Photographing Markarian’s Chain With A Stock DSLR
Imaging Markarian’s Chain was something I tried last year. To a poor degree in my opinion. I was imaging with the Altair Hypercam 183c and it was a struggle as you can see in the video where I fought for the image.
Fast forward to the next year and after having given back the ZWO ASI 533mc Pro that I had to review, I was left with an unmodified Canon 450D and there I sat – trying to find targets.
In the end I decided to revisit this old nemesis of mine. Markarian’s Chain; a group of galaxies located in the constellation Virgo.
After all for me: nothing says “Galaxy Season” more than a huge chain of galaxies spanning a vast distance in space.
A DSLR is more often than not good enough for astrophotography duties. The Canon 450D is an old camera now – about 9 years old. But it’s a reliable little unit. More often than not people will modify their DSLR – by removing the IR cut
filter and increasing the sensitivity to the red spectrum. This is most useful on emission type nebulae like the California Nebula.
Leaving it stock, however, is more than fine galaxies. So, with this in mind – and no mains power adaptor for my camera – I set it up and begun preparing for the night.
One main problem about using a DSLR camera’s standard battery is that imaging through the night, combined with long exposures, puts a large strain on it. Regularly we’ll run our batteries all the way empty. Also since it gets cold at night this also adds to a battery’s draining – they don’t like the cold.
Fully charged, locked and loaded. I waited for my equipment to cool down and for night to descend.
If you’re interested in modified DSLRs get in touch, I sometimes modify and sell DSLRs.
As mentioned, this is the ultimate galaxy target for me. The chain itself has some 13 or more galaxies in it. Starting from the end and working up to an eerie intergalactic face staring back at us. Sometimes I think it’s fun to sit and wonder who may actually be looking back at us. Does the Milky Way to them pose an interesting galaxy to target?
What I love about Markarian’s Chain is that it has an absolute three-dimensional shape to it. The end of the chain looks further away than the face. It just adds to the composition and I think it’s best framed with the dip in the chain running along the bottom of the camera frame and the face, as well as the tip, on the thirds.
Markarian’s Chain returns as M84 in the brilliant program Stellarium. Though this is the right eye of the face. It also includes what I think is the farthest away galaxy I’ve ever attempted – NGC 4388: a distance of 126 million light years away!
The brightness of this target, naturally, differs depending on each galaxy. The brightest is about magnitude 8. This is M86 (the left eye) and magnitude 14.5 for the dimmest! IC 3363. It’s barely visible on the final image.
Setting an image plan for a target with such variance in its luminosity can be tricky. I took a few test shots of 2 minutes, 3 minutes, 5 minutes for example trying to find an exposure that balanced nicely. The difficulty is balancing the brighter galaxies against the darker ones. Attempting to get the farthest and dimmest galaxies to have a good signal will probably blow out the brighter galaxies though.
Sometimes in astrophotography it’s a game of compromises.
I eventually settled on ISO 800, as that’s a nice value on the 450D. Decent noise control and can give you some okay exposure lengths. I settled on 240 seconds – 4 minutes.
I felt this gave me a good balance between all factors, also having to take into account the ambient temperature as well so the sensor didn’t get too hot and destroy any details with thermal noise.
I’ve had this before when I tried to image the Cygnus Loop with a 600D and Triband filter – that can be found here.
So the plan was set. As many 4 minute exposures at ISO 800. Ambient temperature felt about 12 celsius and the sensor was reporting about 13-18 ‘ depending on the time of night.
Attempting such a large target like Markarian’s Chain requires wider gear. The Sky-Watcher Evostar I was using was clocking in at 510mm focal length after it was reduced by the dedicated Reducer Flattener.
The Canon 450D with its APS-C sized sensor and 1.6x crop factor gave a good field of view also. And as always any long exposures require an EQ mount and potentially guiding. The EQ6-R Pro is a bit over-qualified for this role. My Sky-Watcher HEQ5 Pro would easily have worked for this configuration. But hey, I spent a lot of money on my EQ6-R Pro so I’m going to use it!
Each image was dithered as well, to help spread the noise, reduce random noise and generally clean the image a bit.
- Scope: Sky-Watcher Evostar 80ED
- Mount: Sky-Watcher EQ6-R Pro
- Filter: Skytech L-Pro Max
- Camera: Canon 450D Stock
- Guide: Astro Essentials Mini Guide Scope
- G-Cam: ZWO ASI 120mm Mini
- Mount: SynScan App
- Capture: Astrophotography Tool (APT)
- Guide: PHD2
- Stack: Deep Sky Stacker
- Edit: Adobe Photoshop
- QHYCCD PoleMaster
- Dew Heater Bands
- Nevada Power Supply Unit
- Lynx Astro Dew Controller
- Bahtinov Mask
I was able to image over 3 nights. The weather was in a strangely good mood and gave the United Kingdom an extended period of clear nights. So over the three nights I imaged and imaged.
The limiting factor for me was the battery life. As I had mentioned, I didn’t have a mains power plug. So I wasn’t able to image all night from 10pm to 4am or so. Which is a bit of a shame. I had the 450D for a while and had plenty of time to get an AC adaptor.
The final image is an integration of 93 x 240s images. Just under 6 and a quarter hours of integration.
The downsides of the Canon 450D sensor shows its ugly head. Even though I used a full set of calibration frames and bias frames. There is an obvious banding that can be seen horizontally. This is from the sensor, I’ve seen this in other images I’ve taken with the 450D. A limitation for sure. It does bother me.
I think this is a better image than I was able to take last year – then again last year I had like 32 minutes of data. Not 6 hours. But again, for me, Markarian’s Chain has escaped me again. I think this will be a lifelong endeavour. Next year I’ll revisit it again I reckon!