Reviewing the Canon T3i DSLR was a real challenge
I found that I am not able to do a proper astrophotography based review of the Canon T3i DSLR, because I have always controlled it via software on my laptop. An accurate review of my experience using the Canon T3i for astrophotography would actually be a review of Backyard EOS and the DSLR. It made the most sense to me to keep the Backyard EOS review separate from the review for the Canon T3i DSLR for Astrophotography.
For this review, I’m going to spend my time writing about my decision to buy the Canon T3i, as well as the things I’ve used it for. I won’t go into any of the technical specifications because there are probably a million websites out there that have the exact same information. Besides, I’m pretty sure that if you’re reading this, you either don’t care about the technical details, or you already know them. Either way, covering them would be a waste of your time.
Life Before The Canon T3i DSLR
It was June of 2012, and I just got my new Celestron 1100 Edge HD telescope. I spent a few weeks familiarizing myself with how to use it, and learning how to do a proper polar alignment. I attempted, unsuccessfully, to image Saturn through it once using my wife’s Nikon D7000. I researched online to see if there was a robust, easy to use and versatile software platform that would control the D7000 from my laptop. I found a few programs that had a few of the features I wanted, but nothing out there had everything. On top of that, the Nikon itself wasn’t able to take great still shots or decent video. The video was pixelated, like it was being compressed somehow. Maybe I shouldn’t be using a Nikon.
I did some research on Astrobin, and a few other sites looking for images that had deep and vibrant colors like M42, M51, and the planets. I wanted to know what everyone else was using. Then I wanted to know what the very best were using. The photos that I enjoyed looking at the most were made using expensive CCD cameras, as well as narrow band filters. This was out of my price range and my skill set. I needed something affordable, and Canon DSLR users were producing images that were of comparable quality to the CCD cameras but with more noise. I could deal with this.
Canon also allows for true RAW files to be saved to the SD card, or downloaded via software to my laptop. Nikon (at the time of my purchase) had a more complicated process to serve as a work around. Canon makes a good camera, and it would fill two purposes. Searching for that robust, easy to use and versatile software platform for the Canon cameras turned up Backyard EOS. This had everything I would ever need to control which ever Canon DSLR I would purchase. It was also really affordable, too! It was really beginning to look like I’d be using a Canon DSLR for a long while.
I Had To Identify My Needs
First and foremost, I would be able to photograph things that almost everyone else photographs. My dogs. My house. Some squirrel upside down on a tree. You know, the typical stuff stupid guys photograph all the time.
Second… and almost foremost – astrophotography! But which Canon DSLR to get? Canon makes many models. Some are purpose built for astrophotography, like the 60Da and its predecessor, the 20Da. I did a ton of research and was narrowing down the list based on sensor noise, sensor size. Did I want full frame, or APS-C? I needed features, because after all, this is an astro-cam now. I’m surely going to need all of the latest whiz-bang features the digital camera industry has to offer. It’s going to be doing all kinds of crazy low light stuff!
I settled on the T3i, because I was able to buy it at my local “membership warehouse” store as part of a bundle and I ended up saving about $50 over just buying the camera body alone (at the time). After all the research I did and questions I asked my local club members, my deciding factor was that it was on sale. Fear not, I also saw that it can do what I needed it to do when looking online, so it was not a full blown budget driven decision. Plus, this was a birthday present to myself. That gave me a little bit better positioning with the wife when I was explaining why I should buy the Canon T3i DSLR.
With my newly purchased DSLR camera in hand, I started charging the batteries. I bought my license for Backyard EOS that night as well. For those of you who use it, you know why I chose Backyard EOS. For those of you who haven’t used it yet – it gives you full remote control over the camera and enables you to configure the settings like ISO, Exposure Length, and number of frames to capture. With a planetary mode (which is what I wanted more than anything) I was ready to start photographing planets.
Canon T3i Astrophotography Baseline Tests
I did do a lot of experimenting with my Canon T3i when I first got it. Using an oscillating fan, I put stickers on the fan blades and played around with the shutter speed to determine what the fastest shutter speed was before I was simply adjusting the gain of the sensor. For this blog post, I had to recreate the experiment, but I did a more systematic test as I already knew the results, I didn’t have to do a lot of the testing that yielded no results. Instead, here is the distilled down, easy to see results of how the Canon T3i video mode for planetary capture works. As it turns out, there is a limit to how fast the video shutter works, and regardless of what you set it to, the image sharpness does not improve below 1/60th of a second. The first row of images shown on the left provide evidence that a single image taken at 1/60th of a second looks almost exactly the same as a still frame from the video recorded at 1/60th of a second. Also, the entire video column looks the same, just dimmer as the shutter speed acts as a gain setting with the Canon T3i.
The image on the left shows several side-by-side comparisons of the oscillating fan running. The left column shows a single image captured in video mode from Backyard EOS, and the right column shows a single image taken with the exact same settings using normal image capture mode. Regardless of what shutter speed you use in video capture mode in Backyard EOS, it will always be the same shutter speed. It’s practically useless, and only acts as a gain setting for the camera. After many nights of trial and error I’ve dialed in on the settings that work best for a Canon T3i when paired with an 11″ telescope. I keep the shutter speed of the DSLR at 1/125th of a second, and I tinker with the ISO until I get the right exposure. Only if I am at ISO 100, and something is still too bright will I further adjust the shutter speed below 1/125th of a second.
