2

What creates a calisson-like shaped light bokeh such as this one (made with Arri signature T/1.9) ? The further from the center the more present are the angles, why ?

Arri Signature

Another lens (Zeiss Supreme T/1.8) gives another shape:

Zeiss Supreme

How (where in the lense) to craft this shape ? Yet, why (how) in the Zeiss case, the bokeh looks harder, even though the aperture is the same (1.8 ~ 1.9) ?

Michael C
  • 175,039
  • 10
  • 209
  • 561
Soleil
  • 821
  • 5
  • 14
  • TIL calisson. Interesting word, thank you! – scottbb Jun 19 '19 at 21:34
  • Do you mean lenticular bokeh? – xiota Jun 19 '19 at 22:32
  • @scottbb Last question remains without answer ! – Soleil Jun 19 '19 at 22:43
  • The Zeiss lens appears to have been stopped down a bit. I see a nonagonal shape. – xiota Jun 19 '19 at 23:17
  • 2
    If by the "last question remains unanswered", you're asking why the bokeh is different between the T/1.8 Zeiss and the T/1.8 Arri, I have to ask, what is the actual f-number used, not the T-stop? The f-number characterizes the geometry of the lens (the focal length divides by the diameter of the entrance pupil), whereas the T-stop accounts for the total light transmission through the iris (including transmission loss of the optical elements). – scottbb Jun 19 '19 at 23:32
  • @scottbb With cat's eye bokeh it's more than just focal length and entrance pupil size. It is also about any mechanical obstructions (lens barrel, filter ring, etc) that may limit points in the lens' FoV from seeing the entire entrance pupil. – Michael C Jun 20 '19 at 06:50
  • @scottbb There are no F, only T values. – Soleil Jun 20 '19 at 09:47
  • @MichaelC yes, you're right. But to my eyes, the 2nd image has smaller and more more polygonal bokeh balls, and less pronounced cats eyes, all of which are consistent with a smaller aperture. – scottbb Jun 20 '19 at 12:16

0 Answers0