CHAPTER 13: Digital Astrophotography — What’s NEW?Chapter_13__Digital_Astrophotography.htmlChapter_13__Digital_Astrophotography.htmlshapeimage_2_link_0
 
Be sure to check out dpreview.com and imaging-resource.com. Both have excellent reports (though tested for daytime shooting) on all these cameras, and much more.
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http://www.dpreview.com/http://www.imaging-resource.com/shapeimage_3_link_0shapeimage_3_link_1
Nikon D3200

Replaces Nikon D3100
Competitive with Canon Rebel T5i/700D 
• APS sensor (Nikon’s “DX” format)
24.2 megapixels, 6016 x 4000 pixels
3.85 micron (μm) pixels
12-bit processing
Fixed hi-res LCD screen (921,000 pixels)
About $500 US (body only)





http://www.dpreview.com/reviews/nikon-d3200shapeimage_4_link_0
Nikon D5200 

• Replaces Nikon D90 and D5100
Competitive with Canon 60D or 650D
• APS sensor (Nikon’s “DX” format)
24.1 megapixels, 6000 x 4000 pixels
3.9 micron (μm) pixels
14-bit processing
Articulated hi-res LCD (921,000 pixels)
About $700 US (body only) 

Also available:  The Nikon D7100
Competitive with Canon 7D 
APS sensor (Nikon’s “DX” format)
24 megapixels, 6000 x 4000 pixels
3.9 micron (μm) pixels
14-bit processing
Fixed hi-res LCD screen (1,228,800 pixels)
About $1,200 UShttp://www.dpreview.com/previews/nikon-d5200/http://www.dpreview.com/reviews/nikon-d7100/shapeimage_5_link_0shapeimage_5_link_1
DSLR Choices (as of January 2014)

Here are our current choices for recommended DSLR cameras, updating advice in Chapter 13.

Despite our revision of the print version of The Backyard Astronomer’s Guide in 2010, rapid changes in the DSLR market mean any print advice is soon out of date. The cameras we recommend in the book (the Canon 40D and 50D among them) are decent choices for anyone looking for a low-cost camera on the used market. But ... both Canon and Nikon, the two industry leaders, continue to advance the state of the art. Here’s a rundown on our currently recommended models, as of January 2014. Click on the headings to go to reviews or previews at dpreview.com 

Highly Recommended — The Canon EOS 60Da

In early April 2012 Canon announced the 60Da, taking everyone by surprise. This new camera is a modern version of the 2005-vintage 20Da. Like the 8 megapixel 20Da, the 18 megapixel 60Da offers a sensor filter designed to transmit more of the deep red end of the spectrum, particularly the H-alpha wavelength, so that red nebulas will record with more detail and deeper red tones. We’re big fans of filter-modified cameras but these usually require having the camera modified by a third party. In this case, Canon is doing the mod for you as a factory-installed feature. 

In our testing we found that, as expected, Canon equipped the 60Da as they did the 20Da, with a red-pass filter not as wide as the ones installed by third party modifiers like Hutech. As such, like the 20Da before it, the 60Da is perfectly usable for daytime shooting out of the box without any need for special filters, custom colour balancing or post processing. That said, the 60Da does not provide as great a sensitivity to red H-alpha emission nebulas as the after-market modified cameras offer. In same-night testing, the 60Da outperformed a stock camera for picking up nebulosity but did not record as much faint nebulosity as did a Hutech-modified camera. However, the latter cannot be used for daylight shooting without taking some corrective measures (like shooting with a Custom White Balance setting or through a special filter). The 60Da provides a more magenta tone to nebulas with a more even balance of red and blue wavelengths, while the Hutech cameras are more in-your-face red, great for picking up the really faint nebulosity. 

At $1500 the 60Da represents the single best choice for anyone looking for a DSLR for serious astrophotography, without spending a bundle. It does come with some unique accessories: an adapter cable to allow users to connect the superb Canon TC-80N3 interval timer, and a AC power supply cord. The cost is comparable to the third-party modified Canon 60D cameras (roughly $400 to $500 more than a stock 60D) and you get some useful accessories as part of the package that would be extra otherwise. True, it does not record quite the depth of nebulosity of a modified camera but daytime images look close to normal in colour balance, so there is no fear of spending lots on a DSLR great for astro-imaging but compromised for other photography. The 60Da can do it all. In addition, a 640x480 Movie Crop mode unique to the Canon 60D (and shared by the 60Da) allows it to record high-resolution movies at 60 frames per second, ideal for planetary imaging.

