Types of Film Cameras
The first portable cameras consisted of a lensboard mounting a lens (which included the shutter assembly), and a backboard which had a piece of ground glass for focusing. These were connected by a lightproof bellows. The ground glass was replaced by film to take a picture. Today, we call this type of camera a field, large-format, or view camera. You can't beat them for flexibility in terms of making an image, and a 4x5 or 8x10 inch negative is tough to top in terms of resolution. On the other hand, it is tough to lug them around and they are slow to set up. Today, these are mainly used for pictures of scenery.
An improvement to the view camera was the addition of rolls of film to replace the single sheets. The film got smaller, cut into strips 220, 120, or 70 mm wide. Many different models used these wide rolls of film; among them were double-lens and single-lens reflex cameras. Today, many of the cameras using this wider type of film are sold as professional cameras or medium format cameras. Makes include Hasselblad, Mamiya, Pentax, Rollei and Fuji, among others.
The reflex referred to earlier means that a prism is used to bend the light coming from the object to the viewfinder. In a double-lens reflex camera there are two separate lenses on the front of the camera; one for the viewfinder and one to expose the film. Often, this type of camera is designed to be held at waist level, with the photographer looking down into a viewfinder on top of the camera. The single-lens reflex camera, on the other hand, uses the same lens for both viewing and exposing the film. A mirror in the camera reflects the image coming in from the lens to the viewfinder (which may be on the top or the back of the camera); the mirror flips up when the picture is taken, allowing the light to pass through the shutter to the film.
Medium format films are expensive and require larger cameras. Other film sizes appeared, including the now "standard" 35 mm film. Even smaller film formats such as 110 also came about, but we won't go into them, other than to mention the recent innovation of APS. APS, the "advanced photographic system" is basically a repackaging of film. In a container slightly smaller than the 35mm film canister, the APS records not only the images but also information on the exposure settings at the time the image was made. This information is recorded on a magnetic track. The whole system must be processed by special equipent; the film itself is stored for good in the canister. The system also allows several different "formats" to be used, including a "panorama" format. Because of the smaller film canister, the camera itself can be smaller. There are several disadvantages to APS, however:
Because of the smaller film size, and the resultant limitation in the amount of information you can record, these cameras aren't good buys for the imager.
There are a wide variety of 35mm cameras available today. Basically, these differ in terms of lens interchangeability, viewing and focusing methods, and level of automation and control.
The simplest 35mm cameras available are the "one-use" or disposable cameras. Basically a cardboard box with a plastic film transport mechanism and a plastic lens, these "cameras" depend on forgiving color print film to make their images. Since the lenses don't focus, you don't expect a really clear image, and there is no way to adjust exposure (although some do have a simple flash or some limited shutter speed control). For the imager, the only use of these cameras (particularly the "waterproof" ones is to get a picture in situations you don't want to expose a good camera to.
Slightly above this level are a host of cheap cameras. The main difference with these is that you can load and reload the film yourself.
More advanced 35mm cameras will have some control over focus and exposure. Focusing mechanisms range from guessing at the distance and setting the lens to sophisticated autofocus units. In between are rangefinders, which use some optics in the viewfinder to set the focus. Most of these cameras have a viewfinder that does not look out through the lens. This leads to two problems. First, you may not see exactly what the film sees due to parallax. Simply put, the camera lens and the viewfinder lens have different perspectives (just as your right and your left eyes do). This is a particular problem close up. The second problem only occurs with cameras whose lenses have a zoom feature; unless the viewfinder is fairly sophisticated you will not see the effect of zooming. You can pay from $40 to $2,000 for cameras of this type depending on the features; at the top end you can interchange the lenses. Many of these cameras are small, light, and weather or waterproof. They make good backup cameras or cameras to carry into places you just don't want to lug a bigger camera. Without a zoom feature, they are most suited to scenic picture taking.
