Seagull Nebula and Thor's Helmet

[avandonk]

After months of cloud finally a clear night without an interfering Moon.

Details
Canon 5DH, Canon 300mm F2.8L, at f/3.6 with exterior aperture.
Hutech LPR filter.
Exposures 20X( 30s, 60s, 120s, 240s) at 1600ISO, fridge at -10C.
The usual HDR method

Large image 5.5MB

http://d1355990.i49.quadrahosting.com.au/2010_12/seagn.jpg


I have made some modifications to the optic train with a noticeable improvement.
The image has only been very slightly cropped from the full frame notice how the corners and edges are quite good for colour and signal to noise.

I used to get a colour cast due to vignetting and incident angle of light on rear LPR filter. I have mounted an 82mm LPR filter in front of the lens this also acts as an aperture.

Bert

[h0ughy]

great wide field Bert

[leon]

Love it Bert, nice and wide my favorite type of imaging, err, well it used to be.

Leon

[tornado33]

Great image there. A good idia using the filter external to the lens, which is an interference type filter, whose passband changes with fast F ratios. Also, only filtered light can now enter the lens.
Scott

[astroron]

Very nice Birt, puts things in perspective.

[avandonk]

You have hit the nail on the head Scott! Any light in your optic that is not contributing to the image will lower contrast and signal to noise.

Bert