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Posts: 21
Joined: Thu Apr 05, 2007 4:22 pm
Location: stargazer private observatory, near Linz, Austria


Post by stargazer_7000 » Sat Apr 14, 2007 10:19 am

hello Community,

I`m very happy to present my recent result.
actually it is my very first LRGB image.
I was pretty much used to one shot color Cams - see last post (SX M25C)

date: 9.+10.4.2007
seeing and transparency 7/10
CCD: Starlight Xpress SXV H16
FingerLake Filterwheel with Astronomik Filters
9" TMB Apo f/9
2,7 hours luminance 1x1 binned
6 hours color 2x2 bninned (2 hours each channel)
AstroArt4: image acqu. autoguiding
Maxim DL: preprocessing (darks, alignment, color)
Photoshop CS2: postprocessing

here is a small preview:

and here is a medium sized image:
http://stargazer.christelhager.info/ast ... medium.jpg

..full size image:
http://stargazer.christelhager.info/ast ... b-full.jpg

finally I provide an enlarged crop:
http://stargazer.christelhager.info/ast ... l.crop.jpg

the enlarged crop was seperatly processed.

what I find very interesting is that even though I imaged in 2x2 binning mode for 6 hours to get colors, my expectations concerning depth were a bit disappointed...
so I tied to compare M25C and H16.
unfortunately the seeing conditions were not even.
when I imaged with M25C seeing was only some 4-5/10...transparency also a bit worse 6/10 (data in the image bewlow)

so I post here my comparsion image.
the first one representing LRGB
the second one in the middle - L+color from M25C
the third one the pure M25C image.
for fairness reason please keep in mind, that it was very difficult to achieve a good focus in the night I imaged with M25C...
http://stargazer.christelhager.info/ast ... s-M25C.jpg

what I can say about SX H16 is:
"she" a great CCD. even it contains a kodak chip (I`m spoiled by the sony chips with extremly low noise) noise is not the problem. but this chip holds a huge number of hotties. Tery did a great job in building in a 2 stage peltier element; and I love the very fast USB2 interface. a 1x1 binned image is downloaded in "no-time"...2 seconds...
noise can be handled easily with an appropriate number of lightframes. hotties can be worked out with a defectmap.
so the performance of this CCD is very good and I`m deeply impressed with the HR power it has.
in order to improve the images I`m gonna train my mount to perform "dithered guiding" which should reduce noise a bit more.
aligning the single frames with "sigma clip" methode also reduces nois impressively.

I hope You like the images!
best wishes
best wishes,