Fujifilm Finepix F200 EXR Review
In addition to its low-light pixel-binning mode, the F200 EXR also has a mode to allow the capture of a wider range of tones (and therefore offer greater dynamic range). Again this takes advantage of the neighboring pairs of same-colored photosites but also makes use of another new capability of the underlying hardware. The F200's sensor has two readouts with each receiving the output from alternate rows of photosites. In EXR DR mode, the readout process for one half of the sensor begins before the end of the full exposure, giving underexposed information for half of the photosites. This underexposure helps prevent the brightest areas of the image becoming overexposed. The camera then combines the information from these underexposed photosites with the other, fully exposed ones, providing additional detail in the highlights.
In its 12MP modes, the camera also offers the more conventional dynamic range boosting modes seen on previous Fujifilm cameras. These underexpose the entire shot to retain highlights, then apply a different tone curve to present the correct final exposure. The downside of this process is that additional noise tends to be generated as the dark, potentially noisy, regions of the image are 'pulled-up'. These modes limit the sensitivity settings that are available, so that 200% dynamic range is only available at ISO 200 and upwards (because the camera is under-exposing its base ISO by a stop and hence appearing to use an ISO 200 exposure).
However, thanks to the EXR technology, the F200 can underexpose half of its photosites and incorporate that additional highlight data without creating additional noise in the shadows (the detail for which is captured by the other half of the sensor). This allows it to offer up to 400% DRange expansion at ISO 100 (with half the photosites reading out a quarter of the way through the full exposure to provide two extra stops of dynamic range).
At ISO 200 the camera can even provide 800% DRange expansion, but still with the level of shadow noise you'd expect to see in a normal ISO 200 exposure. The results are astonishing for a compact camera, with impressive amounts of additional detail being retained in some scenes. Confusingly, some of the capability (but not the 800% option, oddly), appears to be available in the non-EXR modes if you reduce the resolution to 6MP. Certainly it's possible to engage 400% DR at ISO 100 in 6MP mode but don't expect the user manual to come to your aid in understanding the camera's capabilities.
It's worth being aware though, that you can manually select the amount of dynamic range expansion being used in EXR DR mode, (though you can't set the ISO, as the camera needs to retain the ability to push to ISO 200 to use the 800% mode). The risk is that it's possible to accidentally leave the camera locked at DR 100% - substantially limiting the DR mode's capability.
In the real world...
|HR mode (12MP) DR 100%||100% crop|
|DR mode (6MP) DR 100%||100% crop|
|DR mode (6MP) DR 200%||100% crop|
|DR mode (6MP) DR 400%||100% crop|
|DR mode (6MP) DR 800%||100% crop|
As can be seen, the effects in terms of retaining highlights are extremely impressive, with a great deal more detail being retained. And, since the camera has kept the overall ISO to 200, there isn't the same noise penalty to be paid as when conventional sensors try to underexpose and then pull the brightness back up. There's a slight increase in shadow noise but the F200 seems to be very good at using data from its underexposed photosites to build the highlight areas of the image and the normally-exposed photosites for the dark regions.
For this shot, setting DRange to 'Auto' saw the camera select 400% but it can sometimes be a bit conservative (it rarely appears to select the 800% setting), so it's often worth making sure you've specified a high DRange expansion if there's a high degree of contrast in your scene.
It's worth remembering that if you're want to fit a broader range of tones into your image (by capturing more data between complete black and clipped white), then the tone curve of the image has to be made more gentle, resulting in lower overall contrast. On the whole the F200 EXR seems to strike this balance about right, pulling additional detail into the image without making it look too 'flat' or gaining too much of the 'unreal' appearance that can mar poorly tonemapped HDR images.
In the studio...
We were so intrigued by this result that we subjected the F200 EXR to a version of our dynamic range test. Because the F200 EXR does not offer full manual control or fixed ISO in its DR mode, it was impossible for us to conduct our dynamic range test in as controlled a manner as we'd like. As such, the results should not be considered absolute or comparable to other cameras.
The graph gives a good idea of how the F200 is reintegrating the highlight data that its underexposed photosites are capturing. With DRange set to 100% the camera has a very conventional tone-curve much like the result we'd expect to see from any other compact camera. As dynamic range expansion is applied the top end of this curve is noticeably flattened to accommodate the additional highlight data. Also significant is the way that the tone curves for all settings are identical from middle gray downwards. You appear to get an additional 1EV of highlight range for each step you take up through the range as you might expect (meaning around three additional stops of highlight DR at the 800% setting).
Our tests seem to suggest that the F200 can, in its DR mode, capture in excess of 10 EV - a great result even if you choose to compare this camera to DSLR standards. You're still going to get washed-out skies and tiny areas (such as reflections) of high-contrast images clipping to white but, if you can live with 6MP and a minimum of ISO 200 you'll also find fine highlight detail being retained in circumstances in which most other cameras would simply give up.
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