I would imagine (although have not investigated) that - as eyes age - perhaps the speed at which dilation/contraction occurs reduces, purely just as a muscle function.
In birding conditions, the light generally fades, rather than 'switches off'; same at sunrise, giving the pupils a little more or little less light gradually.
When i used to do more walking at night out on marshes, it took a while to get my night-sight, and i knew enough about it to not look towards any light sources, as it seemed to set me back for quite a while. It seemed that contraction happened faster than dilation, but this might be just my perception.
Contraction may be a defence mechanism, perhaps....
Good job cats don't use binoculars!
https://www.youtube.com/watch?v=i1znmh8d7U4
In birding conditions, the light generally fades, rather than 'switches off'; same at sunrise, giving the pupils a little more or little less light gradually.
When i used to do more walking at night out on marshes, it took a while to get my night-sight, and i knew enough about it to not look towards any light sources, as it seemed to set me back for quite a while. It seemed that contraction happened faster than dilation, but this might be just my perception.
Contraction may be a defence mechanism, perhaps....
Good job cats don't use binoculars!
https://www.youtube.com/watch?v=i1znmh8d7U4