Variable scan mapping: the star of the show
Now for the star of the show. If there's a killer feature on the LS300, it's the system that JVC calls Variable Scan Mapping. Since almost any lens can be adapted to micro four-thirds, and coverage varies hugely between ranges and types of lens, the ability to vary the active image is a huge flexibility gain. The active sensor area is variable in increments of a few percent, all the way down to 80%, which the camera calls “MFT” at full res. When recording HD, the minimum active area is 43%, as presumably determined by the amount of excess resolution the sensor has. It is presumably more than 4000 pixels across, natively, and there's promise for the future in terms of what else could be done with the sensor on this or other cameras, in terms of a raw mode.
ND filtration is particularly important for documentary and other unscripted work
Some way above the minimal HD sensor area, at 52%, lies a size the camera calls Super 16, which is slightly counterintuitive because the super-16mm frame (12.52 by 7.41mm) is not 52% of the dimensions of a super-35mm frame (24.89 by 18.66mm). Nonetheless, whatever 52% means in this context, the option to use lenses of smaller coverage, such as super-16 zooms which may have been searching for a home since the end of widespread 16mm shooting, is a massive plus point in terms of flexibility and value. Calling a mode “HD” tantalisingly suggests that 2/3” broadcast zooms might cover, albeit via a correcting optical adaptor. Either way, VSM is a superb and unique feature, and one that all cameras should have. Depending on the available equipment, it could massively reduce the total cost of ownership of the camera. Sensor windowing has been offered before, on several F-series Sony cameras and now on the Blackmagic Ursa Mini, but neither offer the flexibility of JVC's implementation.
Variable scan mapping does affect aliasing, although test charts are required to reveal it
The only downside is that the feature inevitably requires electronic scaling of the image. Scaling is not easy to do quickly without introducing aliasing. A zone plate is an acid test for any camera, and does reveal a fairly subtle change in aliasing as VSM modes are selected. Happily, this is mainly visible as patterning in the focus assist on the Atomos recorder in these stills, and is not severe enough to limit usefulness of the VSM mode.
The pictures, then. The fruits of JVC's acquisition of AltaSens are visible here, with low noise and highlight handling that is better that comparably-priced competition, particularly with the new log mode in use. JVC claim twelve stops of dynamic range, which is similar to the information Blackmagic issue on the 4K sensor used in their production camera and the first Ursa minis. The JVC, however, is clearly a later and somewhat improved generation, with lower noise and higher sensitivity, although they maintain that it is not intended to be a cinema camera. To the eye, the JVC is perhaps a stop quieter, or a stop faster, or a stop higher in dynamic range (depending on your proclivities) than the Blackmagic, which a welcome development in sensor technology.
The camera takes affordable SDXC cards
Often, log encoding can make noise visible in the unprocessed image, but the LS300 is sufficiently quiet that this isn't too much of a problem. A full evaluation of log shooting with the camera will, sadly, have to wait until JVC releases LUTs to support their encoding, which aren't quite available yet. The standard Rec. 709 setup is, as in most cameras, a little harsh, and reminds us that it would be a good idea for more manufacturers to follow Sony's lead, as established on at least the FS7, and to include a 709-compatible look with softer highlights. Nonetheless, a bit of fiddling in the process menu (which is largely disabled in log mode) yeilds attractive pictures. The video accompanying this article was shot in J-Log1 and normalised by eye.
Conclusions are complicated. The uninspiring viewfinding and lack of 10-bit output conspire to make the camera feel slightly expensive. Still, although the fact that it's a 4K device is no longer all that unusual, it's one of the better low-cost 4K sensors yet released, and the windowing options are unsurpassed. Depending on the application, storage pricing can be important, and the LS300 uses storage which is comfortably under a fifth the price of some brand-specific card formats. This could easily make up for any perceived offset in value, especially with a buy of more than two or three cards.
The compatibility with more or less any lens ever made, in terms of both mount adaptability and coverage, might also mean a really big saving on glass. The variable sensor size itself might make for an even bigger saving on owning two cameras for different applications.
The LS300 will, I suspect, find many friends among owner-operators with a client base covering both drama and documentary, as well as educational institutions who need to teach a wide range of disciplines. Any person or organisation with a cupboard full of old, dubiously-useful glass should be paying close attention – and that's a lot of people.
A big-chip handycam with some killer features is an interesting, not to say hitherto unknown value proposition. More than any other camera, the value of the LS300 depends on exactly what you want to do with it, but that's sort of the point: give or take a bit of rigging up, it's capable of doing more or less anything.