(meteorobs) IR Camera is up. -Important notes....

stange stange34 at sbcglobal.net
Thu Dec 11 00:56:39 EST 2008

Chris I think you made a "typo" :-)  Our telescopes have distinct focusser 
travel noticeable between edge of moon, center of moon, and DSO's or Stars 
for example. Especially noticeable at prime focus with an astro camera or an 

A low power eyepiece or fast telescope tends to not distinguish stars 
compared to moon.

I routinely find cloud focus is far away from moon or stars in my cameras 
even with a 4mm lens. The one in the IR camera is an 8.5mm.

Also for these focussing reasons I once mounted a digital vernier caliper on 
a refractor and a precision 15 turn dial on an SCT.


----- Original Message ----- 
From: "Chris Peterson" <clp at alumni.caltech.edu>
To: "Global Meteor Observing Forum" <meteorobs at meteorobs.org>
Sent: 2008/12/10 21:18
Subject: Re: (meteorobs) IR Camera is up. -Important notes....

> With your camera lens, any object beyond a few hundred feet is at 
> infinity.
> No telescope on Earth can distinguish between the focus of the Moon and of
> stars. I recommend focusing on Venus, since it's high and bright now. Your
> eye/brain will do a better job of determining the best focus if you use a
> point source rather than an extended object like the Moon. And of course, 
> if
> you have an autoiris make sure it is all the way open, so you have the
> smallest possible depth of focus.
> Chris
> *****************************************
> Chris L Peterson
> Cloudbait Observatory
> http://www.cloudbait.com
> ----- Original Message ----- 
> From: "stange" <stange34 at sbcglobal.net>
> To: <meteorobs at meteorobs.org>
> Sent: Wednesday, December 10, 2008 10:03 PM
> Subject: (meteorobs) IR Camera is up. -Important notes....
>> a) Since design is an attempt to determine in what ways fireballs 
>> explode,
>> focus is NOT on stars in the background. A nearer object was 
>> used......The
>> Moon.
>> b) Plate glass window in camera housing is solely to help retain camera
>> heating so as not to corrode lens & camera electronics from dew and
>> condensation. It has worked well for 1.5 years on my outdoor surveilance
>> camera with no downside.
>> Larry
>> YCSentinel
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