Decided to do some hands-on tests so I could see for myself the difference in crop factors and lens quality between the Olympus OM 50mm f1.8 and the Canon EF 50mm f1.8 II lenses. This post contains a lot of images and may be boring if you're not into camera lenses and pixel scrutinising -- hit the jump if you're interested in the results.
These shots demonstrate the difference in crop factor (focal length multiplier) between the Canon APS-C and Olympus Four Thirds sensor sizes. I've scaled the bottom image down to the same "size" as the top one, clearly demonstrating the difference between the Canon (1.6x) and Olympus (1.84x) crops.
Never realised how much was actually lost using a Four Thirds sensor.
Two shots from the Olympus E-510, comparing a 50mm zoom on my telephoto lens (the only other lens I have capable of a 50mm focal length) and "50mm" on the old OM legacy lens.
When I first bought the old OM lens and adaptor, one of the things I had read about was a considerably different focal length resulting on the 4/3 cameras, but this demonstrates that the difference is actually quite minor.
Yes, I realise the top photo is overexposed.
Olympus vs. Canon 50mm f1.8 lenses.
There's a lot of criticism of the Canon lens for having pretty nasty bokeh (out of focus areas) because of its five-bladed aperture, but all in all, it's not too bad, in my opinion. The OM lens loses some sharpness, which is to be expected, but I think I still prefer its result. I find that the Canon 50mm tends to get less pronounced glowing edges on the highlight hotspots.
Same test, same lens, different aperture. Reduced to f4.0, the Canon EF 50mm's bokeh looks significantly nastier than the Olympus OM 50mm's, at least in my opinion. There seems to be a tiny bit of light leaking around the aperture blades on the Canon, making the corners of the highlight hotspots quite harsh, really accentuating the five aperture blades. At the same camera settings, the Canon's image at f4.0 is undoubtedly sharper, though.
Direct comparison between the Olympus and Canon 50mm lenses. All in all, the difference for this kind of image is pretty insignificant. Auto white balance seems to have thrown a yellow cast to the Canon photo.
OM, pros: - $50 from Ebay + $5-$35 for adaptor - More pleasing bokeh. - Quality construction, from the days where stuff was made properly, ergo: sturdier lens. (Lens mount/adaptor, not so much, though) - Very trendy
OM, cons: - Adaptor is atrocious, but for this I can blame someone on Ebay from Hong Kong - Image slightly less sharp than Canon - No auto focus function
Canon, pros: - $90 - Auto focus - Sharper image - Ludicrously lightweight - Adaptor not required, obviously
Canon, cons: - While autofocus exists, it sounds like it's grinding up Legos inside there - Very cheap construction; very cheap lens
Overall, I think I still prefer the Olympus OM 50mm lens. The Canon one just seems utterly disposable in comparison.