Astrophotography with a Canon 40D Revised 25th June 2011 | |||||||
Tips and foibles The Canon 40D is a very versatile camera but if you use it for Astrophotography there are a few pitfalls and tips that I have discovered that may help you with your Astrophotography. These tips are for the 40D but may well apply to later models as well.
I have used my 40D to take Astro photographs both with Canon lenses for wide angle views and mounted at the prime focus of both Schmidt-Cassegrain telescopes and a Skywatcher Pro 80ED refractor.
Most of us are plagued by Light Pollution in particular the orange skies resulting from light pollution from Sodium Street Lamps. There is a quick way of reducing the effect of this - alter the colour temperature setting of your camera or use the electric light bulb setting if your camera does not allow you to set the colour temperature. If you reduce the colour temperature this reduces the cameras red sensitivity and increases the Blue Sensitivity. As a 'orange' glow is towards the red end of the spectrum this results in the sky turning from orange to black. This only effects JPEG images not RAW images. The only downside is that it reduces the cameras sensitivity to red objects such as H-Alpha regions but you will not be able to image these from a light polluted location anyway. A couple of useful programmes have been recommended to me recently: The first is BackyardEOS at http://www.backyardeos.com/ this programme allows you to control a Canon EOS series camera remotely and has a number of features designed to assist you when using an EOS camera to take astronomical images. I have not tried it yet but it comes with a recommendation from a fellow EOS imager. One thing you may notice when you look at the instructions is that BackyardEOS measures the camera temperature when a image is taken. After a bit of hunting around the Internet I found that the EOS cameras do measure the temperature of the imaging chip, presumably for the noise reduction algorithm & to operate the sensor over temperature warning. This information is recorded in the EXIF data in both .JPG & RAW files but the Canon software does not display it. After some more hunting around the internet I discovered ExifTool at http://www.sno.phy.queensu.ca/~phil/exiftool/ which allows you to download all the Exif data including the temperature. You can write scripts using this so that the temperature the image was taken as can be written as part of the filename. This then allows you to see which darks & flats match the temperature the image was taken at. Monitoring the temperature also allows you to see how effective your cooling strategy is. John Murrell
| |||||||
| |||||||
Clicking on the Home logo will return you to the home page |