ollypenrice

A little voice in my head whispers the suspicion that this is a remarkably small distance change to make a perceptible difference. I wonder if it really was the distance in play here or might it simply have been a side effect of assembly/disassembly? Olly

I confess to not having known what a 'Rumak' was but Prof Ian Morrison came to the rescue: http://www.ianmorison.com/maksutov-telescopes-a-survey/ Olly

Good result, Dave. I don't recall an image processed entirely in AstroArt but it's certainly worked. What strikes me, though, is that I'd be lost without Layers. They allow you, in an image like this, to have one layer stretched for the galaxies and faint fuzzies and another stretched (much less forcefully) for the stars. Provided the backgrounds are identical it is than a relatively straightforward matter to retain small stars and deep fuzzies. Anyway it's a very good 'un of a demanding target! BTW, no truer word was ever spoken than, 'I know it's dangerous to say "Final" about anything...' My 'Final' folder has things in it like, Stephan's Final along with things like, Stephan's Final V7c smaller stars BGdown NR reds LS haloes LM twice Dink Op 7 check G. When I read this lot the following day I rarely have a clue what any of it means! lly

Two things strike me. 1) The glare/sunglasses story is absolute tosh and any visit to the neighbour's property would have confirmed this. It's a dome. It can, therefore, reflect very little light directly towards the eyes of an observer since its shape will cause it to disperse its reflected light. The sunglasses chap is a fruit cake. 2) The fact that it is unusual is considered grounds for removing it. Hey guys and gals, don't be unusual. Be just the same as everyone else. Garden gnomes a go-go. Olly

This setup now rings a bell! Olly

I'm in a similar situation. We have a dual TEC rig with 460 in one half and Moravian 8300 in the other for high resolution work. For widefield we have the Kodak full frame in a shorter FL Tak. Although the Sony darks are 100x cleaner than the Kodaks (especially the 11 meg) the stacked results do not put the Sony way ahead. Indeed, the nicest data to process (or at least the data I most enjoy working on) comes from the noisy old 11 meg. Olly

That's a crystal clear Bubble, Lee. Olly

I think you've made a great choice and it's one you've obviously thought through from every angle. I've had a few Esprits visit here, 80 through to 150, and they've all been good. Olly

Are you up to date on the third alternative, the cooled CMOS camera? These are available with decent sized chips, set point cooling and are way ahead of DSLRs and yet way behind CCDs on price? Worth a good look. Olly

Not at all. I've had mine for over six years (it may be over seven, I'm not sure) during which time it has never missed a beat or dropped a sub to guiding error. I then bought another Mk1 (Pre Sitech) example and that's just as good. These mounts are in commercial use, too. They do rely on a plate solve to get started if used remotely but this doesn't seem to be a problem. I host three other Mesu 200s in our robotic sheds. However, the vendor may prefer a mount even better adapted to remote operation since he's been using it in Spain. These are quite extraordinarily good mounts. Personally I would use nothing else, given the performance of the ones I have. They don't come up often but I paid about this for my second one. Olly

You say, Photo A is a MASTER FLAT Ha (Bin 1x1) created with 30 Darks, 50 FLats (3.7sec adu 22000), 50 Dark Flats, 100 Bias Photo B is a MASTER FLAT Oiii (Bin 2x2) created with 30 Darks, 50 FLats (5sec adu 46000), 50 Dark FLats, 100 Bias but if I'm reading your post correctly this is not at all the right way to make flats. 1) There is no need for '30 darks.' These darks are there to calibrate your images, not your flats. 2) You can calibrate CCD flats by either subtracting bias or by subtracting proper dark flats but certainly not both, because they are almost identical and will double-subtract if you do this. I never make my flats in the same pre-processing pass as used to stack and calibrate my images. I want to have a look at any master flat I use before applying it. So I load up all my individual flats as if they were images and load up a master bias to use as a dark flat. I then average-combine my flats and look at the result. If you want to go by the book you can make dedicated darks for flats (AKA Flat darks) but with CCD cameras I really wouldn't bother. A master bias will give the same result as a master dark flat. Olly

The data coming from the camera is described as 'linear' because if pixel B recorded twice as much light as pixel A it will look twice as bright in the image. If pixel B is 10x as bright as pixel A it will look 10x as bright. This is fine for daylight photography but doesn't allow astrophotos to present all the information they really contain. The histogram is a graph or map of the brightness distribution in the image. At the initial linear stage it will run in a straight line from dark to bright, like this: The histogram is easier to see in the Levels window: This graph shows all your pixels. Left to right shows dark to light while the vertical axis shows the number distribution of pixels in the image. Not surprisingly we see a huge number of very dark pixels on the left - the background sky - and a very small number of very bright ones on the right, the stars. Unfortunately the bit we are interested in, the galaxy, is not really much brighter than the background sky so doesn't show clearly and it is made up of pixels of similar brightness so we can't see much structure in it. When we 'stretch' the image (which we can do in Levels or Curves) we brighten all the pixels but we brighten the dark ones by much more than we brighten the light ones. this will brighten the galaxy and increase the contrast between its darker and brighter regions. We avoid reversing any pixel values, though, so the image remains honest. Here I've modified the curve: So that's what stretching means. It is the most important single intervention in processing and can be done with an endless variety of added subtleties. Olly

