Slow transfer(?) rate - SharpCap4 with SXVR-H694

[Atomic]

Hi all

I wonder if you could help me with a problem. I am fairly new to imaging using dedicated Astro cameras. Up to now, I have only used modified webcams and recently a Zwo 224mc planetary camera SharpCap v4. I am still learning.

I have recently purchased a second hand SXVR-H694 camera from one of the esteemed members of this forum to try some deep sky imaging. 

To practice setting up, I have been imaging the moon in daylight so I can see what I am doing

The problem I have is that the frame rate appears to be (apparently) very slow and I can't fathom out what the problem is. Using the 224mc, I have no problems with a reasonably fast frame rate (using USB2). With the H694, I can only capture one frame every 7 or so seconds, even when I set the capture area  smaller than the 224mc and 8bit.

Starlight express have a 'universal' app called Starlight Vision which uses an elderly version of OpenGL (v3) which is not compatible with the laptop hardware.

Camera settings below. Note the Duration and Frame Count. Although the frame rate is 0.15frames/sec, there is no sign of trailing on the image which suggests that the real frame rate is very much faster. To me it looks like the camera is running slowly processing the data but I can't see why.  Is this normal?

 

Any suggestions?

 

Thanks 

Martyn

 

[H694]
FrameType=Light
Debayer Preview=Off
Capture Area=2750x2200
Binning=1x1
Colour Space=MONO8
Output Format=SER file (*.ser)
Pan=0
Tilt=0
Frame Rate Limit=Maximum
Exposure=2.0000ms
Target Temperature=0
Cooler=On
Temperature=1.20000004768372
Timestamp Frames=Off
Black Level=0
Digital Gain=15.4911138101208
Trail Width=3
Minimum Trail Length=100
Trail Detection Sensitivity=9
Remove Satellite Trails=Off
Background Subtraction=Off
Planet/Disk Stabilization=Off
Banding Threshold=10
Banding Suppression=0
Apply Flat=None
Hot Pixel Sensitivity=5
Subtract Dark=None
NegativeDisplay=0
Display Black Point=0
Display MidTone Point=0.5
Display White Point=1
Notes=
TimeStamp=2023-05-27T19:56:40.8530406Z
SharpCapVersion=4.0.9478.0
StartCapture=2023-05-27T19:56:45.0012779Z
MidCapture=2023-05-27T19:57:17.7932779Z
EndCapture=2023-05-27T19:57:50.5860291Z
Duration=65.585s
FrameCount=10
ActualFrameRate=0.1525fps
TimeZone=+1.00

 

and with reduced frame size:

[H694]
FrameType=Light
Debayer Preview=Off
Capture Area=1024x768
Binning=1x1
Colour Space=MONO8
Output Format=SER file (*.ser)
Pan=862
Tilt=716
Frame Rate Limit=Maximum
Exposure=2.0000ms
Target Temperature=0
Cooler=On
Temperature=0.200000002980232
Timestamp Frames=Off
Black Level=0
Digital Gain=15.4911138101208
Trail Width=3
Minimum Trail Length=100
Trail Detection Sensitivity=9
Remove Satellite Trails=Off
Background Subtraction=Off
Planet/Disk Stabilization=Off
Banding Threshold=10
Banding Suppression=0
Apply Flat=None
Hot Pixel Sensitivity=5
Subtract Dark=None
NegativeDisplay=0
Display Black Point=0
Display MidTone Point=0.5
Display White Point=1
Notes=
TimeStamp=2023-05-27T20:09:33.1832153Z
SharpCapVersion=4.0.9478.0
StartCapture=2023-05-27T20:09:35.3503394Z
MidCapture=2023-05-27T20:10:31.5873394Z
EndCapture=2023-05-27T20:11:27.8247724Z
Duration=112.474s
FrameCount=26
ActualFrameRate=0.2312fps
TimeZone=+1.00

[Cosmic Geoff]

2 hours ago, Atomic said:

Capture Area=2750x2200

There's your answer.  It will take time to stuff this much data down a USB2 connection.  That is four times as much data as a ASI224MC even if you are using the whole of the ASI224MC's chip and not a reduced region-of-interest.

However, for deep sky imaging, you will be doing something entirely different: stacking a series of multi-second exposures.

Edited May 28, 2023 by Cosmic Geoff

[Atomic]

Thanks for the response.

 

However, if you look at the lower config file, I am still getting a very poor frame rate using 1024x768

 

[H694]
FrameType=Light
Debayer Preview=Off
Capture Area=1024x768

...

Duration=112.474s
FrameCount=26
ActualFrameRate=0.2312fps

 

To me it looks like the camera is processing very slowly, its not a transfer issue. I am just puzzled about this, I think I'll need to ask Starlight Xpress.

 

Martyn

Edited May 29, 2023 by Atomic

[Atomic]

I have had a very auick response back from SX.

<snip>

These cameras were designed to give minimal readout noise and this requires a relatively slow download speed. Your 7 seconds is pretty typical for the SXVR cameras.

CCDs have a single readout amplifier, unlike CMOS cameras that have severalthousand, and so they cannot be downloaded very quickly. This is not anissue for a deep sky camera, as the exposure times are typically hundreds of seconds, and so a 7 second download is a small part of the time per image.

 

Problem resolved.. 

Best wishes 

Martyn

[newbie alert]

Hang on, the SX 694 is a CCD deepsky camera, it's strengths are to capture deepsky long exposure for dim targets.. you don't need frames per second, it's one exposure over several minutes,with my atik branded 694 chip i use 300 sec for broadband and 600-900 sec subs for narrowband..The 224 is usually used for planetary where rapid frame rates are their strengths, more FPS if using a smaller part of the chip, IE using ROI.. it can be used for deepsky but not the usual tool for it..

Planetary and deepsky are vastly different