anitaw2 wrote in post #18532605
I'm thinking maybe it's time to try a FF camera. I would buy used because I'm not ready to invest a lot of money right now. I shoot a lot in low light, which my 7D really struggles with (bad at high ISO). I don't really do sports anymore, my daughter is done swimming. I've never used a 5D but a lot of people here seem to praise it. Which copy should I go with? I hear a lot of good and bad things about the 6D so not sure if I want to put money on that. any feedback would be great.
6D would be appropriate for what you're looking to do. Some incredible deals right now in the for sale board on a 6D or two ($700~800). This is not my ad, and I have no association, but this price is a no brainer: here and here. For the low light, this price cannot be topped.
There's more to low light than simply high ISO performance. There's AF locking in low light, which the 6D does at -3EV with the center point (the 5D2 can't do that, and the 5D3 can't do it either at this level).
The 5D2 has slightly less top ISO performance, but significantly weaker overall AF engine, this body has not aged well for it's price. The 5D3 has similar ISO performance to the 6D, but the 6D still tops it but only by a hair at highest ISO values. The 5D3 has significantly better AF all around, but the 6D still beats it for low light AF with the center point being significant more sensitive in low light than the 5D3 can manage (but only center point and only in low light; in good light the 5D3 has the superior AF engine and points). Resolution is a total wash amongst them. The 6D has a cap of 1/4000s shutter, and the 5D's have 1/8000s shutter. This really only matters if you find yourself using F1.4 in the brightest possible light (and you can always throw a 1~2 stop ND filter or CPL on there and cut that difference out). For the cost, around $700~800, the 6D is simply the better purchase. The 5D3 is the better overall camera, but at $1200~1500 used, basically double, and the 6D still has better (by a hair) high ISO and better center point low light AF sensitivity (-3 EV).
If you want to take it to the next level on a dime, for low light, then the Sony A7S body is the next price tier to consider ($1000ish; you can mount Canon glass via an adapter and it works great). The A7S has significantly better high ISO performance than all of the above. AF is not superb for action, but it's good in low light, but key being the significant high ISO performance difference over all the 5D bodies except the 5DIV ($2500~$3k). Again an adapter lets you use basically any glass you want with the Sony body. It's also a little quieter, being mirrorless. It's ISO performance at $1k cannot be matched currently by Canon in that price range.
After that, prices go up significantly (especially for a Canon high ISO body, such as a 5DIV or 1DX). Otherwise, you look to Nikon or Sony bodies if you want full frame and better ISO performance.
If you simply get a modern crop, you don't need full frame for high ISO, a modern crop is going to be better than the 7D by over 1 stop anyways, so you don't have to go full frame for this endeavor.