I have the opportunity of owning both a 55mm 1.2 and 50mm 1.4 Canon FD lens. I'll have more comparisons up perhaps tomorrow but this was just one quick test I did at my desk. Hopefully this will help people decide if they really want to spend the big bucks on the faster lens (or if you already bought it, if you spent your money wisely).

Nothing was done to the footage, the camcorder was left on REC and I simply switched the lens out and focused on the speaker grill (I get a nice Moire pattern when I'm in focus on it).

50mm 1.4 at wide open (http://www.frozenphoenixproductions.com/misc/50mm.tif)
55mm 1.2 at wide open (http://www.frozenphoenixproductions.com/misc/55mm.tif)


As a side note: Anyone know why I can't use the attachment function?

It's pretty hard to tell the difference... until you get it into photoshop.

I shrunk the 55mm image and lined it up almost perfectly with the 50mm image, then cropped them. If you toggle the layers, it's noticeable. The histogram also shows a difference. It also seems as if the 1.2 50mm is showing less grain even though the 1.4 55mm image was shrunk.

Well I guess it's a good thing my audience isn't watching my stuff with photoshop, because the 55mm focusing ring is in bad shape and my 50mm isn't nearly as scratched. I'm amazed the image is as good as it is because the front element is all kinds of messed up. After these tests I'll definitely be sticking mostly to my 50mm.

If you concentrate on the start menu vs. black background on the lcd, as well as light and dark parts of the speaker, you notice greater contrast on the 50mm. I'm seeing a little sharper speaker grill on the 55mm actually, but not really seeing much of a light gain.

This is the first time I've done a direct lens comparison like this, and it's actually really cool. Seeing an instant change in contrast, sharpness, even DOF instantly is a lot different than talking about it abstractly on these forums for so long.