JVC GZ-MG155 Camcorder Review
The JVC GZ-MG155 is second from the bottom in Everio’s hard disk drive camcorder line. While this year’s Everios have been reliable, the GZ-MG155 has a hard time proving its worth. Outclassed by the step-up GZ-MG255 and outperformed by the step-down GZ-MG130, this camcorder shows what happens when a company spends more time pursuing the “megapixel count game” and less time looking at the effects of those actions.
Video Performance* (3.5)*
The JVC GZ-MG155 is outfitted with a single 1/6-inch CCD sensor, which has a gross 1,070,000 pixels. This is the typical imager size found in entry-level camcorders of all formats, though the pixel count is higher. This is likely to result in a sharper image in bright light, but could cause problems in low light. The issue is the pixel density. Because the number of pixels increased, but surface did not, that means the pixels themselves must be made smaller. Smaller pixels result in a decreased ability to capture photons in low light. High pixel density can also lead to noise. But we’ll get to low light in a couple sections.
First, we want to look at the results in bright light. For standardization, we shoot a DSC Labs ChromaDuMonde color chip chart at an even 3000 lux. Under these conditions, ideal for any camcorder, the GZ-MG155 does not look so good. The color performance is adequate for the price range – well saturated and fairly even. Noise and compression are the two factors at play in creating the dissatisfying image. Too much of the fine detail is lost, negating the resolving power of the increased pixel count.
We can see quite clearly how the GZ-ZMG155 stacks up in the Everio line, having already reviewed the step-up and step-down models. The entry-level GZ-MG130 has a baseline 1/6-inch 680,000 pixel CCD, which produced a much fuzzier looking picture. Color performance was roughly the same. The GZ-MG255 has a larger 1/3.9-inch CCD with 2,180,000, about twice the pixel count of the GZ-MG155. The MG255, while hardly a champion, did perform better. The image suffered from less noise and sharper details. Again, the color performance was similar, indicating that these camcorders are likely sharing the same processor, or at least the same color processing algorithms.
The Sony DCR-SR42 is priced the same as the GZ-MG155, but has the standard 1/6-inch, 680,000-pixel CCD. It shares the same imager as the DCR-SR40, which we reviewed last year. The SR40 produced more saturated colors, which a lot of consumers are going to prefer. Though the resolution is about the same between the camcorders, the Sony SR40 looks sharper because of the increased in-camera sharpening. Unfortunately, the SR40 suffered from a blue noise issue that affects many Sony camcorders. Overall, the JVC looked better.
Finally, we considered the Hitachi DZ-HS300A, a DVD/HDD hybrid. While the dual recording media offers a lot of flexibility, the video quality is quite poor. Resolution in fine detail is virtually non-existent. The JVC GZ-MG155 performed much better.
In casual shooting, the GZ-MG155 proved to be extremely noisy. We also saw some of the same ghosting problems as we did on the GZ-MG255 – white or colored borders around the outlines of objects.
Overall, the JVC GZ-MG155’s main selling points are price and portability. This is not much of a performer.
Video Resolution* (3.25)*
To test the video resolution, we shot a DSC Labs video resolution chart at an even 3000 lux and reviewed the playback footage on a high definition monitor. This test measures the line widths per picture height (lw/ph) of the final outputted resolution. We found the GZ-MG155 to be a weak performer, producing an approximate horizontal resolution of 325 lw/ph and a vertical resolution of 200 lw/ph. Because this test considers the outputted files, the noise factored into the low score, which obscured much of the fine detail.
Low Light Performance* (2.71)*
The first part of our low light test involves shooting the DSC Labs ChromaDuMonde color checker chart at an even 60 lux and 15 lux. At 60 lux, the JVC GZ-MG155 produced an excessively grainy image. A great deal of fine detail has been lost compared to the bright light test. Surprisingly, not that much color information has been lost. This is likely a function of the automatic gain, which would also explain the noise. The auto gain control (AGC) can be turned off and on, but the actual level of gain cannot be adjusted – only Panasonics offer that option in the consumer range of products.
