Hi all,
This may sound stupid, but I am having some doubts as to the need for most people to fully dark-adapt when observing at anything other than naked eye or the largest of exit pupils.
I did some casual observing from Tahmoor (semi rural) on the weekend. As I was looking at some globulars at around 3mm exit pupil, dinner time came around. I later resumed my observing. I found that it took very little time (much less than expected at any rate) for my eyes to adjust sufficiently to give the same level of detail on the same objects, Omega Cen and M22. Initially I tought increased altitude of the objects after dinner might have something to do with it. (Or perhaps something I ate
) But the increased elevation thing only applied to M22. Omega Cen had descended considerably during the same period.
Could the explanation be that a 3mm exit pupil (or any other value) only requires a pupil dilated to the same size to reach optimum performance? "Medium sized" dilation appears to be achieved relatively quickly as this discussion suggests (scroll to "Adaptation" about halfway down):
http://michaeldmann.net/mann7.html
As I was not doing any experimenting, it's not possible to tell whether other factors might have something to do with it, or even whether there really was the same detail visible. Also, the above targets aren't exactly faint objects, so I am going to experiment with some other objects later, paying specific attention to level of detail seen versus time elapsed since lights-out. I just thought this was an interesting observation. The reason I had not noticed it before might be that I generally start at low power and large exit pupils at the beginning of a session - (the only?) circumstances where good dark adaptation is essential.
If there was any substance to this, the effects would be profound. I could stop walking around the house with eye patches and sunglasses for ages before going outside
I would just need to start the session at medium to high power and everything would be sweet. Or would it?
What are your thoughts?
