A quick cautionary note for those using EOS M series cameras (or more particularly, those using the EOS M3) You may be tempted to get a cheaper off-brand EF to EF-M adaptor, after all it’s not that complicated, what can go wrong?
That’s what I thought, and that’s why I tried to save some money by buying a cheaper adaptor on ebay. Turns out is was a foolish move, and I’ll show you why.
Firstly, take a look at the two adaptors above. The one on the right is the official Canon adaptor, the one on the left is the unbranded cheap adaptor I bought from ebay.
Firstly, I was happy, there were no compatibility problems at all with my older EOS M body. So when I started using it on the EOS M3 it seemed fine at first, but I soon noticed there were some problems with a purple haze in some photos. Here’s an example taken using the adaptor and the EF 50mm f/1.4 USM lens.
Not all photos exhibit this behavior, only when at certain angles. I was kicking myself at this time thinking it was my fault for forgetting the lens hood. But then this was another photo taken with the EF 70-200 f/2.8L IS II USM – with the lens hood in use!
So, today I finally got an official Canon EF to EF-M adaptor and decided to put it to the test.
Firstly, EOS M3 with EF 50mm f/1.4 USM and third-party EF to EF-M adaptor.
Result: Nasty flare.
Next, same combination but holding my hand above the lens, beyond the lens hood. I found by doing this I could cut out these purple hazes.
Result: Good photo.
Finally, EOS M3 with EF 50mm f/1.4 USM and official Canon EF to EF-M adaptor.
Result: Good photo with no messing around.
Also, my 15 month old son has a ridiculous amount of Lego Duplo. What you see is just a fraction.
Let’s look again at the two adaptors side by side
What you’ll notice immediately is the different shape of the central hole on the Canon adaptor (right) giving better masking to the APS-C sensor. It does mean that if Canon ever do a full-frame mirrorless camera then neither of these adaptors will be any good, we’ll need a brand new one (which won’t be backwards compatible with the APS-C models either!). But that’s no big hardship.
It’s interesting that the adaptor worked fine with the EOS M and not the M3. I notice when comparing the two that there are more purplish reflections from the sensor itself when looking at the M3 sensor compared to the M, so it’s likely that the purple haze is an internal reflection off the M3 sensor being bounced back by the lens. The shape of the official adaptor cuts these reflections out.
I was curious as to whether this problem would also appear on other adaptors for other lens types. I tried a Fotga FD to EF-M adaptor with a Canon FD 50mm f/1.8SC lens and could not get the purple haze to appear at all, even though the adaptor doesn’t mask the sensor at all (and would probably work fine with full-frame!). Here’s a photo of that adaptor:
So. If you have an EOS M3 don’t buy a cheap EF to EF-M adaptor, buy the real thing. Luckily there are unbundlers selling the adaptor split out of bundles pretty cheaply on ebay now – that’s how I got mine.