QHYCCD

Exposure start time!

Exposure start time!
« on: April 05, 2021, 02:38:42 AM »
Hello!
I need to determine the start time of the exposure of the frame with an accuracy of 1 ms. I set the exposure time between 0.2 and 0.8 s. Then I call function ret = ExpQHYCCDSingleFrame(camhandle). If you set a timer and count the time that has passed since the moment the command was sent and the moment the response arrived, the time is about 100 ms! When I try to determine the remaining exposure time using function
uint32_t expTimeLeft = GetQHYCCDExposureRemaining(camhandle)/1e+6 I always get 0. Function GetQHYCCDCameraStatus(camhandle, buf) also returns an incomprehensible answer.
So, at what point did the exposition start? How to determine this time?

Thanks, Murat

Re: Exposure start time!
« Reply #1 on: April 05, 2021, 09:32:35 PM »
Hi,
    Which camera do you use?Now not all camera support these two functions.
Best Regards,
QinXiaoXu

Re: Exposure start time!
« Reply #2 on: April 06, 2021, 02:01:48 AM »
QHY600M-8f248548af2218dc6
Pro(water cooled version)

Thanks, Murat

Re: Exposure start time!
« Reply #3 on: April 06, 2021, 09:03:26 PM »
Hi,
    GetQHYCCDCameraStatus function is not be supported for QHY600M,but GetQHYCCDExposureRemaining is suppored.If you don't count with /1e+6,what the result of this function?
Best Regards,
QinXiaoXu

Re: Exposure start time!
« Reply #4 on: April 08, 2021, 06:19:25 AM »
Hi,
for example
    _cam.exptime = 500 * 1e+3;
    _ret = SetQHYCCDParam(_camhandle, CONTROL_EXPOSURE, (double)_cam.exptime);
    QElapsedTimer timer;
    timer.start();
    _ret = ExpQHYCCDSingleFrame(_camhandle);
    qDebug() << "Time ExpQHYCCDSingleFrame = " << timer.elapsed() << "milliseconds";
    uint32_t expTimeLeft = GetQHYCCDExposureRemaining(_camhandle);
    qDebug() << "expTimeLeft = " << expTimeLeft;
This code returns Time ExpQHYCCDSingleFrame = 30 ms, expTimeLeft = 0.

Thanks,
Murat

Re: Exposure start time!
« Reply #5 on: April 08, 2021, 09:03:54 PM »
Hi,
    I need check it,please wait for some time.
Best Regards,
QinXiaoXu

Re: Exposure start time!
« Reply #6 on: April 12, 2021, 03:34:18 AM »
Hi,
    I tested it,this function is not a very user-friendly function,it can only be use when expose time longer than 3s,and it will return remain percent,not real remain expose time.
Best Regards,
QinXiaoXu
« Last Edit: April 12, 2021, 04:00:59 AM by QinXiaoXu »

Re: Exposure start time!
« Reply #7 on: April 14, 2021, 03:10:55 AM »
Hi,

Thanks for the answer. Then, please tell me, when does the exposition start? How to determine this time?

Thanks,
Murat

Re: Exposure start time!
« Reply #8 on: April 14, 2021, 08:27:18 PM »
    Well,now we have no function can get this,but I can try add a function to record the time of sending expose command to camera,but it will also have deviation.
Best Regards,
QinXiaoXu