When the Camera Lies!
OK, it might be a bit of mis-statement. But it’s more or less true. 😉 What I’m talking about is my history of occasionally blurry shots when shooting handheld with my 50mm f/1.8. I noticed that shots would sometimes be bang on and sometimes they would be off ever so slightly. Most of the time I would lock the camera into Aperture priority mode, dial in ISO 320 (I’m not a huge fan of noise) and let the camera work out the shutter speed. It would work out an exposure for me and I would click and sometimes it would be blurry and sometimes it would be bang on. I blamed it on photographer shake and went on with life, with lots of occasional blurry shots.
Then, I learned about the handheld rule – this literally changed my photographic life! When I finally learned that if your shutter speed drops below 1/your focal length (in my case 1/50th for a 50mm), you’re shot will be blurry if it is handheld. You can compensate for this somewhat by cranking your ISO but your overall picture quality will degrade too. Now, when shooting handheld inside in natural light, I switch to M mode and dial in no less than 1/100 to be safe.
The logic is because the handheld rule originally applied to film and it still works on full sensor cameras. But on crop sensors like my D300s, you have to multiply the focal length by a factor of 1.5 (for Canon crop sensors it’s 1.6). So, a 50mm prime on a C-Sensor camera is actually a 75mm. You’d need a shutter speed of no less than 1/80 of a second to get a sharp shot.
Keeping this rule in mind, you can tell why shots taken in Aperture Priority mode would sometimes be blurry. If the camera calculated your exposure to be 1/60 at f/4 at ISO 320, on a handheld 50mm lens, end result is a blurry shot which is a real drag! Switching to M mode and watching my meter has virtually eliminated my blurry handheld shots.
Try out the handheld rule the next time your taking inside shots in natural light handheld. You’ll be surprised at the difference it makes! It’s now become innate for me, that is to say, I never deviate from the principle now as it just comes automatically. I don’t even have to think about it anymore. Which is a real plus! It means I can get back to concentrating on composition and making photographs.