Still no Moon and still plenty of cloud – you just can’t win. Got a nice shot of the 4-minute ISS pass around 11:06 p.m. which you can see here. Also managed to get 4 meteors, but the images are not very good for reasons I’m about to give.
This Perseid session has shown me how to take meteor images with a DSLR. I have read bits and pieces on the web, but they weren’t really all that helpful, and some were downright contradictory. So here’s my take on it.
Although meteors look pretty impressive to the naked eye, they simply don’t kick out all that much light, and the ones that look faint to the eye are REALLY faint to the camera. The first and most important thing you need to do is go to your nearest dark site to minimise the skyglow. As it was cloudy this year I didn’t bother to take the kit over the forest but just worked from the light polluted back garden – this is the main reason my results were rubbish. You MUST have a good dark sky background. Why? Because you are going to use an exposure time of a few seconds at high ISO and all through this exposure time you will be integrating up the skyglow. If you capture a meteor right at the beginning of opening up the shutter the skyglow will build up as the exposure progresses and the meteor will appear to get dimmer and dimmer, faint ones simply won’t show up at all. So we already have a conflict problem here. You would like to have a longish exposure time of say 30-seconds or so in order that you’re not firing the camera off like a machine gun, but long exposures will build up the background skyglow. A short exposure stands a good chance of missing a meteor event as the meteor will always come along in the interval between shots. I recommend using an exposure time of about 10-seconds with an interval between shots of one second – my intervalometer doesn’t work with an interval of zero seconds, if yours does, great. Now you come to what lens? I use a 15mm Canon fish-eye lens wide open at f#2.8. Whatever lens you use you need it wide open to grab as much light as you can. Short focal length means bigger field of view, so you grab more of the sky per shot. The reason I really like the Canon 15mm fish-eye is because when I have the focus ring fully anticlockwise it is automatically focused at infinity and I can start shooting. None of my other lenses are this considerate and I have to waste time using the Live View facility to focus up on a star before taking pictures. What ISO? Probably best for a bit of experimentation here – try starting off with ISO 1600 and go from there. With a short focal length lens and a short exposure time there’s no need for fancy AstroTracs or other mounts to track the stars, a plain tripod will do fine. Also, you can stack all your images together for a nice time-lapse video of the night sky which might be a worthwhile exercise if you don’t manage to get any meteors. Happy Hunting!!
