Pete Lawrence is an
expert astro imager
and a presenter on
The Sky at NightASTROPHOTOGRAPHY
CAPTURE
Take the perfect astrophoto with our step-by-step guide
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How to pair a planetary camera and CCTV lens and capture the peak of the Perseids
Imaging the Perseid meteor shower
Þ Get your setup
ready for the peak
of the Perseids
on the night
of the 12/13
August between
23:15-03:20 BST
(22:15-02:20 UT)C
lear skies may produce plenty of bright
Perseid trails, but capturing one on
camera isn’t easy. This month we’re
looking at how to record meteor trails
using a high frame rate camera, the
sort normally used to image planets.
These cameras have good sensitivity and the
option to take really short exposures. However, we’re
ignoring this and extending their capability to record
wide-angle shots of the stars using longer than
normal exposures, like we would do with a DSLR.
There are lots of planetary cameras on the market
and many can be used for this task. A lens will be
needed and these can be obtained through many
online sources. A fast C-mount CCTV lens is required,
along with a T-thread to C-mount adaptor (the
T-thread being the thread in your camera into which
you screw a lens). Once the adaptor is in place, the
lens can be screwed directly into the camera body.
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length and it’s recommended to choose a lens with aSend your images to:
[email protected]76 BBC Sky at Night Magazine August 2021
focal length below 4mm to give good sky coverage.
The lens aperture should be fully opened to let the
maximum amount of light in.
You’ll need to mount your camera body – on a
tracking mount and tripod if you have them. Some
models have camera-threads on the body for this
but, if not, an impromptu platform where the camera
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the camera can’t accidentally move about.
Accurate focus may be achievable by using the
lens’s own adjustment, but you may also need to
make rough adjustments to the lens-chip distance by
screwing the T-thread to C-mount adaptor in or out to
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Planetary cameras require a computer and control
software to work. If you’re outside, a cover or box
placed over the computer will prevent moisture
building up, but be careful not to block cooling vents.
The control software is down to personal preference;
popular choices include SharpCap and FireCapture.
Focus can be achieved by setting the camera
exposure to a second or two and using a bright star.
Take your time to get this as sharp as possible. It’s
advisable to view a clear unobstructed sky if possible.
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view, pointing directly up is a good choice.
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the lens doesn’t mist over on a damp August night.
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can be used to rapidly get rid of any misting.
Try and make setup tweaks early, so you’re ready
IRUWKH3HUVHLGSHDNRQWKHQLJKWRIWKH$XJXVWRecommended equipment: Planetary camera,
a wide-angle CCTV lens> See the ‘Perseid Perfection’ feature on page 28
and ‘The Sky Guide’ on page 46 for more details