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Starman1
Vendor - Scope City
Reged: 06/24/03
Posts: 12230
Loc: Los Angeles
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Using averted vision really makes the difference. I find that averting my vision and slowly making a circle around the object brings the object into different parts of the retina and results in seeing more image.
The old idea was that a right eyed person should look to the right of the object and a left eyed person look to the left--this to avoid the blind spot--but I found that the portion of the retina with greatest sensitivity varied from moment to moment according to the brightness of the object and small differences in dark adaptation (sensitivity), so that making a circle around the object always resulted in better detection than simple unidirectional averting of vision.
One thing that does not seem to aid detection of extremely faint details is staring. The eye does not build up photons like film. In fact, it seems that engaging multiple retinal cells results in activity in the brain, while the brain seems to ignore light on a tiny spot of the retina. Probably why our vision is always shifting slightly, even when we think we're staring without moving the eye.
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Don Pensack
12.5" Truss Dob, 5" Maksutov, Fujinon Binos
Sustaining Lifetime IDA member
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Jack Tripper
sage
Reged: 05/10/09
Posts: 349
Loc: Canada
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Quote:
I don't believe that's an accurate characterization of your eye's functioning. Chemical changes improve dark adaption but I've never heard of "accumulating" photons in your eye/brain system.
While I totally agree with your statement on a scientific level, it has been my experience that if I view an object for several hours, the next night that I view it, the object somehow seems more detailed and easier to see. I think that it has to do with knowing exactly what details to look for, and where the details are.
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Celestron CPC 1100 
Denkmeier S2 Power Filter Switch Diagonal (.66x Reducer, 2x Barlow)
Ethos 17mm, Baader Scopos 30mm
Lunt 60mm Hydrogen-Alpha Solar Scope, Lunt Zoom
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Jack Tripper
sage
Reged: 05/10/09
Posts: 349
Loc: Canada
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Quote:
Using averted vision really makes the difference. I find that averting my vision and slowly making a circle around the object brings the object into different parts of the retina and results in seeing more image.
The old idea was that a right eyed person should look to the right of the object and a left eyed person look to the left--this to avoid the blind spot--but I found that the portion of the retina with greatest sensitivity varied from moment to moment according to the brightness of the object and small differences in dark adaptation (sensitivity), so that making a circle around the object always resulted in better detection than simple unidirectional averting of vision.
Awesome tips Don! I have often wondered about things like that. You just added about 1" of aperture to my scope...Thanks!
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Celestron CPC 1100
Denkmeier S2 Power Filter Switch Diagonal (.66x Reducer, 2x Barlow)
Ethos 17mm, Baader Scopos 30mm
Lunt 60mm Hydrogen-Alpha Solar Scope, Lunt Zoom
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Jim Curry
sage
Reged: 10/29/07
Posts: 432
Loc: Maine
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>it has been my experience that if I view an object for several hours, the next night that I view it, the object somehow seems more detailed and easier to see. <
Experience, my good man, experience.
Further to Don's post re: averted vision. In concert with small eye movements I put my driven mounts drive on very slow hand paddle control. Slow trolling across the FOV will bring out subtle details or even objects otherwise at the limit of detection.
Jim
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Vixen 140 refractor
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Jack Tripper
sage
Reged: 05/10/09
Posts: 349
Loc: Canada
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Ahhhh...I like it! I used to try and mimic the old "jiggle" method by using the maximum slew rate and then pressing left and right really quickly. I'm definitely gonna try slow slew speeds the next time out. We've really gone really off topic, but this is just too interesting!
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Celestron CPC 1100
Denkmeier S2 Power Filter Switch Diagonal (.66x Reducer, 2x Barlow)
Ethos 17mm, Baader Scopos 30mm
Lunt 60mm Hydrogen-Alpha Solar Scope, Lunt Zoom
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FirstSight
Post Laureate
Reged: 12/26/05
Posts: 3898
Loc: Raleigh, NC
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Quote:
Chemical changes improve dark adaption but I've never heard of "accumulating" photons in your eye/brain system.
Yes you can, but it's a skill which requires quite a bit of experience and patience to develop sufficient "averted imagination" to make useful observations.
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Chris M., aka "First Sight"
Orion XT12i Dob with Moonlite CR-2 focuser
WO Megrez 90 refractor on UniStar Light mount
Nikon 10x50 Binoculars
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wfj
sage
Reged: 01/10/08
Posts: 259
Loc: California, Santa Cruz County
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Please remember the "afterimage" effect - the visual system does dwell images to a degree, as well as use multiple correlation to vastly increase SNR. "Visual purple" enhances reception by decreasing the bleaching effect of light on receptors - increasing noise as well.
The cognitive aspects of vision may play a very significant role in enhancing this process, given the many layers of the human visual system and its "feedback loops".
Early NMR sensors, looking at noisy, error prone data used the positive correlation of a "lock-in" amplifier to improve SNR by 2-3 orders of magnitude, making the technique possible - helped Owen Chamberlain win a Nobel prize. Similar processes in visual cognition probably work to reduce SNR and heighten acuity to even higher magnitudes. Multiple visual "triggers" / edge detections could be a very effective strategy for seeing in the dark.
The point of this post is to illustrate that you want to think of human vision very differently than photon counting. It would not surprise me that as we learn more techniques from the human visual system, they may be used to improve CCD imagers as well.
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Jeff Young
Post Laureate
Reged: 08/04/05
Posts: 4119
Loc: Ireland
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Quote:
Ahhhh...I like it! I used to try and mimic the old "jiggle" method by using the maximum slew rate and then pressing left and right really quickly. I'm definitely gonna try slow slew speeds the next time out. We've really gone really off topic, but this is just too interesting!
I use both techniques. It's funny, but sometimes panning works better and other times jiggling does. I haven't yet been able to correlate it with target size, presence or lack of defined edges, etc., so I don't know if it's based on some of these factors (or others), or essentially random.
Cheers,
-- Jeff.
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Nikon 18x70s / UA Millennium Colorado:
Solarscope SF70 / TV Pronto / AP400QMD Coronado SolarMax40 DS / Bogen 055+3130
APM MC1610 / Tak FC-100 / AP1200GTO Tak Mewlon 250 / AP600EGTO
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PeterSurma
super member
Reged: 08/24/06
Posts: 122
Loc: Heidelberg, Germany
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Hi Don,
sorry I missed your reply/post. Actually I'd recommend this pretty good page to you:
http://www.strnad-emskirchen.de/qso_beobachtungen.html
Yes sorry, it's in german, but the object IDs are given in english ;-) :-)
Good luck
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Peter
Web: http://www.eyes4skies.de/home_EnglishVersion.htm
Scopes: From 3inch photographic APO to 20inch f/4 Dob
Edited by PeterSurma (10/18/09 06:39 PM)
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Starman1
Vendor - Scope City
Reged: 06/24/03
Posts: 12230
Loc: Los Angeles
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Thanks.
What a project. Sounds like fun.
They're all listed in my computer program, too, so I can print finder charts.
Let the hunt begin! (assuming I ever get clear skies).
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Don Pensack
12.5" Truss Dob, 5" Maksutov, Fujinon Binos
Sustaining Lifetime IDA member
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