Rosette

JY · Post by JY » Tue Jan 18, 2005 5:46 pm

Hi,

Saturday night weather was not bad, at least until 1 am at night when the clouds closed in ...
I managed to capture some 2 hours 30mn of data through L, R, G and B filters, the result at:
http://www.geocities.com/jybeninger/rosette.html

Cheers

Jean-Yves

AGMI · Post by **AGMI** » Tue Jan 18, 2005 5:53 pm

hello,
care to share your astrophoto tips? your pictures are WOW :k-sad: :k-shock:

Post by **weixing** » Tue Jan 18, 2005 6:17 pm

Hi,
The sky is actually clear till 4am (before I sleep) after the large cloud passes.

Anyway, very nice image as usual... this is what a CCD camera can do when design for Astro Imaging!!

Have a nice day.

ariefm71 · Post by **ariefm71** » Tue Jan 18, 2005 9:00 pm

now willing to share your astrophoto tips? your pictures are WOW

Sky90, field flattener, SBIG ST8, mounted on AP600EQMD

tanguan2001 · Post by **tanguan2001** » Tue Jan 18, 2005 10:10 pm

Very nice JY,

Thought of imaging the Rosette, but it doesn't fit into my FOV!

The AP mount must be really excellent to go 3 mins unguided. What sort of PE do you have? Any image processing details? Also any filter on the luminance?

Regards,
TG

JY · Post by JY » Tue Jan 18, 2005 11:06 pm

Hi,

The key element #1 is the mount.
The key element #2 is good flats. (still can improve on that)

After hesitating between different mounts, I spotted a good deal on Astromart.
OK, it's very expensive ... but it does not loose value (... not like cars in Singapore ...) and is the most sturdy mount I have ever seen.

After a 30 minutes drift alignment , it will keep 5 minutes tracking with the Sky90.
I have not had enough clear sky to check the PE, but I guess it is pretty good.

Reducing (darks and flats), alignment and stack is using CCDSoft (which is used to acquire images with the ST8, another good deal on Astromart).
Image processing is with Photoshop, mostly levels and curves.
I have tried other Photoshop tricks but need to experiment more, there is still plenty of room for improvement.

Luminance is with the L filter from the Astronomics set.

If only we could have more clear skies ... Hopefully in 2005,

Cheers

Jean-Yves

tanguan2001 · Post by **tanguan2001** » Tue Jan 18, 2005 11:58 pm

JY,

Interested in how you do the flats. I point the telescope at a wall lit by my driveway light and take out of focus shots enough to saturate 3/4 of the sensor range. After compositing the flats I split them into R,G,B and use these different components on the different channels of the image.

I've tried using a flat that's reduced to monochrome (as suggested by the workflow in Iris) but it give terrible results in the red channel. This is probably because I use an LPR filter which tends to vignette the red more.

Still, the flats are not perfect - I still notice a slight dark ring around the image after processing...

TG

Post by **Airconvent** » Wed Jan 19, 2005 12:18 am

Hi JY
nice!!

so rich and full of colour...how did it compared with the visual image on the ccd ? I suppose it is at most a dim glow ?

rich

JY · Post by JY » Wed Jan 19, 2005 5:53 pm

Hi,

I have added some images at the bottom of the webpage :
- 3 mn shot through the R filter
- 3 mn dark frame
- Light frame
- Result
I have resized all and stetched the flat to give an idea of what it looks like

You can see that the nebula is clearly visible on CCD but need stretching to bring out the details.

Visually, we can see the stars only.

I tried imaging it with the 300D but it did not come through, too much pollution, captors saturated.

Cheers

JY

tanguan2001 · Post by **tanguan2001** » Wed Jan 19, 2005 6:49 pm

JY,

Thanks for the additional info. Very interesting. Your illumination (the flat) seems to be very uneven - is that all optical path vignetting?. Mine is more just circular vignetting...

Hey - about time you cleaned that CCD - lots of dust!

TG