Canon introduces the EOS Ra, a version of their 30-megapixel, EOS R full-frame mirrorless camera designed specifically for astrophotography.

At long last, Canon has re-entered the astrophotography market with the release of its EOS Ra Mirrorless camera (estimated price: $2,499). While most DSLR and mirrorless cameras work well for general photography, they often require modification to perform best while imaging the night sky. This is the third “a” camera from Canon after their 20Da in 2005 and 60Da in 2012, both cropped-frame DSLRs.

We received an advanced sample of the EOS Ra from Canon USA, to expand upon the review already  underway of the stock EOS R that will appear in an upcoming issue of Sky & Telescope. Both cameras perform identically for noise and image quality.

The EOS Ra differs from the stock EOS R in its greater red sensitivity (due to a special infrared cut-off filter), factory-calibrated white balance, and 30x Live View magnification.

Outperforming the 60Da

All consumer digital cameras have a filter mounted in front of the sensor that cuts out infrared light that would otherwise add an unfocused haze over the image. But filtering out IR also filters out most of the hydrogen-alpha light in the deep red region of the visible spectrum emitted by nebulae.

Not so with the EOS Ra. Its factory-installed IR-cut filter transmits a much higher level of the 656.3-nanometer emission line of hydrogen-alpha emitted by star-forming regions in the Milky Way and other galaxies.

It appears Canon has fitted the EOS Ra with a filter that transmits a higher level of the H-alpha line than on its earlier “a” cameras. Canon claims it is four times higher.

While we couldn't confirm that number, the Ra's performance does seem to be on par with my filter-modified Canon 5D Mark II that I have used since 2009. My venerable 5D MkII is an example of a DSLR modified by a third party, in this case by Astro Hutech.

The EOS Ra (far left) picked up the North America Nebula with richer red nebulosity than Canon’s 60Da camera (far right), and with a level similar to the third-party modified Canon 5D MkII. By comparison, images with the stock EOS R and 6D MkII show what a normal camera typically records — very little red.

And yet, despite its special filter, the Ra can be used for normal daytime photography using Auto and Daylight white balance. Color correction filters are not needed.

Due to its factory calibration the Ra produces raw files with a color temperature about 2200 K bluer than what you shot at. Shoot at 5200 K daylight and you get a raw file set to 3000 K (left) that looks similar to a normal camera’s image (middle). But use your raw development software to raise the color temperature to 5200 K and you get a pink image (at right), just as with third-party modified cameras.
The EOS Ra’s unique 30x magnification when in Live View (seen here through a telescope with a Bahtinov mask added over the telescope aperture) to aid in precise focusing.

Both the EOS R and Ra offer a bright Live View screen making it much easier than with most DSLRs to frame scenes at night. The EOS Ra, however, has a welcome firmware upgrade from the standard EOS R that benefits astrophotography. Instead of the usual 10x, the EOS Ra offers a 30x magnification in Live View, great for achieving accurate focusing on stars, especially with wide-angle lenses.

The EOS Ra proved identical to the stock EOS R for noise. Both cameras’ 30-megapixel sensors have  5.34 micron-square pixels.

At the high ISOs we typically use for astro-imaging, the R cameras exhibit noise levels that are as good as, if not slightly lower than Canon's 6D MkII, despite the latter’s larger 5.7-micron pixels. Read more about the cameras' performance comparison to competing models in an upcoming issue of Sky & Telescope.

The North America Nebula, NGC 7000, in Cygnus, taken with the new Canon EOS Ra factory-modified “astronomical” version of the Canon EOS R mirrorless camera. This is a stack of 4 x 6-minute exposures, with LENR on and at ISO 1600, through an Astro-Physics Traveler 105mm f/6 apo refractor with Hutech field flattener.

Comments


Image of Curtis Urban

Curtis Urban

November 7, 2019 at 12:34 pm

Dear Sky and Telescope,
I own several Canon 60Da cameras
Is it possible to get a better comparisons with the Canon 60Da?
The article is very good however the photo in the article is very limited for the comparison...
I contacted Canon and they have limited information and nothing on the sensor
Does Sky and Telescope have one of these cameras for a better comparison?
So how about the sensor comparison on wavelengths etc.

Is S&T going to do an article in the magazine on this product?

Thanks Curtis
Please email back at Curtis.urban11@gmail.com

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Image of Monica Young

Monica Young

November 8, 2019 at 8:02 pm

Hi Curtis - great question! Yes, this is just a first look. An upcoming Sky & Telescope article will do a more in-depth review of this product.

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