Cats eyes=f?

I was just thinking about how wide a cats pupil is at night and how small it is during the day...if a lens were that capable, what lens would that be?

Put camera into Tv mode, shutter speed remains constant, camera changes aperture... is that what you are talking about?

Keep in mind our eyes do that too... so do most animals...

Yeah just a cat is more sensitive to light than we are...I was drawing comparison to the similarities...its cool how our cameras mimic nature.

I was just wondering what ISO equivalent a cat's eyes are?

Sorarse wrote in post #9313293
I was just wondering what ISO equivalent a cat's eyes are?

Even more interesting, what shutter speed are they set too?

I'm sure the f stop isn't too amazing, but the "iso" ability of their eyes is probably amazing.

Quite a bit of the increased 'ISO' of a cat's eye is due to there being a reflective membrane (the tapetum??) behind the retina. So any light that doesn't get absorbed by the light-sensitive cells has a second chance of getting caught.

Human (and cat's) eyes would be more sensitive it it weren't for the fact that the light-sensitive cells actually lie below layers of nerve cells, blood vessels and supporting cells. So quite a bit of light is absorbed before it even gets to the sensor. It's another great example of idiotic design (a similar concept to 'intelligent design' but the creator was an idiot). Interestingly, octopus eyes are built the right way round so that all the light hits the sensor. Perhaps the designer is a squid?

The ability of a cat to see in reduced light is a result of the tapetum lucidum, a reflective layer in the retina of the eye. More than you ever want to know about how this works can be found here: http://www.ncbi.nlm.ni​h.gov/pmc/articles/PMC​1395665/

Yes, a cat's eye has a very high effective sensitivity—ISO—much more so than a human being. They also have a wider dynamic range—aperture—than a human being. This allows them to see in very dim light. They see well enough in the dark to hunt by starlight.

But trust me, you don't want to have a cat's eyes. The resolution is terrible, for two reasons.

First, the number of rods and cones in the macula lutea, the central spot on the retina where the most critical vision takes place, is much fewer than ours, resulting in less perception of detail overall.

Second, the shape of the pupil causes distortions in the image—very poor bokeh—that precludes fine detail, period. A super-intelligent cat couldn't read, because it could't perceive properly the shapes of letters on a page. And no, glasses wouldn't help.

What a cat's eyes do do very well, much better than ours, is perceive motion. This is why a cat can see a mouse at 50 feet by starlight, but can't see the mouse's whiskers, no matter how close or how bright the light.

And one other thing. They have really crappy color vision. Not as bad as a dog's, but nowhere near as good as ours.

I believe a cat's eye in darkness opens to about f/0.8.