From: "Tom Krajci" 
To: 
Reply-To: "Tom Krajci" 


>From: "Richard F.L.R. Snashall" 

>...I'm surprised that with all the aperture and resolution to burn
>that some of these larger Newts seem to have that someone has
>not tried to put a flat window with a silkscreened apodization
>pattern on it. But then again, the spider will still be there.

None of my 16 inch scope's aperture is 'to burn.'  I want to keep and use all of it.

If I apodize, I discard some of my resolution performance.

See:  http://www.willbell.com/tm/tm5.htm And make note of what the author
says about apodizing, and the related modulation transfer plots.

Apodizing reduces 'ringing', but maximum possible resolution suffers.

Also, check the ATM archives at for plenty of previous discussion on
apodizing.  See:  http://astro.umsystem.edu/atm/search.html

Then, search for ATM sites that use or encourage apodizing...why so few?
Perhaps because costs outweigh benefits?

Good luck,
Tom Krajci
Tashkent, Uzbekistan

PS.  I won't even begin to talk about the non-trivial matter of making a
large flat window in front of a Newtonian that does not degrade the image.

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