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Stratis

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About Stratis

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  1. I have three SCTs in the stable, a SkyWatcher 127XLT (so basically a blue-tube C5), a 2014 orange-tube 8SE OTA, and most recently a reasonably-new 6SE OTA. All three are Synta-era XLT-coated. Unfortunately between them I am missing several mounting screws that previous owners have lost over the years, so adding finder shoes is really difficult. Does anyone know the appropriate finder shoe screw thread for these Synta OTAs? There's a post on here which states that the old USA models used an Imperial thread, but I feel like the chances of a Chinese manufacturer using Imperial sizing is very, very low. Please help if anyone knows, or if anyone has any of these scopes and a way of determining thread pitch and screw size
  2. Well it's been a bit of a rollercoaster since I started this thread, thank you to those offering advice My CEM60 has to have a full service as it turns out the previous owner (since learned he is a convicted criminal....) did some 'DIY' inside the mount and badly screwed it up. It's entirely correctable, but I want a proper repair warranty on it for the next owner so they can be assured it'll work as advertised. Til I get a new mount I am confined to my AstroTrac and baby refractors. I've reviewed the payload specs for the CEM40 and it really should work fine with my largest imaging scopes, the C8 and the 115mm triplet. My biggest and most irritating scope to mount is a 152 f/5 achromat which is both long and heavy so that may be out of its comfort zone for imaging, but for visual should be ok. I recently sidegraded my imaging camera to a much lighter setup which should help a lot with its payload moment too. I've confirmed I cannot use my beloved Avalon T-pod 110 with the CEM40 so if I go that route I will have to abandon it. Anyone in the market for a near-mint black Avalon T110 T-pod with free CEM60 adapter plate?
  3. Great news for us remote imagers (or people who just don't like having a laptop constantly open), the Raspberry Pi 4 has been released! This model is WAY more capable than previous versions, and has some major upgrades which make it very attractive for AP; Up to 4GB of RAM - this speeds up platesolving and enables on-board stacking of larger subs Much faster CPU - everything runs better, at much greater power efficiency, and more high-demand apps at once USB3 - finally! So new CMOS cameras and large-chip sensors can rapidly transfer their subs to the Pi without amp glow Gigabit Ethernet - for people with observatories, this is critical for transferring subs Onboard wifi - sadly the same as the old Model 3 but still, it enables remote control and connection to wifi mounts We've seen the Pi and other SBCs used in things like the ZWO ASIair, I really feel the new Pi blows everything else out of the water though in its price range. The efficient CPU means you can effectively run this off a power bank and never have to worry about its draw, and the USB3 means you can link up numerous add-ons like long-range wifi adapters without impacting your sub downloads from the camera which was always a risk with the shared USB2 bus on the old Pi. I've ordered mine and going to be setting it up as a remote Kstars-based imaging controller bolted to the scope itself; anyone else thinking of doing the same?
  4. Hi all, Coming back to astro after a long break, many ups and downs I recently hauled my trusty CEM60 out of limbo and realised I'd like to shift to a smaller mount, as I have never come near the incredible weight limits on this mount for imaging or visual. The new CEM40 really looks perfect in most regards, so I am hoping that will serve as my new main imaging mount. I image with apo refractors, from a 7kg 115mm TS triplet down to a little WO Megrez 72 at only 2kg on an AstroTrac, with both DSLR and QSI 583wsg (so about 2kg camera package). My greatest imaging load has never exceeded 12kg. I already have an amazing Avalon T-110 T-pod underneath the CEM60, with an iOptron adapter atttached, this one in fact: https://www.teleskop-express.de/shop/product_info.php/language/en/info/p10799_Avalon-T-Pod-110-130-Adapter-Kit-for-iOptron-iEQ45-and-CEM60-Mounts.html This adapter has the central peg for iOptron, plus mounting holes set around the perimeter for the alignment pegs. The adapter has two sets of two threaded holes; the first set is 130mm apart across the centre, and fits the CEM60 perfectly. The second set is 120mm apart across the centre, and I think is meant to fit the smaller iOptron mounts like the iEQ30. So the £1400 question; can the adapter accept a CEM40 mount? Can the two threaded holes set 120mm across the centre mate with the CEM40? If anyone has any info on the absolute mounting hole arrangements for the CEM40 alignment pegs it would really help
  5. Hi there, That is really nice work given you're using an ST80. My first bit of advice is to make sure your focus is dead-on and locked-down. Even if it looks ok on the screen, it probably isn't. The difference between in- and out- of focus can be 1/16th of a turn on the wheel I would advise you to buy a cheap Bahtinov mask for your scope, and use that to achieve focus. It is surprisingly easy and very accurate. That will improve all your images from then on. Other than that... it's hard to know which technique will work best with the GPCAM, single-shot or video stacking. I've heard of people installing cooling mods on the outside of their GPCAMs to reduce the noise in the images, usually with old CPU heatsinks etc.
  6. Hi all, After months of back injury, busted ribs and cloud, I finally got to use the CEM60 in anger These are taken with a QSI 583wsg, shot through a 115mm T-S triplet apochromat, and I continue to be amazed by how well this scope controls false colour. Didn't get as much data as I'd hoped for as houses kept getting in the way, but these are decent enough I think LRGB, 10 x 600sec exposures HaRGB, 17 x 180sec exposures total. There are some slightly eggy stars here and there, I still haven't got my flattener spacing right. Can anyone offer any advice on LRGB processing software? I'm using AstroArt but trying to look at alternatives.
