BrendanC

Thanks! 

Hi,

So I've been getting to grips with polar alignment with Sharpcap.

Tonight, I got the best yet, really close to perfect.

Then, out of curiosity, I set my scope to the home position, took a shot, plate solved it, and sent the result to Stellarium. This is what I saw:

Polaris is only just about in the frame (the red outline).

Does this say anything about my polar alignment being good/bad? Or is it more about how I've set the home position? Or doesn't it really matter as long as I align my stars properly?

Also, related to polar alignment: if I slew horizontally, and the star I'm looking at on my screen goes across at a slight, non-horizontal angle (same for vertical - slewing vertically and star deviates from the vertical line), does this imply anything about my alignment, or more about whether the mount is level?

Thanks, Brendan

OK, just took a screenshot of an unfocused star - my collimation is terrible and I can see the focuser intruding.

So, this could be at least partly the issue. I will look into this!

Hi all,

I have a problem with my 130PDS (I think - or it could be the mount, the software, or any number of things, but it's probably the optics).

I've posted elsewhere about this (see https://stargazerslounge.com/topic/358322-what-on-earth-has-happened-here/) but was advised that the resident 130PDS experts (that's you!) might be able to help. So, apologies if this counts as a double post, I'm just doing what I was told...!

So, the problem is, I'm getting subs that look like this (zooming in to show the details at the corners and middle - these are all from one, unprocessed sub, at actual size):

Top left

Bottom left

Bottom right

Top right

And finally, middle

There are several things going on, as you can see. The directions of the blurring changes. Some stars are out of focus. And none of them look at all right to me.

A previous similar problem seemed to be fixed by making the mount east-heavy, but as you can see, it's far from fixed the problem.

The latest thinking is that it could be the focuser impinging on the image?  This is what someone has found when zooming in:

For comparison, here's a sub I took a couple of months ago, exact same setup except that I've disassembled the kit a couple of times during bad weather, I'm now using EQMOD directly connected to my mount, and I'm also trying to improve my polar alignment by using Sharpcap (click image to see larger version then save that to see original, albeit jpg). The problem doesn't seem to be here?

You can see my kit list in my signature.

I'm tearing my hair out (or at least what's left of it) to figure this one out. If anyone has any ideas, I'd really appreciate it.

Thanks, Brendan

Thanks, will do.

For what it's worth, here's a sub from M13 that I took a couple of months ago (click image to see larger version then save that to see original, albeit jpg). Doesn't look like there's a problem here? As you can imagine, going from this, to what I have now, is fairly dispiriting...

Well, blow me darn wiv a fevver.

I never considered actually zooming into a star like that to see what was going on! Doh...

OK, well, this is all very interesting. I don't quite understand why this should have started becoming a problem - although it's entirely possible that it's only revealing itself to be an issue now that I'm using a decent mount, compared to the old AZ mount.

I'm EXTRAORDINARILY reluctant to start sawing bits off the tube however. Are there any other ways around this?

Oh, and one more very quick question: would this also account for the way the blurs are in different orientations? Or would that be something else entirely?

Thanks for all the help so far.

Thanks.

I have both, the Lynx and the Prolific cables, which is why I've been talking about direct connection (via Lynx) and handset connection (via Prolific).

I can't get either to work with the app. It was really just to see if I could. I refuse to believe tech will not bow down before me and accept me as its master.

Anyway, as you say, time to move on, forget Prolific, live in the now, etc.

Thanks for your help (all over again!)

Cheers, Brendan

Right. So. Here we go....

I've drawn a blank with the direct connection, so I tried the mount -> handset -> Prolific cable -> laptop approach again.

This thread is quite interesting: https://stargazerslounge.com/topic/352831-solved-synscan-usb-dongle-not-connecting-to-synscanpro/

It implies it's either drivers, or USB3. My new laptop doesn't have any USB2 sockets (and my previous laptop and netbook both did have them but didn't work either), so I explored the drivers angle.

Downloaded the latest Prolific drivers, set the handset to PC Direct - and it worked! Connected to the app straight away. Go into APT, I can select the Synscan App driver, all good. I could scarcely believe it after all this.

So I tried it a few times to make sure, exited the app, fired it up again, all good. Then I unplugged the cable and plugged it back in as a test... and it didn't work. Unable to connect again. 

I tried with another port and got the same result - again, just once. I've since not been able to get this to work at all with any ports.

