Low rent M51

[BlueAstra]

Just to bring the tone down a bit here is my shot at M51. Had a number of equipment issues last night, with the guide cam going funny on me, but eventually sorted it out. Decided to do some flats while it was getting dark, then when dark focussed and took a test shot. Arrgh! massive dust bunny in centre of image! Flats junked, camera removed, cleaned, replaced and - amazingly - still in perfect focus! Trouble finding guide star, but eventually managed 17x3m with the C8+OAG+1000D, and a few flats, before tear down and some sleep before work.

I rarely see any colour in my images, unlike some of the other magnificent M51's posted. Is that because of not enough exposure time with a OSC camera, or is it the false colour added when using a Ha filter?

[jgs001]

That's looking good. As for colour, are you using DSS to stack and then saving with the adjustments applied ? If so, you need to push the saturation slider up to between 15 and 25% to get the colour in there. If you are stretching the curves in PS or some such, then you should have the colour still there. I get colour in my images with my 450d

[BlueAstra]

Thanks for that tip. I've not touched the saturation slider before, I'll try stacking again in DSS.

I usually find that the individual R, G, B histograms in DSS are separated, presumably because of the LP filter, and the image has a colour cast. Is it valid to use the DSS R and B slider to centre the histograms on G to remove the cast, or should they be left alone? Not sure how to do it in PS.

[jgs001]

If you set the raw settings to not use a white balance, make sure both boxes are unticked, and set DSS to RGB Channels Background calibration (I think it is) then DSS should create a custom white balance and align the RGB histograms for you.

[BlueAstra]

In DSS settings:

Light: RGB B/G Cal selected, entropy weighted selected

RAW: Col adj: 1,1,1, White bal both unticked, Bayer bilinear, black to 0 ticked.

Here is a typical result:

[jgs001]

I always get weird results with black to 0 selected... Are you using bias frames ? if not, then don't set black to 0.

[BlueAstra]

OK, will try that. Until I find the answer is it OK in principle to move the DSS R, G, B sliders to superimpose the histograms and remove the cast?

[jgs001]

I don't see why not .... That's what the RGB Background calibration does...

[sgazer]

it's a lot better than I acheived last night.....3x3min subs for 2 hours of effort . It doesn't look low rent to me, I just think todays standard is very high.