If you love your SL1 you know there is a Canon EOS Rebel SL2 DSLR Camera. Everything has been upgraded in it over yours.
As for a lens upgrade I think you would really like and benefit from the Canon EF-S 17-55mm f/2.8 IS USM Lens. It is a constant, fast aperture zoom that covers most of the best range for a SL2.
"My question is, should I upgrade to a better crop-sensor body, or a full-frame body?" First don't get sucked into the hype over FF. If your current SL1 is doing what you want the newer SL2 will do it better. There are reasons to go FF but you may not, doesn't sound like it form what you have said, have one of them. On the other hand there isn't any reason why you shouldn't. Big help ain't I ?
Full frame is going to be bigger, heavier and moe expensive. Keep that in mind.
As far as shooting the band photos, something I do all the time, no biggie. Use what you have and if it isn't the best choice, make it so in post editing. How about using a 120mm lens for a pano? Not the best choice? Right.
I would also recommend the SL2.
Your SL1 has a Digic 5 processor. The SL2 has a Digic 7 processor which will improve your high ISO photos.
But for really clean high ISO nothing beats Full Frame. In addition to the cost of the 6D you would need to buy at least one new EF lens.
Your EF 40 STM could replace your EF-S 24 STM and your 85 1.8 USM could replace your EF 40 STM, so you really just need something like the EF 135 f/2 to give you the same field of view as your 85 did.
Yeah, I know if I change to a full frame I'm losing the 24mm lens. 🙂 Actually, I would *love* to switch to using my 85mm for portraits, but with my current crop sensor I'd have to be in another room of my tiny house to make that work.
Would I be better off with the 135mm prime, or - given the photos I posted above (I was surprised to see I had taken those at f/4.0) and what I'm trying to accomplish - would the 70-200mm f/4 L USM be a reasonable option? Refurbished, they're both similarly priced and both weigh similarly a lot...
You will not lose your 24mm for as long as you have your SL-1. If you’r shooting a night a lot, then a full frame 6D just might be the ticket for you. I recommend it.
"Would I be better off with the 135mm prime, or - given the photos I posted above (I was surprised to see I had taken those at f/4.0) and what I'm trying to accomplish - would the 70-200mm f/4 L USM be a reasonable option? Refurbished, they're both similarly priced and both weigh similarly a lot..."
IMHO, as always. I have been shooting high schools, GEHS in particular for over 30 years. I can tell you how I do it. I shoot all school activities not just the band. But mostly the band for sure. Again, IMHO, the gear you have is not upo to the task. If you really want to do this I would invest in a FF and the 6D Mk II is the least expensive way to go. Once again, IMHO, the lenses you have are not helping.
My gear through out the years has always included a 1 series. Not exclusively but usually. As you may know not all 1 series are FF. Most are croppers so FF in itself is not a cure all. I currently still use a 1D Mk IV and it is not a FF camera. My lenses of choice are the ef 24-70mm f2.8L II and the ef 70-200mm f2.8L II. Secondary lenses I carry are the ef 16-35mm f2.8L II and Sigma 120-300mm f2.8 EX OS HSM.
"...would the 70-200mm f/4 L USM be a reasonable option?" Again, IMHO, no this is not a good choice.
How about in the rain? Yup, they don't stop FB and neither does our band.
The most inportant factor here doing this is three things. Location, location and location. You indicated you had free range of the sidelines. Great, but you also need to become up close and personal with Photoshop. Good gear, good location and PS, how can you fail?
Ditch the primes and get, "My lenses of choice are the ef 24-70mm f2.8L II and the ef 70-200mm f2.8L II." Even if you have to buy used these are the way to go. The primes' day is done!
So...I agree that an SL2 would be an improvement over my SL1 (especially if it works consistently.)
But these are the sort of band photos I'm trying to take. The parents *really* like individual performer action shots, and that is something I'm struggling to get with the equipment I currently own. These were all shot in RAW, ISO1600, f/4.0, 1/160s. These particular ones are barely cropped because I was able to be on the sidelines instead of in the stands. Cropping further just makes them noisy. I feel like they could be better with a better sensor, but maybe it doesn't have to be in a full frame body?
<<Would a full-frame body and an f/4 70-200 zoom lens be a reasonable combo, or am I going to need a faster zoom even with the full-frame?>>
I cannot give you sufficient answers to your specific questions, but maybe some of my experiences may be useful in some way...
I have a FF and do shoot a lot of high-school sports (football and soccer), including night time. I typically capture the game action itself, which requires a min of 1/1000(ish) shutter speeds. Occassionally, if I slow down the shutter for the non-action shots, I find that I can use f/4 on my 70-200 (it's a 2.8, but sometimes I want more DOF for group shots), but that's with a really slow shutter speed (i.e. ranges way less than 1/640, which is what yours were).
So I think you are going to be pushing it for action shots on a nightime high-school field if you want to totally stop the motion. If youre OK with the faster moving flags having some blur, you might be OK with f/4. But as you say, some of those fields are rough when it comes to lighting, and from my experience, you're pushing the envelope if you also want lower ISOs to eliminate noise.
Only last bit I can pass along is that I find most parents love the shots and care absolutely nothing about mild noise in the picture (the way I do), given they are shots that they cannot get with their smartphones. I find that just applying some noise reduction in lightroom is fine.
I wish you could rent a lens for one of the events before sinking in the cash, but you say there are none around you. 😞 Are there mail order rentals?