ollypenrice

Sure. There are various ways but the easiest on this is just to use a small clone stamp brush, medium feathered, and set to Mode Darken. Just make your way along the line with single dabs of this small brush, choosing the clone from nearby sky each time and avoiding stars both when collecting the clone and applying it. Once near the galaxy pick up the clone from a patch of outlying galaxy of the same brightness as the background to be repaired. Blend mode Darken is less invasive because it will only be applied to the lighter pixels of the line in most cases. Took three minutes at most. If you have Noels Actions (AKA Pro Digital Astronomy Tools) you can rotate the image either way till the line is horizontal on screen and then run 'Reduce horizontal banding.' Next make the result a layer underneath (also in the Actions) and erase the line from the top layer. That way you're only messing with the line itself and not the whole image. I also stack and calibrate in AstroArt. This has an excellent 'remove line' feature which repairs sat. and 'plane trails pretty well. It would work on your line, I'm confident. The healing brush in Ps is tricky and picks up stars, etc. The spot healing brush next to it is much easier, but slower. Olly

Have you tried dropping a line to Noel Carbone? He's very helpful. Olly

No, the light cones into which the OAG dips its prism (so to speak!😁) will probably have different diameters in different scopes at the relevant distance from the objective. Olly

It's very courageous of you to haul it all down! Couldn't it stay in situ? Olly

Maks used to be significantly more expensive than SCTs. The good news with SCTs is that they are freely available on the used market and hold their value badly, making them a good buy. Olly

I really wouldn't spend a single penny on astrophotographic gear until you've had a good read-up on the subject because it is, time and again, totally counter intuitive. I would start here: https://www.firstlightoptics.com/books/making-every-photon-count-steve-richards.html You should also beware of the claims of manufacturers who will often assert that their products are optimized for imaging when they are not. In order to find what works it's a good idea to browse the images posted here and elsewhere to see what real imagers really use. Olly

Lovely image, natural and unforced. The all important background sky is tip top. There's a horizontal line passing through the galaxy, most visible on the right hand side. Any idea where it came from? It would be an easy cosmetic fix. Olly

The 'Levels and Curves' routine is common to all processing packages and lies at the heart of astrophotography. Give it a Google! Olly

That's odd. It doesn't happen to me. I have used this excellent set of tools in Win XP, Win7 and Win10. Olly

Exactly so. There is no need for an OAG with an 80mm scope. They are more or less essential with reflectors but my high resolution refractor imaging is done with simple guidescopes. Olly

Any reflector is best guided via OAG because the mirror can always move. The term 'mirror flop' is a mighty exaggeration but a tiny movement will harm your results in high resolution imaging. Also, at high resolution, an increase in guider resolution is to be preferred. My foray into catadioptric imaging involved an OAG and, once set up, it worked fine. Olly

I just use ST4 because it doesn't introduce any new software and because I'm a dinosaur. Olly

It might also be worth considering the Sony A7 but I have no astrophotography experience outside CCD. Best of luck! Olly

The 16200 (a great camera) would probably be a tad oversampled in the C8 but, if you can get the guiding good and have stable seeing, it would give you a galaxy imaging scale similar to mine. (Caution, here. High resolution imaging means you have to get the tracking and focus spot on and you need a night of good seeing. That means of high stability, not just high transparency. In the Quattro it would give you a very nice 1.7"PP. The camera has a large chip. You'd need to check your manufacturers' published image circles. Proper hardware binning is confined to mono CCD cameras. You can't do this with OSC cameras because you'd lose the colour information which is single pixel by single pixel. But, yes, a 4x4 micron pixel, binned, becomes a more sensitive 8x8 micron pixel. You'd need to ask a CMOS expert about binning those cameras. It's complicated. The Atik 4000 would also be a good match for your focal lengths. Note that the optimal sampling rate is also target dependent, in the real world. For small targets like galaxies you want detail, so ideally about 1"PP. For wide field nebulae you can have a coarser sampling rate and gain speed. The Atik chart suggests that their 11000 camera would be grossly under sampled at 530mm. But this is what you get from it: 0.9"PP looks like this (1000mm Atik 460) Do be careful to check the chip size. Some of the cameras on the list have very small chips. Persoanlly I would nt buy a DSLR for deep sky imaging. I'd go for a cooled CMOS if CCDs are most costly than you'd like. I know it's a lot to take in!!! Olly

