Is the Canon 5D noise at low light better than the Rebel T3i/4i/5i/6i models?

Question

I have the T2i (550D) and T3i (600D) and they are basically the same. The T4i, T5i, and T6i seem to be only minor improvements in ISO, saturation, and video/still quality as well.

Now that the full frame 5D classic is so cheap. How does it compare in low light with the Txi APS-C cameras? I've been having trouble finding comparison crop shots to see the noise levels in lower light (indoor and outdoor). What I have found seems to show sharper images with lower noise.

Note: I resize almost all my photos down to 1080p or 2k for online use so I don't need much more than the 12MP the 5D classic provides.

Answer 1

This comparison at The-Digital-Picture between the 5D at ISO 3200 and the Rebel T5i/700D at ISO 1600 looks fairly even, especially if one considers the difference in scale. (I chose the T5i because the T6i samples are even larger.)

The 5D and 5D Mark II look very close at the same ISO 3200 and so any comparisons you might find between the more recent Rebels/xx0D series and the 5D Mark II should be fairly helpful.

Things you should also consider:

• ISO 1600 is the maximum on sensor ISO amplification setting for the 5D. The "H" setting is equivalent to ISO 3200 by doubling the values obtained from the sensor amplified at ISO 1600. That's as far as ISO goes with the 5D.
• The 5D's AF system is 9 points (plus six invisible assist points for the center point when in AI Servo AF mode - again, the 5D mark II is very similar). The AF systems of the T3i/T4i are similar, but the more recent Rebels' AF systems are an upgrade.
• The 5D has no Live View or video capability. None. Zilch. Nada.
• The 5D has no built-in automatic sensor cleaning. Plan on cleaning it much more often with a physical method such as a wet swab.
• Used 5D Mark II bodies are also getting pretty cheap. The increased ISO options, self cleaning, and Live View/video capability might be worth the difference.

Answer 2

I know it's not quite what you're after, but DxOmark will give you a nice comparision of the 5D Mark II and T6i (aka 750D). That shows the 5D Mark II being a whole stop ahead of the 750D (1815 vs 919 on "Low Light ISO"). Given that, I'd be pretty confident that the 5D will beat out the 750D - there wasn't a stop's worth of improvement between the 5D and 5D Mark II.

Alternatively, you can try DPReview's comparision tool where there's a possible marginal win for the 5D - but practically there might not be much in it.