ollypenrice

Thanks for the thought but it's not a competition, especially since Jonas and I are friends and I host some of his kit here. The Andromeda mosaic was, quite rightly, the subject of huge appreciation - and it was a one man show. Ours is a double act! Olly

Again, thanks folks. Your kindness does matter to both of us and is deeply appreciated. Olly

PM'd Olly

Good question. My own Lunt LS60 was damaged in an accident so I'm wondering about the 50 instead. It's a lot cheaper! On the face of it I wouldn't expect a huge difference visually and the shorter focal length of the 50 would make it easier to capture full disk images on smaller chips - and most of them are small. I hope someone will have tried both and comment. Olly

Thanks Maurice. If I'm not mistaken that means, My hovercraft is full of eels. In trying to eat them all my choking sounds are getting better! lly PS Dutch is not listed in Google Translate. You need to complain!

AAAARRRRGGHHH!!!!!!!!! A mortal wound! Only joking. All panels preprocessed in Astro Art 5 using flats, bias-used-as-dark and Bad Pixel Map. ABE or DBE used to de-gradient the linear stacks in Pixinsight. Individual panels from different cameras combined in Registar then co-registered to a master widefield template but not combined in Registar. Images paritially stretched in Ps and then combined by eye using Ps tools to balance the brightnesses for a seamless blend. At this point Tom and I will have done our own thing. What I did here was my own final stretch of the three images, ie L, RGB and Ha. Tom has more PC power than I so I could only do certain things to the whole image. I generally had to break it down into four or five sections and do the same thing to each. (Even just doing a 'Save As' took a couple of minutes...) L was added to RGB conventionally enough in Ps using interations, boosting the RGB saturation under a partial L application, smoothing then re-applying till L was at full opacity with enough colour to fill it. Ha was added to red in blend mode lighten. The application was rather thuggish! That's to say, to bring the Ha into play against the strong red layer I had to give it a massive contrast (S shaped) curve while it was in situ over the red channel. By doing this I could keep the low Ha signal below the red (to stop the entire sky turning red) while allowing the brighter Ha signal to lift the reds for the Loop and Meissa nebulosity, etc. Images I already had from the TEC140 at higher resolution (Horse, Flame, M42, Running Man and M78 were taken 'as is' in finished form and registered/resized to the mosaic in Registar. They were then blended in using Ps, with adjustments to levels and colour balance as necessary and very much by eye. Challenges included getting the overall colour balance consistent (Selective Colour in Ps) and keeping the seven big stars down. This was done using Layers and multiple stretches in Ps and took a long time. (Half a day on Rigel, for instance...) It's easy enough to get a small Rigel but not to get a small Rigel without a dark shadow around it. That took longer! (The final size of the seven bright stars is a matter of taste, though I noted their magnitudes and respected that as best I could. I felt they needed to be big enough to show the Orion shape but splitting Alnitak was a matter of professional pride so that set an upper limit on all seven! ) So, Astro Art, Registar, Pixinsight (vital for DBE/ABE) and mostly Ps. (I'm a Layer-oholic.) Olly

I think we're both knocked out by the kindness of these comments. Many many thanks. Olly

ORION. This is a marathon O'Donoghue-Penrice production owing more to Tom than to me. Tom began the luminance and Ha in Spain four years ago using one Tak 106N/Atik 11000. We then set up the dual Tak rig here and carried on, finishing the colour and Ha acquisition a couple of weeks ago. (Running three Taks and three full frame cameras we collected 24 hours of data in two memorable nights!) Tom did the stitching of the part-stretched data and handed a copy over to me, so the final processing here is mine though Tom's own version is in the pipeline. Higher resolution data has been added from the TEC 140 to enhance M78, the Horse, Flame, Running Man and M42. It's a thirty panel mosaic weighing in at 1.03 Gig in Tiff format and covering nearly 270 million pixels. A full size print would be nearly 8 metres high, which is the whole point, really. We'd like to find a corporate buyer or museum interested in funding such a vast print. Exposure time is over 40% longer than the Hubble Deep Field at about 400 hours (AKA 1.44 million seconds or just over 16 days. ) Thanks also to Yves for the use of his camera when we had three Taks on the job or when mine was tied up on the TEC. We cannot link to a very large version because of the risk of theft so this is little more than a thumbnail to give the idea of the beast. We're sorry about that but with so much time invested we have to be careful. At full size M42 alone fills the screen. Just to reiterate, Tom's contribution exceeds mine on this. We hope you like it. Tom and Olly Link to a bigger one here: http://ollypenrice.smugmug.com/Other/Best-of-Les-Granges/i-LgK642h/0/O/ORION%20400%20HRS%20WEB.jpg

Yes but I've got an excuse! I earn my living with it... OK, I never said it was a good excuse! What I would say, though, is that in a vote for best optics for buck I think I'd have to go for the subject of this thread, the 6 inch RC. Or the 8 inch. John and Sara really do show what's possible. The resolution on that Pacman above is astounding. Olly

Retire at will, Andrew, as is your perfect right, but please don't do so before accepting my heartfelt thanks for the most edifying of posts! I must admit to functioning at about 15% of an already limited mental capacity following an accident which leaves me unable to sit in comfort for more than a few minutes, so my mind is not really on the task. I'll go through all this in a month or so when I'm back to what passes for normal! Olly

OK, it's the class Dunce again! Why wouldn't Andrew's ray diagram apply to a reducer? I don't understand why a reducer produces a beam different from the one produced by the objective. Olly

You are quite mistaken Mr Wolf. My husband has the prices absolutely right. Mrs Goldman.

