tl;dr: Fujifilm’s EXR sensor is extraordinary, mostly for its dynamic range. If you’re after the best non-DSLR image quality around, your choices start at the Fuji F200EXR, F70EXR, S200EXR, and end there.

Fujifilm has long been a leader in revolutionary sensor technology, particularly at the smaller scale sensor market where the majority of manufacturers have long been content pumping out traditional, vanilla CCD sensors with square grid-based Bayer Filter Arrays.

In September of 2008, announced plans for their latest sensor: the Super CCD EXR, which combines the unique color filter array (CFA) and pixel binning features of various previous sensors into a single “switchable” sensor that can be optimized in one of several areas (which are typically mutually exclusive when designing a sensor): high resolution, high dynamic range, and low noise.

High resolution

High resolution mode is the default mode, which utilizes the full set of photosites on the sensor and produces an image with a corresponding pixel on each photosite – nothing too special here, though Fuji claims the diagonal layout of photosites (as opposed to simple square grid) helps to improve resolution.

High sensitivity

A comparison of a typical Bayer CFA (left) and the CFA on Fujifilm's new EXR sensor (right)

The second mode of operation for the EXR sensor is a high-sensitivity mode which Fuji calls “Pixel Fusion Technology”, which is fancy marketspeak for pixel-binning (combining reading from adjacent pixels together to produce a better signal). With the EXR’s pair-based CFA layout, Fujifilm claims that interpolation (and thus color resolution) will be more accurate because the binned pixels are closer together (e.g. the pair blue pixels are pretty much in the same location, while they’re separated by two pixel lengths in a standard square-grid Bayer array. I don’t know that I buy this argument particularly well – it’s true that same-color pixel values will be more accurate since they’re closer, but you can’t get something for nothing: for example, the average distance from red-to-blue is going to be increased, which lowers accuracy for interpolating blue values at red pixels.

Regardless of whether their CFA and photosite layout nets them better interpolation, the key element here is the combination of pixel readings to generate a stronger signal, thus decreasing the proportion of noise. Using microlenses to patch up the fill factor (area of the sensor which is actually responsive to light) and various optimizations to lower read noise will get the high sensitivity mode EXR sensor closer to the noise level of a natively lower resolution sensor.

Wide Dynamic Range

A diagram detailing the two exposures captured by the EXR sensor when operating in large dynamic range mode

The third mode of operation for the EXR sensor uses variable photosite sensitivity to greatly extend dynamic range.  The concept is taken from some of Fuji’s older generation SuperCCD SR sensors – at a given pixel location there are in fact two photosites, one operating at a lower sensitivity and one operating at a higher sensitivity. This essentially produces two images for any particular shot, one at low sensitivity that is underexposed (capturing highlight detail, such as a bright sky), and one at high sensitivity that is overexposed (capturing shadow detail, such as a shaded building face). These images are combined, much like HDR combination is done, to create a single image which captures a much larger dynamic range than a single exposure could.

Edit: dpreview seems to report that the EXR sensor actually achieves this by operating one image at a shorter exposure time (shutter speed) than the other, rather than actually varying the sensitivity. If so this would be even better, as you’d have lower noise due to operating both sets of photosites at the same lower sensitivity.

As with pixel binning for greater sensitivity, the pixel count in the resulting image will have to halve as well.

There are some notable improvements compared to Fuji’s older SR sensors. For starters, the low and high sensitivity photosites are now of equal size, which Fuji claims will allow for a greater dynamic range extension (the SR sensors consisted of mostly “regular” photosites with tiny “low sensitivity” photosites sandwiched in). Furthermore, based on most of the image samples that can be found, the recombination method used for EXR is a bit closer to HDR blending, which doesn’t map values linearly on the same tone curve – this produces a punchier photo with better contrast that still looks natural upon viewing (due to the way human vision judges brightness in relative terms rather than absolute), even if its not quite pixel-accurate. This seems to address one of the complaints about Fuji’s older SR sensors, which provided a large dynamic range but ended up squashing it linearly to the same 12-bit RAWs or 8-bit JPEG images that all other cameras provide – the results were images that did have more highlight detail but looked “flat” and lacked contrast (because that 0.5-1 stop of highlight detail at the top is squashed into a small 250-255 pixel value range).

