[MLonlooker]

Hi guys and especially Klaus ......
 Recently there has been a thread on DPR Nikon MLCs about busy background bokeh with Nikon tele-photo lenses ...... all sorts of theories were put forward including modern exotic glass elements etc ..... my theory was nisen bokeh.
(the splitting of OOF subjects such as multiple grass etc where the hard edges all jumble together to form ugly irregular backgrounds)

   It's there on the Tamron G2 150-600mm, the AF-S 600mm F4E FL which are both modern designs, but also equally on the older AF-S 500 F4D which must be nudging 20 years old and has I think only one ED element.
  The latest Z tele-photos also seem to have it in just the same way.
 
 The million dollar question is why is it happening ..... and is it possible to design tele-photo lenses that can get round the issue?
 
 I've looked all over the web and have never found an answer to this question.

  thanks in advance ....

[Rover]

Very few lenses don't look ugly when there's grass, foliage or twigs in the OOF background (especially if it's just-OOF). Not a Nikon specific issue by any stretch of the imagination. :-)

[MLonlooker]

Very few lenses don't look ugly when there's grass, foliage or twigs in the OOF background (especially if it's just-OOF). Not a Nikon specific issue by any stretch of the imagination. :-)

I wasn't saying nor implying it was a just a Nikon issue, the Pentax FA300mm F4.5 * lens was also very nervous also the Sigma 50-500mm ..... however the Nikkors were full pro lenses and the ones I have the most experience with .. 
  
  I have no experience of Canon or Sony lenses so I can't comment on them ...  
  I have found and good less good rendering in shorter FL lenses though, especially in the specular highlights ......

[Rover]

Never said you did. It was just that the Nikon forumites are discussing it...
I guess STF may be the answer but it's not been seen in lenses longer than 135mm to date.

[MLonlooker]

Never said you did. It was just that the Nikon forumites are discussing it...
I guess STF may be the answer but it's not been seen in lenses longer than 135mm to date.

  Now your out acronyming me .... I guess I'll have to bow and scrape to ask wtf that is  ......

[Rover]

Oh... It's this
https://photozone.de/sonyalphaff/737-sony135f28ff
https://photozone.de/sonyalphaff/1016-sony100f28stf

[MLonlooker]

Oh... It's this
https://photozone.de/sonyalphaff/737-sony135f28ff
https://photozone.de/sonyalphaff/1016-sony100f28stf

 Ah yes Rover, I remember seeing those reviews now I'm rereading them  ..... but somehow it didn't click with me at the time, I was too busy trying to get Pentax cameras to focus.
  With modern Sonys and an A mount E mount adapter, these lenses make absolute sense for portraiture ...... I wonder if many are available on the used market? 
  Those apart, short of crusading that someone manufactures a 600mm STF F4 version for the well heeled extremists in this world, a simpler and more practical answer is to either choose less busy backgrounds in the first place or making sure your backgrounds are exactly that, well in the distance ..... whilst laying on your stomach to boot.  
   Perhaps I'll start marketing "Say no to nisen bokeh" T shirts!

[Klaus]

I don't know the answer but I would speculate that the highlight outlining that we are discussing the reviews is somehow related.
This outing may be very distinct with highlights due to their brightness. However, at less contrasty edges the same outlining may produce these shadows.
However, don't ask me what's causing the outlining in the first place.

[MLonlooker]

I don't know the answer but I would speculate the the highlight outlining that we are discussing the reviews is somehow related.
This outing may be very distinct with highlights due to their brightness. However, at less contrasty edges the same outlining may produce the shadows.
However, don't ask me what's causing the outlining in the first place.

Thank Klaus.

I was surprised by the bokeh in the jalopy image, other images looked fine ....

All the teles I have shot with have an issue with highlights as well as nisen bokeh, which makes getting a good image a struggle ....

Both these images were taken at ground level and the effect is alleviated:

https://www.flickr.com/photos/124690178@N08/50477969187/

here the transition around the plane of focus remained edgy/gritty and PP was needed:

https://www.flickr.com/photos/124690178@N08/51990331750/

Both taken with the AF-S 600mm F4E FL wide open .....

[Klaus]

These 2 images look pretty fine to me, though :-)

Generally, long telezoom lenses tend to have bokeh issues.

---

FWIW, this is what ChatGPT tells about it ...

"The root cause of a "nisen bokeh" is spherical aberration. Bokeh refers to the aesthetic quality of the out-of-focus areas in a photograph, often highlighted in images with shallow depth of field. Nisen bokeh, sometimes also called "double-lined bokeh" or "ni-sen" (Japanese for "two-line"), occurs when out-of-focus highlights appear as double lines or have a harsh, edgy look instead of smooth, creamy blurs.

Spherical aberration happens when light rays that pass through the edges of a lens are focused at different points than those that pass through the center. This inconsistency causes the out-of-focus highlights to appear with doubled or hard edges, leading to the characteristic look of nisen bokeh.

To minimize spherical aberration and improve bokeh quality, lens manufacturers often use specialized lens elements or designs, such as aspherical elements, to ensure light rays converge more uniformly. This results in smoother and more aesthetically pleasing bokeh in out-of-focus areas of a photograph."