zug55 Loc: Naivasha, Kenya, and Austin, Texas

Thanks for doing the math on this. I just did a non-scientific test with my 18-135mm on the a6000. So a longer zoom might be a good idea. I usually shoot with the A7 III, and the a6000 is just my backup camera, or my ultra-light travel camera.

rmorrison1116 Loc: Near Valley Forge, Pennsylvania

Interesting; funny thing; literally all my Canon EF lenses work perfectly on my M50 with a Viltrox EF EOM M2 adapter. I have over a dozen lenses that work on my M50 and not a single one is an EF-M mount.
Why is the clarity of Canon's plans to develop more M series in any way a strike against the M50? Looks to me like neither of your strikes actually matter. The M50 is a nice little camera and it works just fine. My only problem with the M50 is, after all the many, many years of shooting with a DSLR, my hands are just use to something a bit larger than the M50. It looks so tiny attached to my EF 28-300L, which I use with it quite often.

zug55 Loc: Naivasha, Kenya, and Austin, Texas

I am glad that you make all the Canon EF lenses work for you. But assuming that you do not own any Canon lenses (like our OP), why would you recommend the M50?

rmorrison1116 Loc: Near Valley Forge, Pennsylvania

Instead of a MILC, have you considered a good bridge camera? I have shot several concerts with a Canon
G1X mk III with really good results, both video and audio. The last concert I shot with it was the Trans Siberian Orchestra winter show last year at the Giant Arena in Hershey PA.
The bridge camera is smaller and many venues won't allow an interchangeable lens camera but, since just about everyone carries a smart phone with a camera these days, it's hard to ban cameras completely and they almost always allow bridge cameras.

rmorrison1116 Loc: Near Valley Forge, Pennsylvania

I own an M50 and although it's a good little camera, I really wouldn't recommend it for what the OP wants to do. The M50 is one of the OP'S two stated choices. They were asking what lens to get. Personally, I'd recommend a good bridge camera like the G1X III. It performs quite well recording indoor concerts in low light and its audio is also pretty good. Yes, the G1X III is fairly expensive but, when you combine the cost of an M50 or a Sony what ever, and a lens, the G1X III is less expensive and since it has a zoom lens, you've now got multiple focal lengths to work with. As for image quality, the M50 is APS-C and the G1X III is APS-C so, pretty much the same.

My point about my EF mount lenses was, they "will work" just fine on the M50 with a $50 adapter. No need at all to buy a single EF-M lens. And you know how many good used EF lenses there are out there; a whole lot of them...

miked46 Loc: Winter Springs, Florida

M50 W/18-150mm, -M lens should workout fine.

Fotomacher Loc: Toronto

If I was going out to shoot in this venue and wanted to keep costs to a minimum, I’d get a used Nikon D300 and a used Nikkor AF70-200mm f/2.8G VR2. You will capture amazing images with this kit if you know what you’re doing.

Scruples Loc: Brooklyn, New York

When I want to get close up, I will. I rather be as close to the subject simply because a long zoom lens will get fatiguing. As for the shutter clicking, I don't it will be an issue

sb Loc: Florida's East Coast

Keep in mind also that unless they are brightly lit, you will need to use a tripod with the telephoto lens. The portraits might be best done at dress rehearsal.

gvarner Loc: Central Oregon Coast

Use the angular field of view calculator at http://www.tawbaware.com/maxlyons/calc.htm to figure this out. Just plugging in a 1.6 sensor factor and a 50' distance gives a vertical field of view of about 7', plenty to catch a standing violinist. You could check this out at a camera store too.

wapiti Loc: round rock, texas

gvarner Loc: Central Oregon Coast

My mistake, it’s the field of view calculator, not the angular one.

Jaackil Loc: Massachusetts

Here is my 2 cents. If you can’t get 30-50 feet away you don’t need the reach of 200-300. Those are expensive lenses. Probably more than you want to spend as a beginner. I would suggest either a 50mm 1.8 at about $200. Or an 85mm 1.8 for about $400. Both will give you tack sharp images. The 85 will give you enough reach. Both will give you excellent low light capabilities. The 70-200 2.8 is definately the gold standard of proffesional lenses but expensive. If you can rent on for the concert great. The other two lenses I suggest are lenses you will find yourself using all the time and will want to have in your kit anyways.
To give you an idea where I am coming from. I consider myself an intermediate level hobbyist. While I would love to own those expensive lenses. I continuously get great results shooting college ice hockey with the 85 mm 1.8. And college Lacrosse with a Nikon 70-300 4.5-6.3 even night games, which I picked up manufacturer refurbed for $150. Consider your skill level. No offense is meant by this but if your skill level is novice the expensive lens will not make your pictures better.
Don’t worry about the shutter noise no one is likely to hear it.
Here is another suggestion I would make. If you can get into a rehearsal or two before the actual concert and take photos. This will give you an opportunity to try different settings and figure out what will work best under the conditions you will be shooting. People also like to see rehearsal pics of their kids if you get something good because no one ever takes them. You will get some great natural expressions during rehearsal because the kids aren’t as nervous. Obviously you will have to clear this with the person in charge first. Good Luck.

lehighjack Loc: somewhere in FL

With a 70-200 mm lens, slow shutter speed and wide open aperture, one should look to both "In Body Image Stabilization" and "OIS (Optical Image Stabilization)" in the lens. If IBIS, the Sony A7 ii, Sony A6500 (IBIS) and then the Lens. Sigma makes an new and outstanding e mount 70-200 that is somewhat pricey, but the OIS would work with the 6400 Sony well. You could purchase a used Canon or Sony A mount and use an adapter to the 6400, 6500 or the A7 ii. I chose the A7 ii for price and features, though the 6400 seems superior except for: 1) lack of IBIS and 2) crop sensor (an advantage in your situation.)
Unfortunately, we often start our photographic journey to a single destination; then discover everything else. Keep flexibility. At least there are plenty of used, good lenses that can be adapted to the sont e mounts. Good shooting...

markngolf Loc: Bridgewater, NJ

I shoot school concerts with Canon 5D MIII, 7D MII and Sony RX10 IV. With the Canon DSLR's, I use a 70 - 200 f/2.8 II lens.
Mark