Dropping Frames During Polar Align

A place to report problems and bugs in SharpCap
Forum rules


If you have a problem or question, please check the FAQ to see if it already has an answer : https://www.sharpcap.co.uk/sharpcap-faqs

Please also read about Troubleshooting USB Issues before posting.

*** Please do not post license keys - please report any problems with licensing to 'admin' by private message ***

Please include the following details in any bug report:

* Version of SharpCap
* Camera and other hardware being user
* Operating system version
* Contents of the SharpCap log after the problem has occurred.
[If SharpCap crashes, please send the bug report when prompted instead of including the log]
Post Reply
User avatar
Stub Mandrel
Posts: 19
Joined: Wed Apr 12, 2017 6:48 pm

Dropping Frames During Polar Align

#1

Post by Stub Mandrel »

I've had real problems with polar alignment for the last few months, I has assumed that when I turned the mount 90 degrees the USB lead was being disturbed causing the camera to glitch.

After a frustrating session it took about 10 time to get an alignment, I have worked out the symptoms, and I think it may be a bug.

I use a ZWO ASI120MC for guiding. Sharpcap was solving almost every (2s) frame so the optical setup and settings were optimal.

It would solve as soon as it had built the index. I follow the step by step exactly.

I could rotate 90 degrees, and critically I noticed it would still be capturing new frames.

As soon as I clicked 'next' for the adjustment phase, it would start dropping frames.

In the past, four or five camera resets would eventually leave me with a working polar alignment.

I had assumed this was the camera disconnecting, but after reconnecting the camera and starting again several times I realised it would actually pick up and solve about one in eight or so frames and I was able to reproduce this with it always failing after I had rotated and then clicked 'next' to move on to the adjustment phase. In the end, I was able to polar align, but at around sixteen seconds per adjustment it was a slow process and I accepted 1' when I usually aim for 16" or less.

In the past this did NOT happen but after some change or other it started happening on my old laptop and also happens on my new one.

The ASI1600 appears stable with Sharpcap, and I use the ASI120MC for guiding with PHD2 and it's able to run for hours without dropping out.


So key findings: It isn't me jiggling the lead when rotating the scope. It doesn't appear to be plate solving. It does appear to be triggered (reliably) by Sharpcap moving to the adjustment phase. This seems peculiar as it shouldn't be changing anything about its relationship with the camera.
User avatar
admin
Site Admin
Posts: 13177
Joined: Sat Feb 11, 2017 3:52 pm
Location: Vale of the White Horse, UK
Contact:

Re: Dropping Frames During Polar Align

#2

Post by admin »

Hi,

If you look in the log when the problem is happening, you should see some messages about the dropped frames which will tell us what sort of dropped frame is happening (they can happen due to several causes). The only thing that I can think of that would possibly behave the way you are describing would be if the handling of each frame was somehow taking much longer once you've moved the adjustment phase – I can't quite imagine why the handling of the frame would take more than two seconds though. If the messaging in the log say something about previous frame not processed then we are looking at that sort of cause.

Cheers, Robin
User avatar
Stub Mandrel
Posts: 19
Joined: Wed Apr 12, 2017 6:48 pm

Re: Dropping Frames During Polar Align

#3

Post by Stub Mandrel »

Hi Robin,

Last two sessions have been fine, but on the first of these I had terrible connectivity issues with PHD2 (refusing to find the guide cam, even though Sharpcap could see it) and CcD (refusing to find the mount, even though...)

That said I connected up my Touptec mono to do Venus first yesterday and it wouldn't go above 6 fps full frame with nothing else connected to the computer and only Sharpcap running. Very odd.

I'm starting to think it's an ASCOM issue and a bit of a lottery with what will and won't connect/remain stable.

This is an almost new HP laptop with USB3 / USB3.1 and an SSD which is much faster than my desktop.

I think cables may be an issue so I'm going to get some good quality ones to eliminate that.
User avatar
admin
Site Admin
Posts: 13177
Joined: Sat Feb 11, 2017 3:52 pm
Location: Vale of the White Horse, UK
Contact:

Re: Dropping Frames During Polar Align

#4

Post by admin »

Hi,

It does sound like it may be a cabling issue – either poor connection in one of the cables or USB hubs or extenders playing up. Obviously with a laptop you are limited in the number of USB ports, but try bringing different hardware back to different ports on the machine as much as possible rather than having everything run off a single port. There are a lot more troubleshooting tips for USB issues in the page linked in the Orange box at the top of this thread.

Cheers, Robin
Post Reply