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Barns

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About Barns

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    Nebula

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    Plymouth, UK
  1. To bring up to date, FLO got advice from ZWO that apparently I should use the standard adaptor bracket that comes with the EAF to fix to the Esprit 100 focuser, NOT the Takahashi one. However I do think I need to be using the flexible coupler that came with the Takahashi bracket as this has a different inner diameter to fix to the Esprit focus "rod" from the 4 couplers that come standard with the EAF, none of which fitted snugly. So it's quite a lot of money for one coupler but that's astro gear for you! I've changed the mounting over and it does seem much more secure and lined-up now, even though it's still by a single bolt. I'm still having issues with the EAF however, some largish backlash that I think is internal to the EAF itself, but that's the subject of another thread.
  2. I've spent this morning trying to pinpoint where the backlash is coming from and am coming to the conclusion that it's internal to the EAF unit itself and not with the scope focuser. With the EAF attached (unpowered), I can turn the microfocuser about 1/8ish of a turn each direction until it's stopped by the EAF. With this turning I can see the focus tube immediately go back and forth a little - so I diagnose no backlash between the focus mechanism and the tube (i.e. not on the rack/pinion). However I can see the EAF motor shaft being turned as well whilst I do this little back and forth turn on the microfocuser, meaning the backlash isn't somewhere in the coupling between the EAF and the focus mechanism. Hence I think it has to be internal to the EAF itself; it's allowing a small amount of back-and-forth play on the motor shaft. Does this sound like a "bad" EAF unit? I've read elsewhere that the EAF itself shouldn't have any "play" on the shaft like this.
  3. Right I've had another go at the fitting of the EAF now. After discussion with FLO it seems like ZWO now recommend using the standard bracket that comes with the EAF to attach to the Esprit 100, rather than the additional "Takahashi bracket" that was advertised as being needed for Esprit compatibility (and which didn't fit very well). So I've used the standard bracket, which does seem more rigid, plus used two worm screws on each of the EAF to flexible adaptor and flexible adaptor to focus rod fixings (previously only used one worm on each, as per instructions, but there are two holes in each position at 90degrees to each other). Now when I measure backlash I get a value of around 65-70, which still seems quite high to me but at least is possible to set in the EAF ASCOM settings and thus compensate for. When I tested with SharpCap autofocusing, the "Best Position" calculated for both IN and OUT focus search directions ended up agreeing within ~20 units, which is pretty close I thought. Still, I can feel a little wiggle looseness on the fine focus knob, not being held completely rigid by the EAF, so I suspect this is where this small residual backlash is coming from. Not sure how I can fix that (this wiggle isn't present when the EAF is detached and the Esprit focuser is back to manual - it's smooth and firm both directions with no backlash as far as I can tell). So, anyone else got EAF backlash measurements to report? Does my value of 65 seem unduly high, or "about right"? Basically I need to know if this is what I should be expecting, or whether this EAF needs returning.
