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Averted vision - low-tech but potent !


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I don't see the technique of averted vision discussed that much lately - it's probably taken for granted by experienced observers but it might be news to someone new to the hobby.

Basically it means looking to one side of an object rather than straight at it - it works with faint objects like nebulae, galaxies etc and also faint stars and moons (eg: Saturns fainter moons). With a bit of practice it can make a lot of difference to what can been seen - as much, or more, difference than a filter sometimes I find.

I believe it works because the light detectors (rods and cones ?) at the edges of your eye are more sensitive than the central ones.

Have folks who use this technique found looking on a particular side, or above or below to be more effective ?.

I'm now probably going to get bombarded with links to recent SGL threads on this topic which I've missed ... oh well :rolleyes:

John.

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When I first visited this forum i kept hearing about averted vision and thought....your all mad....but after sitting out doors just staring up i could swear i was "seeing" things in the corner of my eye, then you go look at it directly and it disappears. Now I know your all mad.... but it works :rolleyes:

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The region of most sensitivity differs from person to person, but generally the side of the eye away from the nose tend to be more sensitive. Top and bottom can be more so in some, too. Try it out and see for yourself. The best target I know of is The Blinking Planetary, (Ngc 6826) in Cygnus. (It's unfortunately very low now, but you may still see it from the UK...?) The central star is very bright, while the nebula is faint, so looking directly at it, you only see the star, but if you look "away", or "sideways", the nebula magically expands! Try it!

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I use it all the time. It can almost be like changing eyepieces - i.e. by varying where you look over the range of extremes from straight at an object to the edge of the FOV (and other places in between) it's possible it see details that emerge at different points according to their brightness and contrast.

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Another related tip, when trying to find a very faint target is to tap the telescope. The movement often reveals the target - if you're pointing in the right place that is. The classic example is M1

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Interesting thread - I use averted vision all the time - and Astroman is right, I look left (with my right eye) and see more with the side view away from my nose. I wonder why that side is better? More rods on that side of the eye? A survival adaptation to make peripheral vision better in poor light??????

Don't know, but it works.

Tom

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Another related tip, when trying to find a very faint target is to tap the telescope. The movement often reveals the target - if you're pointing in the right place that is. The classic example is M1

Thats a good tip as well Martin - I found the Owl Nebula using that technique, I think I'd been staring straight at it for ages !.

John

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i'll need to try that once I get a half decent sky.

As for M1. One reason I didn't find this little thing is because it's in the middle of nowhere. As far as I can remember, there aren't many bright stars nearby and no easy hopping tips. Maybe I'm wrong, or maybe i need Goto

Andrew

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I use averted vision alot with the faint doubles I am tracking down.

I usually put the target in the centre of the FOV and look left with my right eye.

As I am usually trying to split the pair I then slowly start to look right and this allows me to bring the stars to a better visual focus before they disappear.

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