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Looking into a eagle nest at 3,200 feet away. Indoor glassing options (1 Viewer)


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I left my 120ED out for half an hour, which usually does the trick. It is slightly undercorrected which I combat a bit with some glass path in the form of a prism diagonal.

If I recall correctly on this example the crayford was ok - my ED 80 needed a lot of crayford love when I bought it, but now also very smooth.

Sure, an eagle is a bit easier to see than a magpie... but the chicks are about the same size.

Since seeing was the limiting factor, I guess the a 150 would not have fared better...



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Thanks Joachim,

I notice a big difference between a magpie and a crow.
Although the magpie is black and white, the bigger crow is easier for me to see without glasses, 3 dioptres out of focus, no binocular, at 124 metres.

I usually identify the crow correctly.
Sometimes I guess the magpie.
A blackbird is too small.
Herring gulls are easy.

So a full size eagle might be seen well in excellent Seeing at 1000m with the 120ED.

It is possible a Celestron 9.25 might do better than even a 150ED because of the larger aperture.

I think 180x is probably the best power even in excellent Seeing in morning light.

Unless one goes for a 12 inch scope, when 200x to 250x might work in the best conditions.

I doubt that the distance can be reduced to 300m easily, although a remote telescope and live feed is a possibility. But someone could remove the telescope.

Astronomers successfully use telescopes on the other side of the planet on a regular basis.

Best regards,


Well-known member
Has anyone experience of Dynamic Optics Adaptive optics for small telescopes?

I wonder if it would dramatically improve the performance in the daytime of say a Celestron 9.25 SCT or a 150 ED refractor.

The company, Dynamic-Optics.eu seem to be near Venice, Italy.

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Yep, as mentioned, the weakest link in using an astro scope will be the erect image prism diagonal.
I have a 45 degree Tele Vue erect image prism diagonal but it’s ok only up to moderate powers. My dielectric mirror diagonal provides better views.


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For image erectors, have a look at http://www.pt-ducks.com/cr-telescopes.htm#Test of image erectors
Within the economical image erectors, the Vixen is the best, but is long, will probably make the scope even longer since probably will need extender tubes to reach focus, and will have a increase factor around 1.5x - on this case isn't a limiting factor - with a Baader Hyperion Zoom Mark III increases 1,18x.
There is another erector of good image quality and more compact but needs some special adapters and I still didn't updated the web-page...


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Re. adaptive optics.
Interesting conversation.
Vertically, lots of work done.
Horizontally, the variations are great.
It should work during the day.
They have provided daytime equipment, but maybe not for simple observations.

Basically a light source is needed over 1000m or 1 km.
Could be a laser or a street light lit during the day.
50 cycles a second.
However, I am not sure whether modern street lights are 100 per second or different.
I have photographed street lights at night during a snowstorm with high ISO and I think I got 100 times a second for the light.
I don't know what the new LED lights do. They may be continuous.

Basically a camera is used with high frame rates per second.

Visually, they don't have much information, but one could look at the screen.
I am not sure whether it would work just using an eyepiece.

They have used a Celestron C11 and a 1 metre telescope, Omicron? in Nice.

They supply the parts etc.
Probably 15,000 euros at least.

So theoretically at least one may be able to view an eagles nest well at 3200ft, but one needs to be a wealthy and probably scientifically trained individual to get it all working.

The problem is that the light source would disturb the eagles, but infra red light usually works best for adaptive optics anyway.

A camera like a Nikon P610 or Canon 50HS situated nearer the nest is much cheaper, but the focus light would disturb the eagles.
The Konica Minolta Z6 uses an infra red focus light but is probably too slow etc.
Some video cameras may use infra red light for focus?

Or just use a 120mm ED refractor and accept that the detail seen would be less than hoped for, but one would see something in early morning good Seeing.



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There is a stunning Mars photo with the Omicron 1 metre telescope at Calern, France posted on Cloudy nights.
November 2020.


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