Appendix A: VR and IS Lenses Exposed

o the question is, “Do VR and IS lenses live up to their promises?” What is a VR or an IS lens? VR (vibration reduction) or IS (image stabilization) lenses are lenses that counteract the normal camera shake that often occurs when handholding your camera and lens. In effect, with one of these lenses, it’s like having a built-in gyroscope. When you find yourself shooting, say, images of your friend’s wedding and you’ve had one too many glasses of champagne, a VR or IS lens will move in the opposite direction of any camera movements to counterbalance your shake, resulting hopefully in an in-focus picture. There is a switch on the side of these lenses that you must have in the On position when handholding your camera in order for VR or IS to work.

A word of extreme caution: Read the instructions that came with the lens first, but most of the time, the On/Off switch found on the lens barrel of most VR and IS lenses should be switched off when you’re using these lenses and a tripod. Since the VR or IS lens responds to movement/camera shake, and since either is highly unlikely with a tripod, the VR or IS function will still act as if camera shake is present and introduce a countershake when you take the picture. This means that an image that would normally be tack sharp when taken on a tripod will actually be blurry! Yikes! This has happened to a number of students, and in a few cases, they didn’t notice the blur until returning to their hotel rooms following an evening of shooting cityscapes (photo-ops that, in all likelihood, they would not have again anytime soon). I’ve also heard similar stories from readers of my other books who made this discovery too late, having already shot those once-in-a-lifetime photo-ops while on vacation.

The promise made by the VR and IS lenses is simple: You will be able to handhold the lens and camera at as many as four shutter speeds slower than what are normally considered safe handholding shutter speeds. And what is normally considered a safe shutter speed for handholding? Whatever lens is in use, it’s a safe bet that you can record tack-sharp handheld images at the closest shutter speed to the lens’s longest focal length. So for example, an 18–70mm street zoom can be safely handheld at shutter speeds of 1/60 sec. and above (60 being closest to 70), while a 70–200mm telephoto zoom can be safely handheld at shutter speeds of 1/200 sec. and above, and so on. If your lens has VR or IS, manufacturers promise you can safely handhold at shutter speeds up to four times below the normally accepted shutter speed range. So, that same 70–200mm VR lens can be safely handheld at shutter speeds down to 1/15 sec., while the 18–70mm IS can be safely handheld at shutter speeds down to 1/4 sec. Don’t you believe it!

In test after test after test, most VR and IS lenses do deliver on the promise of handholding at slower shutter speeds—but no more than two times slower than the accepted norm. So with that 70–200mm, you will, in all likelihood, be able to shoot handheld at shutter speeds of 1/50 sec. Nikon’s Micro-Nikkor 105mm with VR has left many unsuspecting photographers a bit miffed as they quickly discover VR (or IS in Canon’s case) is virtually useless when shooting close-ups. It’s something to think twice about if you’ve been looking forward to buying and shooting with a VR or IS macro lens. To be sure I’m not misinterpreted, the VR or IS found on a 100mm or 105mm macro lens does indeed work—but only when your working distances are at least 8 to 10 feet and greater. Keep in mind that both of these lenses are great for portraits, and therefore, the VR or IS can come in really handy as you move about, handholding the camera and lens, while shooting portraits at the company picnic or family reunion.

So, as you frame up that lone flower and with your aperture now set to f/22, you see that a correct exposure is indicated at 1/40 sec. Of course, you can’t possibly shoot at that shutter speed without camera blur, so instead, shoot a DTSU—in other words, a deliberate 2-stop underexposure. This would be f/22 at 1/160 sec., and as you’ve already discovered, you can safely handhold your camera and 70–200mm lens at 1/160 sec. At the end of the day, you simply load the images into the computer and those 2-stop underexposures are ready to be adjusted in Photoshop by simply moving the exposure slider over from left to right, correcting what was a “dark” histogram. The result: your tack-sharp image with the added depth of field you had hoped for, all correctly exposed.

I do not suggest that you could just as easily change your ISO from 200 to 800 and achieve the same thing, because you can’t. Yes, you’ll get the same exposure (f/22 at 1/160 sec.), but you will also introduce more noise, more grain. Also, do not try to shoot any DTSU with an ISO beyond the lowest ISO setting that your camera offers (for example, 100, 125, or 200). If you try this with ISO 400 or 800, for example, it will not be a clean image. Due to an anomaly in raw processing, any higher ISO than the lowest will actually produce far more noise than what you ordinarily see when shooting at these same higher ISOs and not deliberately underexposing.