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Hicks

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About Hicks

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    https://www.mups.co.uk

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    West Yorkshire
  1. I image with an LX90 8". tl;dr The LX90 8" can produce really nice images. It is however far from the easiest setup to image with. Not that imaging with any setup is a piece of cake. So you may be right to consider a wider field setup for jumping in. Once you've overcome the imaging challenges that all setups share, the LX90 will still be there to challenge you at long focal length if you fancy it Details Without a way to lock the mirror, you can experience mirror flop which will knock your focus out as the scope tracks across the sky. This can however be limited by ending coarse focus in a counter-clockwise direction. Also, manual focussing is painful due to the image shift it causes, especially as you often need to tweak focus throughout an image session as temps change. A zero image shift focuser solves this (I have a moonlite focuser on mine). The LX90 has a fair amount of backlash too. This can be mitigated to an extent as the RA axis will never need to reverse and if you deliberately don't do perfect polar alignment the DEC axis only ever has to correct in one direction too. It does need to be tamed to an extent however so that PHD can successfully calibrate. It can also make matching a targets position exactly from a previous session a little more painful. Due to the high focal length, you'll also likely want to use a F6.3 focal reducer and match up a CCD accordingly. Even then, you will be imaging around 1270mm and perhaps 1" per pixel so guiding needs to be quite accurate to keep round stars. That means you need an off-axis guider too. A separate guide scope isn't imo a good idea as you will inevitably have to fight flexure. Even an OAG brings some issues, the pickoff prism will mean you may need to adjust the position of your targets in order to have a suitable guide star. On a good night I have had guiding < 0.6RMS however. Bad nights tend to be poor seeing or user errors (often the latter). The other issue with using a focal reducer is the need to deal with spacing issues. If you go too close/far away on spacing you can see coma. The SCT with a F6.3 also has quite a bit of vignetting. So flat frames become a must. Although imo they're a must anyway as you really don't want to find a session ruined because you had some dust motes you'd not noticed Last Issue There's just one issue I've not yet overcome with my LX90 and that's a rather high spike of periodic error which hits once every 9 minutes. It's rapid enough that it's not possible to guide out and means the exposure it occurs within is no good. I'm not sure if this is some dirt in the RA or just a manufacturing tolerance issue, but it's frustrating to lose that exposure every 9 mins. Unsolvable Issues One final issue is, due to the fork mount setup you will find the long train of gear you hang off the rear cell of the SCT will impact the base. This will make imaging a relatively large portion of the sky around polaris, impossible. For my setup, the filter wheel impacts the base so I lose (give or take) a 25 degree circle around polaris. This and the PE mentioned above are two of the reasons I'm considering a move to a CEM60. Silver Lining It's not all doom and gloom however. All the gear I've bought to image with the LX90 over the years (had it 17 years now) ccd, guidecam, filter wheel, FR6.3, moonlite focuser, rasp pi, cables, dew heater... are all items I will continue to use even if I decide it's time to move on from the LX90 mount. As I really like the quality of the OTA, I'd likely defork it just replace the mount (maybe a CEM60). That means the only real sunk cost in all this would be the LX90 counter weight system and wedge. That said, the above assumes you're happy imaging at a long focal length. Even with a better mount, long focal length imaging has many challenges. You can spend far less money and have a far easier time imaging if you go for a much lower focal length (and weight) setup. I thrive on challenge however and taming the LX90 has been frustrating at times but also as enjoyable as the imaging itself. PS: Whilst one shot colour can be easier to get started with. I'd consider a mono ccd. You can get used to it and still produce pleasing greyscale images before adding a filter wheel into the mix, but once you do have a filter wheel, you open up not just colour imaging but narrowband too. That can be quite useful for moon lit nights as we lose enough nights to cloud as it it that it's nice to not have to suffer through the moon lit nights too.
  2. LX90 8" fork mounted with F6.3 reducer. Moonlite focuser, SX Filter wheel, Lodestar OAG and SXVR-H9 main ccd. Polar alignment was only rough, with a 125s DARV exposure showing overlapping lines but I expect 185s+ would show more refinement needed. Guiding was pretty poor until second half of the night when I managed to make some improvements. Still more to practice there. Seeing conditions were reported as 1.75" which is almost double the 1.04"/px I was imaging at, might have been worth binning.
  3. Just looking at the top left image and wondering if the eggy shape to the stars is likely polar align error causing field rotation. Anything stand out as a likely cause? PA, tilt or focal reducer spacing? If it's PA I can improve that as I only went to a 125s DARV exposure. I think the next clear night, I could do with getting a few subs of a rich star-field and very short exposures to eliminate PA/guiding.
  4. Thanks for the links, I'll have a read. If you want to have a play with the subs, I've pm'd you a link to the download (821MB 7zip). Note with the flats, first 100 were compromised by dew also. Last 50 were taken with a clear corrector. Be interesting to see how your process stacks up (pun intended). I'll hopefully find some time next week to re-process and learn more about RGB in pixinsight to improve on my attempt :)
