Tuesday, January 3, 2012

Is it normal for the Canon kit lens to exhibit lens flare even without a UV filter?

Question

I recently bought a Canon 550D and have been experimenting with this for a week. I have been pretty satisfied with the quality, until I faced this lens flare problem. Notice the unwanted blue light near the red board with yellow star:

Attached are two pics

  1. Shot with Canon 550D - 18-55 kit lens with UV filter on: with UV filter

  2. Shot with Canon 550D - 18-55 kit lens without UV filter on: without UV filter

Is this level of lens flare normal? Or are there any quality issues with my camera?

P.S.: Pics are little blurred — I have quite shaky hands.

Answer

Yes, this is normal. It's important to realize that this is almost entirely to do with the lens and not the camera body. See What causes lens flare? for more detailed background, but basically, flare is the result of stray light bouncing around, and is common with lower-cost lenses and with wide-angle lenses — and the 18-55mm kit lens is both.

You can see that the problem is worse with the UV filter. A large, flat, and probably cheaply-coated glass element is ideal for bouncing light (but not so ideal for avoiding artifacts like this). A higher-quality filter will contribute less to the problem, but won't improve the lens itself. A higher-quality lens will have a design intended to protect more against random bouncing light.

A cheap thing you can do to help, though, is to shade the lens from out-of-scene light. You can use your hand or a piece of cardboard in a pinch, but really this is what a lens hood is for. It screws on the front of the lens and keeps some of the "extra" light away. (For your Canon kit lens, the item you want is the EW-60C lens hood.)

Of course, that won't help flare caused by lights in the scene (as in your image, where the blue ghost light appears to be caused by the bright white lamp on the building). For that, the best option is to compose differently — move so that light source is obscured, or just hits the lens in a less-obtrusive way. If that's too limiting — sometimes, that's the picture you want to take! — a lens which better controls flare (which is to say, a more expensive lens) will help get this kind of shot.

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