From: Ray Byrne <ray@in4media.co.uk>

Date: February 20, 2010 4:35:05 PM MST

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] Mars with a 74" reflector!!!!!!!


Hi Alan, 


I used to use "High Resolution Astrophotography" by Jean Dragesco as a kind of bible many years ago. Now I know he was referring to imaging on film which is nothing akin to what we do (or try to do in my case) but he suggested that any scope over 400mm aperture would not be any better than a 400mm scope (of course quality of optics etc. taken as being equal) because of the limitations of seeing. Do you think this still holds true even though we are taking images at an unbelievable speed compared to exposures he was used to when he wrote the book (my copy is 1995)?


ATB

Ray


 


On 20 Feb 2010, at 18:55, Alan Friedman wrote:

Hi Jim, 


Thanks for this fascinating look at and through a large aperture telescope. Tell us more about the night and about the instrument. Did you observe visually at all? I'm not sure why the focal length would be a problem for imaging, though I can imagine a huge mirror like that could be hard to tame on a night of poor seeing. Did you use a color chip for imaging? Would love to see a stream of data from this scope through an IR pass filter. If you will excuse me for this comment, the image is remarkably awful. I've heard of large instruments being handicapped by air turbulence, but it would be very difficult to imagine this result. 





On Feb 20, 2010, at 10:07 AM, Jim Chung wrote:

 

Sorry, missing a slash!

http://tech.groups.yahoo.com/group/Astro_IIDC/files/Planetary/MarsDDO.jpg

Quoting Terrence Redding <tredding@mac.com>:

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>
> terry
>