BrendanC

Thanks. Perhaps I have a lot of cone error, but this has never, ever happened before. Having said which, I don't think I've ever imaged such a high object pre- and post-flip before either. Guiding was great and I'd polar aligned only a couple of nights previously, and I don't tend to need to keep doing it every time, going by experience. Collimation seemed fine. Perhaps the OTA wasn't seated right? I did recently replace the secondary vane with one of those Backyard Universe spiders. Could this have anything to do with it? I really don't know any more. I've had repeated weird, random issues for about a year now and I'm pretty much running out of steam with astro. This feels like the last straw, to be honest. Thanks anyway.

Hi all, I'm having the darnedest time with my rig of late. So many issues, and now, after I thought I'd fixed them all, I get this: It's from my shoot last night. It only appears when I stack images before and after the meridian flip. If I stack just images before or just after - even stacking with images from the previous night, matching before with before and after with after - I just get nice, single, crisp spikes. Stacking before flip with after flip gives me... this. I always thought the only thing that determines the angle of spikes is the OTA's rotation within the clamps, and I most certainly did not change this last night. Everything is solid. I've read that it could be cone error? Any takers? I'm fixing to chuck this game in sometime soon if I cannot get just one decent night's shoot in months... Thanks Brendan

Latest on this is that last night, I increased the Flip Moment from 5 to 10, on a hunch that I may have changed it to 5 a while back and that could be an issue. I tested a flip before the shoot, and it went perfectly - shooting M57, the Ring Nebula. So, I started the main shoot, which was the Dark Shark nebula. Still, I decided to wait around and make absolutely sure the flip worked - and it failed again. A different fail this time, because I wasn't getting the 1s flip fail errors (which hopefully was because of the increased moment, which stopped tracking etc before hitting the EQMOD limits), but when I went out to check the scope, it was solving on one side of the pier, calculating several thousand pixels out, and slewing across to the other side, flipping each time. I stopped it, waited five minutes, and it was OK. This tells me that I needed to add some time to the Delay Flip Move, but as it was already set to 15 minutes, it's now set at 20 minutes. It seems to me that 10 minutes Flip Moment plus 20 minutes Delay Flip Move is excessive! That's 30 minutes gone, not including the actual slewing and imaging and solving time. So, I'm wondering a few things: * I've been getting large values for the initial offset when plate solving, so my scope must be slightly misaligned compared to where it thinks it's pointing when parked. Would it help to physically try and shift the rig so that I at least get Polaris in my view when it's parked, to reduce this error? Obviously polar aligning too. * Might the large offset combine with a high altitude object to produce the flip issue? Because the Dark Shark is pretty high in my sky and I can see how small changes can result in large offsets at those altitudes (like the errors you can get if you try to plate solve near Polaris). In which case, could it be that I just need these large moment and delay values for such objects? * As part of my routine, would it help if I perform a solve sync routine before a shoot, just to help establish a more accurate sky model? Any/all comments welcome. I'd much rather not have to stay up till 2am again checking that everything is working! @Yoddha, can you shed any insight please? Thanks, Brendan

Thank you.

Thanks, I've posted there, not received a reply yet but I agree, Ivo is great so hopefully they'll take a look sometime soon. I'm just trying everything/everyone!

Hi all, I recently had a meridian flip fail on me, and I cannot figure out why. If anyone here is clued up on APT and fancies taking a look at the log and offering suggestions, that would be great - attached. The fun and games start at the line Starting Automated Meridian Flip at the time stamp 2023/08/17 01:22:27. There are mentions of 'Slew state is false in less than 1s.'. Any recommendations welcome. Thanks, Brendan APT_LogFile.log

How about these? https://www.gwr-fasteners.co.uk/m4-x-6mm-socket-cap-head-screws-din-912---aluminium-7075-91248-p.asp I'm finding it quite a challenge to find anything that isn't stainless steel. How about placing washers or grease between the screws and the scope?

Argh, I did not know this. I'll try and cancel the order! What material would be best? And in fact, seeing as I'm clueless with this sort of thing, if you could provide a link to what I need, that would be amazing.

Good point, but it really was the head of the screw that was the issue. It had been dodgy for a while

Excellent, thank you so much!

Hi all, I just had a bit of a mare with the external screws that hold the primary cell in place which I've just fixed. One of them had stripped but after about 30 minutes of panic, I finally got it out. Now, of course, I need a new screw. So, does anyone know please which are the right screws for the job? I'm talking the ones that secure the primary cell - see photo (complete with stripped screw that has since been dislodged!) Actually, thinking about this some more, if anyone knows the size and pitch, I might invest in something more robust. Thanks, Brendan

Superstar. I just PMd you.

Yep. I mean, I'm not bad - I've collimated the scope (many, many times), added a primary mask, flocked it (used the technique where you get a vinyl sheet, flock that, wrap it and insert it into the tube so you don't have to remove the spider), chopped the focus tube, added auto focus etc. But every time I do anything with it, I get into a hot sweat and absolutely dread doing it. And this project, even though plenty of people have done it before, is just a step too far for me. I could do it - in fact, I've already asked other places with no luck so I probably will have to do it myself - but I just won't enjoy the experience. At all. Hence my willingness to pay someone to take away the pain!

