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Cygnus widefield

ashworthacca

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ashworthacca

ashworthacca

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Last night was the first night I have been out imaging for a while. Sky was very light and it was a little breezy. Got the Astrotrac set up with my Canon 1000d and 70-200F4L Lens. Thought I'd give it a test at the wide end so grabbed a quicked 50 subs at 45sec with same amount of darks and 20 flats using EL Light Sheet. My LP filter seemed to do a reasonable job but the image is very noisey, needs loads more subs to smooth it out. Anyway, here is what I have got so far.

5866639798_3f4a5c77f0_b.jpg

Cygnus widefield by ashworthacca, on Flickr

Thanks for looking.;)

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MjrTom

MjrTom

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My lens at F5.6 200mm gives distorted stars but I'm really happy with the stars at f5.6 at 70mm.

Ah ok that's useful to know ;)

I tend to use my 85mm f/1.8 @f/4 for that focal length so not tried it with the 70-200mm @ 70mm.

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MjrTom

MjrTom

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Just out of interest, you have used flats for this image but Canons DPP software has lens profiles for vignetting correction have you tried this before?

OK does not get rid of dust and such like a flat will but intrigued to know how useful it is in this application :D

I'm pretty new to imaging ;)

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MjrTom

MjrTom

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Mark, I've not used lens profiles in DPP but I have in photoshop. TBH I have never had much luck in getting them to work very well and now always take flats.

OK thanks, I shall sack that idea then ;)

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ashworthacca

ashworthacca

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OK thanks, I shall sack that idea then ;)

I know Psychobilly has mentioned this tool before so maybe he has has success with it? Give it a go and see how it works for you.

Sorry to all the observing guys, I've asked the mods to move this so it will be out of your way in a short while.

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steppenwolf

steppenwolf

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I think this is a most attractive image and amazingly well coloured for 45 second exposures. I suspect that your F4 version will be disappointing in comparison but would love to be proved wrong. The CCDInspector chart shows everything nicely aligned - Well caught!

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swag72

swag72

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Mmm, very nice - I tried wide field last night and it was a total disaster, I didn't plan enough. So perhaps I'll give it a go tonight. I was thinking about using my 50/1.4 probably at about f/2.

Obviously no guiding needed at these length subs? Would it benefit at all to get the guiding up and running? Also Martin, just as a reference really - What's the bright star in the middle, Vega?

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Psychobilly

Psychobilly

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Nice result Mark..

I normally try and shoot a minimum of 2 min subs.. and try and get a couple of hours of them..

I havent done that much with my 70-200 yet want to fish of "testing" the 24-105 first...

Adobe provide the tools for creating lens profiles from your own lenses and cameras... To get decent results you need to evenly illuminate the test targets

If you update adobe camera raw or the DNG convertor you can get the latest Lens profiles .. they have added a load more...

Peter...

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ashworthacca

ashworthacca

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Steve - thanks, I have have the same feeling about using this lens at f4 but I'm going to give it a go just to confirm my suspicions.:hello2:

Sara - I centred on Deneb and fired away. I would have thought that at 50mm and good polar alignment you would be able to get 5 minute subs, plenty long enough to get a nice deep widefield image. Thanks Sara.

Peter - I tried a few subs at 2 minutes and they were just too bright, the histogram was nearly off the right hand side. After testing at 90 sec and 60 secs I decided 45 was just about right because of how bright the sky was. That was with a LP filter fitted.

Ive tried the lens profiles before but not had much success, I'll make sure I've got the latest ones installed and try again.

Thanks Peter.

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Psychobilly

Psychobilly

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Flats would still be better than the lens profiles... but the lens profiles are better than nothing... I find I am using the lens correction tools quite a lot for general photography...especially since I now have the camera and lens profiles for just about all my kit...

I like to shoot widefield at ISO200 or ISO400 to maximise star color...

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