A look at the image with the AGC off gives an indication of the benefit gain can offer, along with the cost. The image is obviously much darker, but there is less noise. Were the camcorder to offer manual gain rather than simply turning the auto response on and off, one might be able to find a better balance.
Fortunately, the camcorder gives you the option for shutter speed control. This can also be found on most Canons and all Panasonics, but not the Hitachi DZ-HS300A or any Sony camcorders. At 60 lux with the shutter lowered from 1/60 to 1/30, the JVC GZ-MG155 (with the AGC on) managed to produce the same level of exposure and roughly the same color performance without all the noise. Of course, at this shutter speed you will see an increase in motion blur, but it could be worth it depending on the kind of shooting.
Comparatively, the JVC GZ-MG130 produced a slightly brighter image with less noise. This is precisely the problem caused by the increased pixel density on the GZ-MG155. Because the pixels are larger on the GZ-MG130, they function better in low light. The GZ-MG255, which has a significantly larger imager than either of them, produced a much better looking image. The colors are unhealthily saturated, but the entire image is brighter and less noisy.
The Sony DCR-SR40 performed absolutely terribly at 60 lux – by far the grainiest, dirtiest looking image in the bunch. This was virtually unusable footage. The Hitachi DZ-HS300A performed only slightly worse than the GZ-MG155 in terms of exposure and color, but the overall resolution was so bad, even in bright light, that it pales in comparison to the GZ-MG155.
At 15 lux, the image is totally shot. This test in the widow-maker for all but the best camcorders, so these results do not come as a surprise.
With the AGC off, the image is essentially black.
At a shutter speed of 1/30, the camcorder manages to squeak out more color and detail, but it’s not a great looking shot.
The competing camcorders yielded the same poor results at 15 lux, though the GZ-MG255 was the standout for capturing the brightest image.
The second part of the low light test determines sensitivity. We shoot while continuously lowering the light until the camcorder manages to produce a peak level of 50 IRE (IRE is a measure of exposure). At best, the JVC GZ-MG155 managed to produce 50 IRE at 22 lux. We’ve certainly seen better sensitivity scores this year, but 22 lux is not the worst for such a small chip. The high auto gain is likely a contributor to the score.
Finally, we shoot a GretagMacBeth Color Checker chart at 60 lux, then output stills to Imatest imaging software to determine color accuracy, noise, and saturation. At best, the GZ-MG155 was able to produce a color error of 12.5 – a very high error. The noise levels measured 0.875 percent, and the saturation was 68.68 percent. These scores are right in line with the assertion that the pixel density is too high for such a small chip, and is causing poor low light results.
The GZ-MG155 is equipped with Digital Image Stabilization (DIS), which functions by creating a digital buffer around the recorded frame. It corrects for some shake, but lowers the effective resolution. Optical Image Stabilization (OIS) is superior because it corrects by shifting a lens element around, leaving the imager to do its regular job collecting as many photons as it can. OIS is found primarily on higher-end models, so it is no surprise that the GZ-MG155 is saddled with DIS.
We tested the effectiveness of the GZ-MG155’s DIS by using our custom-built camcorder shake emulator. With the LCD flipped out and the camcorder set to Manual mode, we used two different speeds to ascertain a weighted average. Speed one is the equivalent of walking casually down the sidewalk, camcorder in hand. Speed two is more tumultuous, simulating a jolting car ride or brisk jog while recording. Unfortunately, the GZ-MG155’s DIS faltered significantly at both speeds, with only a 33 percent shake reduction at speed one and 0 percent shake reduction at speed two. The GZ-MG130 produced a near-identical showing. This is most likely due to the camcorders’ petite size and cheap DIS system.
Wide Angle* (9.2)*
We tested the GZ-MG155’s maximum field of view by placing the camcorder on a tripod with the zoom fully pulled back, LCD open, and DIS disabled. A vertical laser was used to measure the left and right angles, and the recorded footage was viewed on an external monitor. The GZ-MG155 displayed a wide angle measurement of 46 degrees, which is fairly average.
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