[M]: M: pictor problems
| Subject: | [M]: M: pictor problems |
| From: | Email address hidden |
| Date: | Fri May 05 08:02:19 2000 |
Hey everyone,
Last night I set up to use the 201 to autoguide my 10"@6.3 through my ST-80.
The focal length of the ST-80 w/barlow is half the imaging scope. For doing
small length (5-10 minute) exposures that should have been adequate. There are
varying opinions about that ratio out there.
Bottom line - not very pleased. I was experimenting with 6 minute exposures.
On the one image where I was able to successfully find a guide star I had consistent
small errors looking at the star images. The stars looked as though the scope
has lost tracking for an instance or had been bumped. Each time they were the
same. I suppose this could be from bad polar alignment but I doubt it. PEC
error (dont have mine corrected) perhaps. I do not think it is a matter of the
focal ratios - though I could be wrong (heaven knows).
There were some other problems.
1- the field of view of the guidescope w/barlow is essentialy the same field
as the imaging chip (416xt). I could never really get a star in tat field that
the 201 would pick up on (I was imaging certain galaxies). I would then off-set
the guidescoe a small amount to center on a bright star. I believe this is alright
as long as the two scopes are fairly close to alignment.
2- The hardest task was getting the 201 to lock onto a star. I was able to make
a parfocal eyepiece the other night. Even with (what I consider) a fairly bright
guidestar I had extreme difficulty getting the 201 to see it - even with varying
Ets. I did remember to take darkfields for each different setting.
3- When I did have a guidestar I would notice corrections like 10, 01,20,11,00
- fine. then suddenly for one iteration I would get something like 51. Sometimes
I would simply lose the star (--).
In conclusion there could be several problems.
Poor alignment.
Bad scope/guidescope ratio.
Either way I am remembering back to a time when I used an SBIG ST-7 self guiding
CCD on a 12" LX200 I miss it dearly. I am very attempted to sell the system
and go with an SBIG camera that can self guide. I have never been very happy
with the Meade imaging equipment - this is not without lack of trying.
I would appreciate any comments.
By the way, I agree with the veterans of this group who have spoken at legth
about the difficulties of guidescopes. Thank you for the very informative articles.
Jeffrey A. Edmonds
1LT AR
http://www.oz-online.net
Last night I set up to use the 201 to autoguide my 10"@6.3 through my ST-80.
The focal length of the ST-80 w/barlow is half the imaging scope. For doing
small length (5-10 minute) exposures that should have been adequate. There are
varying opinions about that ratio out there.
Bottom line - not very pleased. I was experimenting with 6 minute exposures.
On the one image where I was able to successfully find a guide star I had consistent
small errors looking at the star images. The stars looked as though the scope
has lost tracking for an instance or had been bumped. Each time they were the
same. I suppose this could be from bad polar alignment but I doubt it. PEC
error (dont have mine corrected) perhaps. I do not think it is a matter of the
focal ratios - though I could be wrong (heaven knows).
There were some other problems.
1- the field of view of the guidescope w/barlow is essentialy the same field
as the imaging chip (416xt). I could never really get a star in tat field that
the 201 would pick up on (I was imaging certain galaxies). I would then off-set
the guidescoe a small amount to center on a bright star. I believe this is alright
as long as the two scopes are fairly close to alignment.
2- The hardest task was getting the 201 to lock onto a star. I was able to make
a parfocal eyepiece the other night. Even with (what I consider) a fairly bright
guidestar I had extreme difficulty getting the 201 to see it - even with varying
Ets. I did remember to take darkfields for each different setting.
3- When I did have a guidestar I would notice corrections like 10, 01,20,11,00
- fine. then suddenly for one iteration I would get something like 51. Sometimes
I would simply lose the star (--).
In conclusion there could be several problems.
Poor alignment.
Bad scope/guidescope ratio.
Either way I am remembering back to a time when I used an SBIG ST-7 self guiding
CCD on a 12" LX200 I miss it dearly. I am very attempted to sell the system
and go with an SBIG camera that can self guide. I have never been very happy
with the Meade imaging equipment - this is not without lack of trying.
I would appreciate any comments.
By the way, I agree with the veterans of this group who have spoken at legth
about the difficulties of guidescopes. Thank you for the very informative articles.
Jeffrey A. Edmonds
1LT AR
http://www.oz-online.net
