Selecting a DSLR Lens for Video
Compared with using a standard fixed-lens camcorder, this is the most exciting part of the whole DSLR experience for me: Thousands of lens choices are on the market. And the prices vary from $10 in a backyard sale to $20,000 for a high-quality sports telephoto lens.
The two main choices you have are a prime lens (which has a fixed focal length) or a zoom lens (which lets you adjust the focal length). Even if you find a lens that doesn't fit the lens mount on your DSLR, you can buy adapters that make pretty much any lens fit on any camera. That said, autofocus features and the display of aperture readings from the lens may not work if you use a converter or an older lens with a newer DSLR. It's important to think about how each lens will react with your camera, and whether you can live with not having all the features and information you'd get with a newer, natively mounted lens.
When choosing a lens, keep several key points in mind.
1. The faster the lens, the more freedom you will have.
In this case, "fast" refers to the maximum aperture of the lens. Lenses that have very wide apertures (such as f/1.4 or f/1.8 lenses; the lower the f-stop, the wider the aperture) can gather a lot of light in near-dark situations, and they let you use faster shutter speeds as a result. Fast lenses also allow you to capture footage with a dramatically shallow depth of field, meaning your foreground subject will be in sharp focus while the background is blurry. In general, you get a lot more visual versatility out of a fast prime lens than you do with your standard f/3.5 kit zoom lens.
2. Spend the bulk of your money on the lenses, not the camera.
Camera bodies will age quickly, and as new technology becomes available your camera body will become obsolete. Lenses have a much longer shelf life, and you should plan to buy a lens that you can use with new DSLRs down the road. If you spend the money on a few good lenses, they'll last you 20 to 30 years. Some of the best lenses around are 30 years old, and they're still just as crisp as anything on the market right now.
3. Then again, don't overpay for a lens you don't need.
Get the lens that is right for you. If you're filming home movies, a good, fast zoom lens will cope with everything you throw at it. Buying a $20,000 sports telephoto lens is probably overkill for capturing your 8-year-old's soccer game.
4. Go bargain hunting.
A lot of great, new lenses are priced very competitively, but the deals don't end there. Look around in second-hand shops, as you can often find amazing bargains on older-but-excellent lenses.
5. Don't buy blindly.
Research is important. The specs for a particular lens may seem perfect for your needs, but there's no substitute for a real-world test drive. Always take your camera with you and test a lens out before you buy it. Get a feel for it and make sure it works for you. Rushing into a lens purchase can often be a disappointment and a waste of money.