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How to use "Averted Vision"?

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#1 Maverick199

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Posted 16 April 2011 - 01:48 AM

I know what averted vision is and try to do that all the time to locate galaxies etc.,

I train my eye to look at the sides of the object in question while concentrating on that object. Now is this right?

I would appreciate if someone can really explain how to use Averted Vision. If someone can add some sort of pictures would be even more helpful. :bawling: Thanks.

#2 jimmy101

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Posted 16 April 2011 - 02:19 AM

I know what averted vision is and try to do that all the time to locate galaxies etc.,

I train my eye to look at the sides of the object in question while concentrating on that object. Now is this right?

I would appreciate if someone can really explain how to use Averted Vision. If someone can add some sort of pictures would be even more helpful. :bawling: Thanks.

Yep! You are correct. I was scanning zenith one night and come across a teardrop shaped cloud through the eyepiece. Now I could not see it at all if I looked at it, but looking off to the side of it , I could see with my periphial vision!

Try this: As you are driving down the road looking straight ahead, with out moving your eyes try to study the driver of an on comming car without looking at them. Over time with practice, you will be able to pick out what color eyes they have. It's amazing what kind of detail you can see by using concentration. I believe that is where the term "having eyes in the back of your head " comes from. Not sure though!

#3 Maverick199

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Posted 16 April 2011 - 02:28 AM

Wait..are you saying that instead of looking at the sides, I must actually train my eye on the object but while holding my eyes steady concentrate towards the sides? :confused:

#4 jimmy101

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Posted 16 April 2011 - 04:16 AM

NO! Just the oppisite! Look away from the object. Don't even look at the edge of the object. Pick a point that is close to but not on the object.
OK try this. You are looking at your computer screen reading this response right now. With out letting your eyes leave the screen, bring one of your hands in from the side
but do not look at it directly. Keep looking at the computer screen. Your hand should be about 5-10 degrees from the center of your screen. Now with out looking directly at your hand,Meaning keep looking at the screen, try to make out some details on your hand.
You may find that you have to move your hand closer toward the center of your screen to start. The more you practice the use of your periphial vision, you will be able to make out subtle details further away from your center line of sight. Soon you will be able to pick out details of those items in your eyepiece that you cannot see while looking directly at them!

#5 Asbytec

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Posted 16 April 2011 - 05:50 AM

LOL, man, now that's dedication...practicing averted vision to pick out facial characteristics of the on coming driver while driving at night :lol: It's okay, when going through pilot training, I'd practice my taxi and departure procedures during different phases of driving, including the radio chatter and control movements. So, yea, go ahead. :)

Jimmy is hitting the averted vision thing well.

One thing I find myself doing while averting my eyes is they tend to dart around a lot. Look over there, NO! Here! Okay, now, down there! Dart, dart, dart...sometimes keeping them still, but all the while trying to find that sweet spot. And when it shows up, my eyes dart right to the object. Anyone else do this, or am I the only one with a lack of discipline?

#6 Jon Isaacs

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Posted 16 April 2011 - 06:14 AM

I suggest practicing while observing. Averted vision is about using the rod rich areas away from your fovea. This area is not sensitive to color and has poorer resolution than the center.

My favorite practice is to pick a cluster with both faint and dim stars, my favorite for this is the double cluster. Look at it using a lower power eyepiece and then slowly start to look away. Suddenly it will seem to light up, the stars you were seeing are brighter and more are there to be seen.

If you practice lighting up easier objects, then using averted vision becomes second nature and when you are viewing faint objects you use it naturally.

Jon

#7 swpaisley

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Posted 16 April 2011 - 06:42 AM

In high school psychology, we did this experiment. It works, give it a try.

Have a helper pick three colored sticks, like a colored pencil works well. You want the entire pencil to be painted a single color. Fix your sight on an object straight ahead. With your helper BEHIND you, have them randomly pick a pencil and slowly move the colored pencil into your peripheral vision. Have them stop once you "notice" the pencil. You will NOT be able to tell what color the pencil is. This is because the part of your eye that is "seeing" the pencil is formed from rods and the rods are not able see color. However, the rods are very good at picking out detail. They are more "sensitive" to detail you might say... Continue to move the pencil slowly until you can now see the color. You have now started to use the rods of your eye. Color yeah, but less detail. Cool eh?

My mother was quite good at averted vision. *sigh*

-Scott

#8 clengman

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Posted 16 April 2011 - 06:58 AM

Asbytec - That is exactly what I find to be tricky. I can propose a little exercise based the experience I had viewing the eskimo nebula the other night. First, I was able to see a very dim point of light on and off at the location of the nebula with direct vision. It happens that there is a dim star several arc min away. When I would look at the star next to the nebula, a fairly bright disc of nebulosity would just flash in to existence around the point that I could only *kinda sorta* see before that. my eye would be drawn to it and it would just as promptly vanish. I spent a good bit of time that night trying to center my vision on the star, but focusing my attention off to the side on the nebula. I think an important part of learning averted vision is to subdue that reflex to look directly at an object that catches your attention.