The EXR sensor has a big advantage over conventional HDR as well (i.e. taking multiple exposures and blending them): it captures an extended range image in a single instance, making it usable for moving subjects (HDR sports photos, yay!).

The Results

The first EXR sensor, the Fujifilm F200EXR, debuted in February 2009, and was followed up not long afterwards by the S200EXR bridge camera and the ultracompact ultrazoom F70EXR, giving us a chance to see some hard results.

Imaging-resource, as always, has perhaps the most comprehensive test bed of images, and samples from their express review of the F200EXR can be found here: http://www.imaging-resource.com/PRODS/F200EXR/F200EXRA7.HTM

Their site isn’t the most comparison-friendly however (though you can give their comparator a shot) so I’ll link to dcresource’s reviews of the F200EXR and F70EXR as well and reference these.

The first thing to note is that Fujifilm hasn’t lost a step in the noise race – in both the standard high resolution (no binning) and high sensitivity (binning, lower resolution) modes, the EXR sensor simply wipes the floor with every camera on the market this side of a full-fledged DSLR.  In the F200EXR review there is a side-by-side comparison (search for the text “Again, things look great through ISO 400″ – it’s right above this) between the 6MP high-sensitivity mode image, and a 12MP high-resolution mode image that is downsized to 6MP – essentially doing the same as pixel binning but off-camera, and digitally, rather than in-camera and analog.  The result is a slightly crisper image but noticeably more noise, though the effect isn’t dramatic.

What’s interesting is that the side-by-side comparison in the F70EXR review shows that the high-resolution mode, downsized to the same resolution as the high-sensitivity mode, actually produces better results – the same amount of noise but much crisper detail. This seems to punch a hole in the effectiveness of the EXR’s in-camera pixel-binning: if the digital data (full of rounding errors, and compressed to 8-bit jpeg) can be averaged and produce more effective results than binning the analog data (the raw readings from the sensor), then we can surmise that having more accurate data on the location of brightness values (i.e. more pixels) helps us produce more accurate images overall than having slightly more accuracy on the actual brightness values.

Further down on the F200EXR review (search “so the two would be the same (6MP) resolution” – right below this), you’ll see a direct comparison using the camera’s wide dynamic range mode. As opposed to the high sensitivity mode, here we can see real, significant benefits – highlight detail that is hopelessly blown out in the left image is very much visible in the wide dynamic range image. For those of you too lazy to navigate the admittedly long and cumbersome dcresource review pages, here’s a marketing image from Fujifilm that gives you the general idea:

Standard dynamic range (left) and wide dynamic range (right) - probably exaggerated a bit

This image gives you a general idea of the difference, though I wouldn’t take it at face value. The image on the right is probably a fair representation of what you’ll get using the wide DR mode (and you can compare this with shaded interior/sunlit exterior/sky photos you’ve probably taken), but the image on the left has way more contrast (and less DR) than any typical camera would, on its default settings at least.

The Triumph of EXR – Dynamic Range

So is Fuji’s EXR sensor a success? It depends on what you’re after. Many diehard Fujifilm Super CCD fans fell in love with the low-resolution F10/11 and F30/31 ultracompacts, both of which came in at just 6MP and absolutely wiped the floor with the competition in terms of noise performance.  And while subsequent SuperCCD iterations have maintained a clear advantage over competitors in this area (and this newest EXR sensor does to it better than its predecessor), the fact is that the high 12MP or so resolutions found on today’s sensors still compromise noise performance, despite any fancy “Pixel Fusion Technology” that Fujifilm tries to market.