Regarding polar alignment, have you checked the alignment of the polarscope within the body of the mount? (By day, aim the polar axis of the mount at a distant point like a steeple top and rotate in RA. The crosshair in the middle of the reticle should not describe a circle but stay on the steeple top. If not, adjust it.) However, you are not aligning your tripod, you are aligning the RA axis onto Polaris, so the leveling of the mount and its scales are not important anyway. Why do you say you've blown out the detail of the nebula? It's hardly visible so you can't have done. When you have a full stack I don't see why it wouldn't stretch nicely using either Levels or Curves. Olly

For 1 hour and 20 mins of data you are doing well. All you need is a great deal more of the same to get something better. What you have is sound. This is a game of patience... I think you must have got out of this data most of what it has to offer but there is a slight colour gradient right to left. The left is more green, the right more red. I don't know how you tackle this in APP but it's a good programme and will have the tools you need. Olly

This thread includes diagrams posted by Demon Performer which show the effects of too much and too little chip distance. If you really can't get the OAG to work it's worth saying that you certainly don't need one with an 80mm refractor. A very budget guide scope or finder guider will do fine. It isn't necessary to buy guidescope alignment rings. You simply bolt the guidescope down roughly parallel with the main scope and get on with it.

Don't expect images to look like much when they come straight from the camera or the calibrated stack out of DSS. Processing is a big subject. You could do a lot worse than enlist the help of Steve Richards via his book: https://www.firstlightoptics.com/books/dark-art-or-magic-bullet-steve-richards.html Olly

I only just spotted this thread but it's a good one! I'm sure you've made the right decision. I host six instruments on a semi-informal basis, nothing like Colin and Ian's highly professional setup, but I get a real buzz when I'm setting up our own kit for the night and I hear the other roofs open. It's just nice to think of people in light polluted or cloudy places enjoying our clear night. Please say Hi to Colin and Dave if I'm not too late. They've both been to my place. Olly

It doesn't contain excercises but this is a tremendous text book prepared for students without prior knowledge. https://www.amazon.com/Universe-Robert-Geller/dp/1319039448/ref=dp_ob_title_bk Olly

The thing about the core is not so much how bright the bright parts are but how to get the less bright parts into play. I don't know how Jonas did it but I found that ruthless brutality worked remarkably well! Olly

This is not a bino to consider for hand held use, in my view. Does the bino have a good tripod adapter and do you have a good compatible tripod? I know FLO recommend Hawke and they are very honest and reliable in their reviews. Olly

I wouldn't consider separate EP focusing for birding for one second. Useless. Just imagine how many quick glimpses you'd miss. 8x or 10x magnification? A 20% increase in magnification will have very little effect on the detail you can resolve but may have a considerable effect on how still the image appears. It depends on your hands. I use 8x42 for both wildlife and astro, hand held. When younger I was OK with 10x but, pushing 70, I prefer 8x. I wouldn't worry about the difference in apparent brightness between 42 and 50. Olly

This was and is a truly great image by Grinde, who is one of my robotic clients, though this image was taken from his home country. The high dynamic range makes it a very difficult target, despite its popularity and the fact that it's the easiest galaxy to see naked eye (and the only one I can see naked eye, though some can see M33.) Good for you for giving it a go. These big projects are great fun and very rewarding. Olly

That's a very good list of questions. I also think your last paragraph makes for an excellent summary. I think the questions might well help someone to get their head round the problem and/or help someone trying to explain it all to them. Clarity is everything. The diagrams I did were primarily for use with our beginner guests and can be fleshed out during discussion. Like a lot of people I'm very visual in my conceptualizing so I do like a picture to set myself straight. Of course others think differently, some greatly preferring a mathematical approach. Thanks for your reply. Olly

That's a very creditable result but remember that, unlike the OP, you weren't sampling at 0.7"PP. Olly

This does happen sometimes. This time, for you, it seems to have been updates, which is common enough. It can also be due to the software thinking Artemis is already connected so you have to go into Device Manager to see if this is so and then disconnect it before re-trying to connect. If you don't already do so I suggest you label all your USB cables and all your USB ports on the PC itself and never, under any circumstances, change what you plug where. If you use an Atik filterwheel you may find that it won't connect when the camera will. If a couple of unplugs-replugs won't get it to work, and you don't want to waste a clear sky, you can forget Artemis for the filterwheel and run it in Atik's standalone Filter Wheel Runner instead. That's saved my bacon a couple of times. Olly