For me it seems reasonable that if I kept my gaze on a fixed point in a room with low light, a progressively brighter and better picture would appear before my eyes, just like a camera can see in the dark if the shutter speed is really slow, e.g. 4 seconds exposure. Why can't our brain do this trick as well (accumulate visual information over time)? Or is it a limitation of the eyes?

edit:

To further clarify what I'm after; I will show a concrete example from the world of photography (images taken from this website).

Here is an example where we have a series of underexposed images - this would be what the brain receives:


Now, combining all of them with a simple add-operation reveals one image that has normal exposure.


This seems like a simple trick for our powerful brain - surely it can add incoming signals?

For simplicity's sake, let's really reduce this to something like photography.

A camera's aperture can stay open indefinitely, allowing the plate (or whatever is receiving and recording light) to "collect and save the effect of photons" over time, if you want to phrase it that way. That allows a camera to make images that our eyes never can, for example, of "star trails".



The retina isn't like a photographic plate or a digital sensor's photosites (or pixels). It can't "collect and save" like a camera can. There is a "refresh rate", if you will, that disallows a collection and saving of light that doesn't apply to cameras, because cameras don't care if something in their vicinity is sneaking up on them and presenting a danger to their lives. Not being able to detect change rapidly is something that would be most inconvenient to survival.


  It is the time sampling with long exposures that really makes the magic of digital astrophotography possible. A digital sensor's true power comes from its ability to integrate, or collect, photons over much longer time periods than the eye. This is why we can record details in long exposures that are invisible to the eye, even through a large telescope.


How Digital Cameras Work