Looking at this more broadly it seems Prolific and Windows 10 don't get on well - see https://answers.microsoft.com/en-us/windows/forum/windows_10-hardware/prolific-usb-to-serial-comm-port-windows-10/0a4f8e48-7135-4434-9d10-349c9ce87fcf?auth=1 which also links to http://wp.brodzinski.net/hardware/fake-pl2303-how-to-install/ - which I've also tried with no success.

So this is the darnedest thing. It has worked, twice, once for two ports, so it does actually work. But I've tried every combination I can think of:

• Different ports
• Different order of switching things on
• Different order of plugging things in
• Different drivers
• Different values for resent tries and read timeouts
• Alternative, non-Prolific USB-serial converter (which probably wouldn't work anyway but tried it nonetheless)
• Handset PC Direct mode enabled and disabled
• Running Synscan app as Administrator
• Rebooting

... and none of them work.

@stash_old - in case you're interested, here are the screenshots of what's happening:

The COM ports are definitely being read correctly - as in, plug the cable into one USB socket and it says COM5, the next one, says COM6, etc, all repeatable, all agrees with what I see in Device Manager.

So I'm wondering whether there's just something not right with either the Synscan driver, the Prolific driver, or both.

I'm probably going to tie this one off now. It was just out of curiosity to see whether a new laptop would mean I could use the app, but it appears not. I just like things to work the way they should!

Thanks, I'll do that. I'll also try and get myself in gear and show some screenshots, after I've played around a bit more.

Thanks, I really, really appreciate the time and thought you must have put into this.

However, I fall at the first post I'm afraid!

When you say 'start the Synscan App and connect to the mount via the Synscan App connect method' - I can only do that with the drivers UNinstalled, which means there are then no drivers to select in APT.

If I install the drivers, without fail, the app simply will not connect. The drivers appear in the scope chooser, as per your screenshots above, but that doesn't connect either. I've checked everything, COM ports etc.

That's the dilemma here! It's just plain weird.

Given that this is a new laptop, I can only assume there's something amiss with the drivers and/or my mount. It still beats me though that the app works WITHOUT drivers! I mean, how on earth is that even possible? That's my real query here, I guess.

Aaaaanyway, it was just a query about whether there's anything I could do about this. Looks like there isn't, unless I dig around and see whether anything's being blocked but I doubt it.

Thanks again.

Bit crazy, this one.

I used to have a Skywatcher AZ Goto mount, which I controlled from my PC using the Windows Synscan app, via the handset. Worked like a dream.

I then got a second-hand NEQ6 mount. I couldn't get the app to work with it, but EQMOD did work, so I thought that was that. I still really liked using the app though - it just suited me.

I've recently had to get a new laptop, so it's all a fresh new build. And, out of curiosity, I wondered whether the app would work with it.

Installed it, plugged in the cable (one of these: https://www.firstlightoptics.com/sky-watcher-mount-accessories/lynx-astro-ftdi-eqdir-usb-adapter-for-sky-watcher-eq6-or-neq6-syntrek-pro-mounts.html) - and it worked! And I was glad.

So, over to APT to get that working with it, but there was no Skywatcher option in the scope menu. Of course, that was because there were no drivers... and yet the app worked? Hmmm.

So, I installed the Skywatcher mobile drivers, which are the ones that the app  uses - and the app no longer connected to the mount!

I uninstalled them - and it still didn't connect.

I restarted the laptop - and it connected.

Repeat a few times just to establish that, against all logic, the Sysncan app connects to the mount when the drivers are UNINSTALLED, but NOT when they're installed! 

So, questions are:

* If I uninstall the drivers and can connect, then how would I get software like APT to work with the mount?

* If I install the drivers, can anyone suggest a reason why it then doesn't connect?

I know that I could continue with EQMOD but I have some other issues and I'm trying to identify whether they're to do with optics or alignment, so using the app would come in very handy as an alternative way to control the mount from the laptop.

Thanks, Brendan

The intruding focuser is a candidate, I agree, but I just don't understand why it should suddenly have become a problem.

Also, wouldn't the images all be in the same direction? The examples I posted show that the corners all have different directions, which @ollypenrice pointed out.

Interesting, I'll take a look at that too.

I just collimated the hell out of my OTA, and reconnected the handset.

If that doesn't work then I'll be out of ideas.

I've had so many issues over the past few months I'm seriously considering throwing in the towel.

Brilliant. I am so very grateful for your help with this. I will take another look at the optical setup and might repost as you suggest with a new title.

If I still have problems I'm going to plan B (actually, plan Z given all the issues I've had): use the handset and see if that improves things at all.

Thanks again.