A review of the 60Da by co-author Dyer appeared in the September 2012 issue of Sky and Telescope magazine. Also, check out Jerry Lodriguss’s comparison of the 60Da vs 60D and modified 550.

Great Value — The Canon EOS 70D

If the price of the 60Da is a bit much, a stock Canon 70D released in September 2013 is the best alternative. Its predecessor, the 60D, exhibited slightly less noise than the older Canon 7D with the identical sensor. The new 70D with the latest DIGIC V processor and new sensor should be slightly better for noise yet again, though we have not tested a 70D. 

The 70D offers 20.2 megapixels on an APS-sized chip (23 x 15mm) and Canon’s DIGIC V+ processor, a slight bump up from the 18 Mp 60D and 60Da. The main area of improvement in the 70D is a new hybrid sensor for faster autofocusing – nice but of little value in astrophotography. Note that the higher-end and more robustly constructed 7D remains available, with the older 18 Mp sensor, but is due for a major upgrade. While we have recommended the Canon 7D in the past as a good choice for someone wanting a higher-end rugged camera, we have both sold our 7D cameras. The new cameras outperform the 7D for noise and in features for astrophotography, like the flip-out screen.

As with all cameras now, the 70D offers HD movie recording capability, in 1080p and 720p formats. This can be very useful for some astrophoto applications, let alone home and vacation shooting. It also has both HDMI and AV outputs for video & audio. Plus it has the aforementioned 640x480 Movie Crop mode, turning the camera into a 60 fps webcam, able to record full resolution (i.e. no pixel binning) movies right to the SD card, with no need for a computer when doing planetary imaging.

In addition to lightness and size, the 70D offer one unique advantage for astrophotographers — the articulated LCD screen, a first for a Canon DSLR. A tilting screen makes it much easier to live focus and inspect images when the camera is on a telescope aimed up at the sky. Like the Rebels, the 70D’s screen is also a touchscreen for changing settings, an upgrade over the 60D. 

If you are upgrading from an earlier xxD series Canon, be aware that the 70D and 60D do not use Compact Flash cards that earlier xxD cameras used, but instead use smaller SD cards, like the lower-cost Rebel cameras. It also uses a different battery (and therefore charger) than earlier xxD cameras, but not the same battery as the Rebels use. It is the same battery as in the 7D,6D and 5D MkII/MkIII, a very good long-life battery. So consider all that if you are adding a 70D or 60Da to an existing suite of Canon cameras and accessories. If it is your first DSLR, it’s a moot point. 

However, the 70D has one glaring shortcoming (avoided by the 60Da). In keeping with its Rebel-like design the 70D uses the Rebel’s mini-phone-style jack (the P3) for its remote control accessory. It does not accept the wonderful Canon accessory, the TC-80N3 interval timer, at least not without modifying the timer with a new plug. Alternatively, third-party interval timers for the 70D/60D/Rebels are available from Phottix, Satechi and other suppliers. Which ever model you choose, an accessory intervalometer is essential for deep-sky shooting, negating the need for a computer just to automate exposure sequences. 

Bargain Megapixels — Canon’s Rebel T5i/700D

If your camera budget can’t swing the 70D or 60Da, consider the Canon Rebel series. The latest model (they change yearly) was announced in June 2013 as the 700D, or T5i “Rebel” (as it is called in North America). 

The 700D/T5i is a minor upgrade to its predecessor, the 650D/T4i. It offers the same 18 megapixels the 650D and as the 7D and 60D but with the new DIGIC V processor and Canon’s new hybrid sensor that offers faster auto-focus tracking. The other main feature is a touchscreen on the rear LCD screen for adjusting camera settings. Cost for a body-only package is an attractive $800 for a stock camera, with third-party filter-modified units going for about $400 more. Past Rebels have offered similar noise levels to their more costly kin in the Canon line up, making a Rebel a good low-cost choice.

The Rebels do have one annoying deficiency — they do not have a top-mounted screen for readout of cameras settings, unlike the 70D, 60D and all other Canon models. All settings are made by looking at the rear LCD screen, which can be blinding at night. However, the colour can be changed. On the plus side, the T5i and older T4i offer the same articulated screen as the 60D, which does make it easier to use when imaging through a telescope. 

