It’s hard to imagine a camcorder without some kind of viewfinder. Some low-cost, no-frill camcorders come equipped with a simple optical viewfinder, which functions like the peephole on a snapshot camera. You observe your intended scene through an opening or frame, sometimes with the aid of a lens to help make sure the view matches the video image as you tape.
But with an optical viewfinder, what you see isn’t what you get. You might be out of focus or out of gas (dead batteries), or the scene could be too dark for a decent picture. In all of these instances, the optical view would remain the same.
Enter the electronic viewfinder. Besides letting you know where youre aiming your camcorder, most electrical viewfinders offer helpful information that may include battery reserves, color settings, tape remaining (or elapsed time) and more. And the latest full-color viewfinders help you see more accurately just what you’re aiming at.
So–what’s inside a viewfinder? How do they work? And which one is best for your videomaking? In this article, we’ll look at the basic types as well as the latest options to make you more of a viewfinder expert than (perhaps) you were before.
So Many Choices
Once upon a time, most video cameras came with a black & white viewfinder mounted on the left side of the camera. You aligned your right eye with the little picture tube while balancing the whole thing on your right shoulder.
Today, we have more choices. Viewfinders come in two flavors: monochrome and color. Monochrome means black and white, the way television was in the beginning. Although color TV has existed since the early 1950s, color made its way into the tiny viewfinder only recently.
While black and white viewfinders are indeed miniature TV monitors (picture tubes shrunk down to under an inch across), color models work on a very different principle. To view in color, we take advantage of the latest in liquid crystal technology, microscopic transistors and compact optics.
Whether color or monochrome, camcorder viewfinders come in different styles with different features. As with most things, one person’s favorite viewfinder can be another’s cursed device. Here are a few ways in which they differ:
- Electronic design. There are two basic designs: cathode ray tube (CRT) and liquid crystal display (LCD). Both kinds exist in monochrome or color, although miniature color CRTs are extremely rare.
A CRT display uses a miniature picture tube that glows when an electron beam hits it from inside; LCDs have a flat screen made up of tiny crystals that go from transparent to opaque on (electronic) command, letting light (from a source behind) shine through.
- Size. Think small. The traditional viewfinder, with its black rubber eyepiece and recessed image, ranges from about 1.5 inches across down to less than a half inch.
Small viewfinders require optics to increase the apparent image size and to help you focus your eye. This takes the form of magnifying lenses mounted in the eyepiece–the hole into which you peer.
If your eyesight isn’t 20/20, or if you’re farsighted or have to wear glasses, you need an adjustable viewing lens called a diopter. By sliding lens elements in the viewfinder either closer or farther away from the eye, the diopter lens can help many a camera person to shoot comfortably without glasses or contacts.
- Position. Everyone has their favorite viewfinder location–on the left or right, in the middle or on top of the camera. Sometimes it has to do with dexterity–whether you’re right handed or a lefty. If you favor one eye over the other, you’ll want the viewfinder to cooperate and be there for you, left or right.
The majority of camcorders do not offer fully adjustable viewfinders. While you can move the eyepiece in and out and slide the finder laterally, its basic location, to the right or left of the camera’s body, doesnt change. The more flexible designs are the ones in which the entire viewfinder can move easily from one side to the other by swinging it up and over, or by unscrewing the mounting bracket and reattaching it.
On some camcorders, manufacturers permanently affix the viewfinder within the camera shell. On this type, if you dont like where it is, you just have to live with it.
Large-screen (two- to three-inch) viewfinders have appeared in the last few years, noticeably on Sharp’s ViewCam VL-HL100 or Sony’s Handycam CCD-SC7. These models, as well JVC’s GR-SV1U and a few others, integrate their liquid crystal display (LCD) viewscreens right into the back of the camcorder. These models often have shapes more like a still camera than a traditional camcorder.
While you cant move most of these larger flat viewfinders, the manufacturers often compensate with a movable lens assembly. In some models, the camera lens tilts up or down or flips 180 degrees so that it points directly at its user–perfect for self-portraits.
