Should the other eye be closed or not?

[Astro Imp]

I'm one of the pirates but it really is a matter of trying various options and picking what suits you.

[dick_dangerous]

When I learned to use a microscope we were taught to keep both eyes open looking down it. I seem to remember there is some kind of perceptual reason why it's better, other than being easier on the eye, I just can't remember what the reason is!

Paul

[Charic]

One eye for my eyepieces ( the left eye either closed or patched ?) both eyes open for the straight through 9x50 finder scope and lastly prescription glasses needed for the Telrad ?

Do what feels best!

[glowingturnip]

think it goes to how dominant or not one eye is over the other.

I had a clay pigeon shooting event (which I was rubbish at) and the instructor started out by testing our eye dominance and strength of dominance.  If you're very dominant one eye over the other, as I was, then he recommended keeping the other eye closed, if not, you can keep the other one open.

You can test which eye is dominant by making a small hole between thumb and curled forefinger, hold it at arm's length, and while looking through the hole, slowly bring it towards your face - you'll almost always end up on the same dominant eye.

As for me, I usually end up cupping both hands round face and eyepiece to let no other light in.

[swimmingdonkey]

Some comments here have certainly piqued my interested for using an eye patch.   A relaxed eye would be nice

Then a tricorne hat for.. a bit extra shadow 

[Astro Imp]

Some comments here have certainly piqued my interested for using an eye patch.   A relaxed eye would be nice

Then a tricorne hat for.. a bit extra shadow 

If you go that far a parrot is obligatory 

[Relpet]

So far in my experience as a novice observer I've been concentrating on the moon and planets where their transit across the eyepiece is so rapid that eyestrain has not been a problem.  Now we are moving into longer nights and deep sky objects this question and the various answers seem especially valuable.  Old airline sleeping mask (currently at the bottom of a wardrobe) with one half removed might be the answer for me.  Certainly worth a try.  Thanks to all.

[J_N_Y]

I have an eye patch but don't use it too much as it irritates my left eye when I keep it open. So I either cover my left eye with my hand, or as glowingturnip mentions, mup both eyes with my hands.

I may well try the sleeping eye mask though, still have one left over from an unopened Virgin 'convenience' pack from last year I think. But on a completely non-practical level, eyepatches have got to be the cooler option, plus it may encourage pesky neighbours to keep away from you
 

[Merlin]

I use a pair of sunglasses with one of the shades removed and the other painted mat black on the inside. I also removed most of the plastic ring on the shadeless side so that it doesn't foul with the top of the eyepiece.

As a matter of fact, I have two pairs of sunglasses modified in this way for each eye. Sunglasses with deep sides are best for shading side light.