SharpCap Forums

Hi Robin,

Just to be sure:
Is it true that the current version of SharpCap always stamps the start time of the exposure into the frame, regardless of the file format and whether GPS data is included or not?

Cheers,
Niko

Hi,

the current version *estimates* the start time by taking the time when the frame arrived at SharpCap and subtracting the exposure length. This relies on the exposure time being known to SharpCap (it usually is, but there are some situations with certain webcams or other cameras in 'auto' exposure mode where it might not be).

If you capture a frame to FITS and look at the headers, SharpCap adds comments to the timestamp headers explaining what they represent and the time source - by default 'DATE-OBS' is commented as 'System Clock : Estimated frame start', but the comment will change if for some reason SharpCap doesn't have an exposure time.

It's worth noting that if the camera is running in video mode (typically SharpCap is in 'Live View' mode and exposures less than about 2s) *and* the exposure has just been changed, the exposure SharpCap uses will be the newly changed value, even if there are still frames arriving that were captured at the camera before it received the exposure change message. This will typically apply to at most 2 or 3 frames after the exposure change.

cheers,

Robin