I did notice a few things that I think are worth considering when you work with the equipment:
- There's a list of lenses that basically won't work with the EOS M3, even with the mount adapter. In a fit of absent mindedness I can no longer find that list, but basically anything that doesn't say USM or STM on the lens is pretty much not going to focus well on the EOS M3. (And yes, unfortunately my 50mm/1.8 II is on that list, which explains the poor performance!)
- What really really drains the battery on the EOS M3 is the WiFi/NFC picture transfer to smartphone. It actually doesn't drain the battery that much to actively transfer photos. What kills it is that once you're done with the transfer, if you do not turn off the camera manually, it doesn't go into sleep mode and instead just drains your battery maintaining a WiFi network. I would advise getting a spare LP-E17 and keeping it charged because you will forget!
- One of the principles of flash photography is you want to keep the flash as far away from the camera as possible. Thanks to how small the camera itself is, and the relatively small sensor size, the standard for this is very low for the EOS M3. Even my ancient 220EX performs very well on the EOS M3, and I can only imagine that newer flashes and/or bigger flashes do even better. Note that the 220EX is relatively tall compared to the newer (even smaller) 270EX, so I'm not sure I'd bother upgrading. By the way, since my primary use of the external flash is as a fill flash, I always dial in an exposure compensation of -2/3rd.
- Get an OP-Tech strap for it. The camera and lens combo might be light, but if you're in the habit of wearing T-shirts or collar-less shirts, then you'll discover that the OP-Tech straps work much better on bare skin, and it does reduce bouncing.
- Lightroom 6, for whatever reason, tends to raise the exposure levels of the photos taken with the EOS M3 if you hit the "auto" button. Either don't use the "auto" button, or manually set the exposure back after hitting it. (I use the auto button to get some of the way towards adjusting the highlights and shadows sliders without having to do it manually)