QHYCCD

QHY268C Buffers Three Frames

QHY268C Buffers Three Frames
« on: March 11, 2021, 09:26:02 PM »
Hello,

I have a QHY268C.  It works great, except it always buffers two or three frames even in still mode.  I have tried all recent and beta drivers, USB speeds, and short 3.0 cable.  Nothing seems to work.  It's very difficult with longer exposures because it can take a half an hour before I see the first frame and focus can change by then.

Here is some discussion in the SharpCap forums that could not be solved:

https://forums.sharpcap.co.uk/viewtopic.php?f=28&t=3717&sid=24f9ea82bfc06e9edd624e5cb97b05e7

Other users seem to have the same issue, and a variant where it keeps buffering but never displays.  I've had it also occur where it buffers about 20 seconds even with sub-second exposure setting.

Thanks!


Re: QHY268C Buffers Three Frames
« Reply #1 on: March 14, 2021, 08:59:05 PM »
Hi,
    You mean SharpCap need take triple time to get one frame?
    I need check this issue,please wait some time.
Best Regards,
QinXiaoXu

Re: QHY268C Buffers Three Frames
« Reply #2 on: March 14, 2021, 10:42:21 PM »
Hi,
    You mean SharpCap need take triple time to get one frame?
    I need check this issue,please wait some time.
Best Regards,
QinXiaoXu

Yes, specifically that it buffers three frames before displaying the first, then the second frame captured displays after the fourth one is done capturing, and on, so is therefore always 2 frames behind.

Re: QHY268C Buffers Three Frames
« Reply #3 on: March 15, 2021, 11:36:06 PM »
Hi,
    I tested this issue,on my side,it can work normally,I tested 5s 10s and 15s,only first frame need double time,after frames can work well.
    My firmware version is 21.02.20,FPGA version is 20-6-2-128,SDK version is 21.02.19.19,connected directly to PC USB3.0 port.
    If you adjust traffic,and setup DDR on or off,is this helpful?
Best Regards,
QinXiaoXu

Re: QHY268C Buffers Three Frames
« Reply #4 on: March 16, 2021, 11:21:17 PM »
Hi,
    I tested this issue,on my side,it can work normally,I tested 5s 10s and 15s,only first frame need double time,after frames can work well.
    My firmware version is 21.02.20,FPGA version is 20-6-2-128,SDK version is 21.02.19.19,connected directly to PC USB3.0 port.
    If you adjust traffic,and setup DDR on or off,is this helpful?
Best Regards,
QinXiaoXu

I tried all your suggestions, and the best I can get is two frames buffering with USB Traffic at 20.  So with six minutes subframes, the first one appears after 12 minutes.  Please see attachment image to see the settings and  the counter right before the first frame displayed after 12 minutes.  Did you try one this long?   Thank you for helping.

Re: QHY268C Buffers Three Frames
« Reply #5 on: March 16, 2021, 11:25:49 PM »
(Oh, and also, with DDR buffer "Off" it endlessly counts negative and never displays. So I must keep that on.)

Re: QHY268C Buffers Three Frames
« Reply #6 on: March 17, 2021, 05:24:21 AM »
Hi,
    I tested long expose time,5mins and 10mins,the result is same,only the first frame need double time.
Best Regards,
QinXiaoXu

Re: QHY268C Buffers Three Frames
« Reply #7 on: March 23, 2021, 02:20:27 AM »
Hi,
    I tested long expose time,5mins and 10mins,the result is same,only the first frame need double time.
Best Regards,
QinXiaoXu

Thank you, but is it possible not to double buffer the first frame? It actually causes every frame to be a frame behind for me when it's double buffered.

Re: QHY268C Buffers Three Frames
« Reply #8 on: March 23, 2021, 03:25:42 PM »
I'm suffering from the same issue of overlong first frames with my 294c as well, even with the latest 21.02.26 all-in-one package.

There is a discussion about this on the ShaprCap froum

https://forums.sharpcap.co.uk/viewtopic.php?f=28&t=3532

best regards
Bernd

Re: QHY268C Buffers Three Frames
« Reply #9 on: March 23, 2021, 09:01:56 PM »
    Well,maybe I can try it,but our result seem not same,Bernd and me only first frame need double time,but you seem all frame need double or triple time.
Best Regards,
QinXiaoXu

Re: QHY268C Buffers Three Frames
« Reply #10 on: March 24, 2021, 02:15:45 AM »
Hello all,

I see the same problem: The first image after changing settings needs double time.
Why is this? Other cameras do not have that problem, so this seems to be a bug?

Thanks for looking into this
Best regards
Stefan

Re: QHY268C Buffers Three Frames
« Reply #11 on: March 24, 2021, 08:29:42 PM »
    Well,not bug,in my memory,this is order to make frame can expose correctly,so we skip first frame.
Best Regards,
QinXiaoXu

Re: QHY268C Buffers Three Frames
« Reply #12 on: March 25, 2021, 12:43:05 PM »
Hello QinXiaoXu,

thanks for the info.
I do not see this behavior with my other QHY cameras (QHY5III462C and QHY164M-GPS), only with the QHY268C.
Why is it needed for the 268C, but not for the others?

Also, this is not documented, so it feels like a bug.

Thanks
Stefan

Re: QHY268C Buffers Three Frames
« Reply #13 on: March 25, 2021, 08:13:53 PM »
    I remember that once there was a time our camera will take double time to get frames,after that my colleague modified it.So it maybe a leftover problem,and QHY5III462C QHY163 and QHY268C use different Live functions,this also has possibility make the differnet results.
    And in any case,I will check the source for this issue,please wait some time.
Best Regards,
QinXiaoXu

Re: QHY268C Buffers Three Frames
« Reply #14 on: March 29, 2021, 03:17:52 AM »
Hi,
    I modified a new SDK,it can output frame directly after you change the expose time.You can try it,this SDK is 32 bits.
Best Regards,
QinXiaoXu