Comment by gyomu
7 hours ago
> Odd bokeh was one of the risks of adding a mechanical aperture, and bokeh is very often weirdest at the first or second down from open.
Why? Where can I read/learn more about this?
7 hours ago
> Odd bokeh was one of the risks of adding a mechanical aperture, and bokeh is very often weirdest at the first or second down from open.
Why? Where can I read/learn more about this?
This is usually due to the blade shape and quantity I believe. The aperture is most likely to be less circular on the widest apertures after fully open unless you have quite a lot of aperture blades, as the curve to make a rounder aperture is usually applied more towards the tip of the blade, and you're only seeing the base of the blades at wider apertures. That varies a lot by aperture design, however - if you have the more banana-shaped blades where the retaining pin and pivot pin are at opposite ends (like in a Yashica TLR) then I believe they can maintain a more consistent curve along the length. Those also suck massively to reassemble, but that's a different story.
I haven't seen a diagram of how the aperture in this new iPhone is designed yet. There's a lot of different ways to do it, with lots of odd shape possibilities.
> This is usually due to the blade shape and quantity I believe.
Also because of things like angle of incidence?
The purely round lens will generally have nice round (or at least cats-eye) bokeh across the frame with an edge that degrades softly as a result of aberration, so beams of light from different angles tend to blur into each other.
As soon as you get aperture blades, you lose that soft edge, get contrast but also a lot of competing shape influences at different angles. They will tend towards more rounded shapes as you stop down more.
And that is putting aside that some aperture shapes are just really insane when they are nearly wide open, right? (Konica 40mm f/1.8 AR I am looking at you with your shuriken bokeh)
> I haven't seen a diagram of how the aperture in this new iPhone is designed yet. There's a lot of different ways to do it, with lots of odd shape possibilities.
Not a diagram but one closeup photo:
https://petapixel.com/2026/09/19/apple-explains-why-the-ipho...
and an animation:
https://petapixel.com/2026/09/09/iphone-18-pro-has-apples-fa...
Six blades with a slightly rounded hook in them by the look of it. Very noticeable sun stars at f/1.8, nice looking results at f/2.8.
Absolutely insane mechanical challenge and assembly challenge.
Ooh yeah I love those weird shapes nearly wide open. I found a lens that had a torx bit shaped aperture the other day, I'll have to fish that out and see what it looks like in an image. Lots of compact cameras have a diamond/square-ish hole, notably the Minox 35 range from what I can recall.
Edit: just saw your update with the photos of the mechanism. Wow that's impressive miniaturisation. The hexagonal shape looks surprisingly good. I wonder what's causing the odd effects in the OP. I have noticed in the past that iPhone cameras produce square specular highlights through tree foliage, so I wonder if it's an extension of that oddity.
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