ollypenrice

I'd see what comes up and then look up the spec. There was (and may still be) an Atik 460 on here for about £500. That can take world class images which a DSLR of comparable price cannot. Olly

Have you considered a second hand CCD camera? Market prices have fallen enormously since CMOS cameras appeared yet CCDs are as excellent as they always were. There really is no comparison between DSLR and CCD. Olly

M33 is not terribly colourful and you have, in my view, a truthful amount. I think it could be better balanced but not by all that much. I'd certainly try to fix the background gradient which is lighter-redder in the upper left than the lower right, but don't fix this by bringing in the black point. An astro-specific gradient tool should have no trouble with it since it isn't extreme. Olly

Another RASA project with Paul Kummer. We shot a wide M45 mosaic last season in the RASA but it was done before we'd found the best front end cable routing and this compromised the star shapes. We are doing a mosaic right over to the California but Paul felt we ought to re-shoot the Pleiades rather than stick with the rather rough first version. Good decision, this is much better. Paul did the capture and assembled the linear mosaic in APP. The post processing is mine, mostly in Photoshop and using StarXterminator for star control. Olly

Very nice, especially the dust. It has just the right texture to my eye. Olly

Another thought: we seem to assume that the appearance of life on Earth was a passive process requiring an accidental set of circumstances. What we've learned from Darwinism, though, is that evolution is not passive but is actively directed by natural selection. Can we be certain that no equivalent processes actively drive matter into forming living organisms? I don't know what such processes might be but that doesn't mean that they cannot exist. Has anyone ever looked for them? If ever such processes were identified it would change, radically, the probability of there being alien life. Olly

It seems to me that, being weak in tension, 3D printed brackets should not be tightened by having one part pulled towards the other, but squeezed, where possible, by a surrounding and constricting metal strap. If/when we get it all going I'll gladly send you a data set from it. Olly

Missteps into the canal, from memory... Splosh! lly

I do have a Cassady TGAD tilt-pan adjuster capable of carrying a 14 inch scope. We used it for the twin Taks and then the twin TECs. It is currently idle and cost a fortune! Olly

Very nice indeed and so much more efficient than multi-panel mosaics for catching large objects with little localized detail. Olly

I feared as much! Very nice work indeed. So no escape from 3D printed semi-tat for us then! Olly

I does make sense and is on the cards, maybe for next year... Yours looks tasty. Is that a commercial metal ring carrying the ens? Possibly so, yes, but I like a bit of space around things for cables, dew heaters and general access. Olly

I'm using what we have on site, Goran! My own guiders have always been bolted down, which I prefer. This one's Peter's. My objection to guide rings is largely that they are an unnecessary complication and expense as well as being less stiff than a fixed mount. The Samyang won't be piggybacking the RASA, partly because that's on an Avalon Linear and close to its limit already. We mainly want them on different mounts so we can image the Samyang's regions of special interest at higher resolution in the RASA. We'll then blend them into the widefield. I've been doing this for years with the Tak/TEC combination here. I enjoy the processing and the result can be great, all the more so now that we have such control over star sizes. Since the RASA regions of interest will be downsampled to the scale of the Samyang and used only at partial opacity, I can envisage doing a three hour run with the Samyang and 3x1 hours for different ROIs in the RASA (or 2x1.5 hours, etc.) The Pixinsight developers dismiss such composite imaging as as 'painting,' but I call it a good use of time. Olly

Pixel size determines resolution of detail (assuming you are not over sampled), chip size determines field of view and quantum efficiency (mainly) determines sensitivity. A good rule of thumb regarding decisions is not to make any. Buy everything. lly

