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attempt at Cassiopeia wide field


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Hi guys,

would love your thoughts on this early attempt at wide field astrophotography.

Cassiopeia is supposed to be centered and not right and low, but other than that I wondered where I can improve? What is happening at the edges? Its cropped and what was left behind looked pretty bad - is this a limitation of the kit?

I used Canon 1100D with 55mm F1.8 lens @ISO800 F2.2

26 x 19 secs exposures +20 darks

Stacked in DSS and post processed in PS5.1

Any ideas on how to improve it very happily accepted :)

post-24090-0-36075200-1350320983_thumb.j

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If the problem at the edges that you're talking about is the stretching of the stars then that's probably a limitation of the lens. As Digz suggests, stopping the lens down a bit more might help with that. I get a similar effect (though perhaps not as pronounced) with my kit lens. In fact, if you have the kit 18-55mm lens, it's worth a try at 18mm. It covers so much sky.

James

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Stopping the "Nifty 50 " down to around f4 will help sort out the corner stars... if you diont like the diffraction artefacts that this cna produce on brighter stars then you might want to consider using a front aperture mask instead..#

Another thing to try is using a star on a thirds point rather than the center of the FOV when your focusing...

Peter...

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Aha! Just found the image I took. I didn't do much processing because it was rubbish. Wide open I was definitely getting the same sort of effect as you. It doesn't look quite as marked as yours, but that may be down to the image being badly focused to start with.

James

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I used to use a lot of skyflats with camera lenses... now I use netbook displaying a white screen...

I put the camera onto AV to get an estimate of the exposure then set the shutter speed in manual to make sure all the flats have the same expsoure. I then shoot a load while moving the nettbook around on the end of the lenshood to even out any variation in intensity from the screen...

I just dug out a link to one of my cassiopea image with the nifty 50 from a few years ago...

http://www.graigolaobservatory.org.uk/EQ3%20Widefields/Cassiopea%201h32m%20ISO400%2050mm%20f4-0%20BCF%201000D%20v2%20QS%208b.jpg

Peter...

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