ollypenrice

I lack the courage of my convictions, Tony! On the dual rig, at least, there is no reason to use an electric wheel since I shoot either NB or lumnance on one side and stick to one filter all night. I still have a manual wheel, too. There is no doubt at all that the filterwheels are the least stable of my PC-controlled devices. Olly

I try to stay close to the science so if I were going to add Ha to a channel besides red it would be to blue, since the blue H beta line traces similar gasses to Ha. In truth I'm not in my comfort zone here because, when I add Ha and OIII to RGB data I have the RGB image available as a reference for the colour. The tail is very much an OIII feature, Peter. It only glimmers and fizzles out in Ha! Olly

Since I've grumbled about Straton, the star-removing software, in the past I must be fair and say that I've finally got some sense out of it. It was an SGL member (I'm sorry but I can't remember who it was) who suggested ignoring the manual and trying it on the stretched image. I did this on a 10 hour Ha stack on Thor's Helmet. Being a tree-skimmer here at Lat 44, the target produced unhappily large stars but Straton removed them very well indeed from the stretched version in a single click. I didn't want to produce a starless Thor's Helmet but simply wanted more smaller stars so I then pasted the original linear data on top of the starless image in Ps, set it to Blend Mode Lighten and stretched till stars appeared in the blend. Some stars needed a little attention but I'm pleased with the way this experiment worked. I could have kept them smaller than this had I wanted to. When adding Ha and OIII to RGB I'll consider using a fully starless version so as to be sure that the NB data has no effect whatever on the final star colour. Olly

Maybe my sample is one made up not of 'astronomers, some of whom fly,' but of 'people who come to my place, some of whom fly.' If this is so then it would be instructive to know how many people going to other gites in this area also fly. Since flight is a major sport in this area we would have to exclude anyone who had come here for that purpose, since none of my flying guests has ever come here to fly as well as astronomize. I'm sorry, but I cannot believe that your average local gite will, in the last 12 years, have hosted three RAF pilots, one Swedish air force fast jet pilot turned airline captain, four builders-and-flyers of their own aircraft, two glider pilots, three helicopter pilots, four PPLs wise enough to prefer professionally built aircraft, two sailplane pilots, two microlight flyers and numerous paraglider pilots. That cannot be an average slice through gite customers in the Hautes Alpes, can it? Unfortunately the two other gite owners I know locally cater specifically for the free flying market so asking them won't get me very far! And... the grandfather of astronomy holiday rentals abroad is, himself, a PPL. I speak of that talented fellow, Mr Bev Ewan-Smith of COAA. Nope, I think there is a disproportionate number of flyers in our astro community. Olly

Another plus is that, when observing with others, you can hand over to the next person without losing the object. Olly

My used price baseline is 60% of new, not 70%. I don't ask more than that, or pay more than that, without very good reason. Most of my kit has been bought that way as well, despite its being used professionally. I have an advantage and disadvantage as a seller in that, as an astronomy provider, I would be mad to sell bad kit to anybody since it would hit my reputation where it hurts. Like anyone else I have, on rare occasions, ended up with bad kit (not because it was second hand but because it was just bad, or way over-priced. Tak EM200 mount bought new. Ouch. Never again.) In these circumstances I either give it away or sell it, fully declared, at very low prices so that nobody will accuse me of dishonesty. That's the down side of my situation. The plus side is that people know this, so when I offer kit for sale they know they can rely on me and I generally sell - quite seriously - within half an hour. I'm not joking. The father of my childhood best friend was a nationally famous antique dealer. He had a rule that he never made offers, he either accepted the asking price or rejected it. He never gave valuations and bought at the same time. (How can you make an honest profit if you do that?) I think these are good principles to follow within our community, for that's what it is, a community. I've never had a bad experience buying second hand. The few bad experiences I've had have been when buying new, truth to tell. Olly

Precisely so! Olly

Of course there is another, more radical solution to the perfecting of the dual rig. A manufacturer could steal a march on the competition by making a 'binocular' instrument - two parallel optical tubes in one body with one piece drawtube to boot. Is Yuri Petrunin reading this??? 😁 Olly

I found some old low resolution RGB data to get an idea of how it might be brought into play. Much stronger signal in green and blue, particularly blue, will (I think) be the way to go. Just thinking out loud. This is essentially HOO with RGB stars. We're off to Thor's Helmet till the moon goes away. Clear skies, Olly

Resolution has a lot to do with it. When we ran dual Tak 106 scopes at 3.5"PP we saw no problems at all. We just bolted the dual rig together and it worked from the off. At 0.9"PP it isn't quite as simple. The SX active optics gadget is a good idea but we can manage without it - I think! Of course, the other solution would be two mounts... Eek. Olly

The quickest mounts to align are Takahashi (100% electronics-free so reliable to boot!) and they have no leveling facility. Olly

