Digigraphica

Picking the Right 35mm SLR

35mm SLR Features

Dan Knight - June 2002

Now we're getting down to brass tacks - what the various features are and how to know if they're important to you.

Shutter Speeds

Back in the 1960s and 70s, entry level cameras often topped out at 1/500 sec., and almost all other SLRs had a maximum shutter speed of 1/1000. A rare few could reach 1/2000. Today there are cameras hitting 1/4000, 1/8000, and even 1/12,000 of a second - but do you really need those speeds?

Let's start with the old "sunny 16" rule: On a sunny day, set your lens to f/16 and the shutter speed to match your film speed - for ISO 100 film, that means 1/100. Pretty much any lens ever made for a 35mm SLR (except for mirror lenses) will have an f/16 aperture, and some go further to f/22 or f/32. Here's a table of equivalent exposures for a sunny day:

       ISO 25   ISO 100   ISO 400  ISO 1600
f/32      1/6      1/25     1/100     1/400
f/22     1/12      1/50     1/200     1/800
f/16     1/25     1/100     1/400    1/1600
f/11     1/50     1/200     1/800    1/3000
f/8     1/100     1/400    1/1600    1/6000
f/5.6   1/200     1/800    1/3000   1/12000
f/4     1/400    1/1600    1/6000       n/a
f/2.8   1/800    1/3000   1/12000       n/a
f/2    1/1600    1/6000       n/a       n/a
f/1.4  1/3000   1/12000       n/a       n/a

Back in the days of Kodachrome 25, a top shutter speed of 1/500 was plenty, even with a moderately slow (by the day's standards) f/4 lens. And 1/500 stops all but the fastest action.

With "normal" ISO 100 print film, you didn't have to go beyond 1/1000 unless you really wanted limited depth of field. As we move to the ISO 400 film that's common today, having a 1/2000 top shutter speed becomes helpful if you want to limit depth of field - but if you're after limited depth of field, you should probably shoot a slower film.

As for the ISO 1600 stuff, it has its place, but shooting this expensive film outdoors is far from ideal. You can do it, but I recommend something slower when the sun is shining bright.

You may encounter very bright light situations, such as snow and beach scenes, that are a stop brighter than your typical sunny day, but chances are that you'll rarely need shutter speeds beyond the 1/2000 mark.

Flash Sync

The focal plan shutter in today's 35mm SLR cameras and some medium format cameras uses two curtains or sets of blades to cover the film before and after exposure. The speed at which these blades move and the distance between them creates different shutter speeds.

Both blades need to be completely out of the way at the instant the flash fires, so 35mm SLR cameras have had sync speeds ranging from as low as 1/30 to as high a 1/300. Today's entry-level SLRs typically have a sync speed in the 1/60 to 1/125 range, while advanced amateur models tend to be in the 1/125 to 1/250 range. On most cameras, you can select a lower speed.

Benefits of a higher shutter speed flash sync include minimizing the effect of existing light and making it easier to use fill flash in bright light. I consider a faster flash sync one of the main benefits of more advanced cameras.

High Speed Flash Sync

There is an exception to the flash sync rule - some cameras will work with certain flash units at higher shutter speeds by reducing the flash unit's normal output to a lower level and precisely triggering the flash several times as the shutter blades zoom past the film. This can be very useful for fill flash outdoors, and if that's something you'd like to be able to do quickly and easily, buying a camera with a built in flash that supports high speed sync can be a real plus.

Second Curtain Sync

Another nice flash feature when shooting moving subjects in low light and with slower shutter speeds is second curtain sync. Normally the flash fires as soon as the shutter is fully open; this is exactly what you want most of the time. But if you're shooting a subject that moves during the exposure leaving an image trail in your photo, this can result in an unnatural looking blur that comes after the initial flash exposure. Second curtain sync fires the flash just before the second shutter curtain fires. If you shoot with flash at low shutter speeds, this can be an important feature.

Built-in Flash

All of the entry level AF SLRs have flash built into the camera, and it's making inroads on pro cameras as well. The internal flash has limited power (a guide number of 40 in feet with ISO 100 film is typical), limited range, and increases battery consumption. If you plan on doing a lot of flash photography, seriously consider a more powerful add-on flash unit. This will also greatly reduce the chance of red eye in your flash photos.

