Shibby

Well, it's nice to image something a bit different, right?

Hi. I'm partly commenting to agree with others about your flats, these dust rings are almost certainly from the camera's sensor window judging by their size and they should calibrate out no problem. You can always take a blower to the window to try and reduce them. The first flat does seem to have a separate issue, though. Is it the refresh of your LED panel? Secondly, I just wanted to say that your observatory is a real beauty!

As you suggest, it's probably down to field distortion due to your optics. I can't think of any easy way around that, other than cropping or avoiding the flip when using a particular filter. I'm not sure about your concern with registar - you may get away with it, because even in order to rotate an image the stacking software will surely be messing with the pixels of each sub and that seems to work okay? Why don't you give it a trial and see what happens?

Both flats look very similar to me, so surely something else is going on with the second image? You say you used DBE... The dark area around the galaxy in the 1st image looks typical of DBE when it gets confused and includes the object in its measurements of the background. Have you tried without? The second image, not a clue what's going on there.

Very nicely done! Impressive depth. Planning any Oiii?

Obviously, they're both great! I prefer the nebulous detail in the new image (due to lack of NR), but the stars and colour scheme of the original.

Don't tend to see many RGB images! This is really nice, the colours so rich. Look forward to seeing the final results, though it's already looking great.

Excellent how much you've picked up there - nice and deep. What camera did you use?

Excellent. Forgetting the conditions, parts of this are very faint so the depth you've achieved is great.

Lovely job!

Damn, don't see these come up too often. Boat missed!

Awesome. Super clean and smooth. The result from your handling of the core is very pleasing.

I recently finished capturing data for a bi-colour image of the wall in NGC7000. It's taken about a month, which I suppose isn't that bad all things considered! As I'm sure you're aware, this is one of the brighter regions in the 1700 lightyear-distant North American Nebula. Although huge (estimated 100 lightyears across), NGC7000 is believed to be mostly 'lit up' by a single giant star HD 199579, also known as Miro's Diamond. You could call the nebula V37 if you wish, as Herschel designated it #37 in his 'V' catalogue when he discovered it - the 'V' standing for Very large The image is a bi-colour, 2-panel mosaic with total integration time of around 13.5 hours. Processing is just curves in Photoshop with a star layer to prevent star bloat, especially in Oiii, with which the Baader filter gives a few halos on the brighter stars. I don't know if I've combined the layers in a sensible manner, I just pasted the Oiii in to the green and blue layers then tweaked it down a bit in the green. I was aiming for roughly 'natural-ish' looking colours, although it looks massively different on my two monitors. Any feedback on that is appreciated. Thanks for looking! Acquisition Hα: 2x24x600s Oiii: 2x17x600s Equipment Optics: MN190 Camera: 460ex Mount: AP Mach1GTO Guding: Orion mini 50mm guidescope & QYH5L-ii [direct link] You may not like the colour combination, but if you're interested here are the separate channels so you can see the difference between hydrogen and oxygen Hα: Oiii:

A good improvement and good practise for your next image! Although there might be a hint of extra nebulosity hiding in the background, I think one can push an image too far, to its detriment.

Good job. Really nice portable setup you've got there! I just wonder if you could squeeze more colour out of it? Unless the high ISO is making that difficult?

Incredible detail, lovely image! With your current kit working so well, I'm sure it'll be some time before we see the next M27 from you

Well, I'd been waiting 12 days for a clear night (also to gather further data on NGC7000) so was determined to get some data whatever the conditions! My guiding was averaging ~0.7" RMS, so I hope the data will be good enough. I think the altitude of the nebula helped somewhat. I've just checked FWHMs and they're only 0.5 higher than the previous session. It is frustrating when you miss an opportunity, knowing how infrequent they can be in our country. But you have to remind yourself there will eventually be others! Work is already a struggle this morning! The comforting prominence of Orion isn't a bad reward for powering through

Well, it's good to get those troubles addressed on the nights with worse conditions! I could tell as soon as the clouds cleared, the stars were twinkling lots. I noticed it while focusing, but thankfully the guiding has been fine so have somehow gathered nearly 4 hours of data!

I agree with pretty much everything that's been said. Use your DSLR on a tracking platform such as the Star Adventurer or - if you don't need high portability - find a second-hand, motorised, equatorial mount. I'm not certain how you came to the conclusion of a small refractor on a tripod, because this really won't help you at all with astrophotography over what you currently have! If you want to try lunar/planetary then look into a high frame-rate camera for your dob. If you want to try long exposure using your DSLR, the key is the tracking platform, with which you can initially use your existing lenses to get started. Anyway, as you've quite rightly decided, definitely digest a few books and do some further reading first. Then, take the first tentative steps onto the slippery slope

I have no problems with my SX mini filter wheel, although they do specifically boast about the accuracy of the filter positioning in the blurb. Perhaps you can let us know how your flats come out with the ZWO.

You can get (the excellent) Stellarium on Android. The desktop version allows you to filter DSOs by brightness. Presumably the mobile app allows you to do the same but don't quote me on that!

Just checking, when you say vignetting, do you mean circular? That would be odd, suggesting that it's caused by something between the prism and guide camera. If the vignetting is from the edge of the main imaging circle then, as others have said, you need to move the prism as close as you can to the main camera's sensor without overlapping. Moving the prism in/out has no effect on focus - remove the whole reducer/OAG/camera assembly and look back towards the main sensor while moving it into position.

I'm a bit surprised that the Altair guide scope only suggests guiding 500mm focal length. FWIW, my guide-scope is a mere 162mm in focal length and I have no trouble guiding my 1000mm FL scope at 1.14 asec/pix. The guide camera does have pretty small pixels at 3.75µm. This gives a 4.77 asec/pix and a healthy enough ratio of 1:4.2 (You'll often here 1:5 quoted as a maximum).

Just thought I'd add that you can also use a custom white balance to correct the colour. I have a 50% grey card that I take with me everywhere for this purpose! (It's a cheaper option than the filter)

Looking great - keep up the good work!