SharpCap Forums

I never change the number of frames - the only option in the dialog box - correct ? I simply hit start capture.
thanks


j

Robin:

I'll try another thing - reconfiguring my system so that only the camera is attached to the PC and see if that makes a difference.

At present I run the camera, the mount ( a Celestron ASGT or SLT mount) and the focuser (JMI through a shoestring astronomy FCUSB device) through a powered USB hub and 15 feet of USB 2.0 cable.

J

Robin:

More testing

Basic system:

Rising Tech IMX 224 camera ( Drivers, SDK etc available at https://drive.google.com/open?id=0B6vbp ... FJuN0VJU0U)
Celestron SLT Mount
JMI motofocus operating through a FCUSB adapter
Dell Latitude d430 computer running Windows 7 Pro, 64 bit.
Running cartes du ciel planetarium program
All connected through a powered 4 port USB hub on the mount connected to the PC with a 15 foot USB 2.0 cable
SharpCap 3.0.4002 with astrotortilla installed for plate solving

Quick Bottom Line: when running the ASCOM version of the camera, I can get everything to work and collect darks, but only if the camera is connected directly to the PC, bypassing the USB hub. In this conficuration the Focuser and Mount both respond to sharpcap. If the camera is connected to the USB hub, I can collect darks, but the focuser is inoperable. The SLT mount does respond to SharpCap. I've tried low and medium frame rate settings to see if that impacted anything but it does not.

When running the Sharpcap pipeline version of the camera I can collect short exposure darks (at 16 microseconds) if the hub is disconnected from the PC, and the camera is direct connected to the PC. Meaning no mount or focuser control. But when I try to collect 2 second darks the system hangs up. Changing the frame rate from medium to low resulted in the system collecting more subframes ( 8 versus 2), but at that point the system hangs.

I've got a lot of different logs as listed below. Let me know if you want to see any of them:

Sharpcap pipeline version of the Camera:

All systems connected through USB Hub - Hangs on 2 second darks capture
All systems connected to PC - camera directly, others through USB hub - hangs on 2 second exposure
Only camera connected (directly) to PC. Hub completely disconnected. Successful at 16ms exposure, hangs up at 2 seconds exposure on 2nd frame.
Dropped frame rate to low,camera directly to PC, Hub disconnected. 2 second exposure Hangs up at 8th frames.

ASCOM version of the camera

Running through Hub at medium frame rate setting. Success capturing darks at 2 seconds, but focuser inoperable
Running through hub at low frame rate setting. Success at 2 seconds, but focuser inoperable.


Thanks in advance for your thoughts

John

One last point - this only impacts the collections of dark frames ( and perhaps flats, I've never tried). Sharpcap running the camera in the Pipeline mode works for live stacking of images without dropping any (many) frames,including subtracting darks that I had previously captured.

j

Ah, I think we are onto something (sadly the black arts of USB cabling, but at least we now know the cause of the issue).

Some things to try

* Use a shorter USB cable to connect the hub - 15 feet (5m) is right on the limit for USB cable lengths and can cause issues especially with high data transfer rates. Something to be aware of is that the 5m limit on USB cables is down to timing of signal flow, not loss in the cable, so it doesn't matter how high a quality 5m+ USB cable you buy, it's still going to be dodgy.

* Try to run a separate cable from a different USB port for the camera and then let the ASCOM hardware share the hub. This was my approach in the end after spending ages fighting with intermittent USB issues - every single thing goes back to the PC on a separate USB cable.

* Show the filter options for your camera in SharpCap (Options->Video Capture Filter or the 'Show...' button in the controls) and adjust the frame rate in the misc tab. Turning that down might be enough to let your camera work nicely with the ASCOM devices without changing the USB cabling.

cheers,

Robin

Thanks much. Ill play some more. Are there any functionality differences between the ASCOM and Pipeline versions ?

Dumb questions: If all go back to the pc separately, will I still be able to do plate solving inside of sharpcap ?

There's a summary of ASCOM vs DirectShow here http://docs.sharpcap.co.uk/2.9/#Choosin ... DirectShow, although the restriction of only saving to AVI when using DirectShow is no longer an issue in 3.0.

Going back on separate USB cables to the PC won't remove any functionality.

cheers,

Robin

If I were to use a 15 foot USB2 cable, I would only consider using an active one (as opposed to passive) - you don't mention which you have. Life experience has shown repeatedly the unpredictable events that can occur with longer cables. I have one of these which works fine

https://www.amazon.co.uk/gp/product/B00 ... UTF8&psc=1

Dave