#9 RTLR 12

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Posted 16 April 2011 - 07:15 AM

I was taught averted vision in the service and the technic I was taught was to keep your eyes moving around the target you are looking for as Norme does. Seems to work for me. Never to look directly at the center of vision, but to continuously look around the perimeter. Of course that was a long time ago before people had eyes...

Stan

#10 Al Canarelli

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Posted 16 April 2011 - 07:34 AM

My understanding of why averted vision actually works is as follows...

All of us have a natural blind spot exactly in front of where the optic nerve enters the eye. Therefore, if we look directly at a dim object, we are using that part of our fov with the blind spot to view the object. The results are that the dim object disappears. When we look at the same dim object using peripheral vision, the object reappears.

Here is something interesting you can try. Find NGC 6826 with your telescope. It's a planetary nebula in Cygnus and is called the Blinking Nebula. In order to see it, you will need to scan the area using averted vision. Once you find it you will quickly see why it's called the Blinking Nebula. When you look at it directly it disappears and will reappear (blink on) only when you use peripheral vision.

#11 clengman

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Posted 16 April 2011 - 08:24 AM

Al - That's not really it. There is a blind spot on the retina, an area with an absence of light detecting cells, where the optic nerve enters the eye, but it is not at the center of the field of view. The center of the field view, the fovea, contains the highest density of photosensitive cells and these are almost exclusively comprised of cone cells. The high density of photo sensitive cells means that, provided you have sufficient light, you can resolve the finest detail using this part of your retina. However, cone cells have a higher threshold for activation, they require more intense light to transduce a signal, than the rod cells which are more common everywhere *but* the fovea. Since the rods have a lower threshold of activation and are capable of detecting light sources of lower intensity, very dim objects are more easily detected when their light is projected not on the fovea but on the peripheral area of the retina.

#12 Jon Isaacs

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Posted 16 April 2011 - 08:49 AM

I think an important part of learning averted vision is to subdue that reflex to look directly at an object that catches your attention.
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Carl: Once you have located an object, that's exactly what you want to do, with practice it will become second nature. When hunting for targets they will be away from the fovea so they will be in the rod rich region, learning to notice them when they are not centered is another skill.

Jon

#13 Asbytec

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Posted 16 April 2011 - 09:04 AM

Stan and Carl have me confused. :)

Truthfully, yes either works, probably. The darting technique just kind of developed over the years. But, this idea of looking directly at it, well...as is being explained very well here...is NOT averted vision.

Yes, I believe Carl is correct, rods are more prevalent away from the center of the eye as Scott's demonstration shows (though I never knew we could see more detail with them.) The blind spot is not centered, and is not the cause of the blinking nebula blinking in Al's example. What might cause this blinking is directly looking at it, pretty sure.

There was a test in this forum a while back that showed the effect of the blind spot. Wish I had it bookmarked, but it's probably easy to find. There might even be a averted vision test one can perform. Off to see...

Meanwhile, here's a nice thread on the subject.
http://www.cloudynig...&vc=&PHPSESSID=

#14 Jon Isaacs

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Posted 16 April 2011 - 09:22 AM

The fovea, the center of the field with the concentration of cones, has the best resolution so if you are looking at the planets or splitting doubles, this is where you want be.

#15 Maverick199

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Posted 16 April 2011 - 09:24 AM

Jimmy:Try this: As you are driving down the road looking straight ahead, with out moving your eyes try to study the driver of an on comming car without looking at them. Over time with practice, you will be able to pick out what color eyes they have.


I tried this and ended up nearly knocking over a man crossing the road. :( He gave me a glare so bad I picked up the colors on his eyes instead. :lol:

But thank you everyone and Jimmy. So many good examples. I am going to try this out on a clear night, probably today.

I have also asked my children to read your advices thoroughly.

#16 wagner lip

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Posted 16 April 2011 - 10:26 AM

Interesting fact about the angle of our vision our brain really process deeply. Approach your face 12" from the computer monitor, now look at the block of letters and numbers below, look directly to the "A" at the center and do not deviate your vision from the "A". Now, with your peripheral vision try to identify the letters neighbors to the A, and then their neighbors. "Identify" doesn't not mean "see", it means recognize what letter it is. Then you will understand how narrow is the field of vision for recognition and understanding. Perhaps one could extend that area with training.