Hi all, I recently got me one of these, hopefully to cure issues with collimation and diff spikes on my 130PDS (see https://www.firstlightoptics.com/misc/backyard-universe-secondary-mirror-spider-for-sky-watcher-130mm-newtonian-telescopes.html) HOWEVER... I'm really not good with practical stuff. I was the kind of kid who would buy an Airfix model, promise himself he'd do his very best to make it look as good as possible, then end up with glue and paint everywhere. So, here's my proposal: is there anyone here who lives near the Oxfordshire/Buckinghamshire/Hertfordshire/Bedfordshire area who is confident with taking the existing spider out, removing the flocking that will have to come out, siliconing the washer onto the secondary (and ideally give the secondary a bit of a wash), assembling the spider, inserting it back into the scope, and re-collimating it for me? I am very willing to pay a good price if someone could do this. I've done things in the past with this scope (primary mask, flocking etc) and one thing I've learned is that I HATE mucking about with it. I keep trying to force myself to do this myself, and putting it off. If someone else fancies having a go, please let me know. Thanks. PS I've seen lots of videos and suchlike about how to do this, and I still don't want to do it. Even if it's supposed to be easy, I'm pretty confident I'll mess it up.

Outstanding. Thank you Olly.

Thanks for the links but I'm afraid I started reading that page and just got lost. I guess I'll just keep collimating with the secondary centre aligned to produce the offset pattern as before.

This is probably about right!

"My God, it's full of dust." Awesome image. I've come across HDRMultiscaleTransform before and intended to find out more about it, perhaps now is the time. Also, I'm intrigued by standard 30s exposures! I guess that with an 11" RASA you have a huge light bucket which enables that. I'm going for 30s for the core but I'm generally about right with broadband at 120s gain 101 with my rig and conditions. After previewing the data last night I'm going to ditch the 300s stuff because it's just overexposing everything and not really improving things, so the next couple of nights it's going to be 120s as per usual, and I might just try an hour or so of 15s to really get to the heart of the nebula, just as an experiment. That's what I did with my M42 and captured the trapezium, and how I approached my M3 too recently to avoid it just being a big bright blob. Ended up looking like a dandelion! Thanks for the advice all, really appreciate it.

On it like a car bonnet. Thanks!

Hi all, I've been gathering data for the Iris nebula this month. I want to do as good a job as I possibly can on it, and so I've decided that I'm going to collect three sets: one for the overall image at 120s subs (this is with an ASI533MC Pro and 130PDS, that sub length works fine for noise levels); one at 30s exposures to try and get as much detail from the core as possible which is often blown out; and 300s so that I can get as much of the surrounding dust as possible. The idea is to stack them separately, remove the stars, process, layer and mask in Photoshop, then put the stars from the 120s group back in. Or, would it be best just to stack the whole lot in one go? Or, should I just not do this at all and go for the standard 120s, and assume the core will be fine, and that I'll be able to process the dust without additional ultra-long exposures? Any/all advice appreciated! Thanks Brendan

Thanks for this (and I was sure I was following this topic otherwise I'd have replied sooner!) So, of the diagram I included, which should I be looking at? Option 1, 2, or something else?

I know this is an old thread, but I was just reading it again and realised I don't understand this bit: 'allows for perfectly centering the secondary under the focuser' vs 'the seconday is not supposed to be physically centered in the tube'. Aren't they contradictory? Should the secondary be centered in the tube or not? I've been thinking about this recently. There's supposed to be an offset in fast (above F5) Newts, but I always thought that meant the secondary was centered, but the image from the Cheshire relative to the primary showed an offset. But, I've been wondering recently whether the secondary should also be physically offset, in which case, would that produce a central image? Diagram below showing what I mean.

I did consider sellotape but the tolerances are very narrow - I honestly don't think I'd be able to get the coma corrector into the tube even with a very thin tape around it. However, the parfocal ring just worked perfectly. The only problem was that the grubs also kept popping over the ridge! So I tightened them just enough to keep the ring in place, but not pop out. The ring is after all just there for the spacing, it doesn't have to be tight. In fact, this fixed three things in one go: The coma corrector is now very well held because the screws aren't gripping at the ridge I was able to recommission an old compression ring so it has an even surer grip After chopping the focuser tube to stop it intruding on the primary mirror path a while ago, I'd left myself with very little additional play and it had popped off a couple of times during auto focus. I'd bought the parfocal rings especially to fix this, but it hadn't happened for a while so just left well alone. Now however, I've got a few mm spare which is good for peace of mind. So, all in all, a great suggestion, thank you @michael8554!

This. Not least because I had the exact same thought about five minutes ago, not even kidding. I even have some parfocal rings. Thank you.

Hi all, The SkyWatcher 0.9x coma corrector has a ridge around it that almost exactly coincides with where the focuser tube screws hold it on my 130PDS Newt. When they grip it right, I have virtually no tilt. However, sometimes they sort of slip off it, causing the camera to slip imperceptibly, but enough to create tilt in the images. I tried a compression ring but that's even worse - you can actually see the camera 'pop' up as the ring is tightened and it slips off the ridge. You can even see it on their promo images - that black ridge line running around the shaft. It's a bad design! But I really, really don't want to have to buy a different coma corrector if I can avoid it. Anyone have this coma corrector? Anyone have a similar problem (I have read about other people saying this in the past but can't find the links again)? If so, anyone have a fix? I've heard tell that a third thumbscrew can sort this out, but it would still be on the ridge, and I wouldn't have a clue how to do this. Thanks Brendan