portrait lens...which is better???

[neuroanatomist]

After seeing the bokeh comparison in Bryan's review, I actually think I'd choose the 85 f/1.8 over the sigma f/1.4. IMO bokeh is super important for a portrait lens.

I agree that bokeh is critical. However, one thing worth pointing out is that the Sigma 85/1.4 has 9 rounded aperture blades, whereas the Canon 85/1.8 has 8 blades without rounding. Bryan's example shots don't have any OOF specular highlights in them, but if they did you'd see them showing up as octagons by f/2.8 with the Canon, whereas the Sigma blades don't start showing up until f/4, and are more pleasant even then due to the rounding.


Photozone.de's reviews with both lenses on the 5DII show that the while both lenses have very sharp center performance, the Canon 85/1.8 has better performance away from the center. That doesn't really match up with Bryan's ISO 12233 crops, where the Sigma looks sharper at the edges. I wonder if that's not a result of the oft-reported Sigma QC issues and copy variation, and Bryan got a sharper copy than photozone.de reviewed. Still, note that Bryan states he went through three copies of the Sigma lens, and even the best of the three still has AF issues. That's something to keep in mind if you plan on using AF with the lens (and if you plan on manually focusing, you'll need to use Live View with 10x magnification, or if you want to use the viewfinder, be sure you change out the stock focusing screen for the Eg-S focusing screen).

[Jon Ruyle]

That is a good point about the shape of the blades, John, though of less importance when the lenses are used close to wide open, as they often will be.


Actually, I don't understand why the f/1.8 looks so much better in Bryan's examples, despite having blades that sound inferior to the sigma. Neither lens has funny bokeh-enhancing correction (that I know of), so I would have thought aperture blades would tell most of the story. But then, there is plenty I don't understand about optics. (I'd love to hear from someone who can explain something of how factors other than shape of aperture blades and spherical under/over correction can bokeh)

[Daniel Browning]

This web site seems to be pretty informative: www.bokehtests.com/.../About_Bokeh.html

[cxr]

thanks everyone!!! still deciding though...

[Jon Ruyle]

Thanks, Daniel.


That is a good site (I think I've read it before). It has a lot of good info, but it doesn't really unconfuse me (I guess that is pretty hard to do []).