SharpCap Forums

Hi Robin,

I stumbled over a small but annoying thing with recent versions of SharpCap in combination with a Moravian camera and the direct driver. In all of the recent versions, including the latest v4.1.13651, the "Quick Picks" selection for the exposure time is empty. The camera works and I can change exposure times by entering it directly or using the slider... so, in a sense it is a small inconvenience

I have been using version v4.1.13268 for a long time - and this and earlier versions do not have this problem. I went back and forth between old and new version on three different computers with three different Moravian cameras (C3-61000 Pro and C1x-61000 Pro) and it is fully reproducible. The problem does not appear when using the ASCOM driver. But I would like to stick to the direct driver, since the download speeds are much better.

I have attached a log file from v4.1.13651 when connecting via the direct driver. Maybe you find a hint there (no obvious error, I think).

Thank you very much for your great work with SharpCap... one of the best pieces of astro software ever!

Best wishes,
Robert

Hi Robert,

that's an odd one - I have two Moravian cameras here myself, but both seem to give no problem with the quick picks selection list, and as you spotted there isn't much of interest in the log

The most likely cause would be some glitch with the calculation of the minimum and maximum exposure values of the camera - those are used to exclude some of the items in the Quick Picks drowndown if they are outside the available exposure range of the camera. What exposure range do you see for your cameras in SharpCap (minimum / maximum)? My camera seems to allow from 0.125ms to 1000s.

cheers,

Robin

Hi,

one more quick question... are your cameras GPS enabled? Most of the changes between the two versions you mention (13268 and 13651) that are Moravian camera related are to do with the GPS support rather than anything else. I wonder if that could be interfering in some odd way...

cheres,

Robin

Hi Robin,

thanks for replying so quickly.

The cameras are not GPS enabled, just two C3-61000EC PRO (with different firmware versions) and a C1x-61000.

Exploring the minimum and maximum exposure times in the up-to-date version (v4.1.13651) of SharpCap indeed gives a funny result. The minimum exposure time accessible via the slider is 0.156 ms, which is exactly the number from the camera specs. The maximum exposure time I get via the slider is 10 000 000 s... which is crazy large.

In the log file there are the lines

gipMinimalExposure : 156
gipMaximalExposure : 429496729

with the units probably being micro-seconds -- in this way the minimum matches the Moravian documentation and the SharpCap slider. So the maximum exposure time reported there would correspond to approx. 430 sec -- if the units of both outputs is the same.

To test things further, uninstalled the up-to-date version and installed v4.1.13268 again. With everything else unchanged (same computer, camera drivers) the log files now has the following information:

gipMinimalExposure : 156
gipMaximalExposure : 429496

The slider gives me a minimum possible exposure of 0.156 ms and a maximum of 429 s. The quick picks selection is populated with values from 1/4000 s to 5 m. This would be consistent with the log information, if the minimum exposure in the log is in micro-seconds and the maximum exposure in milli-seconds.

Did something change in the way SharpCap handles (the units of) these numbers?

I am a bit surprised by the 429 s as well. The Moravian documentation for the C3-61000 says there is "no theoretical limit on maximal exposure length". If I manually enter 600 s in the field for the exposure time, it works just fine. Maybe the Moravian driver just returns garbage numbers for the maximum exposure... 429496729 is remarkable similar to 4294967295, the maximum for an unsigned 32-bit integer, just missing the last digit

Thanks again for your help!

Cheers,
Robert

Hi Robert,

thanks for the detailed analysis - very welcome

As soon as I saw the value 429496729 in your post, my spider senses were also tingling that the value looked like a maximum integer value. I suspect what is happening is that internally the camera is measuring maximum exposure in 100ns intervals (this is quite common for cameras and video file formats, etc). The SDK probably divides by 10 to get the maximum exposure in microseconds to report, but in this case the 'internal' maximum is a maximum integer value, so you divide 2^32-1 by 10 and get 429496729...

Next, SharpCap tries to convert that to microseconds for compatibility with the minimum exposure by multiplying by 1000, but that is causing an integer overflow, so a weird value comes out at the end of it.

I am going to eliminate the integer overflow and also cap the maximum exposure at 1000s, even if the SDK reports higher, and we will see if that resolves the issue. I suspect that the problem started with the Moravian SDK update in 4.1.13285 introducing a new, higher value, for the maximum exposure which started causing the issues above.

thanks for the help in (hopefully) getting to the bottom of this!

Robin

Hi Robin,

excellent! The modification you describe will definitely fix the problem. Thank you very much for the great help and service, as always.

Best wishes,
Robert