than happy with the quality of my 85 1.8 wide open. I sold my 50 1.4, I was never very fond of it. If you are looking for an upgrade from the 50 STM in that focal range, I would look at the new Tamron 45 1.8 VC.

Best regards!