[SJAAboard] our solar scope's H-alpha filter

[Rich N]

> Mark Wagner wrote:
>> Gary Mitchell wrote:
>> > I beg to differ about those little PSTs being useful.  I looked
>> > through a couple of them at Houge a while back (solar event) and
>> > was NOT impressed.
> 
>> That is of course a matter of opinion.  I've found views through the
>> small PSTs acceptable, especially given how relatively inexpensive they
>> are.
> 
>  I've run both scopes at public events.  I agree, Mark, that the PST
> gives good views for the price.  I have not compared them side-by-side,
> but my feeling is that the Daystar would sharply outperform the PST.
> 
>>  I had heard comments about the DayStar
>> being finicky about temperature, and possibly tuning.
> 
>  True, but.  The Daystar (in my experience) is more critical and needs
> frequent touching up during the initial 10 to 20 minutes.  This is done with
> a small knob that turns very easily and smoothly.  The PST also needs some
> initial adjusting, and (for a sample of one) the adjustment was more
> difficult due to the great torque needed.  It took considerable care to keep
> it on the sun, even though it was riding atop my own 8-inch.
> 
>  The result was, if memory serves, a distinctly sharper image.
> 
>  A bigger factor is the very narrow field of view, as mentioned by
> Gary.  Moreover, the supplied eyepiece is critical!  When I tried my own
> eyepieces, I got totally unacceptable scattered light.  I've used my own
> eyepieces with the club's Daystar, and had no difficulty.  I could use
> my 30mm Kellner for a 1-degree field, and do a close-up of a prominence
> with a 10mm Ortho.
> 
>  Contrast that against the fixed magnification of the PST.  Yes, it's
> easier to use, but lacks versatility.
> 
> Gary wrote:
>> > I don't remember what the bandwidth is on our filter.  Since we can
>> > easily see detail in the sun's surface, it must be 0.6 Angstroms or
>> > better.  So a new one would cost $2600 or more.
> 
>  I'm uncertain as to 0.6, but I'm confident about the leading zero.
> 
>  That particular scope is a mix of donations and a very special
> purchase.  The scope and machine work were donated (thanks, Kevin!).
> Jack Zeiders was shaking the can for $$ to buy what was needed.  At
> $861, he phoned to find out how far he had to go.  He said that he had a
> donated 60mm refractor and someone to do machine work, and hoped to buy
> only the critical components.  He'd had mentioned that it'd be used at
> schools and other public events.  Mr.Daystar (who had answered the
> phone) asked how much Jack had in the can.  Told $861, he said that it
> was an amazing coincidence -- that was exactly what was needed (with
> shipping) for the energy rejection filter, the 3x Barlow, and the filter
> assembly in 1.25 inch format, under their special educational discount.
> 
>  Thanks, Mr.Daystar!
> 
> --
> Jim Van Nuland, San Jose (California) Astronomical Association
> <a href="http://www.svpal.org/~jvn/ ">JVN's web site</a>

The PST can use different eyepieces.  One of the volunteers at Lick had
one up there several times.  We were trying different eyepieces to see which
gave the best image.  

The Daystar is designed to run in an f/30 system.  Is our 60mm refractor
stopped down to increase the f-ratio?  

I think the Daystar scope is a serious problem waiting to happen.  I'll be 
happy to go into this more at the board meeting.

Rich