The true triumph of the EXR sensor is in its dynamic range capability, and its separate pixel design (it essentially operates two sensors) works not only better than any of its competitors, but far better than even a natively lower resolution sensor.  While a larger photosite does afford more highlight headroom, halving the pixels (doubling the area) affords at most 1 stop. The EXR’s method, which essentially captures two independent exposures, is in theory capable of capturing dynamic range that is infinitely far apart, though for most scenes they’ll likely need to overlap to avoid gaps in coverage, which based on the settings allowed on current cameras is 3 stops.

According to dpreview’s dynamic range test of the F200EXR, the EXR can deliver nearly 11 EV (stops) of dynamic range.  Not only does that far outclass any compact (or even the bulky SLR-like bridges that use the same small sensors) on the market, but exceeds the dynamic range of DSLRs like the Canon 7D, Nikon D300, et. al, which all range around 8 EV for their jpegs. With a bit of tweaking with RAW files in Adobe Camera Raw, the DSLRs just about manage 10EV.

It’s simply remarkable that jpegs from a camera with a pint-sized sensor can beat out RAW images from the highest-end DSLRs, but that’s what innovative technology can do for you over hammering away with sheer physical size and trying small refinements from there (which is how most of the rest of the sensor industry has been operating for years). I can’t begin to fathom how much the Super CCD would change the landscape of photography if Fujifilm ever scaled up the sensor to DSLR size.

Pentax K-x (space white)

Following up on their K-7, Pentax has now come up with an entry-level K-x. While it doesn’t bring anything groundbreaking that wasn’t already seen on the K-7, it packs in many of the features seen on many competitors’ midrange model, and perhaps pending reviews on image quality and disregarding the overall Pentax system upgrade options, is probably the best choice out there currently for the beginning photographer/student.

The big headline features:

• 12.4MP CMOS (different from the K-7 14.6MP sensor, but interestingly also uses CMOS unlike all previous Pentaxes which used CCDs)
• ISO up to 12.8k
• Live-view with face-detect AF
• 720p, 24fps video
• 4.7fps continuous shooting
• $650 MSRP with 18-55 kit lens (and likely to drop further once it gets off pre-order)

A comparison:

Pentax K-x comparison

In a comparison with the $500 entry-level cameras, the K-x blows them away in nearly aspect, and goes toe-to-toe or even exceeds the D5000 and Rebel T1i in every single category, despite being significantly cheaper (especially once the street price drops lower from MSRP)

Interestingly enough, the Pentax K-x will come in a variety of colors, including an ultra-spiffy red (below), the space white shown above, and your ordinary black.

Interestingly enough, Pentax Japan features a site where you can come up with your own custom color scheme, and apparently order it as well, which personally is an insanely appealing prospect.

Pentax K-x (red)

Pentax K-x custom design - design your own!

I think this is a ranking of custom designs that users have created

Pentax K-x press release

Nikon SLR Refresh

Nikon introduced a couple of new SLR updates, the updated D300s and D3s. The D300 is a pretty incremental upgrade to the mid-level D300, offering a modest +1fps improvement in continuous shooting (up to 7fps), and bringing the video capability that’s now standard on every new DSLR.

The bigger story came a few months later, in the form of the D3s. While still not a revolutionary introduction, it is much more than a software refresh. Among the features of note were a video mode (at 24fps!, albeit only at 1280×720 (720p) resolution), 11fps available in a higher-res crop mode (it now crops only 1.2x instead of 1.5x), and an increase in ISO range, up to ISO12.8k natively with a boost to ISO100k. The D3s presumably packs a different sensor, though it still maintains the same 12.1MP resolution.

