Lagoon & Trifid Wide Field

[archioptic]

Full res here. (http://www.astrobin.com/full/122018/0/)

Nikkor 180mm ED AI-S @ f2.8
Nikon D3100
10x120"
NEQ6 & autoguiding

Fairly happy with the image but I suspect my focus was a bit out judging by the red fringing around the stars. I stacked in DSS with darks, flats and bias images but for some reason the flats were causing the final stack to be blurry/misaligned on about 1/3rd of the image, so they haven't been applied.

I'm sure I could improve greatly on this image so any help is more than welcome.

[LightningNZ]

Looks very nice. Perhaps stopping down the lens to F/3.5 would improve the stars and any fringing? What method did you use to take your flats? I ask because your compact setup would be perfectly suited to my (not invented by me) method of taking flats by imaging a white LCD screen.

[archioptic]

Thanks Cam. Considering I'm guiding and using a relatively short focal length I think I can get away with stopping the lens down next time. Unfortunately I didn't take the flats during the imaging session so I suspect that might have had something to do with it. Will definitely give the lcd trick a go next time.

[LightningNZ]

Here's the nice thing about flats - you don't need to take them during the same session - just try not to change the focal length, aperture (focal ratio), focus or the camera's orientation to the lens (if you're able to rotate the camera independently to the lens).

Just pick up the camera and make sure it has the same settings you used to take astro images and start taking images of a white part of your screen. As long as the histogram is roughly centred (far from being black or white clipped) it'll be fine. Just keep it all square-on so the illumination is as even as possible. Move the camera around the white part of the screen (a big screen helps) and rotate the whole lens/camera setup too to break up any regular pattern that might make up the pixels of your screen (the pixels themselves will be massively out of focus, but the backlight or rectangular pattern of pixels could cause funny things to happen).

I have a stack of 50 flats I've taken that way and apply them to all my new images. Every few months I'll take a fresh set just in case dust or something has gotten into the light path.

Hope this helps. For camera lenses and small scopes I reckon this method of taking flats is a total breeze.

Cheers,
Cam

[PeterEde]

Nice shot

[archioptic]

Thanks, Peter & Cam.

That's great, I wasn't sure whether I could have a master set of flat frames for use.