# After-images in relative darkness

**URL:** <https://boards.straightdope.com/t/after-images-in-relative-darkness/391709>\
**Category:** Factual Questions\
**Created:** [February 11, 2007, 7:20am UTC](https://boards.straightdope.com/t/after-images-in-relative-darkness/391709 "2007-02-11T07:20:18Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![panache45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/panache45/32/64_2.png) [@panache45](https://boards.straightdope.com/u/panache45)\
**Post date:** [February 11, 2007, 7:20am UTC](https://boards.straightdope.com/t/after-images-in-relative-darkness/391709/1 "2007-02-11T07:20:18Z")

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Let’s see if I can explain this easily.

I entered a fairly dark room, in which I could barely make out a few objects, but not much. I wanted my eyes to become accustomed to the darkness as soon as possible. So I figured that the best thing would be to have my eyes seeing as little light as possible. So I shut my eyes.

Unfortunately, I still saw some after-images from the brighter previous room I had been in. In fact, these after-images were considerably brighter than the room I was now in.

So were these after-images working against my eyes becoming accustomed to the darkness, or don’t they “count” in that respect, since the light I’m seeing isn’t actually entering my eye through the pupil?

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**Author:** ![Jinx](https://avatars.discourse-cdn.com/v4/letter/j/c6cbf5/32.png) [@Jinx](https://boards.straightdope.com/u/Jinx)\
**Post date:** [February 11, 2007, 4:14pm UTC](https://boards.straightdope.com/t/after-images-in-relative-darkness/391709/2 "2007-02-11T16:14:35Z")

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I have no reference, but as you know, afterimages are from the rods and cones of the retina (a phenomena behind the pupil). Getting accustomed to a dark room involves the dilation of the pupil only; hence, the afterimages would not affect pupil dilation.