Whether you are going on a casual vacation and want to capture some images of your trip or a full-fledged photo safari where you are hoping to capture the “images of a lifetime” there is hardly anything more distressing than looking at your images and finding them blurry. The camera normally gets the blame, but with a simple exercise before you go you can prevent this disaster… [img_assist|nid=527|title=DOF Test Setup|desc=|link=popup|align=right|width=200|height=133]

Simply put, if your technique is good enough for the shutter speed you are using and the action you are capturing then there are only two mechanical issues that can cause your image to be blurry: Lack of Sharpness and Out of Focus. Time after time I’ve gotten images from photographers who don’t know how to tell whether their camera or lens have a problem. It’s a lot easier than you might think.

The key is to put your camera and lens combinations through their paces in a controlled environment. All you need is a fence and some bottles, cans, bowls or other similar items with lots of small text or designs on them. We’ve done this exercise in safari camps with beer cans, outside temples with water bottles, and I do it at home all the time with Burmese lacquerware bowls.

Simply set up a row of your objects from “front” to “back” with a differently colored or arranged one in the middle so you remember where you are aiming. Then go to town, capturing every combination of Lens, Camera, Teleconverter, f-Stop, Shutter Speed, Image Stabilization (Vibration Reduction) Setting and even ISO if you want to check for color and noise. Okay, that’s a lot of different images so I’ll give you a place to start.

[img_assist|nid=528|title=Object of Focus Should be Tack Sharp|desc=|link=popup|align=center|width=600|height=398]
Make sure the object you’ve focused on is tack sharp.
Other than the distraction from the glare the design on the center bowl
is visible down to the individual pen stroke, even at 20 feet. 

First, set up your favorite lens on a tripod if you have one, push the ISO high enough that you have plenty of shutter speed (at least 1/1000 for this exercise) and focus on the center object using a single AF sensor. Now capture a series of images from “wide-open” (the smallest aperture number which is of course the largest aperture) to all the way closed. (If you are worried about your long lens technique you can use a remote release for the first set and then shoot another set using your long lens technique for comparison.)

Upload the images onto your computer (don’t trust your camera LCD or a photo viewer for this exercise) and take a look. The first thing you should see is the center object should be tack sharp. And the ones in front and in back should get progressively more out of focus. If the focus is either in front or in back of the center object you may well have a focus alignment issue with either your camera or your lens. Experiment with different combinations of camera and lens to see if you can isolate which one is the problem. Once you have you can either use the micro-tuning of the AF in your camera (if it has that feature) or send it in for service. But make sure and triple-check that you really have the issue. In particular make sure that the focus point the camera was using was over the center object (viewing software or the LCD can show you which sensor was in use).

[img_assist|nid=529|title=Wide open only the bowl we focused on is in focus|desc=|link=popup|align=center|width=600|height=398]
Wide-open only the center bowl is in focus

[img_assist|nid=531|title=Stopped-down we get much more Depth of Focus|desc=|link=popup|align=center|width=600|height=398]
Stopped down to f32 you can see the effect of the much larger Depth of Focus
as three bowls are sharp and even the other two have a lot of detail.

If none of the images are sharp then you’ve either got a problem with your technique, your IS/VR setting. You need to sort that out before you go anywhere with the lens and try to capture real images. You may want to have a friend sanity check your technique and if you still can’t produce sharp images the lens might need to go in for service. Keep in mind that unprocessed Raw images are always a little soft due to the anti-alias filter unless your raw previewer is set to apply a little sharpening as you view them (most of them are).

The next thing you’ll learn from this exercise is how your Depth of Field varies with f-Stop. If you repeat the exercise for different focal lengths of your zoom. This will give you a sense of how much of an image can be sharp in a single shot. DOF is amazingly small for long focal lengths so often softness is simply a matter of having the camera focused on the wrong part of a person or animal you are photographing.

If you’ve verified that your camera is focusing correctly and your lens is sharp for a specific focal length the next step is to try a range of focal lengths. It is not uncommon for zoom lenses (especially entry level and “pro-sumer” lenses) to get softer as the focal length gets longer. But if the effect is too severe it might be a problem with your specific lens. In particular we’ve had examples of the Canon 100-400mm USM which got very soft beyond 300mm. This can be remedied by a trip to Canon service once you know what is happening.

Now that you’ve got confidence in your camera and lens it’s time to try any teleconverter(s) you’re planning on using. Every teleconverter makes images slightly softer but in this controlled environment you can see the “best case” results you can get from yours. If they aren’t good enough to suit you there is no point in packing the teleconverter (of course if you think it is defective then service is an option). In any case, it’ll never get any better in the field than it is during your experiment.

For extra credit now is the time to experiment with a couple other important variables. First is your hand-holding (for whichever lenses you expect to hand-hold). And second is your IS and VR settings. Depending on the generation of IS/VR and the way you use your tripod it may work best to have it either on or off while your lenses are tripod mounted. In general I’ve found that with the newer VR lenses leaving on when on a tripod works just fine. But that’s something you want to figure out for yourself at home and not be worried about discovering when you’re on a trip.

So while this experiment won’t directly produce any award-winning photos it certainly greatly improves your chances of getting the images you’re looking for on your next trip or photo shoot. Have fun and let us know your thoughts on our Camera Tools Forum.