I'm mostly happy with how my 40d performs , just would like something that performs a bit better in low light.
Doesn't need to be a huge improvement , but don't want to step back either
£150-£200 (maybe a smudge more)
Pre-owned
Body only
OK, that's a big ask. I have a 40D as my old workhorse and part of the reason for that is that I haven't identified an easy and cheap upgrade.
When you say you don't want to step back:
* Do you want to retain the LCD top plate display? If so, that rules out all 4-digit models such as the 1200D, and all 3-digit models up to the 750D. It leaves the 760D as an option, but that's out of your budget.
* Do you want to retain the quick control dial on the rear? Again, that rules out all 4-digit models and all 3-digit models except the 760D.
* Do you want to retain a proper pentaprism viewfinder? That would rule out all 4-digit and 3-digit models.
* Do you want to retain a top shutter speed of 1/800th? That would rule out all 4-digit and 3-digit models.
* Do you want to be able to shoot at 6½ frames per second? That would rule out all 4-digit and 3-digit models.
But if you're in the market for a 2-digit model - and assuming you sell the 40D to fund it - the 50D is probably the only one within your budget. I don't think your funds would stretch to a 60D.
Now, you'll read many comments on the internet that say the 50D noise performance is no better than the 40D. That's probably true, but only up to a point, and you need to understand what people mean by that. You see, most people look at noise by looking at images at 100% magnification. That's fair enough, but the 50D has 15 megapixels and the 40D has 10 megapixels. If you downsample the files to the same size (eg 2 megapixels for on-screen display, or 8 megapixels for a 12"x8" print), you'll be downsampling the 50D image to a greater extent and that will reduce the noise accordingly. Unfortunately I haven't seen any comparisons which look at noise this way so I don't know how much better it would be.
Hope this helps. The other upgrade you might look at would be a faster lens. What are you currently using?