Before the release of the D810A this past summer, Nikon had not manufactured a Hydrogen-alpha (Ha) filter-modified camera for astrophotography. Canon had released two Ha-enhanced versions of earlier models for astrophotography—the 20Da (in 2005) and the 60Da (in 2012)—leaving Nikon night-sky shooters waiting until now. I was one of them. As a longtime Nikon user with a shelf full of Nikon lenses, I ordered one right away.
Why is an Ha filter-modified camera better for astro-imaging than a regular DSLR? The primary reason is that the internal infrared (IR) cutoff filter on the modified camera permits four times as much of the deep red 656nm wavelength of Ha emissions through to the sensor than do nonastrophotography DSLR models.
Until very recently, the 36-megapixel specification of the D810A would have been regarded as a disadvantage for an astro-camera. A smaller pixel count means larger pixels in the sensor, each better able to soak up faint celestial light sources—or so we thought. But judging by the Nikon D810A results, sensor technology seems to have moved forward. Everything is sharper, and faint stars are smaller, with more room to crop, if desired. A direct comparison with images from the top-rated 20-megapixel Canon 6D (introduced in 2012) clearly shows the 36-megapixel Nikon imaging fainter stars with equivalent exposures. Nebulas look similar in both images, but further testing is under way to quantify this.
A very useful feature of the Nikon D810A is a new shooting mode: M*. Similar in all respects to the M (Manual) mode to which Nikon shooters are accustomed, it has added preset exposure times, ranging from 4 seconds to 900 seconds. Also, exposures of 4 seconds or longer can be shot in continuous shooting mode, either until the card is filled or until the battery is drained. No gaps in star trails. No buffer issues. And there is an M* setting called “Time” that acts like a bulb: One shutter click opens the shutter; another click closes it. This allows you to take specifically timed shots easily.
The live-view capability has been enhanced for astrophotography. When live view is on, the “OK” button on the back of the camera acts as a switch, boosting the brightness of the live-view screen on or off. This helps when focusing on fainter stars.
The D810A has been improved over some earlier models by extending the maximum number of shots from 999 to 9999. Meteor-shower and time-lapse shooters who want to leave their cameras running all night will like this change. For the longer nights, 999 was not enough frames to use the on-camera intervalometer. The intervalometer can also handle HDR image sets of up to 9999 x 9 frames (for those who are shooting HDR time lapses).
The on-camera, time-lapse function allows you to create time-lapse movie sequences without having to process a video later from hundreds of stills on a computer. The camera compiles the video for you and saves it as a .MOV file. This is very convenient if shooting an aurora or capturing the motion of the night sky when you want to keep it simple. You can always shoot still frames if you’d like. Time lapse is a nice option.
As astrophotographers know, finding buttons and scrolling through menu options, especially in the dark, can be challenging. Nikon’s solution is to provide an option called “My Menu.” Simply populate the menu with your most frequently accessed menu items. You can program a button on the camera to take you to this menu directly. In My Menu, I have LENR, the Leveling tool, Image quality, White balance, Time lapse and Intervalometer shortcuts, among others.
There is an electronic front-curtain shutter option that, when enabled while in mirror lockup mode, reduces the shake associated with the mirror flip when triggering the shutter, but one feature I wish Nikon had included on the D810A is the swivelling LCD screen that is on the D750. I also wish Nikon had copied Canon so that the camera could apply a single dark frame to multiple exposed frames.
Yes, the camera is expensive (north of $4,000), but it costs less than high-end, one-shot colour CCD astro-cameras and can be used quite nicely for daytime shooting as a regular DSLR, while an astro-CCD cannot. The D810A daylight scenes do not have the distinct pinkish cast that most filter-modified DSLRs do, so colour-balancing in Photoshop or other software is not necessary, nor is rebalancing the white balance between day and night use.
While I have a few minor wishes (a red-tinted cover for the LCD screen, for one), I am very pleased overall with this camera.
Malcolm Park, an experienced Nikon camera user, lives under dark skies in Prince Edward County, Ontario. He is former president of the North York Astronomical Association.