Alf Beharie
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sebboh wrote:
a few people were asking how these two compared bokeh wise a while ago and here is belated half-assed comparison. only at close distance and only from f/1.2 - f/2. i also threw in the takumar 50/1.4 for comparison.
all shots are focused in liveview on the exact same point (i refocused each time i stopped down) and processed in the exact same way EXCEPT for white balance and exposure. both the rokkor and takumar have noticeable yellowing which i haven't gotten around to correcting yet so white balance was taken at the same point in the image when the image was wide open and that value was used for all shots with a given lens. the yellowing also reduces light transmission so all rokkor shots are boosted about 1/3 of a stop compared to the canon and all takumar shots are boosted about 1/4 of a stop compared to the canon. i presume if i left these lenses under a UV lamp for a while the yellowing would go away and i would not need to give them the exposure boost to match exposure. all shot were taken on a tripod with a timer on a camera that has no mirror (sony a55 with mirrorectomy). this is a 1.5x crop camera so don't make any judgements about edge performance. each shot was taken at iso 100 at the same shutter speed for a given aperture (in manual mode) independent of lens. f/1.2 was shot at 1/10 s, f/1.4 at 1/8 s, and f/2 at 1/4 s. all images were downsized to 1024 pixels in width using the exact algorithm described by luka (denoir) in the post processing thread. open each image in a separate tab and switch between them to compare.
first some close in shots where i tried to adjust for the focal length differences a bit (but not enough) by moving the tripod a few inches.
f/1.2:
rokkor
canon
f/1.4:
rokkor
canon
takumar
f/2:
rokkor
canon
takumar
to my eye the rokkor has better (smoother) bokeh at all apertures shown. it also has a bit less contrast and is the least sharp at in focus regions while the canon is the sharpest- you'll have to take my word for it, i'm too lazy to show all the 100% crops. the canon has more color pop, but i always struggle to get skin tones to look realistic with it whereas the rokkor and takumar don't really require any effort in that regard. it's very interesting to compare the canon f/1.4 to canon f/2 shots - the bokeh improves dramatically whereas the bokeh improvement in the other lenses is less noticeable. i believe this is the aperture where SA correction changes from overcorrecting to under correcting on the canon.
here's some shots of the same scene from further back. in this case the tripod was in the same spot for all lenses.
f/1.2:
rokkor
canon
f/1.4:
rokkor
canon
takumar
f/2:
rokkor
canon
takumar
the story is pretty much the same but the differences are more subtle. the stuffed turtle's shell is probably the best place to look for bokeh funkiness.
...Show more →
I've just gone back over these samples and I have discovered a problem...The framing is not identical for each lens. In every comparison the Rokkor has the narrowest FOV, ie: It appears closer to the subject than the Canon, and the Canon appears closer to the subject than the Takumar...The problem is, the closer a lens is to the subject, the shallower the DOF, and hence the smoother the bokeh, so the Rokkor has been given an unfair advantage.
Now obviously the Rokkor has the longest focal length, followed by the Canon and then the Takumar so to keep the framing the same the Rokkor should be the furthest from the subject, then the Canon, with the Takumar the closest. If it were me, I would have made sure the framing was identical for each lens by adjusting the distance to the subject differently for each lens to ensure I got a completely fair bokeh comparison.
Any chance you could redo them with this in mind?
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) feel free to drop me a PM or email.