RE: [APML] STV - Is it worth it?

[Jon Kolb <jkolb@mindport.com>]

Jim, Matt,

> I used an STV for a week last September. I found it had one 
> very annoying calibration problem, perhaps related to the RJ 
> connectors on the back. I have heard others report similar 
> problems. I don't know if SBIG has fixed it yet. It is also 
> more complicated than the ST-4. The documentation is 
> comprehensive, but who wants to read 200 pages?

I believe this is the "no move" problem we discussed on this list some
months ago.  Since I started doing the filter wheel calibration step during
setup, as recommended by Michael Barber (but not noted in the user's
manual), I have never had the problem again.  My experience with the device
over the last six months of use has been very positive since that initial
issue.  The documentation I received is something less than 200 pages -
about 50 or so, but the sections I'm interested in are only maybe 10 pages.
I will admit that I don't care about any of the imaging modes, and if it
would have saved me money, I would have gladly done without them.

Most nights, with good alignment and balance, I'm getting average
corrections of 0.5 to 1.5 arc seconds.  The worst has been in windy
conditions with corrections of 4 to 5 arc seconds.  I'm sure this is alot
better than I ever guided manually.  Now that I have the process pretty well
standardized, I'm calibrated and guiding within a couple of minutes of
composing the photograph.  About the only thing I ever need to change is to
shift the guidescope slightly if the STV doesn't like the star field.  This
seems to happen most often when shooting low in the sky where the seeing is
poorest, or in star-poor fields.  It sure is nice to see the star field on
the screen.

My biggest complaint about the STV is that SBIG doesn't include with it the
appropriate 12v cigarette lighter plug and cable for their reversed-polarity
power input.  For $2K, this omission is absolutely inexcusable.  It also
seems to frequently pick a star at the edge of the field for calibration,
which sometimes causes it to lose the star off the chip during the
calibration sequence.  This is a minor annoyance, though, and is probably as
much perception as reality.  
 
> It is very nice seeing the field on the display and having 
> statistics available. This make using an OAG very easy. The 
> increased sensitivity and accuracy are obviously important 
> for the most critical applications.

Despite having never used an ST4 or an OAG, I would think the STV is far
easier to use with an OAG, since it will pick a guidestar from any of those
on the chip.  No centering is required, no flip mirrors, no parfocal
eyepieces required.  

Is it worth the $$?  Well, I supose that will depend on the individual.
Since I was manually guiding previously, I'm in love with it.  Am I glad I
bought it?  You bet.  I get to observe during the time I would have been
guiding now, and I can warm up in the truck while an exposure is underway,
so I get more shots on winter nights.  One additional cost I incurred,
besides a bigger battery to feed the thing, was for bigger, better binocs to
observe with!

Sincerely,
Jon Kolb
Adventures in Astrophotography
http://home.datawest.net/jkolb/
jkolb@noochee.com

   

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