Please could someone take a look at my image?

[Black Knight]

Having been inspired by some wonderful images of the Rosette Nebula on SGL the last few weeks, I thought I'd give it a go. However, I'm a real noob when it comes to imaging, especially image processing, and at the moment I just seem to be going around in circles. No matter what I do, I just can't seem to pull anything decent out of the image, apart from a vague hint of nebulosity in the bottom left corner.

I've gone through as many tutorials as I can find to no avail. I've tried processing in both CS4 and Nebulosity with approximately the same results.

The image was taken on a SW ED80 with a modded Canon 500D, 24x600s exposures, ISO800, with darks applied. I have no clue how to take flats.

The first image is generally what I end up with. This one was saved from Nebulosity.

The second image is a jpg taken directly from the DSS output TIFF, with no processing applied.

All helpful comments appreciated and very gratefully received.

[Steve 1962]

Hi Andy

I'm sorry to tell you that you're off target south westwards by about 30mins. Your image looks to be rotated so that north is towards the bottom left corner and the nebulosity that you've got at the bottom of your image is the south western outskirts of the rosette.

I've attached a screen shot from Stellarium to show where you are.

Look on the brightside - at least you got some of it!!

Cheers

Steve

[Black Knight]

Ahh, perhaps that would explain it then .... That's so stoopid How did you manage to work out the image was 30 seconds out? Did you line the stars up manually?

[Steve 1962]

Hi again Andy -

Actually you're nearer to a degree out. Judging by the Dec lines on the Stellarium screen print. The "core" of the Rosette is at about +5 degrees - your image is centred down at about +4 degrees.

Hope this helps

Steve

[Black Knight]

Thanks Steve. Argh! I feel such a twit now .... :hello2:

[Steve 1962]

I know how you feel! Still - I bet you won't let that happen again

All the best

Steve

[Sparrow]

Also, looking at your image, you really need to take some flats to remove the vignetting otherwise, when you get on target, it's going to make it very difficult to process.

There's plenty of info on the forum about taking flats, but just to get you started, I put a piece of white paper over the front of the scope, point it at a bright sky and take exposures so that the histogram peak is about a third from the left of the graph. You need to make sure your camera is in the same orientation as when you take your light frames with the same focus. You'll probably find your exposure needs to be somewhere roundabouts 1/100 (just a rough guide)

[Black Knight]

Yeah, I know. I've been reading up on how to take flats the last couple of days. I think I've got a plan worked out, just need to try it out before going "live" with it .

[Psychobilly]

Look at the positives...

The focus is very good and tracking is spot on with 600s subs

I tend to try an pattern match bright stars against a rough framing sketch by taking 30-60 expsosures at max ISO...

Get flats sorted and your well on your way

Billy...

[Luke]

Easily done to miss the target, I try to pick out some main stars in a shorter exposure and check them against a reference image if possible, that seems to work okay for me at the moment.

Your stars are looking good right to the corners!