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Cat eyes observations ...
#1
Just to illustrate the effect when stopping down ... taken at f/1.2, 1.6, 2, 2.8 (from the RF 50).

Also, note the shutter effect at f/1.2 (taken at 1/4000sec).


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Chief Editor - opticallimits.com

Doing all things Canon, MFT, Sony and Fuji
#2
Do you have an explanation for the "shutter effect"? Did you shoot with full mechanical shutter?
And the effect is called "cat's-eye", not "cat eyes" ;-)
#3
Great vignetting test. How much, 3 stops?
#4
(11-27-2018, 07:23 PM)miro Wrote: Great vignetting test. How much, 3 stops?

Cat’s eyes are caused by mechanical vignetting, which is unavoidable with large aperture lenses consisting of more than 1 element fitted to some sort of barrel

Optical vignetting is caused by the unavoidable light fall-off due to light rays falling in at an angle in the image projection by a lens, the cos^4 rule.

Kind regards, Wim
Gear: a gaggle of Canon primes, a lone Canon zoom (sold 5D II recently Smile), an accessory plague, and an Olympus OM-D 1 Mk II, Pen F and Panasonic GM5 with 14 primes, 8 zooms, and 3 Metabones EF-MFT adapters ....
#5
Regarding the weird effect at f/1.2 and 1/4000sec - thinking about it - it may not have been the shutter but a flickering effect from the (LED-)lights.

BTW, multiple "Cat's eye" as shown are surely "cat eyes" ;-)
Chief Editor - opticallimits.com

Doing all things Canon, MFT, Sony and Fuji
#6
(11-27-2018, 08:38 PM)wim Wrote: Cat’s eyes are caused by mechanical vignetting, which is unavoidable with large aperture lenses consisting of more than 1 element fitted to some sort of barrel

Optical vignetting is caused by the unavoidable light fall-off due to light rays falling in at an angle in the image projection by a lens, the cos^4 rule.

Kind regards, Wim

Thank you for the explanation Wim. I was aware only for one type of vignetting
https://photographylife.com/what-is-vignetting
@ Klaus - Are this light dimmable. If yes - well-known Led manufacture gives the flickering factor
#7
I thought I'd give it a go ( as I was out late-ish).

all images are SOOC and taken with canon 7D mark ii + canon 50mm f 1.8

#7749 @ f1.8 1/60 ISO 400
#7689 @ f1.8 1/80 ISO 1250
#7717 @ f1.8 1/160 ISO 1250


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#8
(11-28-2018, 06:34 AM)Klaus Wrote: Regarding the weird effect at f/1.2 and 1/4000sec - thinking about it - it may not have been the shutter but a flickering effect from the (LED-)lights.

BTW, multiple "Cat's eye" as shown are surely "cat eyes" ;-)

No!

It's the "cat's eye effect"......... (cat) 's .... belonging to the cat

When tested the lens produced cat's eyes towards the edges and borders of the frame.....
Dave's clichés
  


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