How could that cause these issues though? I never had them in the previous 18 months of using an AZ mount, with the same OTA, focuser and camera. I also didn't have this problem when I first used the new mount with the handset. 

This is a new problem since using EQMOD. But that could be a red herring. 

It's driving me mad frankly. 

@ollypenrice seemed to have an idea about analysing the corners and middle of the image, so I'm hoping he will pop up and help here. 

I think it's fine from what I can see. 

Personally I think there's some timing issue somewhere. Something isn't set right. When I align stars they're all out more than I would expect. I'm going to go back to using the handset for alignment as a test, unless anyone can pinpoint the problem here. 

@ollypenrice - help!!!! (and anyone else too!)

So I thought I'd fixed this. I was wrong. Right now, I'm looking at every frame coming through with a ton of problems. I've tried changing dithering times and settle periods, turning dithering off, using anti-vibration pause (this is all in APT), been outside to check for snagged cables, moved weights around - no change.

Comparing this with the very first shots I took in May, when I first got the mount, I seem to have taken several huge steps backwards! None of these artefacts were present then. Since then I've moved the setup to a lawn rather than cement, for better vibration and less heat, but a big change has been to start using EQMOD to bypass the hand controller, which means I'm tracking using Stellarium now. I do wonder whether something is very wrong with this setup, and I might just go back to the hand controller next time to check. I've checked that EQMOD, Stellarium and Stellarium Scope are all using the same locations and epoch settings. Put it this way: if the hand controller works, I'm more than happy to go back to it!

So, as you requested, here are five shots, just crops at original size, from one single sub:

Top left

Bottom left

Bottom right

Top right

And finally, middle

You can see my kit list in my signature.

I have absolutely no idea what to do about this, so any/all comments welcome. I'm sure my collimation and polar alignment aren't the greatest (I'm still really learning, I've moved to Sharpcap Pro for the polar alignment, only my second time doing it this way), but anything anyone can suggest, please do.

Thanks, Brendan

It's actually amazing. I've just spent an hour being amazed by it. I love that it integrates with Stellarium and APT too.

Basically, all the data and tools I've been creating myself, have been done much better in Telescopius!

The only gripe is that it keeps forgetting the aperture of my scope which I've set as 5 inches but it keeps changing it to 8 inches. Still, I really like it. Definitely my new toy.

I think I just didn't 'get it' before because it is a little daunting, as is so much of the astro software and sites. But after trying to do this myself, I suddenly understand what it's all about.

And it's free. 

Nice recommendation, thanks.

Hmmmm. Telescopius is rather good isn't it? In fact, it's pretty much exactly what I've been trying to put together!

I might abandon my foolish home-brewed approach and use Telescopius instead.

Lots of food for thought, thanks everyone.

I've come across Telescopius before, wasn't quite sure how to use it but I might give it another go off the recommendation here.

I'm setting up a spreadsheet of objects I'm interested in, and when's best for me to image them.

I'm using Stellarium to find each object to decide whether it's visible from my location.

However, I'm not sure what to list as the 'best' time. Options are:

• When we hit astronomical darkness and the object is as LOW as possible - because that gives me the most time to capture it as it moves across the sky throughout the night
• When we hit astronomical darkness and the object is as HIGH as possible - because that gives the least amount of atmospheric distortion BUT also less time with the object because it's already traversed half the sky
• Or something else entirely.

To take M42 as an example: where I live, towards the end of January, astronomical darkness is at around 6:30pm, and that's about when M42 becomes visible in my garden, at its lowest point. However, toward the end of February, when darkness is at about 7:30pm, it's at its highest. So which of those would be better to add to my spreadsheet as 'the best' time to think about imaging it?

Is this even making sense?

Any/all comments welcome, including ones telling me I'm not making any sense.

Very good! I like the idea of subtracting one from the other.

Until I get around to doing that, presumably there's no harm in continuing to use both? 

Thanks for all the suggestions but it turned out I need the mount to be east-heavy. Having done that, the problem is fixed (until it, or another of the myriad problems I've been having, pops up again).

Thanks, Brendan

I just did a big test with a load of different combinations of calibration frames.

I couldn't tell the difference between those processed with flat darks, and those with bias.

Further research implies that they're essentially the same thing.

So, for a DSLR:

• Is there any case where I should use both flat darks and bias?
• If not, am I actually making my images worse by using both? In which case, which one should I use?

That's all!

Thanks, Brendan

Thanks! I just got an 'official' reply from Ivo at APT and he confirms what you say - so 590mm it is then.

I think I'll also try the FWHM focusing tool too, just for laughs.