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If you are looking to buy a new DSLR for Astrophotography, this article offers some recommended cameras and some of the features to look for in an astrophotography DSLR.
ANY relatively modern DSLR will work for astrophotography, and work pretty well. So if you already have a DSLR and want to get started with AP, go ahead and use your existing camera. If you’re looking for a new camera, here are some aspects to think about, followed by some recommended models for different budgets.
DSLR Astrophotography Features
Characteristics you should look for in a DSLR you want to use for Astrophotography.
Live View LCD
Having a live view makes it easy to center and focus on bright objects. A live view that also includes exposure compensation can also be handy in making sure your camera settings (ISO, shutter speed) are reasonably appropriate for bright targets like the Moon, Jupiter, and Saturn.
A rotatable LCD that you can orient independently from the camera can be very handy when centering a star and focusing. Otherwise as you image higher in the sky, you’ll be bending further and further down while craning your neck to view the screen. (Of course, I just bought a new camera that doesn’t have this feature, so apparently I need to start doing yoga.)
Low Thermal Sensitivity
Professional astronomical cameras are actively cooled down to temperatures well below freezing. This is because of the fact that as the temperature of a CMOS or CCD sensor increases, so does the thermal noise recorded by the sensor. Some sensors and cameras though are less susceptible to this thermal noise than others. Roger Clark has tested a number of Canon cameras over the years, and found the thermal sensitivity to be generally decreasing with the newer generation cameras. (The 7D Mark II exhibits the lowest thermal sensitivity of the cameras he has tested to date.)
Thermal noise is less of an issue in the winter, on cold nights. It can become a major issue on warm summer nights (this is one of the reasons I’m moving from the Canon Rebel T3i to the 7D Mark II).
The CMOS sensors in DSLR cameras can actually capture a wider spectrum of light than the human eye can see, including down into the infra-red wavelengths. If the cameras were offered with bare sensors, the color balance in photos would be heavily shifted towards the red. To correct for this attribute of the CMOS sensors, manufacturers add a filter in front of the sensor that blocks this infrared light, then do processing on the captured images to correct for the white balance and other attributes. The result is a natural color picture like we see with our eyes.
Unfortunately, most of the light from nebulae in the universe is in the hydrogen-alpha wavelength, which is between the Infra-red and visible wavelengths, so the filters in most cameras block the majority of this light (80-90%) from reaching the sensor. Many astrophotographers choose to have their cameras modified to replace that filter with a less-restrictive one that allows more of the Ha light to reach the sensor. There are a handful of companies and individuals that offer this service for fees starting at about $300. The downsides of this modification are voiding any warranty on the camera, and no longer being able to use it for daytime photography without fairly extensive post-processing color corrections.
If you want enhanced Ha sensitivity but don’t want to have your camera modified there have been a few cameras offered by Canon and now Nikon that are designed with improved Ha sensitivity. Canon introduced the 60Da in 2012, which was a 60D with a different IR-cut filter which allowed more Ha light to pass to the sensor. Canon also previously offered a 20Da back in 2005. At this point, neither camera is available new. There was a recent rumor that Canon was working on a full-frame astrophotography camera, but they have not made any announcements. Nikon recently announced their new full-frame D810A, which includes several nice astro-specific features, and retails for about $3,800. At the moment, the Nikon is the only astro-specific DSLR for sale today.
Astrophotography Software Compatibility
Canon cameras have a clear advantage over the competition in terms of the software available for controlling them from a laptop for AP purposes. It’s worth noting that the software updates to support newer cameras often lag a bit behind the introduction of the cameras. At the same time though, one of the great things about a DSLR is you don’t need a laptop to use it for AP – just an intervalometer.
Should you get an APS-C, Full-Frame, 4/3rds sensor?
Depends on your budget. Full Frame cameras are generally in a higher price bracket than APS-C cameras. I use APS-C cameras along with a focal reducer that narrows the imaging circle to bring more light onto the smaller sensor. APS-C is the size you find in more entry level and mid-range DSLRs.
What about Resolution and Pixel Size?
There seems to be an endless debate about whether it’s better to have larger pixels (to capture more photons per pixel) or higher resolution (to capture more spacial detail). Is it better to have a 12 MP APS-C camera, or a 24 MP APS-C camera? Frankly, I’m not sure. However, the choice is mostly being made for us by the ever increasing mega-pixel count in each new generation of DSLRs. As that pixel density increases though, for the most part, the sensors are also improving in terms of quantum efficiency, reduced noise, and increased dynamic range. This is a debate that will likely continue for a long time, with no clear resolution.
What Features Don’t matter?
Many of the features that differentiate higher-end DSLRs from their entry-level counterparts, like Advanced Auto-focus, multiple AF points, Bust Shooting fps, simply don’t matter for astrophotography. What you generally do get as you move up to the higher-end and pricier cameras is larger image sensors, improved build quality, and improved sensors.
