Thursday, September 18, 2014

Modified Canon XS and sample photo

I have always struggled with trying to image reddish nebula...never could get enough red to make it look natural. Of course there is a reason. Digital cameras are made for "normal" daylight exposure, what the human eye naturally sees. What is interesting is that digital camera manufacturers have to place an infrared (ir) filter directly in front of the imaging sensor (CMOS) to PREVENT it from capturing the near infrared, because the CMOS is naturally sensitive to the near infrared!
So to capture the near infrared of nebulas in space it would be necessary to REMOVE that filter.
Of course, if you remove that filter the color cast of normal photography will not be "natural" to the human eye. It is, however, possible to compensate for that, to good degree, with the "custom white balance" feature in the camera.

In searching the internet I found a site that gives a clear step-by-step on how to disassemble a Canon DSLR to be able to remove that ir filter,
Since I own three Canon DSLR's I choose to try this modification to the least valuable camera, my Canon XS. Trust me, I was fearful of making a big mistake and ruining the camera for good. But to my happy surprise it was not as difficult as I imagined! True, one needs a good tiny Philips screwdriver (don't compromise here!) but the instructions are so good that only someone with all thumbs need worry about making mistake.

Modification accomplished! Camera tested! Ready to head out to the observatory!

The night was clear, the temps rather warm (didn't put on a light jacket until almost 11 pm), I did a few exposures to see how it works. The images were much red-er than they were before and my technique still needs improvement but I was able in post-processing (using Lynkeos, Preview, and GIMP) to produce this image of the region of the Milky Way north of Cygnus (the Swan constellation) which included the "North American Nebula" and the bright star Deneb.

So if you have an extra Canon DSLR laying around and you really want to do astrophotography of the night sky then this modification is absolutely essential! You can do it yourself or send it in to the guy who runs the above website and he will do it for you for a fee.
When I get a newer Canon DSLR someday I will do this modification to my Canon t3i or t2i, for sure!

Thursday, September 4, 2014

Observations of the Moon after raising the telescope pier 9 more inches

Ah, the wonders of hindsight! After nearly a year in my observatory it came time to make some more adjustments to the concrete pier that my orange Celestron C8 is mounted to. By raising the height of the pier 9 more inches I am able to view more objects than before and yet be able to roll off the roof without fear of hitting the telescope.
Of course that meant having to realign the wedge and angle of the telescope to polar north. To my surprise it was relatively easy to get really close!
Saturn is just too low now in the southwest for any decent observing but the scope tracked really well.
And though the Moon was going to shorten any observing I went ahead and took some images with my Canon t3i at prime focus in the movie mode, both full screen and digital zoom (maximum to look for any discrepancies in my polar alignment. Here are the results...

The following image is of the crater Copernicus:

Typically I use Lynkeos and let it choose the best stills from the movie but as of late it seems to want to choose some stills that are less than the best. So I hand picked the stills (about 6 of them out of 50) and produced this image, final editing in Mac OS-X Preview.