Thanks
for the input on this. As we are now in the heat in SE AZ, there is a bit
of ground heating during the day, in spite of my tree planting 20 years ago.
I did notice with the shorter guide exposures, the error graph in Maxim looked
better, smoother and there was significantly less variation. I did a
series of tests last night pointing the scope at various elevations and doing a
1 minute unguided shot. I was testing for some sort of sag or flexure in the
optical components. The results were interesting. I shot at 85, 75,
65, 55, and 45 degrees elevation, pointed E, W, and then S. In a series
of several at the same location, the stars were all sorts of interesting
shapes...round, ovoid in one direction, ovoid in another direction. As
there was no guiding, the only "live" axis was RA and the deviations
were not tracking errors as they were not in line with this axis.
Interesting demonstration, at least to me of the effects of seeing variations.
Mike J. Shade
Mike J. Shade
Photography:
mshadephotography.com
In War:
Resolution
In Defeat:
Defiance
In Victory:
Magnanimity
In Peace:
Goodwill
Sir Winston
Churchill
Already, in the
gathering dusk, a few of the stars are turning on their lights.
Vega, the
brightest one, is now dropping towards the west. Can it be half
a year since I
watched her April rising in the east? Low in the southwest
Antares blinks
a sad farwell to fall...
Leslie Peltier,
Starlight Nights
International
Dark Sky Association: www.darksky.org
Curious as to what people have for guider exposures for
various systems. Was having some issues guiding my 1600/CDK 17/Maxim
5.18/STL6303E (guiding with camera) in that the stars were not always
round...almost but not quite, just a few pixels but enough to oblong the
stars. Always had somewhat longer guide exposures (7"-10") to
try and even out seeing variations (which can be quite large with a 17"
telescope). The system can go unguided with reasonably round stars for
the 382" worm cycle near zenith but guided images were a different story
(I do need to guide the system). So last night lowered the guide exposure
to 2", aggressiveness to 5 and round guided stars. What I think
might have been happening is that with a longer guider exposure, there would be
centroid changes between exposures and the system was reacting to these.
With a shorter exposure, this is not happening as the "deviation" is
not allowed.
So, just curious as to what others have their systems setup for
guiding and if my thinking on this makes sense.
Mike J. Shade
Mike J. Shade Photography:
mshadephotography.com
In War: Resolution
In Defeat: Defiance
In Victory: Magnanimity
In Peace: Goodwill
Sir Winston Churchill
Already, in the gathering
dusk, a few of the stars are turning on their lights.
Vega, the brightest one, is
now dropping towards the west. Can it be half
a year since I watched her
April rising in the east? Low in the southwest
Antares blinks a sad farwell
to fall...
Leslie Peltier, Starlight
Nights
International Dark Sky
Association: www.darksky.org
