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View Full Version here: : It pays to refocus....oops


kinetic
19-01-2009, 08:33 PM
I tried last night to make good use of above average
seeing and try and build up a 4 to 6 frame mosaic
of the Eta Carina Nebula. Luminosity only.

Once stacked and stitched together it soon became
blindingly obvious that I should have refocused after each
session. I usually do!
I had 3 results to stitch together , side by side and
you can see the deterioration in the second one compared to
the first. No point showing you the 3rd, it's as bad as the 2nd.

I didn't realise this while I was capturing, I should have listened
to John G when he chimed in on the live chat that it looked a little
off! Sorry John. :)

Here's the stitch...1st result is on the right, 2nd on the left.

Steve

strongmanmike
19-01-2009, 09:00 PM
Mate that's pretty good.

I can see what you mean Steve (I think?) but I think you are being a bit fussy, it's showing some very fine details across both frames there :shrug:. I'd like to see the whole three frame mozaic actually.

You only did a few minutes of imaging all up so would the focus have changed in that time anyway..? Or did you do the three sessions spread over the whole night?

Mike

kinetic
20-01-2009, 06:32 PM
Mike , thanks for the feedback, it was three captures spread over maybe
an hour at most.
The OTA hadn't cooled completely to ambient, it's obvious...it was staring
me (and John G ) in the face!

Here's a stitch of frame 3 added also.
As you can see, frame 2 overlaps frame 3, frame 2 offers the best
rendition of that section.

This is all purely focusing via live preview, DSI, so no Hartmann or Bahtinov
mask used here.....sure shows why they are such great devices.
(Haven't made one yet for the 12...I have one for the 8)

A lesson learned the hard way.

Thanks for the pm sentiments, very appreciated Mike! :)

regards,

Steve

leon
20-01-2009, 09:51 PM
Yea, ya shoulda Steve, :whistle: never mind mate not a bad effort all the same. :thumbsup:

Leon :thumbsup: