Re: [APML]: Beginner Needing Advise

["Philip Perkins" <philip.perkins@pop3.hiway.co.uk>]

> >     I own a Meade LX200HP 10" f/10 scope. I use the Lumicon Giant Easy 
> >     Guider to reduce the scope to f/6.  I want to get into astro 
> >     photography and need some advise.  I need an auto guider.  As I see it 
> >     my options are the Meade Pictor 201XT auto guider, Meade 208XT auto 
> >     guider / imager or SBIG ST4 auto guider.  I have herd that the ST4 has 
> >     problems tracking on the LX200 due to DEC retrograde movement and that 
> >     Meade has designed the Pictor to take this into account.  I live in AZ 
> >     where the temperature gets up to 100+ degrees during the night in the 
> >     summer.  Can the Pictor 201XT acquire and track on guide stars (10 Mag 
> >     and higher) without being cooled for 60 minutes or more?  Please 
> >     remember that I will be tracking through the Lumicon off-axis guider. 
> >     Would I be better off to get the Pictor 208XT which is cooled? Also, I 
> >     would like to see some prime focus pictures taken with a LX200 scope. 
> >     
> >     I would appreciate hearing from LX200 scope owners that use Pictor and 
> >     ST4 auto guiders.
> 
> Jim,  I have the 201xt.  I've not be able to use it for photography yet.
> This is of no fault of the setup, but circumstances beyond my control.
> However it appears to work well.  I've never seen or used the ST4.
> However, I know that Jason Ware uses it with great success and he has the
> same scope as I do (lx200 16").

Jim, I also have the 201XT. I've used it fairly extensively since I
obtained it in June this year. It was an upgrade for my original 201 - a
horrible device, which was nearly useless for practical off-axis guiding in
the real world. The 201XT is a huge improvement and I'm basically happy. 

I used it extensively in the south of France for 2 weeks in July - the
night temperatures were around 55-60 deg. It would fairly comfortably track
stars down to about mag 9. I also suceeded in tracking stars of mag 10/11
but the integration time starts to get long, hence it takes longer to get
through its preliminary cycles, also guiding corrections are less frequent,
so tracking is poorer. Mag 11 is the limit I successfully achieved - the
manual says mag 12, which I believe, but probably not that practical. The
201XT is happiest with stars between mag 6-9, which is not too bad. The
manual says that it won't work with brightness readings lower than 10, but
I subsequently found that it will work OK with readings as low as 4/5
upwards. This means that you can keep the exposure time down to about 10
(much preferred) and still work with mag 10 stars.

The 201XT is a bit prone to "double track" - ie. recognise another star in
the FOV and, if the first star drifts off a tad, hop over to the other star
and resume guiding on that. This can lead to "double stars" in the image.
To avoid this, you need to be aware of the guiding box limits in the
reticle eyepiece FOV, and try to pick a solitary star within this box (other 
stars that are very much fainter shouldn't be a problem).  

I also noticed a problem tracking when the OA guider tube is rotated by
about 90 deg in either direction - significantly less or more than that and 
it seems happy. The cure may be to rotate the 201XT in the OA draw tube to 
compensate.

Other than these things, the 201XT works pretty smoothly and flawlessly
with the LX200 and the results can be first class. Out of a total of about
50 shots (all on film) I've got about 12 that I'd rate as "perfect" (stars
are precision pin-pricks - can't really be improved upon) and about 20 that
look fine, but high magnification reveals a slight defocus / minor tracking
error (sometimes difficult to tell which). The remaining 18-ish are
double-starred, wind-blown, jarred, dewed-up, etc.

I have never used the ST4, however I've noticed that many of the experts
use it. From what I've heard, it will work with fainter stars than the
201XT, however I believe it may require more set up time and be a bit more
difficult to use with the LX200. I have no evidence to suggest that it
actually tracks to a higher standard when used with the LX200. 

Dark skies, beautiful images

Philip Perkins  --  philip.perkins@pop3.hiway.co.uk
51 27'N 1 36'W  --  dark skies, dark clouds (mostly)