I like it best at 75% as well... hey, I like this alot, especially the way you detailed the light around the pupil, but I think the inside curve of the iris where it meets the shadow in the corner of the eye needs more value graduation...(meaning the shadow needs the graduation) either that or extend the curve of the iris into the shadow a little? That's the only thing I see that keeps this from being pretty close to perfect.
(edit: I just noticed the comment on your last revision... it's way too good to give up on it till you're completely happy with it, maybe walk away and come back to it later?)

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oo i love this. the only thing i can probly critque it on is that the eyelashes aren't so close and many when you're actually looking at an eye that close. But that's it, beautiful :)

When looking at the left side of the iris i see a ghostly face taking form, its eye is fairly detailed > -- i like your picture, good work.

The iris itself, and the texture/thickness of the lashes is wonderful.

The lashes are spectacular, all of it is.. really nice

what did your mama tell you about putting the camera that close to your eye
great pic very well done ::stairs back at it for hours::

ooo Great eye!! :-) I love the iris especially!

wowee! talk about a window to the soul...! terrific!

Damn that's excellent. Love it. Great job.

Such wonderful detail on this image, I could only DREAM of drawing this amazing on the computer *claps*