  5. On Tuesday I bought a set of LRGBC baader filters for imaging and as luck would have it, for the first night in weeks we had a spell of clear skies the following day (same day my narrowband filters arrived, I guess they even filter out the clouds in the box Focus offsets need more testing, but I managed to capture (NGC7331) around 70x60s exposures in L,R,G and B. Having had my best night guiding I went to take flats/darks and to my horror realised I'd forgotten to connect the dew heater tape to my heater controller and the corrector was all nice and foggy. Looking back on all the L images via subframe selector you can see the SNR take a gradual/increasing hit after around the first 30 frames. Fortunately I did 1L, 1R, 1G, 1B and then looped around again so I do have data to work with pre-fog. What I'm interested to know is what people feel about including the "bad" data perhaps heavily weighted to favour the good? How bad was it? Well here's the first image of the night and the last, the difference is quite striking. The most frustrating part is, I greatly improved my guiding after the dew had formed*. To the point it was close to guiding out the harsh periodic error that hit every 9 minutes. How would you tackle such a mismatch of data? Dump the dew'd frames and stick to the few good frames from the first 30 (poor guiding/more bloated stars)? Or try to weight in the later frames where guiding was good, stars are tighter and the background is increasingly foggy each frame tbh the main reason I'm even bothering to process this and not chalking it up to a just one of those nights, is that it could be a month+ before we see another clear night and I've much to learn about RGB processing in pixinsight, never done it before. So, some data works better than none even if the results will be limited. I did a calibration, integration and combine of all 72 LRGB images last night both the good, the bad and the ugly with no weighting or processing beyond a bit of histogram stretching I got: Was a little surprised by how that turned out considering how bad (in different ways) the data is from either half. Colour is very washed out. Is that down to lacking in data? there's about 72 minutes of R, G and B. Also I'm under bortle 8 skies I believe. There's a gradient from left to right too, not sure if that's due to including the dew'd frames or perhaps some local light pollution. I've not done any processing as far as sharpening/masking or trying to boost any of the colour. Any scripts/processes I should read up on for pulling a bit more out of this data? * Lesson learned, added check dew heater cable attached to checklists and also added a 30-60 minute periodic check of the corrector to ensure heater is actually keeping up
  6. Firstly, buy/sell forum didn't look suitable for asking about gear prices, since I'm not actually posting an ad to sell, just weighing up options. If this isn't the right place either feel free to move I've got a Starlight Xpress MX716, it's the old parallel style camera with the usb1.1 interface add-on. It's mono and cooled but rather low resolution. As I now have a SXVR-H9, I doubt I'll ever use the MX716 again. I've had the camera running on Windows 10 64bit, although it was a while back so I'd want to retest before selling. Anyone have any idea what it might be worth 2nd hand? I've also got the Meade F3.3 focal reducer/field flattener. It's a nice match for the MX716 but I think too high a reduction to be useful for my SXVR-H9 and 2003mm FL scope. I think it gives around 2" per pixel, whilst the F6.3 I have gives closer to 1". So I'm also considering parting with the F3.3 too. Again, any idea what price this might sell for 2nd hand?
  7. What is the difference between the CEM60 and the rest of the models you refer to? Does that difference impact guiding accuracy, backlash etc?
  8. Yes, I was thinking of doing that as I need a few more connections than are exposed. I was thinking more though of a replacement front panel and input panel that means you'd now have USB3.0 exposed rather than USB2 and a powered hub rather than unpowered. It seems a waste that some people are not using the usb ports as they're unpowered, an upgrade kit would resolve. I'd have to have a look at how it's all hooked up but I'd be tempted to make my own replacement.
  9. I wonder if they've considered designing and selling a new top panel (and input panel depending on where the hub is) to provide a 3.0 and powered hub. It'd save bringing out a whole new model of mounts and provide options for all those who already own the CEM60 to get powered USB allowing them to drop their usage of an external hub and cable run.
  10. Are you on about the polar scope where you eyeball Polaris through it? Or are you asking about the handset based mode which you can use when you don't have a view of Polaris and you can use "Polar iterate align" ? I'd be interested in knowing how close people get with the eyeball method and how much closer iterative gets you vs the time both take.
  11. I was wondering this too. Although I'm thinking I'd want to run a few more cables and that'd prob mean taking out the polar scope to run them through there. So if I did get this mount, it'd either be the iterative align or I'd make use of phd2's or ekos's polar align routines, failing that darv or the old faithful drift align. Would like to know how close the polar scope can get you though. Since it seems to be a quick setup.
  12. I use the Moonlite CSL 2.5" with around 1.5kg of weight and have not experienced any slippage throughout a session, including when imaging vertically. It's apparently set to hold up to 2.7kg from the factory and can be adjusted to hold more, although I've not put that claim to the test and I'm not sure how much more you could push it before breaking something. I don't know how it compares to other focuser's as I've not owned or used anything else beyond my scope's stock focuser.
  13. I guess my current reservation is the extra grand for the RA encoder. As my scope is a 8" LX90 which would be 1270 focal length (1.04"/pixel) or 2000 if I ran without focal reducer, I'm trying to decide if the non EC version is already good enough to achieve consistent nights of trouble free exposures (seeing and other non mount caused issues aside). The other factor is that at least from the way the specs are written, it sounds like the EC version is more likely to have a low/smooth periodic error (< 0.5" over 5min), where as the non-EC just has the peak to peak spec. If it's possible they'd ship a non CE mount with a PE change that meets the p2p spec, but has a few sharp spikes that could be tricky to guide out, I'd lean more towards the EC for that peace of mind. So far though, everyone's factory graphs I've seen have been reasonably smooth changes across the peak.
  14. I think this thread has left me even more unsure about whether the extra cost of the CEM60-EC is worth it when guiding. I've gone from planning to get the CEM60 to getting the CEM6-CE to no longer being sure which Interesting discussions though.
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