Avoid Lens Flare With A Clean Lens


In a recent post, I showed how a UV filter in low light can produce ghosting and flare. You can also get some unwanted results if dust and lint is on your lens. Most dust is not a problem; even small scratches may not appear in your image. But in a high contrast situation, that dust can have a big impact. Take a look at this photo:

Bedroom-Before

 

You can see on the right side of the image a large white spot. This is, of course, an area of high contrast between the bright window and dark curtain. Operating with a narrow aperture (I’m typically at f/10) can also reveal imperfections. If you have dust on your sensor, for example, it will be more noticeable at f/22 than at f/4. When I saw this, I immediately checked the front of my lens and noticed some dust and lint. I blew it off with an air blower then used the brush on the LensPen. Then I took another shot:

Bedroom After

 

Just like that, it’s gone. I did not use Photoshop to alter the “after” image; I simply cleaned out the dust and lint on my lens. The image still needs work and is not the final version I delivered to the client. But if you ever spot the same problem on your images, it wouldn’t hurt to check your lens for dust. Oh, a couple of tips: do not use your breath to blow on the lens and do not use compressed air.

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Why Not To Use a UV Filter for Interior Photography


There are two schools of thoughts when it comes to using UV filters on your lens and I’ve gone back and forth between the two. The first school of thought says you should use a UV filter to protect your lens. You paid a lot of money for it, wouldn’t it be a shame if something poked or shattered the glass? It’s better to lose a $30 filter than a $1000 lens.

The second school of thought asks why put a cheap piece of glass in front of an expensive one? What are the chances of something hitting the front part of your lens anyway? If you’re careful and use a lens hood chances are, you’ll be OK.

I used to belong to the first camp. Then I moved to the second camp with the belief that any filter is a tool which should only be used when needed.

Recently, I noticed some spots on my lens that I could not wipe off. I think it may be areas where the coating has rubbed off. Alarmed, I decided to put the UV filter on and leave it on to protect the lens. Silly me. Take a look at this picture and notice the area above the painting on the wall.

Game Room

You see those yellow spots? That’s ghosting or flare from the overhead light. Different light sources are hitting the glass of the filter which bounce off before reaching the lens and sensor. Here’s a closer look with the flare spots circled in red. The other two spots are not that noticeable until you zoom in.

Flare Zoom

I had heard that UV filters can cause that effect in low light situations. In fact, I experienced it once shooting a night-time parade; it was awful. That is another reason why I moved to the no-filter camp. But as I mentioned, I foolishly defected for a short period.

Just to confirm my thoughts, I removed the filter and took another shot…

Game Room

Is that Photoshop at work? Did I clone it out? Nope. The second shot is just taken without the UV filter. (It’s much easier and faster to get it right in camera than to spend time in post.) Interiors are dark enough and the long exposure times means light has more time to refract from the filter.

Look, you don’t walk around with a hammer or a screwdriver in your pocket all day. When you need a tool, you get it, use it and put it back. That’s how I feel about filters. You don’t leave a polarizing or neutral density filter on your lens all the time. So why leave a UV filter on? Filters are tools to accomplish specific tasks. If you are shooting in hazy conditions or bright sun, sure, why not break out the UV filter? Otherwise, why give up image quality for the perception of increased protection? Ask yourself, in all the time I’ve owed my lens, how many filters have been smashed? If the answer is zero, you can do without it.