Spots at f/22

It might be time to clean the sensor of my camera again. The circles in the photo above are the spots I removed in Lightroom. They’re caused by little specks of dirt or dust on the camera sensor.

Thankfully they’re really only visible when shooting with a closed down aperture like f/22. At f/8 I see nothing! The aperture of a lens describes how big the hole in the lens is that lets light in to the camera sensor or film. Paradoxically, small f numbers are big holes, so f/1.8 lets in lots of light, while f/22 creates a tiny hole and not a lot of light gets through.

Even if you never take the lens off your camera, you might still get spots on your sensor. A zoom lens has bits that go in and out. Air goes in and out and there’s a (tiny) chance that dust will get sucked in. Dust in the lens itself is nothing to worry about as it’ll never show in photos but if you shoot a lot at small apertures like f/22 you can clean your sensor.

It’s actually not that hard to clean the sensor. Last year I wrote a blog post on how to clean your camera sensor including a video and step by step instructions. I’ll probably get around to that this week again. Go have a look if you see spots, or go see a doctor if you’re not looking at a photo at the time …

Author: Donncha

Donncha Ó Caoimh is a software developer at Automattic and WordPress plugin developer. He posts photos at In Photos and can also be found on Google+ and Twitter.

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