Expensive portrait lenses with bad bokeh

On 29/07/2016 19:02, Rich A wrote:
Too many 85mm f/1.4 lenses seem to suffer from this. It is unpleasant and imparts a disorienting feeling of motion to the outer field. Oddly, I've seen some cheaper 85mm lenses and older, slower ones that don't have this problem.

https://www.dpreview.com/forums/post/58110604

There's an attempted explanation in that thread (post #5):
"The off-center "ovals" are caused by internal vignetting -- the fact
that the lens has significant optical thickness. The more complex the
lens design, the harder it is for the designer to minimize this effect
-- an uncorrected single element doesn't really have this problem. If
you hold the lens straight ahead and look through it, the opening
appears round; however, if you look at an angle, you'll see the circular
shape is clipped (typically) as the intersection of two circles of
different diameters, and that's exactly how the bokeh ball (technically
OOF PSF -- out-of-focus point spread function) gets shaped. If you stop
the lens down, eventually the aperture becomes small enough to only let
rays pass that are within the unobstructed intersection, and the shape
will be that of the aperture across the entire frame."

On 30/07/2016 15:08, RichA wrote:
On Friday, 29 July 2016 21:34:07 UTC-4, Me wrote:
On 29/07/2016 19:02, Rich A wrote:
Too many 85mm f/1.4 lenses seem to suffer from this. It is unpleasant and imparts a disorienting feeling of motion to the outer field. Oddly, I've seen some cheaper 85mm lenses and older, slower ones that don't have this problem.

https://www.dpreview.com/forums/post/58110604

There's an attempted explanation in that thread (post #5):
"The off-center "ovals" are caused by internal vignetting -- the fact
that the lens has significant optical thickness. The more complex the
lens design, the harder it is for the designer to minimize this effect
-- an uncorrected single element doesn't really have this problem. If
you hold the lens straight ahead and look through it, the opening
appears round; however, if you look at an angle, you'll see the circular
shape is clipped (typically) as the intersection of two circles of
different diameters, and that's exactly how the bokeh ball (technically
OOF PSF -- out-of-focus point spread function) gets shaped. If you stop
the lens down, eventually the aperture becomes small enough to only let
rays pass that are within the unobstructed intersection, and the shape
will be that of the aperture across the entire frame."

Nikon has a new 105mm f/1.4 ($2200) coming. I'm wondering if it'll be patterned after their relatively recent 85mm f/1.4 which has a slightly oval edge effect? Their 58mm f/1.4 has terrible wide-open edge quality (use a background consisting of point-source lights to see).

I'm not totally convinced by the explanation given by the poster above,
I kind of wonder if rectilinear correction of 50mm lenses also has
something to do with the misshapen blur circles, so longer may be better.
The 105mm f1.4 at $2,200 - more than I could justify for the limited
portrait I do, but I expect it will be very popular with pros. They
better have any aberrations well sorted so that PDAF can be fast and
flawless when using off-centre AF points.