People have been going goo-gah over the last spec in particular, especially given such a high linear number for ISO (and from here, it’s just four more stops til we get to ISO1.6 MILLION), though it’s really just +1 stop natively and +2 stop boost over the previous D3. And it’s important to note that the simple availability of an ISO capability says nothing about image quality at that level – that would be the same mistake as having the maximum shutter speed expanded from 30 seconds to a minute, and somehow thinking this magically makes photos at 1/500s less blurry. Given that the resolution (and thus pixel pitch) remained the exact same, I certainly wouldn’t expect quality to be any worse than the D3, and quite probably will be a tad better (although I have extreme doubts about the ISO100k mode, which is digitally boosted 3 stops; things have always looked terrible at just +2 stops digitally, even boosting ISO100+2 to 400.)

All in all, about as much as you could expect from Nikon, who seems to do very incremental updates and waits a long time to deliver big, revolutionary refreshes. Here’s hoping we see that D3s sensor in a D700s soon, though 1080p at 24fps would be nice (and completely feasible: 1920×1080x24fps = 49.8MP/s throughput, while we definitely know that the D700 supports 12.1MPx9fps = 108.9MP/s throughput in its continuous shooting mode).

Nikon D3s press release (I don’t know why they keep referring to it as “D3S”, past history and even the logo in the image clearly denote “D3s”)

The Nikon DS3, now with 720p video and ISO up to 12.8K/100K(boost)

Nikon also announced a couple of lens refreshes, with Version II’s of their popular 18-200mm VR ultrazoom and a long-awaited update to the 70-200 f/2.8 VR to optimize it for full-frame (FX) sensors. As Nikon had long trumpeted 1.5x crop DX sensors before their introduction of the full-frame D3 in 2007, they cut corners with their introduction of the 70-200 f/2.8 VR in 2003, building a lens that was technically full-frame but had an abysmal drop-off in performance once you actually got to the corners outside of a 1.5x imaging circle. This wasn’t found out until a bit after the D3 was released, finally giving digital photographers a platform to test the lens’ full frame performance, which resulted in tests like these:

http://www.dpreview.com/lensreviews/nikon_70-200_2p8_vr_n15/page6.asp

http://www.dpreview.com/lensreviews/widget/Fullscreen.ashx?reviews=17&fullscreen=true&av=3&fl=105&vis=VisualiserSharpnessMTF&stack=horizontal&lock=&config=/lensreviews/widget/LensReviewConfiguration.xml%3F4

The new 70-200 II promises to fix all of these problems with a new optical design and coatings, and promises to throw in a more effective “4-stop” VR system as well. There haven’t been too many authoritative tests yet to show how it performs (if you’ve found any, send me a link!), but presumably they should have no problem building such a lens – Canon has had two 70-200 2.8’s that’ve performed flawlessly on full-frame, and Nikon itself had a great 80-200 2.8 lens prior to the 70-200 VR I.

The one stickler? As if Nikon’s $2019 price on the original 70-200 I wasn’t enough, the 70-200 VR II will now set you back a cool $2400.

Nikon 18-200 II and 70-200 2.8 VR II press release

This one caught me by surprise for sure – Pentax just last week announced their new midrange K7, which is their first significant DSLR announcement in over a year.  Just as I started assuming Pentax had all but become a bit player in the increasingly crowded DSLR market (with Sony developing the KM/Alpha system into the #3 brand, and relative newcomers Panasonic and Samsung taking the initiative to forge ahead on the cutting edge digital frontier), they come out with a new flagship midrange camera that, on paper at least, rivals and even beats the Canon and Nikon midranges in quite a few areas.