Neither of these scopes, to the best of my knowledge, will cover full frame cameras. Scope manufacturers should quote an 'image circle' in mm. This must be at least as large as the diagonal measurement of the chip. So a 33mm corrected circle will cover a chip with a 33mm diagonal. I've always used this calculator to derive the sampling rate in arcsecs per pixel for given combinations of scopes/reducers/cameras. http://www.12dstring.me.uk/fovcalc.php The Atik graph will do the same job and I'm a very happy user of several Atik cameras. Your scopes have very different focal lengths but if you operate a mono camera in 2X2 binning you make its pixels effectively 4x larger so you can have, in effect, two cameras in one. A word of caution over the phrase 'nebulae and galaxies.' There are a few large galaxies (not many) and quite a few small nebulae but in the majority of cases nebulae need a large field of view (short focal length) and galaxies need a high resolution (longer focal length.) Olly

Firstly is glow problematic for the outer 33% of the chip? Plenty of people use full frame sensors, including uncooled ones, with good results. The real problem is almost the inverse: relatively few telescopes will fully illuminate a full frame sensor. Flat fielding is essential to correct the vignetting produced by many of those which will. My own Tak FSQ106N covers full frame but with a 22% drop off in brightness from centre to corners. Flats correct it. Secondly the question of pixel size should only be considered in terms of the sampling rate it will give you in a particular telescope. It will be difficult to turn details captured below about 0.9 arcseconds per pixel into real details in the final image. Choose the pixel size which suits your intentions. They should be as large as possible consistent with your intentions because over-sampling costs time and brings no benefit. Many people settle for 2 arcsecs per pixel as a sweet spot. In short pixel size matters, for sure, but matters only in connection with focal length. Olly

I discovered just now via a PM that there is an EQ8 forum with a member called Olly. This led to a little confusion till the sender and I realized that this is another Olly and not me! I did have 'history' with the early EQ8 but, since then, it has been revised and is getting a good press. If ever my visual-only 14 inch LX200 packs up (which is not unknown) a new EQ8 would be top of my list as a replacement. It's very affordable for a big mount. Olly (the old one! 🤣 )

If you have both 'before and after' drizzle images can't you just compare the noise directly? Give both images exactly the same stretch and compare them. Olly

All things being equal, mono is faster. During the luminance phase of the capture you are obtaining the red, green and blue light simultaneously on every pixel and this is not possible with an OSC. Also you are likely to want Ha for many nebulae and an OSC works on only one pixel in four with this filter. Finally this efficient capture of Ha can be done on moonlit nights. As evidence of the speed of a mono camera I made up this Heart Nebula image. I do have a better Heart image but this just used 2 hours' data, 2x30 minutes Ha and 2x10 minutes each in R,G and B. The CMOS cameras which interest you would be faster than the CCD I used here. Olly

Photoshop? 👹 Olly

Gracias amigo! Get outta here! 🤣 Anyway, it's supposed to be applied to linear data, no? Think I'd be daft enough to give you that? No way, you'd expose all my bungles! 😁lly

I'm giving the standard and wholesome advice but let me tell you that I used a rig over a two-year spell in which over-correcting flats were a persistent nightmare and which we never really fathomed. We found a solution which worked for a while and which, overnight, suddenly stopped working. Sometimes this game is beyond reason... Olly

There are two sets of parameters in the image, Martin. I don't know how you'd factor them in. One set was at about 2.4 metres FL with 7 micron pixels and the other was at about 1 metre FL with 4.54 micron pixels. I can imagine the gurus of Pixinsight leaping to their feet and yelling ?Qué?????' The first question mark should, of course, be upside down but I can't do that... Anyway, I'm glad you like it and we miss you. Olly

Rather than asking folks to download the originals, I think you'd get more interest if you just made JPEGS of the files and showed them here. For the purposes of showing what's going on this would be fine. My understanding is that the CCD trick of using a master bias as a Flat Dark (a dark for calibrating your flats) does not work. You need to shoot Flat Darks at the same settings as your flats. As Roland said, the third image in his post is pretty flat. Olly

I would try this: Make a new master bias out of 50 bias frames stacked using a simple 'average' algorithm. Save it as Dark Flat because that's how you're going to use it. Save a copy as Master Bias if you like. All this is for mental clarity! Shoot a set of flats. What I now do is lie to my stacking software and tell it the flats are images (sometimes called Lights) and the Flat Dark is a dark for the 'images.' Nothing else. Tell it to stack and calibrate and now you know you have a genuine, simple, standalone Master Flat. Now stack your images with only the following files: Images (often called Lights), Master Dark (same exposure and temperature as your Images) and Master Flat. No bias anywhere. I really don't like throwing all the files into one huge stacking and calibrating operation. I like to do it step by step. Olly