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Can Aperture Replace Seeing?

Started by Jud, 09/25/2010 05:34PM
Posted 09/25/2010 05:34PM Opening Post
Having heard that aperture reveals more detail, has anyone worked out something semiquantitatively the relationships between seeing and aperture? Is there some upper limit on aperture with respect to seeing where the hypothesized curve turns down?

Jud

I Yam What I Yam!
Posted 09/25/2010 07:09PM #1
Hi Judson,
Reality is, seeing always rules no matter what the aperture. But think about this situation like a photograph. When you look at it from across the room, it looks good. Now you get up and walk across the room and you can see all the defects in the photo.

This is very much what you are doing with aperture. The larger aperture brings it closer and makes it bigger and brighter, which reveals the good and the bad.

So, it seeing stinks, it may not seem as bad with a 5" as it does with a 25", but it is still just as bad. 8)

[SIZE="Large"][/SIZE][COLOR="Blue"][/COLOR] Floyd Blue grin
Amateur Imager
Posted 09/26/2010 02:16AM #2
For visual use at high magnifications, the sweet spot for aperture is 20 to 30 cm. Larger apertures are usually seeing-limited at most locations.

Jim McSheehy
Posted 09/29/2010 03:15AM #3
Well for the reasonably small aperture, seeing means image shift within short time.
Human eye response is slower than 0.1sec. then we see blured image.
That might be corrected by fast moving adaptive optics such as Orion photography AO.
I wonder anyone tried with visual observation with 50times image correction per second.

In professional observatory with AO, they think they have to correct at least 50 times per second and correct for each small segment of aperture - typically 20cm.
That means 20 - 30cm aperture needs only image shift.
Even 50cm can have benefit of image shift correction.