Autofocus

Although there are a handful of manual focus cameras made today, most models and the best sellers offer autofocus (AF). Where early autofocus cameras could only focus on subjects with good contrast in the middle of the picture, many of today's AF SLRs have multiple sensors and work with a wider variety of subjects.

Multiple Sensors

With multiple sensors, your subject needn't be in the middle of the picture. Old timers like me are used to focusing in the middle and recomposing our shot, but a lot of cameras will let you choose which sensor to use, letting the camera easily autofocus on the correct subject. Canon even has some models that can track your eye to determine which subject to focus on.

Wide Area AF

Since I got my hands on a Nikon N90s, I've become a huge fan of wide area autofocus, Nikon's term for a larger AF area. The subject need not be as critically centered, and the camera seems to sense just where to focus within that space.

AF Aid Light

Autofocus has limitations in low light, so a lot of AF cameras include an autofocus aid light. On more expensive models, this tends to be deep read and send out a pattern of vertical bars in the near infrared range that the AF sensor is well attuned to. This light is fairly inconspicuous, and most external AF flash units include an even more powerful AF aid light.

More recently, less costly AF cameras have switched to a white aid light, sometimes using the flash for this purpose. I think it's as annoying as all get out, and your subjects will definitely know you're preparing to take a picture. White lights are cheaper, but I'm not a fan.

Continuous AF

Autofocus SLRs can usually be set to focus and lock or to focus continually - sometimes right through the shot and into the next one. Single-shot AF is fine for static subjects, but for moving ones (sports, kids), you'll probably be happier with continuous AF.

Film Handling

Loading 35mm SLRs used to be a chore, and almost every photographer would botch it once in a while. That's much harder to do with today's autoload, autowind cameras. All the AF SLRs include automatic film wind at 1 frame per second (fps) or better - and at least one entry-level model clips along a 3 fps. Unless you're shooting sports or other fast action, though, the convenience is being ready for the next shot, not the ability to fire off 36 shots in 12 seconds.

These cameras will also rewind the film when the roll is finished.

Another wonderful innovation from the 1980s was DX film encoding. It used to be that photographers had to manually enter the film speed. DX changed that by putting sensors in the camera and a code on the 35mm film cartridge to automate the process. Result: You have to work to set the wrong film speed. (But I've done it!)

The only drawback is that some of today's SLR cameras, such as the Nikon N65, have no way to manually set the film speed if you want to push film or use film that isn't inside a DX encoded cartridge (rare, but infrared film is one example). This isn't an issue for most of us, but some schools insist that their photography students have a camera which allows manual ISO settings.

Metering

Another brilliant innovation was intelligent metering. Minolta started this with the CLC (Contrast Light Compensation) metering system in their SR-T 101 way back in 1966. The unique feature of CLC? I was designed to ignore a bright sky and expose for the rest of the picture - assuming you were shooting a horizontal.

The next step in metering evolution was the matrix metering of the Nikon FA, which metered the center and four quadrants of the screen, determined which areas should be given more weight, and calculated exposure accordingly. Some of today's cameras have over a dozen metering areas, but for real world picture taking, I think you'll find the matrix metering in any of today's 35mm SLRs does a fine job over 95% of the time. Each brand may promise superior results, but you're unlikely to see the difference.

If you want sophisticated metering, you'll want to learn how to use a spot meter. A spot meter works by only measuring light in one spot on the screen, usually a small circle right in the middle. The smaller the spot, the more precisely you can meter your subject.

Spot metering is a thinking photographer's tool, since you have to not only decide where to meter, but also whether what you're metering should be lighter or darker than average - and by how much. For the rest of us, spot metering is best reserved for situations like concerts where a spotlight shines on the artist and you want him/her to be exposed correctly despite the dark background.

Most casual photographers will be perfectly content with matrix metering, especially since today's color print films build in a nice margin of error. But if you're serious about photography, consider a camera with a spot metering option.

Next: Picking a Brand and Model.

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