For flexibility, however, you can't beat the 35mm single lens reflex (SLR) camera. With it, you look through the main lens and see exactly what the film will see. These cameras are available with a huge range of lenses and accessories; they can be mounted on optical instruments from microscopes to telescopes; there is a wide variety of (relatively) inexpensive film available; processing is widely available; the equipment is of reasonable size and weight; and there are many models to choose from at a variety of prices. These attributes make the 35mm reflex camera the best buy for the imager.
The 35 mm SLR
First, a disclaimer: These pages aren't meant to be an advertisement for Canon cameras. In 1980, when I bought my first SLR, Canon had just introduced the revolutionary A-1, which had both digital exposure information in the viewfinder and fully automatic exposure. So I bought one. Years later, when the A-1 was showing its age (it's still working fine, thank you, just not as often), I was looking for a new camera. Canon had just brought out the EOS line, and, unlike Nikon, the old Canon lenses would not fit the new cameras. I was pretty steamed at Canon, but I got a good deal on an Elan IIe and so I bought Canon again. A huge number of electrons have needlessly flowed on the web, with flame wars between the adherents of Canon and the armies of Nikon. What a waste of time. All cameras have good points and bad points. I own a Nikon and love it. I wish I had the money to buy more cameras; some of them would be Nikons (or Pentaxes, or Rolleis, or Minoltas). Anyway, when I set up these web pages I had Canon cameras to photograph. Anyone - particularly the camera companies - who wants to tell me that their camera or lens is better, is free to give me one so that I can try it out. If you're not ready to do that, then I will concede that your camera is better, that your camera is the greatest ever, that your camera will cure AIDS and would have stopped the plague cold had it been around back then. Meanwhile, get a life.
Off the soapbox. If you are buying a 35mm SLR today, you are in luck. First, there are a lot of models; second, the use of plastics and electronics in the cameras has brought prices down and features up. Way up. For under $300, you can get a great camera with auto exposure (and manual) and autofocus (and manual) and electric film advance (sorry, no manual).
The figure to the right shows a top view of a modern camera with electronic controls. Some of the more important ones have been marked. On the left are several control buttons, which, collectively, set the camera's exposure mode, autofocus mode, film speed, and film drive. On the top of the camera is a hot shoe or flash mount to mount an external flash. The lens mount (no lens is on the camera) is in the front. To the right side is a control panel where the settings, including the exposure information, is displayed. The shutter release is mounted to the right on top of the handgrip. Near it is a control dial that allows changes to the exposure information to be fed into the camera. Note too that there are other controls scattered over the surface of the camera. This brings up an important point - try out a camera to be sure it fits your hands and that the controls are in a logical position. Even the best designed camera won't work for you if it is too big or too small.
Looking through the viewfinder (left), we see all the essential information. At the bottom is the shutter speed (1/250 of a second) and the f-stop (6.3). To the right is a scale that shows the current exposure as a small green square. Since it is at the center of the scale, the exposure is correct (at least according to the camera's computer). The 5 indicates the number of frames remaining. In the middle of the viewfinder is the view through the lens. A red focusing square indicates where the camera is focusing. On the EOS3 there are 45 such focusing points and they can be selected merely by looking at them - the camera tracks the eye's movements. Other information that can be displayed in the viewfinder includes flash status, flash exposure, autobracketing information, and exposure compensation. The second viewfinder (right) shows another situation. Here, if you look at the scale on the right, you can see that the current settings (1/125 sec and f 29) will cause at least 2 stops of underexposure. Of course, the camera must be in manual mode, otherwise it would have already adjusted the shutter speed and/or f-stop to correct the underexposure. Since the camera is a single-lens reflex, any change to the lens - zooming in or out, refocusing, etc.) would immediately be seen in the viewfinder. What you see in the viewfinder is just about what the film will see when you press the shutter.