Large side-mounted color LCDs could be the latest craze. Available on Sony and Nikon 8mm camcorders, these viewfinders flip out when your need them and fold back in when you’ve finished shooting. Several models give you two viewfinders–a conventional fixed-eyepiece model as well as a fold-out color LCD display.
- Resolution. Measured in lines per picture height (or width), resolution is the ability to separate and display, or resolve, small details. Higher resolution appears to the eye as increased sharpness and greater detail.
Higher frequencies in the video signal are responsible for higher resolution, with both Hi8 and S-VHS formats boasting the ability to cleanly record 400 or more lines from left to right across the screen. A decent black and white CRT viewfinder can easily resolve more than 400 lines, assuming the little picture tube is in focus.
Liquid crystal displays have to break up the image into numerous picture elements, called pixels, in order to assign the proper colors. The CCD (charge coupled device) that captures the image inside the camcorder works in a similar fashion.
While CCDs with 360,000 to 410,000 pixels are commonplace in today’s top-quality camcorders, most color viewfinders are no match in terms of resolution. A typical LCD screen operates with only 72,000 to 200,000 pixels, so that half or more of the fine detail doesnt show up.
Some videomakers, especially professionals, shy away from color viewfinders. With a color viewfinder, they claim, its more difficult to tell if your picture is in sharp focus. However, since autofocus has taken over the realm of home video and low-end pro gear, color viewfinders present less of a problem for most of us.
- Brightness and contrast. Monochrome CRT displays are brighter than LCDs. The light coming off a picture tube can be so bright as to ruin your night vision after a few minutes of shooting. Liquid crystal displays rely on a rather dim internal light source, and so are not nearly as usable outdoors in bright light. Most units come with a removable shield or hood to aid you when you shoot the great outdoors.
Related to brightness is contrast, the range between the darkest blacks and the whitest whites. Again, CRTs have the upper hand for now, because their extra brightness translates into a wider contrast range. But today’s LCDs are much better than just a few years ago, with more improvements expected.
- Data displayed. Viewfinders make handy data displays, telling you a lot more than just what you’re shooting. A flashing "REC" means you are recording and the tape is moving forward. "FF" and "REW" reflect fast forward or rewind modes.
Numbers visible in the viewfinder, whether elapsed time or index markers (based on take-up reel rotations), tell you how much remains, and a stylized "gas gauge" alerts you to battery power reserves.
Other symbols, icons or words keep you up to date as regards white balance/color settings, autofocus status, time and date display, shutter speed and more. Some viewfinders even have a tally light, a red LED visible from the front of the camera, to let the talent know theyre "on the air."
A View Inside
Now let’s examine the inner workings of the familiar black and white viewfinder, and delve inside a color LCD.
The monochrome finder starts with a very tiny cathode ray tube, or CRT. The diagonal measurement of the screen can be as small as 1/5 of an inch, although most are about 1/2 an inch.
The tube is several inches long, and is sometimes mounted at a right angle to the camcorder length. Its like a periscope on its side; you view the image with a small specially-designed reflective surface called a first-surface mirror.
Common household mirrors have a silver coating on the back, or second surface, so as to protect the delicate metallic coating. Second-surface mirrors exhibit a ghost reflection that bounces off the front of the glass; this can be very distracting when you view it up close.
First-surface, or front-surface, mirrors have the silvered material on the top of the glass so theyll only reflect one image. This type of mirror costs more and is very fragile.
Right-angled viewfinders display a mirror image on their CRTs, and the 45-degree mirror flips the image to make it right as you see it.
The front, or faceplate, of the CRT is clear glass, coated inside with a phosphor compound. This coating glows bluish-white when struck by electrons.
At the opposite end of the glass envelope lives the electron gun and the elements that control electron flow. Manufacturers remove the air from the glass envelope during final assembly, making it a vacuum tube.
Surrounding the inside of the tube from the faceplate back to the electron gun is a black graphic coating. This layer is charged with a high voltage (typically 2,000-3,000 volts or more) to help accelerate the electrons towards the screen, as well as collect them so they don’t pile up.
