ollypenrice

I've never liked guide rings and they serve no purpose these days. In the past you needed to head off-axis sometimes in order to find a star. Olly

Watch your black point. Don't bring it in so far because this is black clipped. There should always be a bit of flat line to the left of the histogram peak. Olly

My answer to your question is 'No.' But if ever you wanted to know how to boost colour in Photoshop I'd be happy to try and help. This is over the top, of course, but it would take half a second to tone down. Olly

My suggestion would be to try APP for mosaic making. Olly

The most obvious thing to do would be to lose the very significant excess of green. Any imaging editing suite will let you do this, but here's a quick play in Photoshop. This may be too much but green astro skies are a big no-no. I'd normally use Pixinsight's SCNR green but didn't here. There is also Hasta La Vista green from the Deep Sky Colors website. Then you might think about the reflections. The water seems to have un-tracked stars while the sky has tracked ones. This is disturbing to the eye. I'd probably address this by removing the trailed stars on the water (clone stamp) and replacing them with the stars from the tracked sky shot which I assume will be tight and round. But maybe the elongation on the reflected stars is from the angle from camera to water? I don't know. Olly

That's what I thought as well! Olly

Has to be a laptop? If not, I prefer an office PC with lots of USB ports, possibly an older one., second hand. This gets rid of unreliable hubs and scope-top computers which do not generally impress by their reliability in my remote hosting sheds. Olly

The GIMP-flattened image may have been black-clipped by the operation. It's hard to tell but it's something I'd be looking out for if I were to use it (which is unlikely since I have PI's DBE and ABE available and think they are the pick of the bunch.) The image also has a considerable gradient and is very blue, an imbalance not confined to the background but also visible in the fainter stars. This image would not stretch well. Olly

Agreed. I can only guess that the proprietor had once worked in Nagasaki. I once met a bar owner in a god-forsaken corner of the Picos de Europa who proudly announced that he'd worked for 25 years in Matlock Bath. In the poorer parts of Europe lots of folks find work abroad, of course. Indeed I've just had my trailer filled with gravel by an incredibly nice guy from the mountains of eastern Portugal. Olly

Smooth and delicate. Nice. Olly

Gosh, that takes me back and, yes, I think you have it, by Gad! I wonder if the village had started turning off its lights at 11.00 pm when you were here? My own IFN was done before this and, in reality, it makes little tangible difference. De-starring has to be the way to go on this target. Your result is lovely. I've only run the new StarXterminator once but it does seem even better. Olly

The strangest name for a bar in my recollection was at a small town in inland Spain: The Nagasaki. Was it named, like yours, for a violent explosion? There was something unappealing about it, in any event. Olly

Might there be a whiff of something unusual creeping into the image from the bottom edge, half way along? Slight patch of nebulosity, redder on the right, bluer on the left? Olly

On the other hand, we might argue that the art of astrophotography lies in rendering the object with a meaningful appearance. Some facts are known: the background sky is a neutral dark grey, star colours accord with their spectroscopic classes, the H-Alpha line centres upon 656 nanometres and OIII lies on 500 nm. These colours are identifiable. More generally, galaxy bulges are dominated by reddened Population II stars and bright spiral arms by hotter Population 1 stars. The natural colour imager should be constrained by these facts. I think it's easy to over-state the claim that it's largely subjective, though it is to some extent. We might also exaggerate deliberately in order to bring features into view, but the features themselves are there in the data. I think that's very good. My only hesitation lies in the outer glow as it heads into the image's bottom left corner. In reality that glow would, in all its glory, reach right into that corner whereas here is seems to lose confidence! (Is it being nibbled into by DBE or ABE?) It's a little stronger in your 'full data' version. However, this is a big ask, especially from anything but a very dark site. (Paul and I are working on M31 with the RASA at the moment. This was after a quick test to see what it gave. We thought it did a beautiful job and are now carrying on with it, so I'm not surprised to see how nicely yours is working out.) Olly

Al, the favoured cable routing among my robotic clients is to gather all the cables and run them to the top end of the counterweight bar and from there to the ground. This minimizes the variation in cable position and the lifting moment. Olly

I'd have a check for backlash, which would certainly explain the middle image. (The scope may have been sitting on one side of mesh for a majority of the time and on the other for a minority of the time, producing different sizes of doubled stars.) If you do find backlash you can fix it mechanically or follow these tips: For RA backlash, run the mount out of balance in RA so the east side is heavy. That will keep the drive pushing and won't encourage the payload to oscillate across the backlash. Reverse the imbalance after a meridian flip. For Dec, run slightly polar misaligned and disable one Dec guiding direction so it only corrects for the misalignment (identified by experiment and reversed after a meridian flip.) Fixing it is, of course, best. Olly