The story so far. This is a joint enterprise with Paul Kummer, Peter Woods and myself. (Peter, Paul and Penrice. Oh no! A sixties folk group. ) The image train is Samyang 135 - FLO Bayonet replacing adapter from Astro Essentials, and conceived by Rob (Uranium235 on here) - TS variable length M48 extension - TS M48 to M42 adapter - TS 2600 CP OSC camera. This is all held together by a Wega set of bits dedicated to the Samyang and the EAF focus motor from ZWO. Don't jump out and copy it, just yet: we don't know if it works! What we don't have is any kind of tilt adjustment. Bites fingernails. I suppose there might be room to squeeze one in where the variable extender now lives, I don't know. The other possibility, if necessary, will be to turn components relative to each other in the hope that different tilts will cancel themselves out. This has worked for us before. That the Wega assembly is available at all, given the seriously small market for which it caters, is great. At £139, however, it's a bit closer to something from a Christmas cracker than I'd have liked. OK, call that a Fortnum and Mason's Christmas cracker, but still. The finger nuts for holding in the finder guider were regular hex bolts with 3D printed wingnut tops placed over them. One had already fallen off and how long will they last out in the dark? Since I didn't find a finder-guider shoe in my staggering assortment of bits I couldn't use it anyway and had to make the alloy bridge between the two lens 'tube rings' that you see. Tomorrow I'll be putting all this on Peter's Avalon M Uno and Paul will be trying to communicate with it via our carrier-pigeon-esque internet connection! The price you pay for a dark site... Back soon, Olly

No wonder I feel dizzy... Olly

Good strong squid. Really bold. I think the colour might have more to give. My guess, if you have Photoshop, would be to try Selective Colour. In the reds I'd lower the cyan (a well-known trick for enhancing Ha.) In the cyans, and this is a guess, I'd increase the magenta and lower the yellow. Anyway, a difficult target done well. Olly

Thanks Maurice, I'm sure this will help Rodd. Olly

A fingerprint will have precisely zero impact on your imaging. Yes, I know it's annoying to see one, though! Olly

I don't know, Rodd, but I'll ask a friend who does to comment on that. Olly

Robin, we greatly appreciate your providing this link and information. Many thanks. I would say that these probably are, indeed, our arcs, more or less. Ours are not rainbow-coloured but show up very strongly in the blue channel. It's perfectly normal for blue to be the most affected. In the past I've used a simple compass-cutter to cut circles out of the thin plastic top of a margarine tub. One snippet I can contribute to the discussion is that the 'instant test' for seeing if the arcs are there is the Equalize feature, under Image-Adjustments in Photoshop. It makes them screamingly obvious. It's also a good way to check mosaic joints. Olly

I do. It's brilliantly good in most respects but not perfect. It's very fiddly to set up with good collimation and no tilt. Stellar images are not always top class but, using star removal and replacement, this matters much less than it used to. We've also discovered some broad arc-shaped artifacts in some captures. They can be cosmetically repaired but the origin is as yet unknown. Would I swap it for anything else of comparable focal length? No, I'll work round the issues because the speed is phenomenal. It's a different world. Olly Edit: I'd add that it may not be for pixel peepers. It's a broad brush instrument which, above all, goes deep and is magnificent wherever there is dust.

Let's assume you've dried the front of the objective, which you can do with a hair dryer. Do you then see signs of moisture on the inside? This may be on the innermost service of the cell, in which case you could direct the hair drier into the inside of the tube. There might also be moisture on the internal surfaces of the lenses, those not exposed at front or rear. As suggested, steady, protracted warmth should drive that out and dessicants would help. The UVC light also sounds like a good idea. Olly

Well, I had a look for brown dust in mine and Paul Kummer's and tried to emphasize it. There is certainly brown dust there to be had and what I found is in partial but by no means full agreement with yours. However, that's to be expected, to some extent, since the Ha will out-shine the brown from the IR. My 'emphasizing' methods were crude so I don't regard this as a published image but just as the result of a quick test. If our little consortium is in ageement, I think going for this in broadband colour, without Ha, would help swing the balance towards the dust. An interesting project for next season since we should have both RASA and Samyang 135 as fast systems to point at this. Olly

That is an odd effect, certainly. The nearest I've seen to this in my own imaging came from a QSI camera whose data, when stretched hard, showed a kind of grid pattern of banding, the bands maybe 20 pixels wide and aligned with the frame. It created a square look from the glow around bright stars, not unlike this. I don't know what caused it but I seem to think it was discussed in QSI circles and was fixed by a firmware update. Perhaps something to do with how the chip was read. Otherwise, I like the images. My rendition also created that colour of OIII glow round the outside of the Jellyfish. Olly