Chris wrote:

>> Shift and combine works well in pview2.0, not at all in 6.3, and I
haven't
>> attempted it yet in 6.4, using a 416. As you say, images must be fairly
>> well lined up but guiding is definitely not necessary, just good
alignment
>> and PEC, and I'm not sure you need the PEC. I have never tried it in
altaz
>> mode.
>>
>> If the sky cooperates tonite I'll try 6.4 S&C and report.
>>
>
>Would be very interested to hear about your results. There was not much
>drift on my shift and combine images, polar alignment was reasonable but
>far from perfect. I explain in another post that my guess is incorrect
>calculation of the centroid position, or perhaps the consequent X-Y
>offset from which to generate the combined image. But this remains a
>guess until someone else confirms my own observations.


Well, I agree, Chris: my test images (of SN 1998aq in ngc 3982) using shift
and combine and PVIEW 6.4 showed poor performance compared to pview2.0.
All final images (shot as 4x20sec stacks) exhibited oval stars, whereas the
2.0 images under identical circumstances showed nice round stars. I will
post comparison images on my web page when I get home later tonite.

This may be another bug to address to the engineers at MEADE...

I'd like to see this fixed, too.

Cordially,

Don Dillinger
Snohomish, WA
47 54' 46"N
122 05' 49"W
Snohomish Hilltop Observatory
CCD images: <http://ourworld.compuserve.com/homepages/dillinger>

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