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(Page 2 of 4 pages for this article < 1 2 3 4 >) Filed under: Cameras •Hardware • Review: Panasonic AG-HPX170P 1/3”, 3CCD P2 CamcorderThe P2-only HPX170 is a multitalented, smooth operator with improved picture quality.
PerformanceLensThe lens is a 13x, 3.9mm-51mm (compared to the HVX200’s 4.2-58mm) Leica Dicomar. That 0.3mm at the wide end makes a difference where it’s needed, without robbing the telephoto end of anything significant. By comparison, the HPX170 at 4.0mm has the same angle of view as an EX1/EX3 fully wide; even the 0.1mm difference between 3.9mm and 4.0mm on a 1/3” camera is visible!). The lens ramps continuously from f/1.6 fully wide to f/3.0 at full telephoto. There’s some barrel distortion fully wide, as is normal on the wide end of long zooms; as you zoom in, it turns almost immediately into gentle mustache distortion, which mostly flattens out by 5.0mm. Some residual, very minor distortion is visible on test charts through the rest of the zoom range, but it’s not noticeable under normal shooting circumstances; this lens is very comparable to the one on the HVX200—just a bit wider, with slightly more wide-end barreling. Evenness of illumination is a bit worse than on the HVX200; wide open at wide angle, there’s a gentle falloff of more than half a stop at the edges of the image compared to the center, and even at telephoto the edges are a bit darker than the center. This sort of thing is only visible on the waveform monitor, though; visually it’s not at all apparent. Stopping down to f/4 or more flattens the illumination except at the very corners of the image. (The review camera didn’t go through Panasonic’s final QC, so production cameras may be a bit better in these regards.) As on the HVX200, chromatic aberration was negligible at most focal lengths, with only a tiny amount visible on extremely contrasty edges at full telephoto. Prism-induced vertical CA on out-of-focus subjects was likewise negligible. Overall, I’d rate the optics on this camera as being very good for the money. There was a slight variation in focal-length readout calibration between the sample HPX170 and my HVX200: framing up a resolution chart from the same position reads as 12.0mm on the 170, 11.6mm on the 200. Sensors and ProcessingLike the HVX200 before it, the HPX170 uses three 1/3” CCDs with 960x540 active photosites. The green CCD is offset 1/2 the pixel pitch in both H & V axes from the blue and red CCDs; this pixel offset boosts overall sharpness while still allowing for large (thus: sensitive and low-noise) photosites. The resulting resolution is 540 TVl/ph horizontally, and 540 lines vertically.
There’s ample detail there for SD recording at either 25 or 50 Mbps, and the sensors are a good match for 720p DVCPROHD’s 960x720 sampling. Only when shooting 1080-line formats, or when using the full-raster HD-SDI output, will any lack of fine detail be detectable, and that only in a side-by-side comparison with more finely-detailed cameras. As in the HVX200, the CCDs’ signals are combined in the DSP to form a 1920x1080 progressive image, from which all recorded and output formats are derived. In the HVX200, however, substantial aliasing occurred; fine scene detail had a tendency to cause moiré, often in green/magenta hues due to the pixel-offset method. Additionally the camera’s HD images, when viewed at high magnification, had something of the appearance of pictures shot through a window screen, or early-’80s computer graphics rendered without sufficient oversampling: there was a slight steppiness on diagonal edges, or “pixelization” of fine detail. (Mind you, these image artifacts are not obvious unless you’re shooting a test chart or certain other pathological images. Rather, they render the HVX200’s images slightly “gritty” or “CGI-like”, more a subliminal effect than anything immediately visible.) The HPX170—and the HMC150 and the newer HVX200A—are entirely new cameras in this respect: even though they have the same raw photosite count, and the same limiting resolution, their images are immensely improved, with vastly reduced aliasing, no color moiré to speak of, and none of the gritty pixelization of the older HVX200. The new cameras’ images are smooth, naturalistic, and easy on the eyes. Whether it’s a higher fill factor on the CCDs, better optical low-pass filtering, or more sophisticated digital filtering and rescaling (or all of the above), Panasonic has managed to minimize the undesirable artifacts without degrading apparent sharpness—impressive.
DSC CamAlign MB, HPX170, 1080p DVCPROHD, Detail @ 0.
DSC CamAlign MB, HVX200, 1080p DVCPROHD, Detail @ 0.
(All these images were resized horizontally, using Photoshop’s bicubic interpolation, but aside from that they are native, pixel-for pixel presentations with no additional processing.) For comparison, I also present a 720p sample, captured from a 960x720 DVCPRO clip:
DSC CamAlign MB, HPX170, 720p DVCPROHD, Detail @ 0.As you can see, the recording format is now the limiting factor in detail, not the raw resolution of the sensors; this is why I say that the HPX170’s (and HVX200’s) “sweet spot” is 720p DVCPROHD production. 1080-line recording definitely lets more detail through than 720-line recording does. Mind you, the HPX170 is now the smallest, least expensive camcorder to offer full 4:2:2 DVCPRO50 standard-definition recording, too. Compared to the HVX200, the HPX170 has reduced image noise (especially chroma noise) at all gain levels:
HPX170 and HVX200 compared at +12dB gain. The banding in the images is not due to the cameras, but rather to the Litepanels Mini LED arrays I was using to light my test charts.Vertical smear is dramatically reduced compared to the HVX200. Shooting straight into a halogen light, I got the same smear at F8 on the 170 that I saw at f2.4 on the 200: that’s 3.5 stops better performance. And shooting into a beautiful, coppery setting sun (the California wildfires were upwind at the time), I couldn’t see any smear at all on the 170:
HPX170: “properly” exposed for the sunset, and opened all the way.Those improvements aside, the HPX170’s image rendering tracks the HVX200’s almost identically. It shows the same 8-9.3 stops of dynamic range, depending on gamma and knee setting and how far you’re willing to push it in post. This is pretty much the norm for 1/3” cameras following Rec709 gamma encoding standards. Sensitivity tracks the HVX200 within the limits of measurement; I rate it at ISO 320. The HPX170’s five standard gammas (SD Norm, HD Norm, Black Press, High, and Low) and two cine gammas (Cine-like D and Cine-like V) all render the tonal scale exactly as they do on the earlier camera. The four color matrices (Norm1, Norm2, Fluo, and Cine-like) also behave as before, though the HVX200’s “enhanced” matrix is now called “norm2”: it’s the same matrix, only renamed, as it’s designed to slightly desaturate “brighter” colors rather than “enhance” duller ones.
HPX170 color matrix variations.In standard gammas, High knee cuts in at about 100%; mid around 92%, and Low around 83%. The knees reduce the slope of the tonal curve by about half. Auto knee appears to vary the knee point, based on picture content, between high and med. In the cine gammas, knee is forced to OFF in the menus, but a knee is still applied to the images. In Cine-like D gamma, knee appears to kick in around 101%, while in cinelike V it compresses tones about 104%, and flatten the tonal curve considerably. These, again, track the response of an HVX200 to the same settings. This adherence to tradition is a Good Thing: the HVX200’s reputation is built on its tonal scale and color rendition as much as on its variable frame rates, with Cine-like V gamma especially notable for its gorgeous handling of highlights on skin tones (see Exploring the HVX). Since the camera uses CCD sensors, there is no rolling shutter nor any chance of “Jellocam” images. Next: Formats & Outputs; Features & Functions (Page 2 of 4 pages for this article < 1 2 3 4 >) 
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