Picking the Right 35mm SLR

Pros and Cons of Built-in Flash

Dan Knight - June 2002, revised

We've talked about lenses, features, and cameras. Now it's time to look at your portable light source, electronic flash.

Built-in Flash Considered

Almost everyone starts out with a zoom lens, whether 28-80 or 28-200. Keep in mind that your typical zoom lens these days is f/3.5 at the short end (2/3 stop slower than f/2.8) and f/5.6 at the long end.

The built in flash has a guide number (GN) of approximately 40 (in feet) with ISO 100 film. (The guide number divided by your f-stop tells you the maximum flash range.) With 100 speed film and your zoom set at the long end, f/5.6 means you should be no more than 7' from your subject for proper exposure.

Thanks to the exposure latitude of modern color print films, you can get acceptable results up to about 10' and recognizable ones at up to maybe 14'. That's it.

The guide number increases with film speed. For each doubling of film speed, the GN increases by 40%, so at ISO 400, the internal flash has a GN of 80 and a reach of 14' with your lens at f/5.6.

I hope this helps you understand why so many pictures of school stage shows shot with flash are underexposed - unless you're using 800 or 1600 speed film, the standard flash with the typical zoom just doesn't have the reach you need. This is one good reason to consider adding a more powerful flash (ISO 100 GN of 80-120) to your setup.

Zoom Lenses Considered

Besides film and a more powerful flash, the third way to increase flash distance is a faster lens. Although today's cameras commonly come with a 28-80/3.5-5.6 zoom, there are alternatives. Some are horrendously expensive, such as a 28-105 with a fixed f/2.8 aperture. They're also quite heavy.

If you'll be doing a lot of flash photography in larger areas, think about a 28-105/2.8-4 (or so) zoom such as Sigma, Vivitar, and Phoenix offer. These are up to a full stop faster at the long end than the most common 28-80 and 28-200 zooms. That one stop difference increases your flash range by 40%. Coupled with fast film and a powerful flash, this can be quite a combination. (It's too bad neither Tamron nor any of the camera makers [except for Sigma] offer such a lens.)

What About Zoom Flash?

Odds are you'll hear someone extol the virtues of a zooming flash head, especially one that automatically zooms as you zoom your lens. That sad truth is that while a zooming flash head increases the guide number slightly, it's rarely enough to make much difference. In my opinion you're better off without the zooming flash head; invest in a more powerful flash, and you can still save money.

For instance, my favorite flash for the past 20 years was the Sunpak 422/433/444 series. The 433AF has a GN of 120, giving it three times the reach of the flash built into most of today's cameras.

Sunpak's more expensive PZ4000AF zooms from 28mm to 80mm and varies its GN from 80 to 132. At the long end, it provides 10% more reach than the 433AF. Yet the 4000 costs one-third more, is considerably bulkier, and is more complex. If you really need some reach, look at the PZ5000AF, which has a GN from 99 to 180 and provides fully 50% more range than the far less costly 433AF. Of course, it costs about twice as much as the 433AF.

Other Factors

Flash is one area where camera manufacturers distinguish themselves. If you want high speed flash sync, you're pretty much limited to what Nikon, Minolta, etc. have to offer. The same goes for off camera flash sync. These flashes are not inexpensive, but they may offer features Sunpak, Vivitar, Metz, and other simply cannot provide.

By now my bias should be clear. I think a good flash is one of the most important things you can own if you do a lot of indoor photography. I'm particularly fond of the Sunpak line, which I've been using without any problems since 1977/78.

Next: Putting Your System Together

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