Also included inside the viewfinder is the deflection yoke, which consists of two sets of wires each wound into an electromagnetic coil. The resulting magnetic field guides the electron beam, sweeping it to a specific point on the inside screen surface of the tube. The beam traces out the video image one line at a time, top to bottom, about thirty times per second.
Also stuffed into the viewfinder housing (if not directly into the camcorder body) is a high-voltage power supply, plus circuitry to adjust and control the brightness, contrast, focus, height and width of the image.
If the viewfinder is removable, it will attach to the camcorder by way of a flexible multiconductor cable. This cable may be either hard-wired or plug into a socket on the side or top of the camera.
Inside the LCD
The liquid crystal display has a shape very different than the CRT. The mechanism consists of two flat layers of thin glass, and does not require a vacuum. Rod-shaped molecules of a special liquid crystal fluid become opaque when a small electronic charge runs through them, and transparent when the charge is no longer present.
The LCD panel is really thousands of tiny light valves–hundreds of rows and hundreds of columns. Consider a liquid crystal display with 100,000 pixels. A matrix of hundreds of tiny wires exists along the edges of the glass chip where the LCD resides, with each pixel turned on or off by an array of transistors. Circuitry then simulates the line-by-line scanning that occurs inside a conventional CRT. The entire assembly contains thousands of parts. However complicated it sounds (and it is), the design is compact and manufactured like computer chips and other microscopic components–all done by machine.
The whole thing can be less than an inch across, just like a CRT, with the familiar magnifying lenses so you can focus your eyes on it and a rubber eye cup to keep out extraneous light.
A light source behind the glass LCD panel provides the light you see if the LCD pixel is on. For color viewfinders, the light filters into red, blue and green primary colors, and your eyes mix them together and see them as (more or less) true color.
Liquid crystal pixels do not open and close as quickly as we would like. Moving objects sometimes smear or blur as they cross the screen. Current models are better than earlier ones, but if you’re new to LCD viewfinders, the time-lag effect may take some getting used to.
More pixels (of the same size) translate into bigger LCD screens, and viewscreens from three to four inches (measured diagonally) are making their way into the marketplace. You view some of them from a distance, holding the camcorder away from your body instead of up close. Of course, these larger screens have no optical aids, so you may need to wear your reading glasses if you have problems with your eyesight.
The Viewfinder as an Accessory
Several companies make add-on viewscreens to supplement your black and white viewfinder. Most of these are small, portable LCD screens that attach directly to the camera itself.
What new and/or different viewfinder designs are in your future? One that you may have heard something about is the VR, or virtual reality, viewfinder. Most of these look like goggles or sunglasses with the LCD image reflecting off the inside. The video image appears to float in midair. The military has used this idea with some success in jet aircraft–the so-called "heads-up" data display.
It’s hard to say whether future viewfinders will take the form of goggles or eyeglass-mounted displays. While it’s certainly possible to build them that way, it remains to be seen if videomakers want them so. In the mean time, we have plenty to choose from.
A Brief History of Viewfinders
Many of the earliest television cameras had no viewfinders; pioneering camera operators saw the results of their work, if they were lucky, on a large (and decidedly un-portable) video monitor in the studio or control room.
By the 1950s, many cameras had integral viewfinders. These were actually small monochrome monitors mounted inside the camera case. Eight-inch viewfinders were common, although they were actually too big to comfortably view up close. But smaller CRTs were just too expensive to make at that time.
During the 1960s, Japanese companies were making small picture tubes (and the necessary circuitry); these found their way into TV camera viewfinders. By the late 1960s, the 1/2-inch black and white porta-pac systems were becoming common with cameras using 1 1/2-inch and smaller CRTs in their viewfinders. Finally, the small CRT had arrived.
By the 1980s, the most popular size ended up being about one inch for most field (portable) cameras, and the 5-inch models popular in the studio. Sony offered an optional color viewfinder (3.7 inch) for their studio cameras, but it never really caught on.
Viewfinders on home video cameras (and later, camcorders) were downsized even further from the pro models. Since then, viewfinders have continued to grow smaller and smaller.
–G.C.