Keep in mind accessories should you wish to upgrade. The Rebels use a different battery/charger than the 70D/60D/6D line. But they do use SD cards like the 60D. They use the same remote connector as the 70D but different than on all other Canons.

As of this writing, the older Rebel T3i/600D camera is still available at a lower cost still (~$550) for those on a budget. Canon also offers the diminutive Rebel SL-1, a very compact 18 megapixel camera for about $600 (body only).

But If You Want the Best — The Full-Frame Canon EOS 6D

Having said all that, we have to say that if you really want the best in a DSLR, the new full-frame Canon 6D is it. Out since late 2012, we are now testing a Hutech filter-modified 6D and find that it is about 2 stops better for noise than the already excellent 60Da, and one stop better than the standard-setting 5D MkII it replaces. The 6D can provide presentable images at previously unthinkable ISOs of 6400 or higher. This promises to revolutionize astrophotography. We’ll learn more as we continue to test it under real-world conditions and in A-B tests against our other cameras.

The Canon 6D offers 20.2 megapixels, modest by today’s standards and no higher than other premium Canon DSLRs. But in astronomy that’s good. It means the individual pixels remain large – 6.55 microns in the case of the 6D, slightly larger than in the 5D MkII. This allows the new 6D to provide low noise as a high design priority, vs. cameras with 24 to 36 megapixels where resolution is paramount but pixels are small and noise-prone.

The prime difference is that the 6D is a full-frame camera – the sensor is 24 x 36mm, the same size as a 35mm film frame. The price is about $2,100 US ($2,500 for a filter-modified camera), at the low end of the price scale for a full frame camera. But the price makes this a camera for the serious shooter of the sky. Though more costly than many DSLRs it is similar in price to many entry-level 8- to 11-megapixel CCD cameras, like the Kodak 8300-based models, but with a much larger sensor and 2 to 2.5 times the pixels.

The 6D does not have the wonderful swing-out viewscreen of the 60D and Rebel cameras. Pity. But as a first for Canon, it does have WiFi built in, enabling it to be controlled and its images viewed remotely via an iPad or iPhone, using a Canon EOS app. 

Our previous favourite camera, the 5D MkII, which debuted in 2008, is now officially discontinued. But while supplies last it is still available for $1,800. It works great and is a good choice for a full-frame camera at the lowest price. While its previously top-class noise performance is now beaten by the 6D, the older 5D MkII does have one nice advantage over newer cameras:

For deep-sky shooting the 5D MkII had a wonderful and little-known feature – a special buffer memory that allowed it to take up to 5 long exposures, then internally automatically apply a single internal dark frame taken at the end of the sequence to all 5 previous “light” frames. This means, for example, that five 8-minute exposures and the dark frame for those exposures took just 6 x 8 = 48 minutes. With most other Canon cameras, having the camera take and subtract a dark frame internally means taking a dark frame after every light frame. A set of five 8-minute exposures with, say, the 60Da or 650D will take 10 x 8 = 80 minutes to complete, vs. 48 minutes for the 5D MkII. 

What about the new 6D? It can take four exposures before forcing a dark frame. That speeds up exposure acquisition a lot but isn’t quite as good as the 5D MkII. The new high-end 5D MkIII is the same as the 6D – it, too, allows only four frames to be taken before forcing the dark frame. Even so, the four frame buffer is one of the best advantages of Canon’s full-frame DSLRs.

What about the 22 megapixel 5D MkIII? It shares the 6D’s DIGIC V processor, delivering similar signal-to-noise characteristics. However, at $3,500 for the body (not modified) this camera is costly and offers little in additional features of value to the astrophotographer when compared to the 6D. Indeed, it is a larger and heavier camera, though certainly very well built. Considering its cost, we’ll stay with our recommendation of the Canon 6D or, at lower cost, the older 5D MkII (as long it remains available new or used), as our top choices for a premium DSLR for astrophotography. Get a filter-modified camera if deep-sky shooting is a top priority. However, a 6Da would be great – the perfect DSLR for astronomy! Hello, Canon?? 

But in picking a camera, keep in mind that we say in our book about any full frame DSLR will be true of the 20 and 22 megapixel 5D and 6D series cameras — they will tax the quality of any optics attached to it, ruthlessly revealing off-axis aberrations. For deep-sky shooting through a telescope, you’ll need optics with field flatteners (built-in or added-on) designed to fill large chip cameras. For piggyback shooting, you’ll need top-class glass — like the Canon L-series lenses. A full-frame DSLR is a serious commitment. For most users, the smaller-chip Canon 70D, 60Da, or 700D will be just fine, thank you. 



