Canon Rebel T3i
f 4.0
iso 3200
1/80 sec
I am on a tight budget, and only recently got the t3i for $250 on ebay. But it struggles in low light, which is just about every pic I take. I am wondering if I'd be better off with a used 5D classic, about $300 on ebay, or will that one still struggle with low light? I know I should get a 5D mark iv, but that just is not in the budget now. Ant thoughts? thanks.
Adam
Doing the best I can with a crop sensor Rebel
lens - 50mm
What Adam said, except I'll clarify that what he probably meant was "50mm, f1.4." In other words, what your camera is missing is the ability to see in low light and no camera body will do better if you are shooting at f4.
Personally, I use a 85mm/1.4 for all my concert shots, usually at f2-2.8. It's my fastest lens and it's a bit longer than a 50mm, so I can get tight shots without having to stand too close to the musicians. (I still have to stand in front of the speakers, so earplugs are required.)
Even if you don't shoot wide open, the camera focuses through the wide open aperture and will have an easier time doing so if you have a fast lens to begin with.
A 50/1.4 isn't too expensive and on your crop camera it acts like a 75mm. Even a 50/1.8 will do well, and those are dirt cheap.
You can get a used 5D Mark II for not much more than a 5D classic. It's a better camera in terms of low light image quality than the classic, but the AF is still a little slow in very low light when it works at all.
If you can find a used 7D Mark II for a good price, it will AF much better in low light, and the RGB+IR light meter helps a lot as well, both in terms of exposure and Auto WB. Even if you're shooting raw, good AutoWB gives you a better starting point if you're using a raw converter that opens raw files with the camera measured WB.
Whether shooting with an APS-C or FF camera, the key to low light concert photography is fast prime lenses. Even f/2.8 zooms can be a little slow, and they cost a lot more than a 50/1.8, an 85/1.8, or a 100/2. I love the EF 135mm f/2L for concerts, but it is pricier than the above mentioned primes. Still some of the best bang for the buck in any lens I've ever bought.