REVIEW Canon EOS 600D. Purley from an Astrophotography Standpoint

Ok here goes. Never really done anything like this

DSLR's are used by many as a main imaging camera when doing astrophotgraphy, whether it be with a telescope or a lens. Beginners to expert amateurs. They appeal because they can be used in 3 distinct ways.

Why DSLR?
1: Deep Sky imaging.
DSLR's are great at doing long exposure photography, 20minute exposures at a time or more no problem. This allows time for light from Deep Sky objects, like Galaxies, Nebulae and Star Clusters to hit the sensor and be recorded.

2: Planetary Imaging.
Connect a DSLR up to a telescope, and you have got a relatively good planetary imaging camera.

3: Terrestrial Imaging.

The thing is. All dedicated astrophotography cameras can not do all three of those things. Deep sky cameras start at 1000$ and go higher. Planetary cams start at ~300$ (for one that is acceptable).
DSLR's are the only option when wanting a versatile way to image the night sky and at daytime.

Software Support
This is especially true for the Canon EOS series of cameras. The 600D cost me $400 used, and has been my main imaging camera every since. I had a Nikon D7100, a better camera, but Nikon does not have the software support for Planetary imaging.

Canon has software support in abundance for astro-imaging, with the main one being BackyardEOS, allowing you to control your camera from your computer for a number of astrophotography tasks. Allowing for custom length bulb exposures and ISO levels, capture plans that allow your camera to image all night, and a planetary imaging function.

Along with this functionality, it saves the RAW .cr2 files from the camera onto the computer to a folder of your choice and with the objects name!

Planetary Imaging
That last point is important and is the main reason that I moved from the Nikon camp. Heres the thing. Planets are small in the sky, when imaging them, they only take a small amount of pixels on the sensor, and it has to be done in a video so that the software can separate the bad frames from the good because of the atmospheric distortions. However taking a 1080p video off the camera is absolutely horrible. It is taking the entire imaging sensor of 5184x3456 pixels and down-sampling them to 1920x1080. In the process, all of the fine detail of the planet is basically lost.

To remedy this, BackyardEOS capture the live view signal from the camera at 1024x680. It then zooms in the live view 5x to achieve a 1:1 pixel ratio from the sensor to the video by only using the central 1024x680 pixels. This allows for amazing results with even smaller scopes comparable to dedicated planetary cameras.

BackyardNIKON does not yet have this capability.

Modding
When imaging deep space objects like the famous "Orion Nebula", or the amazing object only viable in the southern hemisphere, the "Carina Nebula", unmodified DSLR's have trouble capturing the red "Hydrogen Alpha" wavelengths of light. Canon by standard blocks 75% of this light with filters to keep daylight imaging in correct colour balance.



Removing these filters is risky as a DIY job, but can be done by professionals for ~200$. Once removed, exposures of 5minutes will equal the amount of red H-alpha light of a 20minute exposure! Allowing for much more information to be captured before star trails start to appear. To keep the autofocus in place, another clear piece of glass is added (Baader Filter), and the only effect for daylight photography is a slight colour imbalance that can easily be fixed with custom white balance.


Graph showing the colour wavelength responses


An example with a Baader filter to pull for H-Alpha from the famous Carina Nebula

Cold finger, or Peltier cooling is basically a cooler that works much like a CPU cooler to cool the sensor down whilst imaging. I am yet to find out how it cools it to negative celcius temperatures, but i'm getting to it!

Bit overkill, but the general idea

Noise Comparison
Couple the sensor mod with a "Cold Finger" cooling mod to cool the sensor to -10Celsius or more! Therefore, reducing noise from long exposures, you have a very capable imaging camera, comparable to dedicated CCD imager, with the advantage of being able to be attached to lens like the 50mm f/1.4 for colour rich wide-field images.

Results
Keep in mind that I am only 16, so 6D's and EQ8 mounts are out of the question! I have to do this on a shoestring budget!

Ok. Now keep in mind that astrophotography is not cheap. The mount that I use limits me to widefield work up to 300mm. My mount is simply not accurate enough to Polar align and track as well as some of the more expensive mounts that I hope to own soon.

The camera is mounted on a piece of wood that I fashioned to hold the camera and the guidescope steady whilst imaging. The guidescope is a small telescope that watches a star and observes its movement, when it moves, it sends instructions to the telescope mount to compensate for the drift, allowing exposures 5x longer than without. I own a Nexstar 4/5SE mount, that is only intend to really be used as a visual mount. It is computerized and slightly modded to allow for a more accurate alignment

Images where wayyyy to large off imgur to insert directly, so you'll have to use the links.
http://i.imgur.com/TwXxBJW.jpg JupiterThis is a comparison image of the 600D compared to a bad planetary imaging camera. Images of the 600D's quality with such a small scope are usually only achieved with scopes larger than 6inches, this was taken with a 4inch MAK Cassegrain.

http://i.imgur.com/4fbmvGg.jpgAndromeda Galaxy
This was done before I had my guidescope or knew how to equatorially align the mount, so these where done with 30second exposures. I would now be able to achieve 10minute exposures on this object when it comes back around it summer.

http://i.imgur.com/iuExOle.jpgMessier 42, the Orion Nebula The great Orion Nebula is visible with the naked eye as the sword of Orion the hunter, or the handle of the saucepan for us Aussies! Like I said earlier, if I had modded my camera before taking this image, most of the background would be filled with interstellar dust that just looks awesome!

http://i.imgur.com/avHEyJy.jpg The Centre of our Milky Way Galaxy Taken with the autoguider, and taken @100mm. This image took 6 hours to take, and that allowed for more of the red H-alpha gas to show up once I pulled it out of the DATA.

http://i.imgur.com/XFKGy4g.jpg My Favourite, The Southern Cross This was another image that I took at the same place that I took most of my images, on a farm outside of Toowoomba. The mighty southern cross was high in the sky. This was done with 10minute exposures with the 600D piggy backed on the telescope before I made the wooden saddle. I put this one up on reddit and got to the front page and got 1.3 Million views!