I can see the point of the extra rings, certainly, but are they not fighting with the alignment device to some extent? Perhaos this doesn't matter. In our case the system generally works but we do occasionaly get 'slave scope trailing' issues, though not bad enough to scrap many subs. I think the alignment device (a Cassady, as you say, but note the spelling for Google purposes) needs to be kept very tight. Perhaps somebody will come up with a purpose built solution. I'll put the problem to my friendly astro-engineer Pieter Vandevelde! How about a dual tube ring in which the bottom halves of a pair of rings is machined from a single piece of metal? If accurately machined in this way would the scope alignment be good enough? It's probably not going to be pixel perfect because of the focusers, but would it be 'good enough?' Olly

A dual rig is so productive! I speak as an addict... 😁 Olly

Nice. I think my Ha was over stretched and rather dominated the structures of the main nebula. I'll do it more carefully when I get the full data set. Olly

15 minute subs, Lee. I don't find the Atik 460 gains much with longer ones though the 11000 does. I did do a bicolour for fun but I'm not a fan. I find the colour a bit two dimensional, which isn't surprising since that's what it is! I prefer to use an RGB image as a vehicle for the Ha and OIII. I didn't bust a gut on this bicolour and it's years since I did one but it will be interesting to see how it differs from the final HaOIIILRGB. Olly

Happy New Year's Eve to all the good people of SGL and thanks to the Admins and Mods, along with the FLO team, for making it all possible. So, alas, I can't present a last finished image before the year's out but here I've built up a monochrome HaOIII rendition of the Crab Nebula using data shot over the last two nights in the dual Tec rig, jointly owned with Mr and Mrs Gnomus and Tom O'Donoghue. LRGB will be next on the list. This has 8 hrs per filter for now. Cameras are Atik 460 and Moravian 8300. The mount is a Mesu 200. The intriguing tail on the left seems to be a relatively recent feature in amateur images. I've no idea if it has been there all along but it wasn't something I remember seeing till fairly recently. It's an OIII structure, mainly. Indeed I found the OIII layer to be much more beautiful than the Ha, with finer filaments and more subtle details. Here's to 2020 (which should be good for seeing, right?) lly Edit: scroll down for bicolour

Give me time.... (This will involve reconfiguring the universe along steady state lines since, of course, the BB universe is rather cramped, time-wise...) Olly

This is not strictly a millenium bug, it struck this year. https://www.theverge.com/2019/3/8/18255847/gps-week-rollover-issue-2019-garmin-tomtom-devices-affected I won't be updating my handset since the manual system is so much more reliable than the GPS. Olly

The Meade 14 inch LX200, which was kindly bequeathed to us by the late Alan Longstaff, fell foul of the belated 'millenium bug' which has affected lots of GPS-related devices. Before the bug it was sometimes spot on, sometimes not, for setting up the alignment and then 'going-to' objects. Post bug I've just been putting in the time and date and doing a two star alignment. This is so much better than the GPS-based palaver! It takes half as long and gives reliable go-to every time. My previous LX200 10 inch was equally reliable in two-star align mode. Meade and Celestron have driven themselves nuts trying to make the self aligning telescope and, in the process, have probably driven quite a few of their users nuts as well. Meade, your semi-manual 2 star align is bliss. Stop right there!!! Olly

Yes, I'm always amazed by clutches. It seems astonishing that they last more than ten minutes... Olly

The difference may be that the friction drive of a well balanced mount is a fairly low-torque application. A focuser pointing at the zenith with a heavy CCD rig, filterwheel and reducer-flattener is a pretty high torque application. I'm not an engineer but I have one staying and will see what he thinks. I'm certainly R and P for preference. Olly

Given the amount of time I spend imaging you might think I'd had all the bugs available, but clearly not; I'm running the dual TEC rig on the Crab, one side doing Ha and the other OIII, the latter in Artemis Capture. I stop the sequence to refocus. I then try to restart the sequence but Artemis tells me, 'Failed to position filterwheel.' I haven't asked it to reposition filterwheel and it still says I'm in position 2, which is OIII, so I ignore the sequencer and just set it to repeat exposures, since I'm not shooting through any other filter tonight. However, I wait for the first sub to come in and it's OK... but there's something odd about it. Finally I look over to the other screen and realize that the OIII side of the rig is now shooting Ha. I never asked it to change filters. It still claims to be shooting OIII. But what's really odd is that it has placed the filter in the correct position for Ha despite having had a paddy and spontaneously moved without instruction. Rebooting Artemis set everything back to normal. Ho hum. Olly

Heh heh, Steve Richards pointed this out many years ago! Guilty as charged. Olly

I'm a notorious doubter of the Crayford design in principle. Monty Python's Flying Focus... nly joking! Olly

Fine, I think we're just at cross purposes in the use of words here. It seems we agree. Olly