S K W O H M B N S 7 2 M G 8 2 3 M D B 2 3 Y L
N O T I E R P 7 5 2 3 4 H S D 2 3 2 7 S K W N V
4 B / W J R O P W 9 2 N R S P E I B D L S 8 3 K
8 Y W R P B S 5 2 Z 0 6 J A L K B M V Q 3 U E N
K S H J W I O S G H S L S G Y W E R N 2 3 8 F L
S K W O H M B N S 7 2 M G 8 2 3 M D B 2 3 Y L
W O U I E R P 2 7 2 3 4 H S D 2 3 2 7 S K W N

I know, it is VERY difficult to keep your eyes targeting the "A" all the time, when you are trying to recognize the letters and numbers around. Your eyes tend to move to the direction you want focus. But with little training you can do it.

I can recognize no more than 3 letters in any direction from the "A", poor me. Funny thing, I can recognize "2" and "7" far away, perhaps because the trace angle and how my brain analyze it.

You can do the same looking at the "H" key at your PC keyboard and try to recognize the letters at other keys. Forget that you already know about them... :smirk:

#17 Maverick199

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Posted 16 April 2011 - 10:55 AM

Hi Wagner. That's really helpful to train with. I could recognize two letters either side and one letter up and down. Need to train some more. Thanks. :D

#18 Asbytec

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Posted 16 April 2011 - 11:15 AM

Wagner, very interesting. Thanks. I could recognize the Z fourth letter to the left, but not the 0 before it. Also, I can do 3 letters up and down, and it seems about 2 left and right. The M at the top, just above the A, can be recognized as either N or M. Maybe it's the sharp angles made by Z's and M's that does something weird. Really weird! Love those kinds of tests, though.

But, for the OP, averted vision also plays a big role in seeing dim objects, as has been stated in this thread. Interesting to see the resolution, though.

#19 Scopyfrank

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Posted 16 April 2011 - 11:28 AM

As Jon says, clusters work so fine: it's that way that I "resolved" M13 for the first time under decent skies with my 4.5" refractor.
Training averted during daytime or during nighttime are two different worlds in my opinion. For me, averted vision is much more efficient during night.
Fixing the object, and then slowly "quitting" it with my eye, the coming slightly back, the again quitting it etc etc ... and the moment comes where you see the object when your eye does not target it any more. Sometimes, when slowly targeting it again (but not dead on) you succeed in keeping the vision. For me, works so great with M13 and recently with M3, Cassini division, M51 under urban skies, or for better seeing some major bright galaxy cores and, after some time, a tint of their halo ...
You may also make the tour around the object with your eye and see whether there are "sweet spots" in your averted vision area: my experience is that sometimes it's subtle, butI feel that there are: but this may also be due to unexpected momentary improvements in seeing.
¨How to use "Averted Vision?" Without moderation.

#20 Doc Bob

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Posted 16 April 2011 - 12:22 PM

Everyone's responses are correct . . . how about looking at the Blinking Planetary Nebula. If you look right at it - it's not all that apparent; but as soon as you "avert your vision" just a little . . . it pops right out at you. A few minutes observing this object should go a long way in training your eye and sensory ability.

Raining a lot here,
Bob

#21 JayKSC

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Posted 16 April 2011 - 12:42 PM

One interesting thing is that the rods are highly sensitive to movement. One common tactic for glimpsing very dim targets is to not only use averted vision but to also gently sweep the telescope back and forth across the object - or - gently tap the scope so that it wiggles a bit. The perceived movement in the eyepiece can more strongly activate rod activity, most likely due to signal threshold spreading across a larger number of adjacent rods which increases sensory transmission via spatial summation.

- Jay
South Florida

#22 Maverick199

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Posted 16 April 2011 - 01:51 PM

Right, tonight was the night where it was "Averted Vision" or bust. And I find it hard to believe myself but thanks to you guys, we finally managed to see M51. At first we thought it was a binary star but kept looking at it and the faint details began to appear. The bottom star was bright and the top somewhat a bit obscured but 'light to dim brightness'. Now due to a gibbous moon, albeit CLEAR night, we found it hard to believe. We came back indoors and looked at Stellarium and the star hopping my daughter did once again took us to this object and there it was, M51. Can't believe our excitement. Mind you the details were not like what I thought it would be but it was there.
This brings to my last doubt to clear this up. Is it possible to view M51 in a clear sky but with moon at its zenith? Also its a mag 9.60. We used a 30mm Plossl. If so, its a confirmed hit for me. Thank you very much. :D

#23 Vic Menard

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Posted 16 April 2011 - 02:28 PM

Try here. Alan MacRobert seems to have covered most (if not all) of the bases.

#24 jimmy101

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Posted 16 April 2011 - 05:03 PM

My mother was quite good at averted vision. *sigh*

-Scott


:lol: Thats funny! :lol:

#25 jimmy101

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Posted 16 April 2011 - 05:15 PM

Hi wagner,
Excellent test! I can pick up six letters to the left and to the right! I see four up and down.
I can almost pick up all of the outside letters!
That is a cool test!


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