Choosing a Camera for Solar Imaging

You’ve seen it! The sun in Hydrogen-Alpha or Calcium K light. Now, you want to share your excitement with everyone by photographing what you saw. Choosing a camera to do this can be a real adventure as there are many unique aspects of solar imaging that will need careful consideration.

Consumer Digital Cameras

Simple digital or DSLR cameras work just as well on the sun as they do on the family vacation. Hold it right up t the eyepiece, set the camera for infinity and snap away. Focusing will be the biggest challenge. To help, try shooting in black and white, the lowest ISO setting and the largest file setting (usually TIFF). Adjust the telescope focus each time and look for a sunspot or prominence to come into view.

Webcams

Webcam devices are the cheapest option. Some can be found for less than $100US and offer image sizes around 640x480. Look for a monochromatic camera that has the best control software (i.e. exposure, gain, gamma, brightness). You’ll also need to find a way to adapt the camera to the telescope. Search the net for Moog or C-mount adaptor depending on which camera you own. Also, to use a webcam with a PST you’ll need to use the lens cell of a 2x barlow screwed onto the end of the adaptor.

CCD Cameras

These cameras are by far the most expensive but, offer the greatest flexibility in imaging the sun. With CCD cameras, you can get large arrays that allow you to image the entire sun in one shot. They also can be used with a barlow to magnify a single solar object (active region or filament) quite well. Find the largest monochromatic chip your budget will allow. Other key considerations are: Shutter speed (.001 is best), Pixel size (usually smaller is better) and download speed (not much user control over this). You may need to use a neutral density filter to knock the light down to avoid overexposure. A simple moon filter, ND 13 or ND 25 should do the trick.

Other options

I’ve found that security cameras work exceptional well for imaging CaK prominences. Their low light characteristics are sensitive to Calcium emissions in the UV portion of the spectrum. Also, electronic eyepieces do a good job at capturing solar details as well. Both imaging platforms will require a frame grabber to get the shots onto your computer for processing.

Your path

If you don’t yet own a solar filter, ask someone at a star party if you can try imaging through their equipment. It’s a great way to get experience. Also, take a look at the equipment other successful solar imagers are using. Most people will be willing to answer any questions you may have. Take time to read the archives of online chat forum too. If you’re stumped, chances are someone else as been there too and found a way to make it work. Don’t worry if the image doesn’t turn out perfect during your first imaging session. It’ll take some time to get it just right. Remember my motto: It’s a hobby, keep it fun!

Enjoy the sun.