I think what I'd do is take the best image from the short stack and adjust the colour balance of the deep stack to match it. I'd then de-star the deep stack (Starnet or StarXterminator) and adjust it so that it was very slightly less stretched than the short stack. I'd measure its brightnesses in various places other than the sought-after outer glow in order to make this adjustment. I might use a kinked curve to pull up the outer glow a bit more as well. Then I'd put the deep starless image on top of the short starry one in Photoshop's blend mode Lighten. In that way only the outer glow ought to affect the short stack below it. (Sounds OK in theory ) As for trying to do it in PI, that would be like trying to play the piano wearing boxing gloves! 🤣 Olly

If your flats were perfectly flat you wouldn't need them. These flats are not particularly remarkable in my view. The vignetting is, indeed, off centre but so it is in many high end refractor flats. Adjust it by all means but this is not outrageously bad as it is. I'd be wanting to measure the linear ADU values in the corners and compare them with those at the centre. If the drop-off in the corners is more than 25% I'd be concerned about their ability to correct the final image properly. However, I had a 23% drop off in my Tak FSQ/full frame camera and all was well in the final image. Olly

There is no simple answer to this question and any simple answer will almost certainly be wrong. The most important thing to understand in DS image processing is that you cannot expect to process all parts of the image in the same way if you want a good result. This has been called 'The Zone System,' meaning that different parts of the image have different processing requirements and should be worked on differently. It follows logically from this that different parts of the image have different requirements in terms of quality. Take Tomato's Andromeda. 1) Stars need to be round so should be made from a stack only of subs with round stars. You have plenty of signal on stars so you can be selective. 2) Fine disk details require quality focus, tracking and sky transparency. Select your stack accordingly. It is likely to be the same as the star stack made from subs with a good FWHM, as Vlaiv says. 3) That faint, soft glow of nebulosity which is so extensive around the galaxy if you take the time to work on it. All it needs is signal. It contains no details, so who cares if it's blurred? Throw everything you've got at it. The outer glow is miles better in Tomato's full stack, though the colour balance is better on the short stack. Have the best of both worlds! Provided you have the processing knowledge to be able to combine them, this will give the best result and use an awful lot of your data at least somewhere in the image. Whenever I'm working on a channel or a layer I ask myself, What am I going to do with this layer? Only when I have the answer to that question do I know how to process it. Say I'm working on an Ha layer to blend with red. I can stretch the Ha's background well beyond the noise floor because, the way I add Ha to red, the Ha background will be fainter than the faint red background so it won't appear in the final image. Olly

I can't see this being possible. 1) If you park the mount, how are you going to balance it without releasing the clutches and unparking it? I suppose you might have both the dovetail and C/W bar marked up in advance but how accurate will that be? The marks on the mount are not going to give a good enough position for a restart. Consider the length of the imaginary line going from the scope all the way to the stars. A tiny change in angle will take you a very long way off target. 2) Swapping scopes will involve a fair bit of pulling and pushing which is very likely to shift it slightly. 3) It is very unlikely that the different scopes will share precise alignment since there is a lot of room for variance in the fit of dovetail to saddle plate, tube rings to dovetail and scope to tube rings. In other words the cone error will not be the same on each scope when mounted and the software has allowed specifically for the original scope's cone error during the alignment process. All in all I think your chances of retaining a useful alignment will approximate to zilch! Olly

Leica 8x42 BN. Even second hand they were very expensive but they give a lovely natural view. Interesting that you mention the field stop because one of the things I like about them is the clearly defined stop. It's either the view or blackness. I hadn't realized how distracting an ambiguous field stop is till I had a perfect one in the Leicas. They are roof prism and very nice in the hand but I agree with the standard wisdom that it's better to go for roof prisms £ for £. Olly

Wrong post. Sorry. Olly

Do you really need the rebate to be in the concrete? I can see that having the floor slightly higher than the bottom of the walls would be good for keeping water from seeping under the walls but would it not be easier to make a flat base then tile the floor only inside the dome to raise its height? Olly

You may also get some natural dither from imperfect polar alignment. Olly

Hi and welcome, Mia. As you know, I'm a friend of some members of your family and hope that the forum can be of help. Olly