ollypenrice

Nice. An OIII layer does change the colour towards the centre of nebulosity around the Bubble. Olly

As an 'invaluable resource' it struck me as staggeringly underwhelming unless the link is not the one intended by the OP. The link to Astrofarm is unfortunate since the much-appreciated Andrew Davies died some time ago. What, exactly, is the point of this post? Olly

I gave one away. If getting a large telescope with an F ratio of 3.3 were as simple as screwing one of these reducers onto an SCT, it is highly unlikely that anybody, anywhere, would use anything else! lly

Fair point but, perhaps, slightly misleading. What Mr Alcock needed for this discovery was a knowledge of previous apparent magnitude to compare with present apparent magnitude. The quality of the view would not greatly affect this observation, especially since the comparison stars would be in the same field, or very nearly. In a similar way, a 'good' stellar view is not necessary for splitting doubles, which is why double star observers will sometimes 'over magnify' since what they are looking for is information rather than a pleasing view. I suggest the OP simply make a comparative test. I'm confident that the result will indicate that observation is possible through a window but that the image is significantly degraded. How much this matters to an observer will vary from person to person. Olly

It was ever thus. The good news is that the astrophotographer wants what the regular photographer does not, which is fixed focal length, manual focus and no stabilization. For once, the market delivers nice prices for the astrophotographer. Olly

I get gradients with OSC and mono from an extremely dark site. They may actually be worse with OSC. Why? Not a clue! Personally, I do DBE on an RGB image but I know one or two other imagers who do it 'per channel' first. I'd give it a go. You could even try it both ways on the same data - DBE the individual channels and then the output RGB. Olly

It looks like the big problem you're facing is a strong left-right colour gradient, so that needs to be your first step. I would place the DBE markers as shown below and with a high tolerance. I avoid ABE on galaxies because it tends to put markers too close to them and so create a dark ring round them. Using too many markers is counter-productive. The third image has the best gradient control but it is still there if we turn up the saturation. In Photoshop you can use the colour sampler tool (set to 3X3 or 5x5 average) to sample the background sky. I like the three colour channels to be equal. Olly

This inspires me to try again, Peter. I have never seen lunar colour but can't say I've ever really looked for it. Time to try! Olly

My impression of the RASA 8 is that it operates on two levels. Stars are not particularly good but extended fine detail is excellent. Olly

Gorgeous and super-subtle. I really like the warm colours of your dust. Olly

Yes, you talked me up a bit from my earlier preference for 0.9. Actually, I was discussing this with my collaborator Paul Kummer with regard to imaging at higher resolution. I'm in favour of a C11 RASA at 1.25"PP. Olly

12 years is a long time. I wouldn't reply now as I did then. What I would say now is that... 1) The number of photons from the object of interest (read that twice) depends only on aperture. 2) How bright that is going to make your image depends on how many of these 'object photons' land on each pixel. (Read that twice as well.) The more light, the brighter each pixel. 3) How much detail you capture (AKA how big your image will be) depends on how many pixels you place under the projected image of the object in your scope. Points 2 and 3 can be adjusted in two ways. You can put more light on each pixel by using a shorter F ratio or you can do so by using larger pixels (or by binning them or by resampling.) The useful image size or pixel count of your object of interest is ultimately limited by a) the seeing b) the guiding c) the resolution your optics d) the sampling rate of your system. The ideal system is one in which you sample at the finest scale your seeing/guiding/optical resolution will support. In a nutshell, if that limit is 1.5 arcseconds, use the biggest aperture that will give you 1.5 arcseconds per pixel. Olly

Subtle addition of Ha to galaxies is the holy grail and I think you are right to be pleased with this one. We often see Ha features looking more like brakes lights in Las Vegas than anything else. Not in this one, though. Olly

I like the blues in the Lobster Claw. I tried this a few years ago and got a rather bland all-red affair which I abandoned. Olly

Remarkable! Olly

Nice. Bold Ha and good star colour make this a fine widefield galaxy image. Olly

Nice delicate imaging. Impressive. Olly

I don't know about the framing or alignment (which I would just do using another filter) but this Ha result is sensational. Love the two jets. Olly

Boy, that's really sharp. The very faint arms are certainly beginning to show but integration time is the only way. I'd keep going because you're onto a winner. Olly

From the man who has made more astronomical items himself than the rest of us put together! Olly

Your wish is my command! Olly

A bit of fun. Following a comment that the basic outline of Orion was hard to spot in a deep sky image, I thought I'd make an animation to show the difference between Orion visually, at a reasonable site, and then what the camera finds over time. Maybe it also answers the question, 'Why do astrophotography?' My first animated GIFF. Good fun - I'll do some more! Olly

Another one with Paul Kummer and the RASA 8. Nine panel mosaic roughly centred on Markarian's Chain. Compressed to fit on a screen, this isn't much of a sight but it becomes more interesting if you open the link to my gallery site, go to full page with the button for full screen, then click on the image for the full. There are plenty of galaxies in there. Olly

Sure. This is how I do it since StarXterminator appeared. (It is much easier this way.) The first step is to get the main image about 70% stretched and de-star it. Take the high res telescopic image you want to incorporate into Registar and co-register it to the main image (with its stars.) Registar does this in a click. Then 'crop and pad' the high res in Registar so it sits in exacly the right place on the main image. Save this. Back in Photoshop, de-star the registered-cropped-padded high res overlay and copy-paste it onto the starless main image. The black 'padding' Registar has put around it means the bit you want is in exactly the right place. Use the colour select tool to select the now unwanted black padding and delete it. Now you have your starless high res sitting on top of your starless main, but it will be very obviously 'stuck on.' Adjust its levels, curves, black point, colour balance, saturation, hue, till it is as close as possible to the main image. You won't get it to look perfect but that's OK. Now feather its edges and reduce its opacity till it becomes seamless. The idea is to enhance, not replace the main image underneath. It's an 'artistic' process, if you like. Even if the high res is only at 40% right in the middle and heavily feathered in, its contribution will be well worth having. When you re-star this image only the main image stars will be used, which makes for a seamless look. Prior to the de-starring software this enhancement was much harder because the high res stars are always smaller and more numerous. Olly

That's got something to say and no one rendition can say everything contained in the data. I wonder if lowering the higher brightnesses might let you find more star and galaxy colour, though? It's a strong image. Olly