- reset camera to factory settings.
- for Nikon go through the DSLR_Settings checklist. For other, essentially make sure the camera is recording in RAW mode, and that stuff like long exposure noise reduction or other types of corrections are OFF.
- set time as best as possible to current UTC, or better plug in GPS unit for 10 to 20 minutes.
- put the camera and/or lens on manual focus (to avoid autofocus ruining your work)
- set the camera to live view, at fully open aperture, with high gain.
- Point towards a bright star.
- Zoom in onto the star at maximum.
- Adjust focus until start looks as small as possible.
tip: using an HDMI cable and portable screen (like our Lilliput A7S 7" monitors) it is possible to achieve better focus.
For fisheye lenses you might want to take a few long exposure shots after focussing and zoom in different parts of the field of view to check focus is good all the way across. If there is an area of bad focus that cannot be improved, rotate the camera so that the fireball does not end up in that area of the picture.
If using a fisheye: ideally once the camera is set up, take some pictures before the Moon rises, and then do not touch the camera/tripod until the fireball happens. Use a remote trigger if necessary.
For narrower lenses, avoid having the Moon in the field of view, baffle. Take a few long exposure pictures before and after the fireball without touching the setup. If recording in video for the fireball, try to change the mode to long exposure still for calibration shots without touching the camera/tripod.
Ideal exposure lengths for astrometric calibration:
- fisheye: 20 seconds
- 14mm: 13 seconds.
- 50mm: 5 seconds.
- 85mm: 4 seconds.
- 105mm: 3 seconds.
- If recording in video, flash the LED of a DFBen and (top of the minute UTC) at the camera before and after the fireball while recording. this brief flash will let us determine absolute timing of the frames in the video.