The shutter button is a primary control on most new cameras. Pressing it partway activates the displays and causes the autofocus to engage. With the shutter button partially depressed, light and autofocus sensors begin to analyze the scene in the viewfinder.
Most automatic cameras have several different settings for the exposure control. The control at left is from a Canon Elan IIe and shows some of the possible settings. Let's start at the "L" and work clockwise.
L is the Lock position; this turns the camera off. Not only does it prevent pictures from being taken inadvertently, it also saves the battery. Get in the habit of turning your camera off.
P is the Program Mode. In this mode, the camera selects both the shutter speed and the aperture. Different cameras have different programs; most will work primarily to avoid camera shake. Some cameras are sophisticated enough to sense what lens is on the camera and make sure the shutter speed stays high enough to avoid camera shake.
Tv stands for Time Value, Canon's name for Shutter Priority. You set the shutter speed; the camera picks the smallest aperture it can to go with the shutter speed. Suppose you are using a 300mm lens. You might set the shutter speed to 1/300 of a second and let the camera worry about the aperture. Or maybe you are using flash and want to make sure the flash synchs with the shutter. Either way, shutter priority is the way to go.
Av stands for Aperture Value or Aperture Priority. Here, you set the aperture and the camera picks the shutter speed. I use this a lot for telephoto work; I set the camera to the widest aperture and know that the camera will then select the fastest possible shutter speed.
M is Manual Mode. Here you set both the aperture and the shutter speed at any combination you want. The vertical scale in the viewfinder will then show where your settings will leave the exposure; if it is above the middle of the scale the picture will be overexposed; below the middle means underexposure. Of course, one reason to go to manual is when you disagree with the camera and want to override its settings.
DEP is Depth of Field Mode. Here you focus on a near object, then a far one, and the camera will try to select an aperture and shutter speed to properly expose the image and keep both of the objects in focus.
The green box and the various symbols are variations of the program mode. Each of these will cause the program to vary in specific ways that are appropriate to various situations (photographing sports, landscapes, flowers, people).
In addition to exposure modes, there are various autofocus modes. These differ from camera to camera, but most cameras have at least 2 autofocus modes. In one of the modes, the camera will focus on a subject and lock. If the camera or the subject move, focus will be lost. In the other mode, the camera focuses continually while the shutter button is depressed halfway, and continues to focus right up to the point where the picture is taken. Some cameras even can guess at what the proper focus will be in the fraction of a second between the mirror swinging up and the shutter opening.
There are many other settings which can be made on many of the newer cameras. Some of these include autobracketing, exposure compensation, single-shot or continuous film advance, exposure or focus lock, self timers, mirror lockup, remote control, and so on.
Essential Features in an SLR
With all the features available on different models of SLR's, you may be wondering which are worth paying for. Hopefully, this table will help, don't do without the features in green, and don't waste money on those in red:
Beyond the features, other things you should look for when considering a camera:
Other Cameras for Special Purposes
While SLR's are the most useful single camera to own for a biological imager, other cameras have their place. As mentioned already, I have a small autofocus camera that I use when I don't want to haul the bigger, heavier SLR. Some small autofocus cameras have decent zoom lenses, and a few even have some basic macro capability. Underwater cameras are useful not only underwater, but also in weather or conditions too extreme for a regular SLR. Polaroid cameras are great when you need quick feedback. Specialized panorama cameras also exist Finally, there is still a role for older, basic SLR's. The Pentax K-1000, for instance, had a simple light meter and was otherwise completely manual. No battery; the light meter was based on a solar cell. Not everyone realizes it, but most newer cameras still need a battery just to fire the shutter - let alone wind the film. Most use battery power to keep the shutter open. Not so the K-1000; advancing the film cocks a spring the fires the shutter. The shutter will stay open all night with no battery power; this makes the K-1000 a favorite of astrophotographers who use long exposure times and who find exposure meters quaint.
That's it for cameras - you might want to continue exploring film camera lenses and accessories, or go to digital cameras from here: