P#20 Q3C: Do You Know How to Focus Your Wide Angle Zoom?

Staying Focused

Bryan Peterson: If you're using a 17 to 18mm wide angle lens on a digital camera with a crop factor, you simply need to focus at five feet and set your lens to f22. If you do that, you will have depth of field and maximum sharpness from three feet to infinity.

If you have a wide angle zoom lens that's going from 12 to 16mm (again, digital format using a camera with a crop factor) you need to focus on something three feet away. You then shoot at f22 and subsequently record a correct exposure with depth of field from two feet to infinity.

It's been that way as long as I can remember. The reason that I know this works is because in the old days, wide angle lenses came with what depth of field scales that were written right on them.

Today, with all this great modern technology, Nikon and Canon in their infinite wisdom said, "You don't need this anymore." Well you do. When you put a wide angle zoom lens together, you have multiple focal lengths and it's impossible to put a depth of field scale on a lens with multiple focal lengths.

In the good ol' days you had a fixed focal length wide angle, such as a 28mm or a 20mm. Those lenses are certainly still available, but most people have migrated to the zoom. There's your little inside tip on how to get maximum depth of field also when shooting wide angle.

Audri Lanford: Do the same rules apply to people who have full frame?

Bryan Peterson: Yes. The difference would be in if you had, for example, a Canon 5D and you're using a full frame 17-40mm zoom, which is one of their street zooms. At 17 to roughly 24mm, that person without the crop factor would need to focus at three feet at f22, at any of those focal lengths. They'll get depth of field from two feet to infinity guaranteed.

Also, I need to mention, when you're shooting a side-lit landscape, you must absolutely positively be using your polarizing filters because at that point you are 90 degrees to the light.

Without the polarizer, you're going to get a fabulous, in focus composition of this great landscape that's going to be somewhat hazy, somewhat more contrast-y than you like without the use of a polarizer -- so get that polarizer on there when you're shooting side-lit landscapes and take it off when you're shooting front-lit or back-lit landscapes.

To Conclude

Once again we're reminded that having the right equipment does you no good if you don't know how to use it. Fortunately, Bryan Peterson was more than willing to give us the how-tos of wide angle zoom focusing, with some lighting tips for added measure.