  7. Nobody has any idea? Is it literally impossible to do this with available parts?
  8. So I have a quandry. I have a suite of good finders and guidescopes of varying types and sizes, all of them in the Synta-style wedge format foot. As fate would have it however, I have ended up with two of my main lightweight scopes being little William Optics refractors, a Megrez 72 and an 80mm triplet imager. These of course, have the William Optics-style shoe installed. I'd like to know if anyone has cracked the problem of using Synta bases on WO shoes. I can imagine the shape of the adapter in my head, just a question if anyone has made one before... Thanks
  9. As a GT-81 owner I can recommend it, but you must budget for a field flattener; the GT-81 does have a curved field. I have no experience with the Esprit but they produce highly detailed and sharp images competitive with the better imaging refractors on the market, so I doubt you'd go far wrong. I also echo the recommendation for the Explore Scientific 80mm triplet; it is a neat and lightweight platform with good CA control and lesser field curvature than the GT-81, although I'd still recommend a generic flattener. In general I think you are on the right lines!
  10. Well, alright. Personally I think a small frac is always going to be easier for the beginner than a medium-sized newt, for the reasons you mention. Narrow FoV, wind and balance issues, collimation, all that jazz. Yes, I advise you to go for a small refractor, they are excellent and vanishingly easy to use. Your setup time is halved, your troubleshooting time is near-zero because there's only about three screws on the whole thing. If it's an 80ED or bust, then yeah, go for it but make sure you have the 0.85x r/c, as far as I'm concerned that is an essential item. You will get good data out of it at a low price. Buuuuut.... If I can persuade you to look into f/6 scopes, I think you will have an easier road of it. With a standard 0.8x R/C unit (also essential...you DO need one) that goes way down to f/5 or thereabouts. You will be able to create lovely images with the SkyWatcher so please don't feel like you can't buy it or that it'll let you down; it won't. But I also know that if you can start your imaging train with that extra f stop under your belt, it will make a lot of headaches go away. Also consider that lower f/ratio almost always means a shorter focal length, translating into an even wider field of view. I tend to image between 500 and 700mm and the difference at the lower end is remarkable, although objects do tend to get a bit small. Either way you'll be better off than mosaics with a large wind-catching tube.... that way be dragons
  11. Actually I don't advise going for the 70ED. A large number of optics are sourced from Taiwan and China, which in itself is no bad thing; these companies (Long Perng, Kunming Optics) are the reason we can buy a sharp, unadorned apochromat for less than the price of Sky TV. The optics are generally good, but not equally so. The 70mm series, in my experience, is a bit of a black sheep in the small apo market. They're nice for travel scopes, but honestly they suffer from an unusually great amount of chromatic aberration, specifically a green/purple halo around stars. The 72mm however, for some reason known only to whichever optician came up with the formula, fairs a lot better. Altair produce the 72ED-R which I heartily recommend, as it contains the same lens group as the William Optics Megrez 72 you see in my signature. It's the lightest scope I can image with, and it's at a nice quick f/6. One thing; it's a doublet, so you will still see some residual halos around stars. Nothing much to worry about really, at small apertures CA is usually well controlled, but it won't stand up to a triplet on colour correction. I advise you to search on Astrobin for the scopes you're looking for, to see images made with them (make sure you're looking at the *imaging* scope, a lot of people with huge telescopes use a 72mm as a guidescope!). The 80ED would serve you well, but as Ive said in another thread, I am not a fan of its focal ratio; f/7.5 for me is just way too slow.
  12. Oh absolutely... I do my photography between f/1.8 and f/4 and even going up to f/4 bothers me when I shoot raw and see all that extra noise. Even with a cooled CCD, every f/stop you advance is not so much robbing signal as it is adding noise. Your final images will always be that much muddier, requiring that much more processing, more subs, more time to bring them to the standard they could have been already in half the time. There are plenty of imagers able to overcome this and process truly spectacular vistas out of data captured at f/8 and above, but they walk a very difficult road, and generally have observatories
  13. I thought of having a go at that, but if you look at the response curve, only the very highest blue frequencies are permitted by the red filter, so simply adding blue to red won't work, as that would effectively make *all* blue stars purple rather than those with a bias towards the upper blue/ultraviolet range. I guess that's the problem they're trying to address, a standard B filter treats all 'blue' light the same, and thus cannot actually make that jump to violet that the rods and cones in the human eye actually show us.
  14. I'm going to offer what may be a controversial piece of advice for an imager looking for a beginning refractor, but its one that I've come to over many nights of amateurish fumbling with imaging setups; Do not bother trying to image above f/7 native I know, I know, thousands of people do it well and someone's almost certainly doing it right now, but honestly, focal ratio is the single most irritating and immovable obstacle to satisfying imaging as a beginner, at least in my case. I see the value of RC and Cassegraine setups at extreme focal lengths for really high resolution, but very rarely is the beginner in possession of the craft and experience to handle that kind of setup. A beginner needs simplicity, and a setup that aids the learning process rather than impeding it with a panoply of possible failure modes. With a fast scope of f/6 or lower, you will accumulate data like nobody's business. One single night of imaging will yield twice as much data, or twice as many targets, as a similar experience at f/8. As a beginner, particularly considering a refractor (I own far too many refractors, I love em ), I advise you to look into faster optics. William Optics do some lovely ED scopes at f/6, as do Altair Astro, with reducer/flatteners available to get you down closer to f/5 even. This will allow you to pull more light and detail out of your target faster, and all else being equal that is always a good thing. As others have said, the 80ED is a cracking scope and gives wonderful views, but it has always struck me as a refined 'classic refractor' concept for visual work rather than an imaging platform.
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