Better focus, it might be a matter of calibration

• Posted By: Robert Lachman
• Posted On: 10:20 p.m. | August 25, 2011

Focus. It’s certainly the most important element to great photography. You can talk about composition, lighting, action, and  emotion, but without focus all seems to be lost.

Occasionally I hear rumbling from photographers about their photographs not being tack sharp with their digital single lens reflex (DSLR) cameras. I seem to notice it occasionally when I hit the auto-focus button and my pics aren’t as clear and crisp as they should be.

Cameras and lenses are manufactured to certain tolerances which should create sharp, in-focus photographs, but it’s possible for certain combinations to be slightly out of alignment.

Of course you could blame it on excess motion or too slow of a shutter speed, but today’s cameras should be able to auto-focus in an instant. However, if all your settings are correct and your shutter speed is fast enough to capture the action but your photos are still lacking sharpness, it’s possible that your lens is slightly out of alignment with your camera. Just a fraction off the manufacturer’s  specifications can make a difference if you’re  expecting critical focus at a shallow depth-of-field.

On the Internet I came across a product that captured my attention. Datacolor, which may be known to photographers for making equipment for calibrating color for computer monitors, had a product that seems to answer my needs.

The SpyderLensCal, a plastic device with a tripod mount, makes it very easy to check your lenses’ auto-focus performance. It simply gives you a focus point and a calibration scale mounted at a forty-five degree angle. It couldn’t be easier to operate. If you want to be the most accurate for your test it’s best to use two tripods and make sure your camera and calibrator are level, the same height and close to the same plane as possible.

A secondary option would be a tripod or your camera and a nearby table top for the calibrator.

The company recommends using a shallow depth of field (f/2.8 or f/4) and zooming out your lens to it’s longest focal length for the test. With everything in place, it’s just a matter of auto-focusing on the calibrator’s focus point and then checking the results on the camera’s LCD screen or your computer. You use the small LCD screen on the back of your camera and upload to your computer to check the results.

Many of the newer, high-end DSLR cameras feature AF (Auto Focus) Micro Adjustment (Canon) or AF Fine-Tuning (Nikon). My Canon 7D does feature this adjustment and it’s not for the faint of heart. I got a little queasy as I started dabbling with this adjustment.

Check your camera manual and follow the directions. Using the wrong setting could affect your other lenses if it’s not set properly. If there’s a consistent problem with focus you should take the camera and lens in for repair.

I decided I would try to center the focus point of my 70-200 mm lens. It appeared to be a fraction off.

Be very careful here. If you have any questions you may want to check with your camera’s manufacturer and send the camera and lens in to be checked. If your lenses are getting older or you’re not happy with the sharpness, have them checked by the camera company’s authorized repair department. That might be the best answer.

Now, it is possible to cobble together your own calibrator out of cardboard, tape, ruler and a pen for those willing to give it a try. But for the rest of us, the SpyderLensCal is available for $59.

Read more reviews and photography tips by Robert Lachman