Originally Posted by Mark Elberson
The "same framing" (original post specification) would put the 200 @ f2.8 with a subject distance of 20ft, the total DoF is .32ft
The 100 @f/2 wins the shorter DoF calculation but does it produce better bokeh?
The EF 100 f/2 USMhas8 aperture blades, but I can't find any review that tests it's bokeh. Bryan has some nice sample shots and you'll notice in this colorful grass photothat even though the background is blurred there is still a bit of edginess/nervousness to the bokeh. This lens probably has straight rather than curved aperture blades. It would also be interesting to see how the bokeh changes stopped down and subject-distance get's shorter. Bokeh can also change across the frame as well as have oinion like rings in speculars rather than flat circular spots. There is also the dreaded bokeh CA. Uuuoooohhhh!!
The 200 f2.8 has 8 aperture blades as well but I believe that twice the reach will yield better bokeh even though the DoF calculations favor the 100 f2. Looking at Bryans Coneflower Photoit's obvious that whatever is in the background has melted away in to ooF land in a very dreamy manner. Even the stem on the flower is slowly melting away so "buttery smooth".
If all-of-a-sudden Ifell into some major extra coin I would not hesitate to purchase a used 200 f1.8L or the new 200 f2.0L. Even the 300 f2.8L would be very tempting. The creamy bokeh produced by these lenses is the reason they're so highly coveted.
Bokeh seems to be a factor of many things not just DoF and not necessarily the lens design. (Though the more aperture blades and the more curved they are the better.) Also, the FOV vs. focal length playsa major role. For any given aperture, as the fov angle decreases the smoothness of the bokeh increases because less of the background is being rendered by the lens. I have some killer closeups that I took years ago with the el-cheapo Tamron 70-300 f3.5-5.6 Di LD at focal lengths of 180-260 at f4-f8 that have very beautiful creamy bokeh.Often, it's the time of day and the harshness of specular reflections and/or contrast areas like limbs against the skywhich either serve to compliment or detract from a len's bokeh ability. I posted 2 photos of my cat in Postyour Petsthe second one is th EF 50 f1.4 @ f1.4. I find the bokeh extremely pleasing in the ooF areas. I do however, have shots of my son playingin the shadeof a crepe myrtle in bright daylight where the speculars from the surrounding leaves creates an extremely nerve racking bokeh. Same lens in two different situations can yield two different results. The EF 100 f2.8 USM Macro... ? I can't say I've ever been displeased with the bokeh performance of that lens. I'm rambling......
So, my vote is for the longer reaching 200 f2.8....
Reply With Quote