I was meaning no purely physical increase but I have now returned to my original belief that there must be an optical increase. Indeed, most intriguing. I'm glad I don't need an LP filter as well! Olly

In reality there will usually be no physical increase in the distance brought about by inserting a filter because the 'increase' is contained with the thickness allowed for the filterwheel. Yes? No?? Arrrgh. Olly

I agree entirely with Andrew S's ray diagram and this is what made me say that I can't understand the subtraction claims. It's exactly the ray diagram I originally had in my head. It's just that when QSI say the reverse I feel outgunned. Now that Don Goldman agrees with the ray diagram I'm delighted. I've emailed my favourite optical engineer and am awaiting a reply. This is a rum situation! Olly

Steve, if I do the ray diagram I can't see how it can be the opposite but both QSI and Optcorp say that it is. When Optcorp specified my extender for the TEC flattener they subtracted I/3 of the filter's glass thickness from the system FL. This is also what QSI say on the link above. I hate doing things by rote without understanding them but, sheep-like, I now follow the subtraction rule without knowing why. I must say that the Optcorp extender has worked perfectly on the TEC flattener with exacting full frame chip, but this doesn't prove that they were right. I think I need to write to Ralf, the font of optical knowledge... No, it applies to chip distance if we are talking about an add-on flattener that moves with the drawtube. It can be entirely ignored in inherently flat field instruments like Petzvals where all it will do is crop a mm off your backfocus. This shouldn't be tight enough to be affected. Olly

I didn't recognize you by your forum name, almcl! Sorry about that. Steve has it with Alnilam, I suspect. I gave the area a quick eyeball on a widefield and decided it didn't line up as a likely candidate but I hadn't allowed for the orientation of your camera. In doing it properly Steve has fingered the suspect's collar, I'd say. Just in terms of good practice you have no flocking in the tube and you also have a couple of bolt intrusions into what might be the lightpath. SInce the tube also has a raised seam I might be inclined to flock it and trim the finder bolts. I've no idea whether this might be a player. I do have a big visual Newt, as you know, but imaging is far more exacting in terms of things having to be right. Best, Olly Edit, I'd maybe blacken the vanes as well. Matt paints using pigments are best since dye based paints can reflect IR, it seems. Barbecue paints use pigments.

I think it is probably a reflection from the vane. You also need to give the vanes some attention, I think. I'm not well up on Newts but how good is your coillimation and is there a twist in the vane? Olly

As has already been suggested, guiding in only the one necessary direction in Dec (experiment to find which that is) is an excellent cure for oscillation. Being slighty misaligned is a positive advantage in this situation, but not enough to give rotation. Olly

David Lukehust uses them, as indeed do Obsession, so that probably says it's a good idea. Olly

All of the aperture contributes to all of the image so you can't locate the planet between the vanes! The only solution (and a very good one) is to use a curved spider along these lines. http://www.rfroyce.com/spider_cv_8/spider.htm WHat happens here is that each segment of the corve produces a diffraction artifact in a different place. Olly

Hehheh, be fair, I've backed these little Newt images from the start. You don't have any choice, they are excellent. They really are. I'm in a slightly different position in that I'm a provider, sometimes running around like a blue-posteriored fly and even with 'plug and play' I sometimes can't get it all working in time, so adding collimation tasks is not on my to do list. But, hats off, I think that bang for imaging buck I doubt that the 130 can be beaten. Olly

While I've been knocked out by Uranium's images for some time, and said so, I've missed this thread. I don't see anything remotely 'entry level' about the best images posted here. If you want to image at this kind of focal length on a medium to small chip then this telescope clearly has a lot going for it. I think it will take on, quite literally, all comers at any price. It is fast enough to be fast but not so fast as to invite exasperating complications that will rob the imager of many good nights. In refractor terms it has a fair bit of aperture. Apart from the coma corrector it is inherently apochromatic - totally so. What do you get with a car-priced Takahashi FSQ that you don't get with this scope? A vast flatfield circle which you only need with a big chip. Freedom from collimation. No diffraction spikes. These are not nothing, but, yikes, they come at a price... Olly

I have one of these as well, and a Pronto. I prefer the Pronto, personally, but it is heavier. However, I don't find the 66 focuser to be capable of carrying much. It was fine with a small CCD and manual filterwheel but would have no hope of holding my present CCD gear. That said, it couldn't cover a large chip so nobody would ask it to do so. It does give a nice visual image and is incredibly competent as a narrowband imaging scope on chips which it can cover. To be honest it isn't far behind a Baby Q in narrowband and with a small chip. Imaging in broadband does show its limitations, though. Stars are far bigger and less controlled than with the premium stuff, but what do you expect? I think it does well. Since this review it might be worth noting that the little TS Quad has, it seems, had its pinched optics cured. I'm not sure that I'd call my ZS66 a keeper but, then again, I've kept it and have no plans to sell it, so I guess maybe it is! I also started imaging with it so it has some sentimental value. I'll put one of my early attempts below. Atik 16HR, 13Nm Ha filter. Olly

Julian, do you know how Shapely calibrated the Cepheid distance, though? This bit seems to be glossed over in most of the histories. Olly