  4. So, I've had the chance to play around a little bit more with the EAF this morning. I used SharpCap's edge contrast focus mode to autofocus on distant buildings, which seemed to work quite well. However it's thrown into light what I think is the real underlying problem with the EAF at the moment - the backlash is HUGE. I've followed ZWO's methodology to measure the backlash - drive the focuser 1000 steps one direction, then use the fine focus adjust buttons to move 10 steps at a time the opposite direction until you see the physical fine focus knob on your scope move. Count how many clicks of the fine focus adjust button it took before the physical focus knob moved, multiply by 10, that's your backlash. Mine comes out at ~850! Which is higher than the max value you can input on the EAF ASCOM configuration (max is 255). So I can't even compensate for it in software (not that I'd want to leave such an obviously wrong thing alone without fixing it, anyway). You can actually SEE the backlash, if you tell the EAF to move a large distance opposite to where it's just been moving, there's about ~1s delay where the EAF is whirring but no movement on the scope focuser. Seems very wrong. What might be causing this huge backlash? It's not the scope focuser itself - that moved perfectly back and forth without the EAF fitted - the Esprit 100 focuser is a lovely unit from what I can tell. I believe I've fitted the EAF tightly such that there's no "play" between the motor and the focus shaft. What might be causing this scale of backlash? Is it likely to be something internal to the EAF unit itself? I should note that this is the customer-returned EAF I got cheap from FLO but it does have a guarantee so I'll return if needs be... Edit: something I forgot to mention, I had understood that with the EAF fitted the focus knob would be held tight i.e. you wouldn't be able to manually focus. This is fine, however, it is not actually held fully tight by the EAF in my case - you can turn the coarse focus knob about 1/5 turn (ish) back and forth before it's stopped by the EAF. I THINK this would roughly correspond to the backlash amount judging by the travel on the focus tube when manually turning the knob this way (NB the tube moves immediately back and forth, no backlash between knob and tube). What fault might this indicate, in the fitting or in the EAF itself?
  5. Very true! Especially in the dark, at midnight, when I'm falling asleep anyway..! Rough guess from memory is that it travelled roughly 31mm for 5000 steps which makes the step size, as you say, round about ish 5microns. I'll measure properly later when I'm near the scope.
  6. Many thanks for all those tips! Sounds like I have lots of messing about to do yet, which is good, as half the fun is getting complicated bits of kit working... Seeing probably wasn't helping - bits of cloud going through.
  7. Hi, got the chance to try out my ZWO EAF for the first time last night between patchy clouds. Sadly, it didn't go very well. I was trying to get autofocus going in SGP. However it seemed like focus never really changed much whilst it was going through its routine, focus steps of 10. I tried upping the step size to 20 and even 50 and also playing with backlash settings but these didn't seem to help. If I tell the focuser manually to go miles (like several 1000) away from the rough focus point and then back again, it seems like it moves back and forth accurately, at least by visually inspecting the focus tube on the scope (Esprit 100). But if the EAF is only moving a few (10s) of steps then it doesn't seem to actually move the tube at all. Does anyone have experience or advice for settings to use with the EAF and SGP? I also have APT so could try that. I used APT's backlash calculator previously and it said there was basically zero backlash after going through all its routines. But there it's moving relatively large amounts each time. Frustrating I can only test on rare clear nights! Or is there some way to test in daylight? Does Sharpcap have anything to help?
  8. Seems like the consensus is that I basically need to get my act together and cobble my flat box into decent shape! I do agree the flats between the filters are definitely different - each of the Ha, OIII and SII flats look quite different when stretched, with weird banding and all sorts. Seems to come out in the wash during processing though. I'm happy to hear that experience shows I needn't worry about the minor refocusing due to temperature changes thouh - that's a relief. I find it tricky taking flats at the end of a session as often I have about 5mins between waking up in the morning and then having to get the kids up, to school etc, in which time I need to hastily disassemble the scope and bring it indoors. Not enough time for flats at that point so they'd get done later in the day or on another day entirely. And with clear skies as preciously rare as they are, I'm not about to "waste" time at the start of a session doing flats (especially when they take quite a chunk of time to get a decent set through narrowband with their longer exposure times).