Another thing I needed to get a handle on was how noisy this camera really is. I know that the advertising material said that the Canon T3i DSLR uses a ‘low noise’ sensor. But that information was meant for soccer moms taking photos of their kid blowing out the candles on a birthday cake. Low is a subjective term, and astrophotographers are a picky group. We want really low noise. For this test, I decided to first ‘warm’ up the sensor by taking a single 300 second exposure. I kept the battery for the Canon T3i in the camera. I wanted to include any heat signature from a warm battery as part of a worst-case scenario.
After that exposure was completed, I then programmed Backyard EOS to take a series of 10 second dark frames with a 3 second pause in between. Each dark frame would be set to one of the different ISO levels to compare how the ISO affects the amount of noise the chip in the T3i generates. I then artificially stretched the frames in Photoshop to enhance the noise enough so it could be seen and analyzed. The sensor was between 34C and 33C, or between 91.4F and 93.2F for each of the dark frames. This is about 20F (7C) warmer than the rooms temperature.
The sensor noise in the Canon is almost identical in the 100 and 200 ISO dark frames. It really begins to increase starting at ISO 400 and up. Knowing this information really helps me out when planning out Deep Sky targets. I know that I really shouldn’t be increasing my ISO above 400. This is the point where the noise just gets way out of control with the T3i. Instead, I increase my exposure time, and take approximately 50% of the total light frame count in dark frames. If that doesn’t make sense let me say it like this: I take 10 light frames, and then I shoot 5 dark frames.
Using the Canon T3i for Astrophotography
My earliest astrophotography image with the Canon T3i isn’t even planetary. It’s of the Orion Nebula from December of 2012. By this point I’ve had the Canon T3i DSLR for about 3 or 4 months. I took the photo as 92 light frames, 60 dark frames, and about a dozen flat frames with about 20 bias frames thrown in. As I was still learning about astrophotography, and my polar alignment skills weren’t all that great – I kept the exposures down to only 30 seconds. I was imaging through the 1100 Edge HD after all. To compensate for the shorter exposure lengths, I increased my ISO as high as the light pollution would allow – which was ISO 800. That’s why I took so many dark frames. I knew there would be considerable noise in the sub exposures.
Recently, I’ve been doing better with deep sky astrophotography, but not awesome. I stick to planets for the most part. My best deep sky shot with the Canon T3i and the 1100 Edge HD may have to be SN2014J. What makes this shot so amazing is the fact that it’s a supernova! Oh, and I imaged it with a focal length of nearly 3000mm unguided. I had to get my polar alignment dead on that night.
My best planetary image to date is Saturn. I’ve taken several shots of Saturn while I was starting out, and I got better at resolving the Cassini Division in the rings. I know that the seeing plays a major part in all of that, but there is also a certain wisdom one needs to learn to establish what settings to use with the Canon T3i for a given subject. It’s been over a year since I’ve tried to image Saturn. I think I’ll give it a go this summer, but so far, 2015 has been a complete cloud fest in North Texas…
I was hoping to have had the chance to image Jupiter near opposition in 2015 with steady seeing, but so far, I’ve only had two nights since opposition that were good enough for me to image Jupiter. The first night was spent creating a time lapse video of Jupiter. The second night I was volunteering with the same students who had the misfortune of witnessing my telescope verify the relentless gravitational attraction between Earth and expensive things. Since that night was all about them seeing Jupiter for the first time with their own eyes, no cameras were allowed!
For deep sky astrophotography, I have only recently acquired a proper telescope. I’ve stuck mostly to the Orion Nebula because this is the biggest, brightest and baddest object in the night sky in January/February. I intend to keep pushing myself to do more deep sky photography, and experiment with the T3i to find the right balance of exposure settings for each target.Now you may not realize it at first, but I’ve used my Canon T3i DSLR with my telescope for things other than doing Astrophotography. I’ve used it many times when doing Polar alignments, and I’ve used it for doing astrometry. Doing these tasks is made possible by the Backyard EOS software, but the camera is sensitive enough to work in this fashion. As part of my planned series (Cloudy weather the last 4 months has prevented me from starting many of these blog tutorials), I intend to show you how I use my Canon T3i DLSR, Backyard EOS and a telescope to achieve excellent polar alignments, and do some basic astrometry. Those topics are, of course, beyond the scope of this review.My impressions of the Canon T3i as an astrophotography DSLR is that it performs much better than I do. When the Canon T3i is paired with Backyard EOS, I can shoot any length exposure I want, up to 20 minutes before the sensor shuts itself off. I have full control over all of the ISO settings and exposure timings which is very helpful. Also, using the laptop as the remote shutter allows me to start snapping photos without actually touching the Canon T3i or my telescope. There is no vibration, so the images don’t have any blur from my shaky hands.
If you are going to consider this DSLR for your astrophotography kit, I highly recommend finding an AC or DC power adapter for the Canon T3i. As you can see in the dark frame images, there is a heat gradient produced by the battery. The T3i sensor warms up in the lower left corner. If you ran A/C power (or made a DC adapter for a field battery) you can eliminate the heat coming from the Canon T3i battery.
A secondary accessory that the DSLR will certainly need if you intend to use it with a telescope is a quality t-ring adapter. I made the mistake early on and bought a rubbish one that was lose, and it actually allowed the Canon T3i to sit askew to the focal plane. For MONTHS I struggled with images out of focus, and a terrible uneven illumination gradient across the whole field of view before I figured out what my problem was. I was seriously about to throw in the towel.
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