Pentax K7

Some of the highlights of the K7:

• A new, 14.6MP CMOS sensor “rebuilt from the ground up”.  At the outset, this would seem to be a slightly revised version of the same 14.6MP sensor used on the previous K20D.  We’ll have to see how much improvement “rebuilding” the sensor has (my guess: not much), but this is encouraging news – Pentax sensors (the K20D’s 14MP sensor especially) have always produced excellent quality with regards to high ISO, if a tad conservative on the default in-camera noise reduction setting.  The K20D also seemed to buck the recent Pentax trend of poor JPEG rendering of RAW images (in other cameras, the in-camera JPEGs were significantly inferior to JPEGs rendered using an off-camera converter like Adobe Camera Raw) – maybe it was simply a different rendering approach to their higher-end midrange cameras, or perhaps Pentax just knows how to deal with raw data from the Samsung-developed K20D sensor better than the Sony chips used in all their other cameras.
• HD Video Capture. For sure a killer feature – the K7 beats just about everyone to video in the midrange market segment (though it could very well have company in a few months). Unlike many others, Pentax seems to be doing video right and hasn’t intentionally crippled the functionality: the K7 supports your standard 1280×720p, 30fps HD, features a jack for an external microphone (a cheap, no-duh add-on that’s sorely missing from the lower-end video-capable DSLRs), full aperture control (no word on shutter speed, however).  Brilliantly, the K7 also offers a 1536×1024, 3:2 aspect ratio mode that utilizes the full area of the sensor, instead of wasting ~16% of the frame like every single other camera does shooting 16:9 video – why no one else (even Panasonic) has seized onto this idea completely bewilders me.  Another complementary feature to video capture is the K7’s sensor-based image stabilization system; video has been regarded on most other platforms as nearly useless without a trip(in the pro-looking videos sense) 
• In-camera HDR blending. This is an interesting one, though much more for the snapshooter rather than the serious HDR enthusiast.  The HDR mode exposure brackets multiple images (three, or five shots) and combines them, producing an overall image with far greater dynamic range than a single shot could ever produce.  Jack Howard at the Adorama TechTock blog has produced an extensive post on the K7’s in-camera HDR ability – while it won’t come close to replacing dedicated on-computer HDR processing, it can produce a decent result, which might be good enough for many, and could be useful for those just looking to capture a slightly larger DR, rather than creating a full-on HDR effect.  Unfortunately, and somewhat perplexingly, the HDR mode can only be used to produce regular JPEGs.
• Live-view. The K7 now features contrast-detection AF, and interestingly enough a face detection mode.  And before you know-it-all “pro” photographers laugh, face detection is a genuinely useful feature – while you’re pulling out every trick and technique in your bag to get the correct focus and adjust for exposure, a K7 user in live view mode simply uses face detection to focus lock onto faces and automatically optimize the exposure for portraits.
• Rotational shake-compensating sensor IS. This is a pretty interesting one, though details are a bit muddy on how it’s actually done.  Pentax uses sensor-based image stabilization, which typically involves shifting the sensor laterally to compensate for camera shake.  The sensor-based implementation has the advantage of staying with the camera no matter what lens is used, which is a huge boon since lens-based IS often puts a heavy premium per-lens, and many classes of lens don’t even have an IS version.  However, one of the criticisms of sensor-shift systems thus far is that they’re not as effective, partially due to the fact that they shift only laterally, which in theory corrects only lateral shake – a far more minor factor of blur compared to rotational shake over longer distances.  If this is true, and the new IS system works, we might expect significantly improved performance, especially using telephoto lenses/working over long distances.
• TAV mode. This feature was present on the K20D as well.  It’s a frankly genius adaption to digital technology, and one that I’ve been clamoring for ever since I first picked up a digital camera – TAV mode is an autoexposure program mode (in the vein of Aperture-priority and shutter-priority modes) which allows for manual selection of both aperture and shutter speed – the ISO then floats to whichever sensitivity necessary to produce the exposure.  For anyone shooting low-light on a consistent basis, this is a program mode absolutely made for you (choose the aperture and lowest shutter speed you’re willing to live with, and this program mode will optimize for noise).
• Interval timer. Nikon has had this forever, but it’s a feature sorely lacking on just about all the other systems – a built-in interval timer allows the K7 to do time-lapses all on its own, without requiring some absurd $100 add-on *cough* Canon *cough*.
• 5.2 fps continuous shooting. Pentax finally caters to the sports/action market with its first high-FPS camera – previously the fastest you could get on a Pentax was 3fps on the K20D.  5fps isn’t exactly blazing, especially compared to 6 or 8fps seen on even the midrange Canons and Nikons, but it’s just about the standard minimum you’ll need for faster sports.  Though I wouldn’t run out and dump my Canon system for Pentax just yet – they’re still sorely lacking in the telephoto department without a single 70-200ish f/2.8 lens, much less any of the big tele primes – it’s now an appealing option for casual enthusiasts, with lenses like the Pentax 200mm f/2.8 prime, a very nice 60-250mm f/4, and of course a plethora of options from Sigma and Tamron.
• In-camera leveling.  One of the more unusual features of the K7’s is the ability to rotate and level images in-camera.  This isn’t a cheap software rotation trick, mind you – the sensor, combined with an electronic level, actually rotates up to 2 degrees in either direction to maintain a flat horizon.  This is a pretty huge boon for landscape photographers, who can now level their images with a mathematical precision far greater than just eyeing it with the viewfinder and gridlines.
• Weather-proofing. Like the K20D before it, the K7 offers exceptional weather-proofing, unlike the D90 which has none and the Canon 50D which has it on paper only.  Additionally, even the budget kit lenses (the 18-55 standard range and 50-200 tele) will be weather-sealed.  One of the more interesting specifications is that the K7 is rated down to 14 degrees fahrenheit (-10C), compared to just 32F/0C on virtually every other “weather-sealed” camera on the market, which includes bodies like Canon’s 1D(s) and Nikon’s D3.  This might make it an interesting camera for extreme travel conditions, where even the rugged “pro” bodies experience significant failure rates.