Conclusion
The 600D is an amazingly versatile camera for use in astrophotography for the money, being an all round good investment.
The software support is unparalleled by other camera manufactures and can easily match the results of dedicated Planetary webcams and Cooled CCD DSO imagers once modified.
For the price, a 600D is the camera of choice for versatility in the amazing hobby of Astrophotography!

 

Nice work!

 

I don't have the time to read your review just yet, but saw the pic with the heat sink off the side of the camera. Thats crazy!

 

Great read mate, keep it up. Astro is something I always wanted to dabble in, but like everything else in life, no time....

 

Unfortunatly thats not my camera! I do intend to mod my 600D like that at some point after I mod the sensor and buy a mount!

 

+1 for this - Excellent.

I love hardware mods and stuff.

Love the breakdown and progress pics etc.


Excellent. Makes me want to do that to my 700D ... but my wife would kill me.

Would love you to link to the full res so we can Pixel Peep. Then we would be getting down to the nitty gritty.

 

Good basis to learn from. Anyone can do astrophotography with any camera if they are willing to learn. Tracking mounts and modifications merely help but are not essential. Even jpegs from a compact can produce good results.

You should look into using flats and darks, Pixinsight would make your shots several heaps better in every way.If you havent already join up on the Ice In Space forums.

 

Great read man, looking forward to your future work!

 

Would love to see photos of the process.

Read through your review - great work!

Question re removing the red filter - does the camera have filters for the other channels too?

 

When you remove the filter complete, it unblocks the UV and IR spectrum. Usually this is bad for refractor telescopes and lens as it bloats the stars. That is why we add back in a badder filter. I allows more light than the 658.28nm wavelength of hydrogen-alpha. Removing the filter and replacing it is just to allow autofocus and to continue to block the UV and IR light.

Its a rather large step up once modified! Usually only beneficial when you can do long exposures.

 

this is awesome

 

I used to think astro was cool once then I got bored..

 

Finally!
A use for all the "extreme" coolers from 1999. A Peltier element is simply a solid-state active heat pump which transfers heat from one side of the device to the other.

Put electricity in and one side gets very warm, while the other gets cooler. The trick is to remove the heat from the hot side - which is where the heat sink comes in. The cooler you make the hot side, the cooler the cold side becomes. The problem is you need to deal with the heat derived from the element as well as the heat source - so a 100w Peltier needs a minimum 100w capable HSF just for starters, plus whatever wattage is coming from your source.

Slap a big enough cooler on and sub-zero cold-side temperature are perfectly possible.

 

Fantastic pictures and a good read. My 7 year daughter says "Wow, amazing". Keep sharing

 

Ok awesome. I knew it had to be something not so straight forward. Thanks for the great explanation!!! Now I just need to actually do all this to my camera without destroying it. I have been reading up and I think that it is possible by me!

Sure thing, I will post them on here when I get the chance. If you want to see some really good stuff, head on over to http://www.iceinspace.com.au/forum for some really impressive shots by some really impressive people!

 

Nice to see a peltier getting some use. Years ago I thought they were going to be the future of CPU cooling, but they took too much power and ended up causing ice to form on motherboards.

So it scales down to 1024x680, then scales back up? Or does it grab the middle 1024x680 section of the raw 5184x3456? I can see how the former would be better than 1080p video, but the latter sounds awesome.

 

Came in here just to see WTF that was about!

 

It actually does the latter!

When you press live view on the camera its outputs a 1024x680 video from the entire sensor. However when you increase that to 5x, it shows only the central 1024x680 pixels of the sensor, giving an approximate 5x smaller FOV and a heap more detail on the target. You dont need to record in 1080p when most of it is just "Empty" space, the 5x live view method is truly awesome!

 

Great review!

I nearly did this to my 20D and 40D about 10 years ago.

For a brief, hopeful moment in '06 Canon released the 20Da, the 'a' for astrophotography, but only in Japan. Designed and sold with no IR filter from the factory and a host of other astro features.

This is what the 20Da introduced and yes, so incredibly useful for astrophotography.

Wonderful shots with the 600D. Beautiful deep sky!

Have you had any issues with the peltier. What is ambient temp/humidity where you shoot? While cold weather should be better, particularly close to the coast condensation so often becames an issue.

 

So unfortunately that actually isnt my camera, I probably should have specified . Anyway I know that people have had problems where the sensor will get condensation on it because of the dew point, and to fix that I believe that they wrap the cam with a bag and fill it with some form of gas, (Argon? I'm not sure but have seen it done).

I also think that I have heard that people have actually taken a good percentage of the atmosphere out of the sensor chamber and sealed it to prevent it but dont quote me on that.

I have to battle with dew all the time up here in Toowoomba, and I am just getting around to making my first dew heater in the next few weeks. With my DSLR and new gear, there is a Coma Corrector that is actually screwed onto the T-Ring, that does a great job at not only correcting vignetting and a uneven field, but stopping dust getting on the sensors during those long 20min exposure times!