Register    Login    Forum    Search    FAQ

Board index » Software » Linux




Post new topic Reply to topic  [ 4 posts ] 
Author Message
 Post Posted: Tue Feb 28, 2017 10:24 am 
Offline

Joined: Wed Apr 27, 2016 9:30 pm
Posts: 5
I'm using the ZWO SDK libraries in a project that monitors the night sky for meteors. During nighttime the camera uses a fixed exposure time of 10 fps, while during daytime the exposure time is set to 'automatic', which typically results in rather short exposure times. Switching between daytime to nighttime mode is done at sunset/sunrise by calling ASISetControlValue with the appropriate setting of an ASI_BOOL.

This worked perfectly fine using libraries up to 3.0324, but when I recently switched to version 6.0110 there was suddenly a change in behaviour. After a one successful night of observing the camera switches to daytime mode, but when it comes back to the dark sky the night after, images suddenly appear much darker. While the exposure time is correct (still at 10 fps), the much darker images indicate that somehow the chip does respond as well as the previous night. The level of gain is set to 'automatic' with the ASI_BOOL flag after initialization, and not touched when changing between daytime/nighttime. Brightness and Gamma are always kept at constant values (and I checked these do not change either).

The level of gain attained in darkness is identical on both nights.

Anyone noticed something similar? I suspect this is related to the driver. I'm now trying a workaround by restarting the camera at each twilight.

Cheers,
Eric.


Top 
 Profile  
Reply with quote  
 Post Posted: Wed Mar 01, 2017 9:40 am 
Offline
Site Admin

Joined: Fri Jul 25, 2014 2:43 am
Posts: 195
what's your camere? what software do you use? you should check auto exposure parameters like maxinum exposure and maxinum gain.

_________________
ZWO software engineer
Location:lon=120.6 lat=31.3
SuZhou China


Top 
 Profile  
Reply with quote  
 Post Posted: Thu Mar 09, 2017 12:09 pm 
Offline

Joined: Wed Apr 27, 2016 9:30 pm
Posts: 5
I tested this extensively with an ASI185MC, but it also seems to appear in an ASI120MC. The issue disappears when returning to an earlier driver.

The software is my own development, using the Linux SDK. All parameters are set before video mode is enabled, and only the exptime setting changes from fixed to automatic (and back). The max gain for the ASI185MC is set to 480, and at nighttime the gain indeed reaches these values. Other parameters remain constant. Max exposure is set to (and stays at) 1s, but this is never reached, since auto exposure is only on during daytime.

I can avoid this issue by stopping and restarting the video stream at sunset/sunrise.


Top 
 Profile  
Reply with quote  
 Post Posted: Wed Mar 22, 2017 9:38 am 
Offline
Site Admin

Joined: Fri Jul 25, 2014 2:43 am
Posts: 195
could you please send me your partial code that set auto exposure?
you should comfirm that the unit of control ASI_AUTO_MAX_EXP is second

_________________
ZWO software engineer
Location:lon=120.6 lat=31.3
SuZhou China


Top 
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
 
Post new topic Reply to topic  [ 4 posts ] 

Board index » Software » Linux


Who is online

Users browsing this forum: Baidu [Spider], Bing [Bot] and 1 guest

 
 

 
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
cron