Editors' note: Given that the D610 is nearly identical to the D600, I have borrowed substantially from my review of the latter camera. I did retest for performance and selected photo quality aspects, however, as noted within the review.
About a year ago, Nikon introduced the D600, the first sub-$2,000 full-frame dSLR to hit the market. Unfortunately, there were some issues that subsequently surfaced, like a problem with dust and oil spots caused by the shutter mechanism that a large number of owners complained about and some frustrating limitations for flash photographers. With this update, Nikon's implicitly addressing the former problem with a completely new shutter mechanism, but flash photographers hoping for an improvement on the latter are doomed to disappointment. On the upside, if you've been waiting for a price drop on the D600, that model seems to be available for about $1,600 in a variety of places.
The new shutter is rated for the same number of cycles as previously -- 150,000 -- but now enables a slightly improved burst of 6fps (from 5.5fps), and adds a new quiet-shutter continuous-shooting mode of up to 3 frames per second. Nikon has also tweaked the white balance, for theoretically better results under artificial light and brighter blue skies. In portrait mode, the company claims more natural skin tones and improved facial depth-of-field by incorporating contrast information.
While I didn't test the D610 as extensively as the D600, I did repeat our lab tests, checked out the white balance for the indicated changes, and compared the portrait quality in the scene program mode against manual settings. Whether the new shutter mechanism fixes the oil-spot problem will require either someone who can test significantly significant quantities of the camera or for large numbers of anecdotal complaints to surface.
For some reason, my D610 evaluation unit seems to meter about 2/3 stop brighter than my D600 evaluation unit; in other words, whenever I chose to let the camera determine exposure using matrix metering, its choices are generally brighter for the D610 than the D600, and it chooses to do so by using a wider aperture.
Aside from that however, the images from the D610 look pretty much like those of the D600, including the problem with clipped highlights; it still doesn't preserve blown-out highlight data as well as I'd like, even using the 14-bit lossless-compressed setting, but the D610 does deliver the same terrific photo quality for the price. It produces relatively clean image data at low and midrange ISO sensitivities, and has very smart JPEG and noise-reduction algorithms. You get very clean JPEGs up through ISO 400. I start to see a little degradation in shadow areas at ISO 800, though there's no corresponding degradation in well-lit areas until about ISO 3200. JPEG images are generally quite usable through ISO 1600; depending upon the scene and lighting you can probably push it as high as ISO 6400, though I'd recommend working with raw to be on the safe side. I was a bit surprised that it wasn't significantly better than the 5D Mark II at ISO 12800, but the D610 does have less clipping in the shadows and I couldn't find any hot pixels.
Like most full-frame cameras, the D610's photos have a nice, natural sharpness and tonality. It renders a broad dynamic range, although interestingly there's a lot less recoverable detail in clipped highlights than more expensive models like the 5D Mark III and D800 as well as the 6D under similar circumstances. It does very well with shadow detail, however.
The color differences between the Standard and Neutral Picture Control color settings have diverged a bit since the D600, possibly related to Nikon's tweaks to get bluer skies, and the Standard setting still seems to push the contrast a bit. (For more samples, look at the images for the D600.)
The D610 does seem to perform a hair faster than the D600 all around. (Caveat: we tested the D600 when we were first working out the new methodology, and some of the differences, with the exception of burst shooting, might simply reflect subsequent tweaks to our procedure.)
It takes less than 0.3 second to power on, focus, and shoot. In good light, it runs about 0.4 second to focus and shoot using the viewfinder (phase-detection autofocus), which rises to about 1.5 seconds in Live View mode (contrast autofocus); in dim light it's a reasonable 0.5 second through the viewfinder. Two sequential JPEG or raw shots take just under 0.2 second, and with flash enabled it's a zippy 0.7 second. With the D610 and its new shutter mechanism, Nikon increased the continuous-shooting speed to 6fps, and indeed the JPEG burst with a 95MB/sec SD card clocked in about about 6.1fps for at least a 30-shot buffer. It can only shoot about 14 raw shots without slowing -- oddly, down from 16 on the D600 -- but it can do so at about 6.3fps, likely because there's less processing overhead for the raw vs. the JPEGs but the bigger files fill up the buffer faster. Once the buffer fills it drops to about 3.3fps. The camera maintains those rates regardless of whether its in single or continuous autofocus mode.
As with the D600, the LCD definitely requires some shading and magnification via a loupe for shooting video, if not for basic Live View operation.
Design and features
As it's identical to its predecessor, I still really like this model's design and operation; I really enjoy shooting with it. It's a little bit lighter than other full-frame bodies -- but not significantly so -- except for its newest competitors. It's got a similar build quality, constructed from a magnesium-alloy chassis covered in polycarbonate, with moderate dust-and-weather sealing.
On the camera's left shoulder sits the exposure mode dial on top of the release mode dial (which is how Nikon refers to its drive modes); the former has a lock button in the center and the latter has it adjacent. As with Canon's, I don't really like the lock button in the center, as I find it a little awkward to operate single-handed that way, and with the Olympus E-M1 we've seen a way to do it better. There are two user settings slots on the mode dial; that's one way in which the D610 differs from the pro bodies, which have a much more sophisticated (and complex) set of options. I happen to like them better on the mode dial, but I also find that three slots is my optimal number of custom sets.
On the right shoulder sit the status LCD, dedicated metering and exposure compensation buttons, power switch circumscribing the shutter button, and a tiny video record button. I'm not a big fan of the tiny top record buttons that seem to be becoming vogue, and am a little disappointed that you can't program one of the buttons on the back for this function.