Bokeh has parallel lines with 100-400 f4.5-5.6 and slower autofocus

[mfostervt]

I recently upgraded from a prime 400 5.6 to the 100-400 4.5-5.6.   Many of my shots have a bokeh with parallel lines in it.  Trying to figure out why.  I have a UV filter on, not a polarizer, which was my first thought.  I have not tried without a filter yet, but will.  Thought maybe someone here might have an idea why I'm getting this.  The other thing I have noticed is that the autofocus is not as fast as with the prime and sometimes struggles to get to focus.  I'm a bird photographer, so sometimes my subject is quite small and in a bunch of branches, but my prime was faster.  I still like the final photo result of the new lens better, so I'm sticking with it.  I attached an example of the bokeh problem

[Waddizzle]

---

@ebiggs1 wrote:

"Black bills, you say? "

Yes, Crows have black bills. The second bird is still a Common Starling.  They have black bills in winter.  It turns yellow in the summer.  It is not uncommon for birds to change colors of some parts with the season.  Starlings can mimic other bird's call. too.  They are considered a nuisance bird by most people.

---

Starlings, it is.  I had assumed they were younger crows.  Like I've said, they're kind of small for a crow, anyway.  I know adult crows are in the area, though.  I wonder if starlings can mimic another bird's call when the other bird isn't anywhere nearby?

[ebiggs1]

" I wonder if starlings can mimic another bird's call when the other bird isn't anywhere nearby?"

They have good vocal ability.  They remember songs they hear but I have never heard one do a Crow.  The males are more vocal then the females.  We have a lot of bob-whites and meadow larks, kill deer and cow birds and they do all of them.

[lhedden]

I've had the 100-400 1 for about 4 months now. I've shot it with the B+W Pro filter on and off. I've used it with and without stablilization but continue to get very weird Bokeh. I shoot mainly wading birds in Florida with it and have a lot of water vegetation in back and sometimes in front of the birds. One reed can turn into 3 or 4 parallel out of focus ones. It doesn't happen in every image, and it doesn't appear in all locations on the images where it appears. I am using hispeed motor drive, maunual focus,  1/2000, F8, ISO 1250. 

When I have specular highlights in the water that are small they end up looking like little wagon wheels that have the spokes sticking thru the wheel. Craziest thing I've ever seen. I've been photographing since 1973 and have had probably 30 or so Canon lenses from the orignal FD lenses, EF lenses, RF lenses and have never had one do what this one does. 

Why does Canon not spill the beans and tell us what is causing this problem? Other than really ugly Bokeh the lens is incredibly sharp and contrasty.

[ebiggs1]

This is a very old thread you may want to start your own new one.  You'll get better results.

But short answer is never, ever use any filter on the 100-400mm ver 1 lens.

"... lens is incredibly sharp and contrasty."  Not really!  It has never been known as a high IQ lens. I had two of them before getting one of the 150-600mm super zooms. Check out the newer ver 2 of that (10-400mm) lens.