[AZ-Observing] Re: Telrad stellar limit
- From: "Paul Lind" <pulind@xxxxxxxxx>
- To: <az-observing@xxxxxxxxxxxxx>
- Date: Mon, 21 Apr 2008 11:39:01 -0700
AJ et al,
An interesting experiment would be to compare magnitude limits when
switching from only one eye to both eyes when using a Telrad. I always use
both. The eye that's looking through the Telrad suffers in two ways.
First, there is some pupil constriction (only in that eye) due to the red
light. Second, since there doesn't seem to be any AR coating on my Telrad,
so the 45 degree glass plate reflects about 10% of the light at each
surface, giving a 20% loss. This is much more than the usual 4% at each
surface for perpendicular incidence. Does all this seem reasonable?
Paul
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