Which Brand is Best – Canon, Nikon, Sony, other?
If you have a preference, go with it. If you already have a set of Nikon lenses, get a Nikon camera. If you have a friend that will let you borrow his Canon lenses, get a Canon. The general wisdom seems to be that Sony and Nikon cameras offer the better sensitivity and lower noise in their newer generation cameras. At the same time, Canon remains the dominant choice for APers in part due to the available compatible software (Windows and Mac) and community of support. I started out with a Canon, and after looking at the landscape in April and May 2015, don’t see a slam-dunk reason to switch.
Is one brand going to offer a significantly better photograph than another? Probably not. Much of it is about the lenses/telescopes, night sky conditions, and processing skill you bring to it. The differences would probably come into play with Ha Sensitivity and Thermal Noise, and for the most part, I haven’t seen any clear data points to say get the Nikon D5500 vs the Canon T6s or vis-versa. (If you want to see a comparative review, let me know. I’d like to do it, but I buy this stuff with my own money, so donations are appreciated!) The difference in Ha Sensitivity will be a factor if you consider the Astro-specific DSLRs. Of course, after-market modifications are also available.
What about Astronomical CCD Cameras?
Astronomical CCD cameras are a whole different world from DSLR cameras. These are cameras designed exclusively for AP, and most offer active cooling. The nature of a CCD vs a CMOS sensor in a DSLR results in a camera that is higher sensitivity, but also higher noise. Many Astro CCD cameras have mono sensors (no bayer color layer) which means they are used with filter wheels with different colored filters to capture a natural color image. They can also be used with various narrow-band filters to capture light outside the visible spectrum.
- Easier to use – no computer required, no filter wheels.
- In-Camera processing reduces post-processing effort
- More Portable – again, no laptop needed.
- Preview and setup on the camera screen.
- Active cooling – reduces the noise from thermal interference.
- Higher sensitivity – typically 30-50% better, making cleaner, more detailed images possible.
- Mono sensor allows for capture of non-visible wavelengths through narrow band filters (Hydrogen-alpha, Sodium, Oxygen-2)
- Higher image noise – despite being actively cooled, CCD sensors are noisier than modern CMOS sensors.
So what camera should you get? As far as I can tell, there is no one right answer. It depends on your preferences and on your budget. The table below includes my personal top picks based on my research, but is by no means extensive or all inclusive. Notably, I haven’t researched the Sony cameras in any detail, no other lesser known brands. If you look on the DSLR forums at Cloudy Nights, you’ll find most individuals using Canon and to a lesser extend Nikon cameras, which tends to lend a focus to those brands.
What do I own? I’ve used the Canon Rebel T3i for the past two years now, but have begun feeling it was time for an upgrade. I just recently purchased a Canon 7D Mark II and a Canon Rebel T6s, and hope to put all three cameras to some comparative astrophotography tests soon. Once the weather cooperates.
|Canon Rebel T3i (600D)
|Canon’s entry level Rebel line is used by a large number of astrophotographers. (I’ve used this camera, with no modifications, for the past two years) They are discontinued now, but you can sometimes find refurbished units from Canon Direct or used on eBay. The Rebel T4i and Rebel T5i are newer versions with some improvements, and the T5i is still available new.
Buy Canon T3i on eBay
|Canon Rebel T6i/T6s
|These are the new Rebels that have a brand new 24 mp sensor. At the time I’m writing this, they were still mostly on back-order. These are also called the Rebel 750D and 760D in other markets. Look for a review of the T6s here soon!
Canon Rebel T6i @ B&H | Canon Rebel T6s @ B&H
|Introduced earlier this year, this looks like it should have the characteristics to be a good AP camera, and I was tempted to buy one, but opted for the 7D Mk II instead.
Shop on Amazon – Buy on B&H Photo Video
|If you want a full frame sensor, this is a good bargain right now. It’s a couple years old and there are rumors of a 6D Mark II within the next year, but this camera remains a good option.
Buy on B&H Photo Video | eBay
|Canon 7D Mark II
|Roger Clark reviewed this camera recently and rated it very high for low thermal noise and possibly better than average Ha sensitivity. I just purchased one of these, so look for a review here in the future too.
Shop at Amazon | Buy on B&H Photo Video | eBay
|Nikon’s first entry into the DSLR AP market. This is a full frame camera just introduced in early 2015. It includes some nice AP specific features like higher Ha sensitivity and taking exposures up to 15 minutes without a separate intervalometer.
An early review of this camera from an astro-imager is here.
Buy on B&H Photo Video
What Else Do You Need?
Memory cards obviously. I highly recommend extra batteries. These run down quickly on cold nights. And for most cameras, an Intervalometer is a necessity. Be sure to search for one that works with your model camera. For prime focus photography with a telescope in place of a camera lens, you also need a T-ring for your type of camera and a T-adapter. (Search for these items on B&H.)
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