60 sec, 60.1 sec, 60.2 sec and 60.3 sec

[adelacruz]

Good afternoon, in my last session the BackyardEOS 3.2 program took photos of 60 sec, 60.1 sec, 60.2 sec and 60.3 sec. Do you know what the problem can be?

Greetings

[astroman133]

0.3 seconds is a 0.5% variance, so not particularly significant. It would be even less if a 600 second exposure was actually 600.3. That is not bad for an exposure that is started and stopped by a program (BYE) running on a multi-tasking operating system like Windows.

I tested my Windows 10 Pro desktop PC with BYE 3.2.0. I took 5 60 second exposures and examined the EXIF data in the captured images. The recorded times were 60.1, 59.9, 60.1, 60.0, 60.0. The only other manually launched programs that were active were an email program and an analog clock widget that I wrote.

I would suggest running the same test on your system with a minimal number of other apps running. If you see less variation in the recorded durations, then that may tell you to minimize the extraneous apps when imaging.

[s3igell]

"Tv" / "Manual" exposures under 30sec are requested by the Camera and Timed by the Camera.

"Bulb" exposures over 30sec are Triggered and Timed by the PC (or Bulb Remote / Intervalometer).  In the case of PC-triggered Exposures, not only does the PC need to Time the Length of the Exposure but it needs to separately Request that the Camera Terminate the Exposure.  This means variables in the instantaneous CPU Load, the Reaction Time of the USB Drivers and Hardware, and the Camera CPU, and even the Granularity of the Camera's Internal Clock Timer; each of these can contribute to minor variances in Reported Exposure Duration.

In terms of the Exposure, as Rick pointed out above, the few additional Photons Captured or Infinitesimal Sensor Noise Accumulated will be very insignificant - less so than any tiny thin cloud that might have drifted through your FOV.

Please advise if we've missed some critical element - perhaps you are running some Astrometry processes that make Timing more critical.