What crucial criteria makers and salespeople and magazine reviewers AVOID telling video enthusiasts like you
Sep 11 '02 (Updated Feb 12 '04)
The Bottom Line Look for wide angle of coverage lens, large lens aperture (f/1.4 better than f/2.8), large CCD sensor size (1/3" better than 1/4.7"), SMALL pixel count
So you are a video enthusiast on the market for a good camcorder, looking to make an optimal choice in your price range. There are a plethora of current and recent models available, lots of advertisement hoopla, piles of reviews in print and on the web - often adding more confusion than clarity.
This article will focus on several parameters and properties of a camcorder that are directly linked to its ability to capture [technically] professional looking footage or come as close to it as your purchase budget allows.
Feb 2004 update: Read what NASA has to say
Don't just take my word for it; read this article describing NASA scientists' thought processes to pick components for the Mars Rovers' amazing digital imagers:
http://www.space.com/businesstechnology/technology/pancam_techwed_040114.html
Maximal lens aperture
Basically means the amount of light the lens is capable of passing through to the camera's electronics. Expressed numerically with the f/[number], with smaller [number] values representing larger apertures. So, a f/1.4 aperture is much larger and preferable to an f/2.8 aperture. Often, zoom lenses will have two different apertures specified, for the beginning and end of their zoom range. A larger aperture not only gives the camera's electronics more light to work with (resulting in smoother, more natural yet vibrant image), but also has a narrower DOF (depth of field), which is a range of distances from the camera where the objects are rendered sharp. A narrow DOF which a wide aperture lens affords (the lens can be "stopped down" to extend DOF when desired), somewhat counter-intuitively, is far superior in most situations as it allows you to make the subject of interest stand out against the background, avoiding the distinct cheap camera look. Most professional work you see in the movies and on TV is captured with a fairly shallow DOF.
Widest angle of view of the lens (vs. zoom range)
Unfortunately, what manufacturers want you to fixate on is the zoom range, the bigger the better. This is simply not true. Engineering larger zoom ratios in a given size / cost range often involves sacrifices in aperture, distortion, contrast, flare resistance, and sharpness. Consumer camcorders with a large zoom range usually extend more to the telephoto range, which is a useless gimmick most of the time due to loss of quality and increased apparent camera shake at lelephoto settings. What's useful is how wide the widest zoom setting is, because it means being able to cover a broad angle in tight quarters (useful for landscape / architecture / general vacation / party / many other situations). Most consumer / prosumer camcorders are not nearly wide enough.
What complicates matters is that not all manufacturers make focal length numbers clear (neglecting to express them in 35mm film camera terms, in which 24mm is considered a great wide angle coverage, 28mm is very good, 35mm is hardly wide enough, and 38mm is borderline acceptable - yes a few mm differences (say 35 to 38mm) are indeed very visible at the wide end!). Commendably, Sony has started listing 35mm camera equivalency focal length specs for their camcorders on their web site. You can use those figures as a basis for comparison with other makers' cameras that have the same CCD chip size. (The 35mm camera focal length conversion factor depends on the camera's optical sensor size). I highly recommend that you compare actual angle of coverage of the camcorders you are considering, as seen through their viewfinders, during a hands-on examination.
A word on optional wide-angle adapters: unfortunately, most of these adapters made for consumer cameras significantly increase lens distortion, and more often than not introduce light falloff (corners darker than middle of the frame) as well as reduce flare resistance, contrast, and sharpness. Still, many consumers have no choiuce but to use them - so pay attention to camcorder lens selection so you won't have to use such an adapter as often.
Lens distortion
Another parameter seldom reported by manufacturers or mentioned by advertiser-friendly reviewers. Many camcorder lenses distort straight lines captured near the edge of the frame, so instead of | | they look like ( ) or ) (. This is another point to check in the store, aiming the camcorder so that any straight line runs near the edge of the frame, and trying various zoom settings, paying special attention at the widest angle setting.
Optical sensor (CCD) pixel count
Contrary to what you may have read, the smaller the pixel count, the better. Increasing pixel count incurs a disproportionately high cost in reduction of the light sensitive area of the individual pixels. As a result, picture quality suffers, particularly indoors or in any subdued light situation, becoming muddy and harsh, and exhibiting "video noise" in the shadows. Video cameras that also have megapixel digital camera capability merit a special word of criticism: not only are their CCD's split in so many pixels that they noticeably compromise the image quality at low light level (often versus cheaper and / or older non-megapixel models by the same maker), but also their video lenses seldom resolve any more than 500 lines across the entire frame, making high pixel count sensors behind them purely a marketing ploy.
Optical sensor (CCD) size
Miniaturization and increasing profit margins in CCD and lens manufacture tempt manufacturers to decrease sensor size. Decreasing the sensor size means smaller individual pixels, resulting in problems described in the previous point. Just for comparison, professional HDTV cameras usually have three 2/3" CCD sensors (one each to capture red, green, blue); professional broadcast quality camcorders usually have three 1/2" sensors; compact prosumer camcorders have three 1/3" sensors; high quality video enthusiast consumer camcorders have three or a single 1/4" sensors. Recent so-called "developments" in consumer camcorders have introduced 1/4.7" and 1/6" sensors. One extra bonus of a larger sensor size is narrower DOF (see above).
And in conclusion, here's a quick run-down on a few features that are really valuable rather than gimmicks:
1. Manual aperture (iris) control, ideally one that allows camera automatically adjust sensitivity (preferred) or shutter speed while you work the iris, to maintain consistent overall exposure. This allows you to select DOF. If all cameras in your price range only have automatic iris control, consider those that have built in ND (neutral density) filters - or get good screw-in ND filters (multi-coated by Hoya or B+W).
2. Manual audio gain control with recording level indicator and microphone input.
3. Flexible autofocus zone selection allowing you to direct the camera to auto-focus on a main subject that your intended composition places anywhere in the frame, even if it is off-center. An easy-to-get to (ideally controlled directly by a switch (preferred) or a button) auto-manual focus control is also important. Better ones let you know at a glance and / or by touch whether the camera is in auto or manual focusing mode, at any time.
4. Button or another tactile control to lock exposure so that in auto-exposure mode it does not change during a particular shot where it is not desired.
5. Zebra pattern in viewfinder and / or flip-out LCD, telling you the extent of overexposure (highlight areas in the frame where the camera in its present exposure setting is no longer able to capture any detail, instead registering solid white).
Good luck!
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Member: Alexander Karasev
Location: New York, NY
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