Overall the K7 is an interesting camera – while Nikon has been forging straight ahead in the high performance, blow-you-away image quality department, and Canon seems to have been stumbling around aimlessly, and new #3 Sony continues churning out junk cameras selling on brand recognition alone, it’s nice to see an old name making a comeback, and in a way that blows past the competition, not just catching up to it.  The K7 carries with it a lot of new innovations – not necessarily in the Panasonic/Samsung “we’re building the ultimate digital imaging device, not a camera” train of innovation, but in a more traditional way that fully leverages digital imaging and electronic hardware for photographic purposes.  So you’ll still find a mirror here, and somewhat disappointingly a lack of articulating screen and higher-ISO capability (the K7 caps out at ISO1600, with +2 boost to ISO6400), but also sensible innovations such as in-camera leveling, TAV mode, full-frame video capture, and live view fact detection, that don’t necessarily revolutionize digital imaging as we know it, but provide subtle improvements and aids that optimize traditional photographic technique.

The K7 slots in at $1300 for the body, compared to $1200 for the Canon 50D, $1000 for the Nikon D90, and $1800 for the D300.  It’s not a camera that will really compete with the 50D or D300 on the action front, but for general photography it packs a number of interesting features that simply aren’t found on any other cameras.  If image quality holds to the same level as the K20D, the K7 should be in the same class as the other cameras here (i.e. top of the class among APS-C size sensors) – better than the 50D, and perhaps a little worse than the D90/D300 sensor at the very extreme high-ISO range, with a little more noise reduction post-processing required.  And if video is what you’re looking for, the K7 completely blows away any of the entry-level and midrange cameras (save Panasonic’s GH1) in terms of features and control, though quality remains to be seen.

The one drawback of the K7 may not really be the camera itself, but the Pentax system associated with it.  Pentax has got a lot of interesting and high-quality lenses (though they’re on the pricier end of things), but doesn’t have anywhere near the selection that big systems like Canon and Nikon have, and doesn’t even cover all the basics, which at least Sony’s Alpha and Olympus/Panasonic’s Four Thirds do.  This is becoming a bit less of a problem, however, as third party manufacturers like Sigma and Tamron increase the number of alternatives available.