ollypenrice

None of them does. The alignment adjusters you'll have seen were invented for the opposite reason: They allow the guide scope to be moved off axis in search of a guide star. In the past, this was necessary for guiding on a star by eye or when using early and insensitive guide cameras which only picked up brighter stars. They are now redundant and I would far rather have a guidescope bolted down hard than carried in potentially flex-prone adjusters. Guiding on an off-axis star has one side effect. If polar alignment is out, the imaging scope will describe an arc around the guidestar. If you guide on a dead central star the chip will rotate on its centre point. If it's off axis it will describe an arc. If shooting in old-school 30 minute subs, polar alignment is critical. Since CMOS cameras use only short exposures, and since stacking software will easily align slightly rotated subs, polar alignment is less of an issue. Nutshell: guidescopes don't need to be precisely aligned, as everyone has said. They do need to be rigidly mounted. Olly

Dramatic improvement. The processing of dense starfields has been transformed. Olly

Dust from the city is very good going indeed! Olly

Good going on a tiny target. Impressive. If you are shooting in RGB, rather than colour mapping in narrowband, there is a right colour, at least in a reasonably broad sense. It can be checked by looking at your background, which should be about equal in RGB, and your stars, which should match the astrophysics of their spectral class. I think that, in this image, the colours are a little out in a consistent way, with the reds too yellow and the blues too cyan. I would guess at this arising from too high a value in the greens, perhaps because of the filter. I haven't used this one. Olly

Super, Rodd. I think refractors are fine on globulars. My TEC140 did well on M13, too. Olly

It will probably have no visible effect whatever, though it might just create a slight diffraction spike on brighter stars. If it does, try covering it (on the outside) with something black, like a small piece of electrical tape or black paint. Avoid straght lines on this tiny blackout patch. If this seems odd, remember that many telescopes have large, opaque obstructions slap in the middle of the objective. Ours, for instance... The obstruction is far too far out of focus to form an image. Olly

Clearly you're going to have to find the right power supply if using it in the field but, running on mains and a regular 12V transformer, ours is fine. It's a great camera and you did the right thing going for a bigger chip. In fact the Redcat covers full frame very sweetly. Olly

I used a motorhome for going to dark sites before going to live at one permanently. It can work well but there are issues. Motorhomes are often totally useless on soft surfaces and get stuck at the drop of a hat. This may explain the campsite rules mentioned earlier. The trouble is that the best places for astronomy are, therefore, often the worst places for campervans. This was a major stumbling block for me. It also proved disappointing not to be able to Certified Locations (minimalist campsites) because, again our coachbuilt got stuck too easily. Olly

Sometimes tilt is improved by rotating the camera in the OTA, probably because a number of imperfections cancel themselves out. There might be a bit of tilt in one component which goes the opposite way to that of another in one particular orientation. It might be worth a try. If you find such a sweet spot, as we did with our RASA, you can still rotate to frame a target by rotating the entire OTA/camera in the tube rings. Olly

I was assuming the camera would be appropriately filtered in this regard. This has been the case with all my OSCs but maybe some just have a clear filter, in which case you'd be right. Olly

Let's think it through. An OSC camera has either a red, a green or a blue filter permanently fixed in front of every pixel. That is what makes it an OSC camera. If you put a red filter in front of this, only the camera's red-filtered pixels pixels will get any light. The same applies to the other colours. With a green filter in front, only the camera's green-filtered pixels will get any light. Clearly, therefore, RGB filters would be pointless. What's a Luminance filter? It's one which passes R and G and B. But your camera's filters are only going to pass the colour they pass, so R or G or B. A luminance filter would, therefore be useless. Basically, you are going to be imaging with the camera's in-built RGB or with the dual band filter which further restricts what you capture to the light emitted by two gasses. Some targets will be best unfiltered, some filtered and some combining filtered with unfiltered. The worse your light pollution, the more favourable the filter becomes. Olly

Certainly did. The most feckless piece of junk ever brought to market. Almost every component has now broken on the one I bought, as the people responsible for it must have known they would., and it has long since gone to the bin, like the considerable sum I laid out to buy it. Olly

That's actually more complicated than my method. Rather than layer mask my NB when adding it to the chosen colour channel in blend mode lighten, I give it the kind of stretch which I think will make it play well over the colour channel. I go for a very, very hard, contrasty stretch and ignore noise where it is darker than the same region in the colour channel. It won't be applied anyway. I make sure my background is not brighter than the colour background and that the bright features in NB are brighter than the colour (or they won't do anything.) I adjust this stretch of the NB while it is in situ over the colour in BM Lighten so I can blink it on and off to see what it's doing. In short I see a NB image to combine with a colour channel as a completely different thing from a nice standalone NB image for publication. Your NB masking seems a sound idea, though. Olly

More colour, as well. Olly

This is going in the right direction! It's such a hard target to do. Olly

To me, it's a sea horse and, yes, I struggled to bring it out in an HaLRGB rendition. This is beautifully clear. Olly

I can't say I've ever heard anybody say you can't shoot DSOs uncooled, but it's a very successful image. Cooling remains an advantage, however. Olly

Not at all! I'm always an admirer of your expertise. Of all the things, though, that go into the making and processing of an image, I cannot believe that much will change under the niceties of different stacking software. My office is always open, and my data available, to anyone wanting to prove me wrong. I'll even put the kettle on! lly

Some of my robotic shed clients did likewise but nobody is still doing so... It's like anything else, when it works, it works. Go with it when it does. What is a guiding problem? I don't have one. I just bung on a cheapo ST80 as guidescope and get on with it. Changes to the imaging scopes, camera rotation, etc etc, have no effect on anything. In over ten years of imaging, my venerable Mesu 200 never dropped a sub. That's a pretty good definition of not having a problem. To be fair, the same mount ran an OAG for the first three years and, once I'd stopped the thing rocking about by adding a strap to the top of the guide cam, it was as reliable as a guidescope. Mini finder-guiders? Very pretty and super neat, but a royal pain compared with the ratty old ST80. They lose focus easily and have this deeply unconvincing 'easy focus' ring wottsit. Why? My ST 80s haven't been refocused in 10 years. Olly

Given that an image circle is - ahem - a circle, the best non-circular chip is a square one. lly

Agreed. If you can't afford it, you can't afford it. Wait till you can. Download some free data and start to learn processing. Olly

Deep, clean, sharp and well composed, with the objects seeming to race away from each other. We don't stop down at all with our Samyang... Pedal to the metal!!! Olly

Go for it. Put it in the middle of your frame and shoot some data. The asymmetry of what you've posted makes it look promising and not just star bloat. Olly