[AZ-Observing] Re: Image Question
- From: "Stanley A. Gorodenski" <stan_gorodenski@xxxxxxxxxxxxx>
- To: az-observing@xxxxxxxxxxxxx
- Date: Sun, 07 Sep 2003 15:41:48 -0800
My mirror has a silicon dioxide coating. That was supposed to be a good
coating although I do not know if it was rated by years of service. I
believe, though, that silicon dioxide affects sensitivity in certain
wavelengths of the UBV system and that is where a quartz (?) coating is best
for some photometry.
Stan
Tom Polakis wrote:
>
> Is this true even here in Aridzona? Other than a lot of dust, what
> attacks coatings in this climate? Shouldn't mirror coating last for
> decades in the desert, or am I misinformed again?
>
> In the misinformed department, I will ask if it's not "technology"
> (Austin Powers quotes added for effect) that is improving mirrors today,
> what is it then? I defy you to find a good mirror greater than 16 inches
> in diameter and faster than f/5 made before 1980 that was available
> commercially for a reasonable price. Today, the shopper has many
> options. What were an amateur astronomer's options 20 years ago?
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