Sensor - DPChallenge Forums

03/11/2007 09:36:33 PM · #1

Some question for you.

How often are you suppose to clean your sensor?

Does Sensor dust affect how sharp the picture will be?

And should I do it or take it some place to get it cleaned. I probably could do it. I just don't want to mess it up.

Thanks for you help
Phillip

strangeghost

Canon EOS-7D

03/11/2007 09:37:55 PM · #2

I only clean when the dust bunnies are so noticeable that they're intruding into every (or very important) shots. I haven't even thought about cleaning for several months now.

03/11/2007 09:45:23 PM · #3

Sensor dust doesn't show up very much at larger apertures (f/2.8 to f/5.6). At smaller apertures (f/11 and beyond), sensor dust becomes very problematic.

So... if I know I'm going to be shooting wide open (or nearly wide open) then I don't even worry about sensor dust. But before a big family group shoot, or a landscape shoot, I'll check it out.

To check for sensor dust, try pointing at a blank wall, defocus the lens, set the aperture for f/22 (and however long exposure it calculates). Don't worry if it's a long exposure. You're not taking a picture of the wall so camera shake doesn't matter (in fact, I usually do it on purpose). Afterwards, bring the image into Photoshop and do an Auto Levels on it. Those dust bunnies will really show up! (it'll be almost scary how dirty your sensor is!)

Message edited by author 2007-03-11 21:46:18.

03/11/2007 09:49:59 PM · #4

thanks for the help but does it affect how sharp the picture turns out?

03/11/2007 10:02:35 PM · #5

The dust bunnies are usually only tiny particles. So how does it affect how sharp the image is? Very much at smaller f/stops. But only where the dust particles are. (that's not a "duh" statement, it's just that your sensor isn't likely to be covered with dust unless you've done a bad cleaning job and smeared something on the sensor)

03/11/2007 10:18:26 PM · #6

Originally posted by dwterry:

OK, thanks for you time and the information.

03/11/2007 10:20:07 PM · #7

f/32

f/5.6

f/2.8

Notice the difference in how visible the sensor dust is at the various apertures? Wide open, the dust is barely visible. But at tiny apertures the dust is very distinct.

03/11/2007 10:22:27 PM · #8

Originally posted by dwterry:

Okay, here are three examples. I just shot these using my Canon 5D and the Canon 100mm 2.8 Macro lens. These were hand held and I didn't do a very good job of pointing at the same location on the wall each time ... so ignore everything else and focus mainly on the sensor dust that I'm trying to show you.

f/32

f/5.6

f/2.8

Notice the difference in how visible the sensor dust is at the various apertures? Wide open, the dust is barely visible. But at tiny apertures the dust is very distinct.

IC, big help!!! Since you brought up the 100mm 2.8 macro. Thats my problem. I just bought it and the sharpness is really bad. So, I'm just thinking about everything that could be wrong. Do you want me to post some pictures of it?

03/11/2007 10:24:13 PM · #9

Originally posted by philup:

Do you want me to post some pictures of it?

Sure. If nothing else, I think you'll learn something (if it's your first time shooting f/32 at a blank wall, that is). Be afraid. Be very, very afraid. ;-)

03/11/2007 10:31:50 PM · #10

Maybe I don't understand what I'm doing but I think it should be sharper than that. Thats why I'm asking about sensor dust. I will take a picture of a white wall in a bit to see how bad it really is. Kinda scared to.