Back to the basics – it has been already eight years since I shoot astroimages with modified Canon cameras: Canon 20D and sometime later Canon 450D. Some time ago I started to miss the simplicity of color camera images acquisition and processing. Dedicated, cooled astronomy cameras are quite expensive, so I decided to spend like 100$ for second-hand DSLR and then replace the IR filter to achieve better sensitivity in the hydrogen alpha band. Soon I found Canon 550D that is quite a capable model for astrophotography.
Canon 550D appeared in the market over ten years ago, but its quantum efficiency and noise are still not much different than current models. One thing that I miss in 550D though is the rotated screen, which is pretty useful in astrophotography. To fix DSLR cameras hydrogen alpha “blindness” I purchased a new Baader BCF filter to replace the original Canon IR pass filter. This way camera sensitivity in the hydrogen alpha band raises about 3-4 times. Using immortal Gary Honis page http://dslrmodifications.com/ I successfully replaced the filter – no camera parts left on the desktop 🙂
A few nights later I attached Canon 70-200 f/4 zoom lens to the camera and put it on the iOptron Smart EQ mount. I have set the lens to 70mm, ISO to 800, exposure time to 60s (with programmable release cable), and shot two targets. The first one was the area around Deneb and Sadr stars in Cygnus, which is quite full of hydrogen clouds. The second target contained Arrow and Little Fox constellations, with Coathanger asterism, Dumbbell nebula, and several star clusters and dark nebulae. I captured 60 frames for each target, and that is not an impressive amount, but should be enough for the first light test.
At 70mm focal length, the apparent field of view is quite large, but the Milky Way star fields are quite crowded and hydrogen clouds are a little bit obscured. But despite short exposure time quite a lot of them have been captured at Cygnus constellation image: North America, Pelican, Crescent, Sadr nebula, IC1318A, and many others, smaller objects. Another image with Arrow and Little Fox constellations contains easily recognizable Coathanger asterism (to the right of center), Dumbbell planetary nebula (left upper corner), several open and one globular cluster (M71 in Arrow). Plus a lot of dark clouds. Both images were post-processed gently, without extended contrast adjustments and sharpening.
Below you will find small maps generated with Cartes du Ciel software that presents captured areas. Some interesting objects are identified there. And you will find even smaller gems when you click at the links below that lead to the higher resolution of these images.
Full resolution media files:
https://astrojolo.com/wp-content/uploads/2020/09/2020-09-10-deneb-sadr.jpg
https://astrojolo.com/wp-content/uploads/2020/09/2020-09-10-sagitta.jpg
https://astrojolo.com/wp-content/uploads/2020/09/2020-09-11-cepheus.jpg
One more test image is a well-known area in Cepheus – IC1396A with Elephant Trunk and Garnet star, and other dark and emission nebulae around from Barnard and Sharpless catalogs. One hour total exposure time is definitely not much for this region with a one-shot color camera, but still, some details can be revealed.
Images technical data: Date: 10 September, 2020 Location: Nieborowice, Poland Telescope: Canon 70-200L f/4 Corrector: none Camera: Canon 550D modified with Baader BCF Mount: iOptron Smart EQ Guiding: none Exposure: 60x1 minutes Conditions: seeing good, transparency good
Beautiful photos. I’m also impressed with ‘no guiding’ thats a good mount for the price