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This is around my third try on M51, in quite a few months, given the weather I haven't got out much! Taken with my new (to me) modified Canon 450d (thanks Pixueto!). I really love having Live View, focusing is a lot easier! I think the image looks better of M51 than the ones I took with my unmodded Canon 20d. I am looking forward to trying the camera on nebula!

I am quite pleased with the image, although it isn't very good! On the other hand it is definitely the best I have managed so far!

Taken using my Orion Optics UK 250mm f4.8 reflector, HEQ5 mount, guided with a finder guider, DMK41 CCD camera and PHD.

I finally got guiding to work for a reasonable amount of time. A total of 1 hour 48 minutes made up of 10x1 minutes,18x2 minutes, 10x3 minutes and 7x5 minutes exposures. As you can probably tell, I am not sure how many minutes per an exposure give me the best result! Darks and flats also taken. However, the flats were taken after taking the camera off the telescope and putting it back on, as I forgot! The picture is definitely better than without flats, but I think some of the problems I had with processing is down to this. Stacked in DSS and processed in Photoshop. I have very little idea about what I am doing with either, but I am practising a lot!

With a modified DSLR is RGB background calibration better or per channel in DSS? I attach two images, the first is RGB the second is per channel calibration. I am using an Astronomik CLS CCD light pollution filter. Auto White Balance and reset all white balance settings ticked in DSS.

I attach a link to Dropbox to one of the outputs from my stacks from DSS if anyone would like to have a try at processing the data better. I am still struggling with levels and curves, despite reading a couple of tutorials!

David post-5219-0-22681300-1370185028_thumb.jppost-5219-0-42955400-1370184964_thumb.jp https://dl.dropboxusercontent.com/u/82184859/M51rgb.TIF

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Having looked at the pictures again, the sky background is especially horrible! I would be grateful if anybody more experienced could give me an idea if this is due to bad flats, the fact that it is rather warm which is bad for DSLR images, or me messing up the processing. Of course it could be all three!

David

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A quick lunchtime effort with Photoshop CS3.

Think you could have a good final image with a bit more work. :icon_salut:

post-849-0-55330400-1370262596_thumb.jpg

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Wow! That's amazing! It just shows what can be done by someone who knows what they are doing in Photoshop! I will read and watch some more tutorials.

I still haven't got the hang of curves. When I try to do them I find I get a curve going backwards below the curve I am trying to do (a sort of reverse curve) and have to anchor the line in a few places lower down to stop this happening. Obviously I am doing something basic wrong!

My main question is how did you get the sky background looking OK? Is it to do with layers (which I haven't attempted yet)? if so I will give them a go.

I am glad my bad flats, the temperature and the light pollution here have left something worth processing! I took around only another 30 minutes of M51 last night (problems with finding a guide star, plus I had to get up for work). I will try to add this to what I already have, (which will take a while as I gave never combined images from two different nights before) Then try processing again.

David

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Hi David,

Firstly, learn about Flats and how many ways you can make them and apply them. Later, look at websites of experienced astro photographers or youtube and you will find numerous videos for free which explain in detail about techniques. Each one will be slightly different from the other, and in time you will evolve your own set of processes that best fit your conditions and comfort.

All the best.

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When you image and take flats with a reflector.. you MUST make sure you have no light leak anywhere. Newts are often terrible for light leak around the primary mirror. My big scope in 'out of the box' condition just has the mirror in the tube with a huge gap between the two, so I have a board on the bottom of the scope to prevent light getting past the mirror. Otherwise light leak gives you odd 'sky glow' and wreaks your flats.

Derek

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