Nothing ruins a post-vacation high like realizing that every one of your 647 photos of the Grand Canyon shares the same blurry spec of dust in each frame. Save yourself the heartache (and a heck of a lot of time using the clone tool in Photoshop) by using this quick, do-it-anywhere technique to test for dust on your lens.
Before you head out to snap a bunch of frame-worthy photos—like say, on day one of your scenic vacation or the morning of your sister's graduation—run through this test to spot any problematic photo-killing dust on your lens:
- Change the Aperture. Set your camera to a small aperture setting. An f-stop of f/22 is ideal on most cameras, but you can go larger (i.e. a smaller number, like f/16) if you need to.
- Adjust the Focus. Set the focus of your camera to infinity. To do this, make sure your camera or lens in in manual focus mode, then turn the focus ring all the way to the mark labeled with the infinity symbol (it looks like a sideways "8").
- Take a picture. Find a bright, plain white surface that will fill the frame, then take a photograph of it. You can also go with a two-shot approach, one white surface and one dark black, to catch even more spots.
- Examine the Photo. Set your camera display so that the photo fills the display with no text or displays on top of it, then view the image (zoom in where you need) and look for spots. Offending dust marks will cast a shadowy blur.
Using your newfound knowledge of your lens' dusty spots, you can clean off the marks and get clean, clear photosgraphs. Just make sure you know how to properly clean your DSLR camera lens.