Re: [MaxImDL] Re: Question on exposure-length timing


Nov 22, 2006

 


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#26767 Nov 22, 2006

The Asus motherboard in my observatory PC behaves very strangely when

the software for a Logitech wireless gamepad is loaded (I use the

gamepad to control my CGE mount through Celestron's NexRemote

software). When the Logitech monitoring/calibration software is

active, the computer's clock changes time dramatically.



I noticed this when my time-sync application re-synced the PC's clock

every 15 minutes. Suddenly the MaxIm autoguider error graph made a

75-second jump backward on the X axis, and continued from there.



Needless to say, I uninstalled the Logitech software when I discovered

the problem, and now the clock behaves correctly.



Question: How does MaxIm time the main exposure? Would the exposure be

extended by the amount of the backward time-shift, or is there a

counter that's independent of the time-of-day clock?



Thanks for any insight. There is no problem now that I've fixed the

problem - I'm just curious.



Mike

astronomy.mdodd.com



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#26771 Nov 22, 2006

Mike Dodd wrote: >

> Question: How does MaxIm time the main exposure? Would the exposure be

> extended by the amount of the backward time-shift, or is there a

> counter that's independent of the time-of-day clock?



That depends on the camera model you are using. The better cameras time the

exposure internally in hardware/firmware. Some of the low-end cameras require

us to time it in software (in those cases, we use the chipset "High Performance

Timer", which is not affected by the real-time clock setting). In several

cases, the camera manfuacturer provides us with a completely "black box" driver,

and we have no idea of how it is done!



Doug



---------------



Doug George

dgeorge@...



Diffraction Limited

Makers of Cyanogen Imaging Products

www.cyanogen.com



25 Conover Street

Ottawa, Ontario,

Canada, K2G 4C3



Phone: (613) 225-2732

Fax: (613) 225-9688



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#26775 Nov 22, 2006

> Question: How does MaxIm time the main exposure? Would the exposure be

>> extended by the amount of the backward time-shift, or is there a

>> counter that's independent of the time-of-day clock?

>

> That depends on the camera model you are using. The better cameras

time the > exposure internally in hardware/firmware.



SBIG ST-8 and ST-402.



Mike

astronomy.mdodd.com



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#26776 Nov 22, 2006

Mike Dodd wrote: >

>>>Question: How does MaxIm time the main exposure? Would the exposure be

>>>extended by the amount of the backward time-shift, or is there a

>>>counter that's independent of the time-of-day clock?

>>

>>That depends on the camera model you are using. The better cameras

>>time the exposure internally in hardware/firmware.

>

> SBIG ST-8 and ST-402.



You'd have to ask SBIG to be absolutely certain, because they supply "black box"

camera drivers, but I'm pretty sure the cameras times the exposure internally.



Doug



---------------



Doug George

dgeorge@...



Diffraction Limited

Makers of Cyanogen Imaging Products

www.cyanogen.com



25 Conover Street

Ottawa, Ontario,

Canada, K2G 4C3



Phone: (613) 225-2732

Fax: (613) 225-9688



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