What About Nikon?

In the last few years Nikon has made great inroads at producing cameras with low-noise for low-light situations where high ISO speeds are required. Tests published on the web and done under normal daytime conditions seem to show that new Nikon models perform as well as, if not better than, competitive Canon DSLRs for low-noise performance, at least for short exposures. 

That said, however, we have not tested any of the models listed below, so we cannot vouch for how well they work during the long (> 5 minute) exposures required for deep-sky imaging. In 2007 we tested a then-current Nikon, the D80, against a competitive Canon, the Rebel XTi/400D, and the Canon won. Download a copy of the SkyNews magazine review here: SLRcameras.pdf While the older Nikon D80 (the D90 replaced it) did have low noise, image quality fell apart in long exposures: 
images turned green after 5 minutes of exposure
amplifier glow added hot spots at the edges of the frame, even after subtracting an internal dark frame 
stars did not de-Bayer well, leading to multi-coloured specks instead of white stars. 
Based on that experience, and the fact we have seen few published long-exposure (> 5 minute) images, or tests of Nikons from other astrophotographers, we are reluctant to recommend Nikon DSLRs. 

However, of the current line, the full-frame Nikon D610 with 5.9 micron pixels (competing with the Canon 6D) sounds the most promising. In most other current models, Nikon has opted for packing in lots of pixels to maximize resolution, great for daytime landscape shooting but not so good for nighttime astrophotography.

• If you’d like a second opinion, check Jerry Lodriguss’ comments at his excellent website, Catching the Light. Jerry also offers a detailed camera comparison chart well worth inspecting.
• Or check Christian Buil’s meticulous measurements of DLSR performance at his website, Spectroscopy, CCD & Astronomy.

Here are the main models Nikon offers as of October 2013 (all have Live View or Live Focus and HD 1080p Movie mode):
http://www.dpreview.com/http://www.dpreview.com/news/2012/04/03/Canon-EOS-60Da-for-astrophotographyhttp://www.hutech.comhttp://www.astropix.com/HTML/I_ASTROP/EQ_TESTS/60Da_60D_550Da.HTMhttp://www.dpreview.com/previews/canon-eos-70d?utm_campaign=internal-link&utm_source=mainmenu&utm_medium=text&ref=mainmenuhttp://www.phottix.com/http://www.satechi.nethttp://www.dpreview.com/reviews/canon-eos-700d-rebel-t5i/http://www.dpreview.com/reviews/canon-eos-700d-rebel-t5i/http://www.dpreview.com/reviews/canon-eos-6d/http://www.skynewsmagazine.com/pages/reviews/telescopereviews.htmlDSLR_Cameras_for_Astrophotography_files/SLRcameras.pdfhttp://www.astropix.com/HTML/I_ASTROP/NIK_CAN.HTMhttp://www.astropix.com/HTML/I_ASTROP/COMPARE.HTMhttp://www.astrosurf.com/buil/nikon_test/test.htmshapeimage_6_link_0shapeimage_6_link_1shapeimage_6_link_2shapeimage_6_link_3shapeimage_6_link_4shapeimage_6_link_5shapeimage_6_link_6shapeimage_6_link_7shapeimage_6_link_8shapeimage_6_link_9shapeimage_6_link_10shapeimage_6_link_11shapeimage_6_link_12shapeimage_6_link_13shapeimage_6_link_14
Nikon D610

Replaces Nikon D3/D3S & D600
Competitive with Canon 6D
• Full-frame 35mm (FX format) sensor
24.3 megapixels, 6016 x 4016 pixels
5.9 micron (μm) pixels
14-bit processing
Fixed hi-res LCD screen (921,000 pixels)
About $2,000 US (body only)

Also available: The Nikon D800/800E
Competitive with Canon 5D MkIII
Full-frame 35mm (FX format) sensor
36.3 megapixels, 7360 x 4912 pixels
4.8 micron (μm) pixels
14-bit processing
Fixed hi-res LCD screen (921,000 pixels)
About $3,000 US (body only)http://www.dpreview.com/previews/nikon-d610/?utm_campaign=internal-link&utm_source=mainmenu&utm_medium=text&ref=mainmenuhttp://www.dpreview.com/reviews/nikon-d800-d800e/shapeimage_10_link_0shapeimage_10_link_1