  9. I've recently bought a ZWO EAF autofocus unit. Not having had clear skies since (of course) I find myself pondering how this will affect my workflow with regards to flats. Currently, I have a stock set of flats taken through each ZWO filter at a fixed focal point (that's the same every night as it's manually set by hand). So I don't re-take flats every night; I reuse this set I took once, and I guess I'll re-take this stock set if I start seeing unwanted dust rings appearing. I actually took the flats all at the same focus point, despite discovering the OIII filter is not quite parfocal with the Ha and SII - but it doesn't seem to unduly affect the use of the flats. However with the new autofocus unit, the whole idea is that it'll autofocus by itself (using SGP) right throughout an imaging run, refocusing for each filter, and also with temperature changes. How do you account for all these different focus positions when it comes to flats? Do you attempt to somehow cover every eventuality with numerous different sets of flats for each filter at each temperature (and hence focus position) ? Or do you just use one set of flats at a "standard" temperature for each filter, and assume that the tweaks for temperature are minor enough that they won't affect the flat utility as focus changes? In general, do people take new flats every night or do you use a standard set you reuse for a while? I'm hoping I can keep using a standard sets as I always find generating flats a right pain, mostly because I haven't cobbled together a decent flat box yet! (I do have an EL panel that works ok but I haven't got suitable housing, t-shirts, bits of paper or whatever to make it easily usable with no faff - more DIY required).
  10. Hmm ok I'll need to do some more investigating. I've already emailed FLO and they've contacted ZWO about how the adapter is supposed to fit. I'm just wary about unscrewing the inner 4 if there's any chance I'll muck up the focuser mechanism, it's my brand new shiny and I'm hesitant to break it!
  11. Thanks for the tip! I'll give that a go. Yes I'm very happy with the FOV of the scope/camera combo. I'm feeling the need for something narrower for galaxies though! That's going on my to-watch list - thanks. So many hours to be "wasted" in processing!
  12. Hi - I'm going to be brave and make my first post of something I've recently captured with my new gear. It's been many years since I've posted an astrophoto publically! This is the Bubble Nebula region in Cassiopeia. I captured the data on the nights of the 17th and 18th September from my back garden in Plymouth (Bortle 6 according to FLO's app). About 4hrs each HA, SII and OIII, in 300s individual exposures using a SkyWatcher Esprit 100 scope, ZWO ASI1600MM Pro camera (200 gain 50 offset -10C temp), iOptron CEM60 mount and ZWO filterwheel with 1.25" HA, SII and OIII filters. Captured with APT, guiding by PHD2 with a Skywatcher Evoguide 50ED guidescope and ZWO ASI120mm mini camera. Processed in PixInsight with a SHO palette colour combine of the filter masters, then various curve adjustments and a DarkStructureEnhance. I'm a real PixInsight novice so I basically followed bits of assorted relevant-looking tutorials I came across. Please critique as I know there's plenty to improve! I did have trouble with too-much-green, and also halos on the OIII subs around some of the bright stars which I believe is a common issue with OIII filters and also especially with the 1600 camera; something to do with a lack of anti reflective coating on the sensor? I tamed the halos using RangeMasks and curve adjusts.
  13. Adding a link to a pic of the bracket fixed to the Esprit 100 focuser with annotations to show the issue I'm having : https://imgur.com/a/SDn2QOO
  14. Hi, picked up a ZWO EAF focus unit recently (in fact, the one advertised here as customer return - thanks FLO!) and I've fitted it to my SW Esprit 100 scope using the "Takahashi Adapter kit" (which advertises as also being suitable for the Esprit 100). However it wasn't a smooth fitting; the bracket will only bolt into one bolt hole under the focus tube, not a pair of two as I'd have thought required for a nice firm non-slipping fit, plus it's at a (slight) angle since the holes don't line up nicely. The holes I'm attempting to bolt into are the OUTER pair of holes as you look under the focus tube; these are apparently the ones designed to have things bolted into them. Has anyone else fitted this focus unit to this scope successfully? It does seem to function like I have it - focus moves in and out ok even when pointing at zenith which I assume strains the focuser the most. But it doesn't feel correct and it worries me maybe it'll be straining something more than it should, being "forced" a little like it is. The bracket would have fitted nicely into two other bolt holes under the focuser (two of the inner set of 4 holes), but I'm 99.9% sure those holes are for adjusting the focus drawtube tension etc, NOT for bolting brackets into underneath. So I'm very loathe to touch those.
  15. Hello Bedfordshire, grew up in Leighton Buzzard so that's my old stomping ground
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