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Reader SurveyShoot Expertise: First Look: XDCAM EX
Sep 13, 2007 12:00 PM, By D. W. Leitner
Getting a feel for Sony’s new PMW-EX1 flash-memory camcorder.
The EX1’s imaging engine is the Exmor Full-HD sensor, another audacious CMOS technology from Sony (hot on the heels of the V1’s innovative ClearVid CMOS sensors with their 45-degree angled pixels).
Imaging
Additional focusing aids include peaking in four flavors—white, red, yellow, or blue—and a new intelligent mode called MF Assist, which supports electronic manual focusing. As you turn the focus ring to bring an object or area of detail into rough focus, MF Assist locks onto the nearly focused object and takes over to ensure perfect focus. (It should be obvious that MF Assist is not available when the sliding focus ring is in the mechanical focusing position.)
This is a welcome development; 1/2in. sensors bring about less depth of field than the 1/3in. HDV camcorders many have grown accustomed to. With so many camcorder operators opting to use LCD panels over viewfinders—particularly younger ones lacking experience with 16mm or 35mm optical viewfinders—the arrival of intelligent digital focus-assist, while not intended to supersede conventional focusing skills, could cut down on soft HD shots and improve usable footage yields. (Images at smaller f/stops will be sharper too, on account of diminished diffraction due wider iris diameters of larger 1/2in. sensors.)
The EX1 is no doubt also destined to see lots of action in dim, minimum-depth-of-field circumstances. When variables of gain, turbo gain, and slow-shutter accumulation are cancelled between the EX1 (1/2in. 3-CMOS) and its XDCAM HD cousins, the PDW-F330/350 series (1/2in. 3CCD), minimum illumination needed for 1080i/60 is roughly the same. When maximum lens apertures are factored—f/1.9 for EX1, f/1.4 for F330/350 (almost a stop faster)—the EX1 arguably comes out ahead.
(A gripe in passing. Sensitivity comparisons would be more useful if manufacturers were to express minimum illumination at practical settings minus the artificial boosts: no pads such as gain, turbo gain, or slow-shutter accumulation. For example, at 1/60-second shutter speed, 0dB gain, and maximum aperture, a PD170’s minimum illumination is 8 lux, a Z1’s is 24 lux, and an F950’s is 40 lux [1/48 second]. Divide by 10 to get approximate footcandles. What could be simpler?)
The EX1’s imaging engine is the Exmor Full-HD sensor, another audacious CMOS technology from Sony (hot on the heels of the V1’s innovative ClearVid CMOS sensors with their 45-degree angled pixels). Comparing EX1’s Exmor CMOS sensors to the F330/350’s 1/2in. HD Power HAD CCDs underscores what makes them special. Each Exmor CMOS has a density of 2.2 megapixels (1920x1080) compared to the Power HAD CCD’s 1.56 megapixels (1440x1080). The EX1’s sensitivity at 2000 lux is rated f/10 compared to the F330/350’s f/9 (EX1 wins by a fraction of a stop). Both camera systems share a superb 54dB S/N. While Power HAD CCDs tout a low vertical smear level of -120dB, remarkable for an IT sensor, Exmor, being CMOS, has no vertical smear.
As indicated above, Exmor CMOS sensors are progressive/interlaced switchable. All images originate as 1920x1080. When 720p is required, Exmor captures at 1080p—in effect, oversampling—then downsamples to 720p prior to signal processing and MPEG-2 encoding. In this manner, EX1 lays claim to both native 1080 and 720.
Sony’s Exmor sensors introduce a new A/D strategy too, with pixel charges sent on a column basis to built-in A/D converters, akin to CCD shift registers. They scan at a wide range of frame rates. As in prior Sony CMOS camcorders (A1, V1), they make possible an active graph in the viewfinder called a histogram, which depicts the distribution of image brightness on the basis of pixel count. (In a heartbeat, I’d trade a histogram for an actual luminance waveform overlay, but I’ll cover this more in a future field review of the camera.)
The EX1’s two other exposure-assist features are zebras, adjustable from 50 percent to 107 percent (all cameras’ zebra settings should dip as low as 50 percent—truly useful) and something Sony calls “brightness-level display,” a video-level read-out averaged from a small area in a little box in the viewfinder’s center—regrettably not as tight as Panasonic’s Y GET center marker system, which better matches the 1 degree of my classic Minolta Spot Meter.
Gain levels are selectable in standard intervals from -3 to +18 dB. For those who would like to tackle greater dynamic range, EX1 provides in addition to four standard preset gamma curves, four CINE Gamma curves identical to those in the F330/350 and, for that matter, F900R and F23. (Where they’re known as HyperGamma curves 1-4. For some reason, the ordering is scrambled in the F330/350 and EX1. CINE1 with a 108-percent white clip is the same as HyperGamma 4. Regardless of the label, however, these are useful tools for finessing delicate highlight and reluctant shadow detail into view.)
Just like XDCAM HD’s 1080-only F350 disc camcorder, EX1 offers over- and undercranking, which Sony calls Slow & Quick Motion. Except that EX1 does it better. Where F350 offers 4fps to 60fps in one-frame increments with reduced vertical resolution from 31fps to 60fps, the EX1 offers 1fps to 60fps in one-frame increments in 720p, and 1fps to 30fps in 1080p, with no resolution penalty at higher frame rates. In addition, EX1 borrows a page from the F23 (taken in turn from film cameras): “shutter angle” can be set in Slow & Quick motion to adjust dynamic resolution—exposure time of each frame—to reduce blur or soften flicker effect. The reverse function of this—shutter angles larger than 360 degrees, for a blurred, streaked, or ghosted effect—is available in EX1 as Slow Shutter, which is expressed in terms of “frame-accumulation periods” of two to eight frames, 16 frames, 32 frames, and 64 frames (same as F330/350).
As to be expected of a professional camcorder recording to a nonlinear medium, EX1 is thoroughly versatile when it comes to time-lapse “Interval Recording” and “Frame Recording” used for animation and Claymation. Both 720p and 1080i/p are fully supported.
