is this a scratch on my lens or could it be something else?

[linguine]

From time to time over the past couple months Ive been noticing faint spots on the pictures Ive taken with my camera in the same locations although until recently I couldnt see any noticeable spots on most of my pictures and they were mainly showing up when that part of the shot included blue sky like this shot.

Now Im noticing these spots more often, although not all of the time, and am also getting shots that have a small line in the same locations where the spot had been showing up.

And Ive even noticed in 2 shots having a spot and line over it like in this shot.

Anyone know if this is how a scratch on the lens would show up or would this be something else wrong with the camera? Thanks.

[Curious]

is it a DSLR? and if so i’d say dust spots. mine has got a couple that only show up against the sky. here’s an article about sensor cleaning. http://www.peakoverload.com/blog/photography/sensor-cleaning.html

[linguine]

That could be it because I havent been able to see anything on the lens.

[monkeybort]

you got dust! if you stop down to 2.8 or so you probably won’t see it at all – with mine it starts to show up at f8.

[anneb]

Looks a lot like sensor dandruff to me, to be honest.

could someone who “gets it” please explain to me, BTW, why you don’t see it at wider apertures, given that it is on the sensor directly? Or, rather, as close to the sensor as it can get, vs. on the other side of the focusing mechanism (past the lens). I always have thought of it as analogous to dust on the negative or an obstruction on the paper, i.e. more of a shadow than anything else.

[Analogy]

Sensor dust. It’s not on the sensor itself, it’s on the low-pass/infrared filter in front of the sensor.

The reason it only shows up at the more closed apertures is because the light from the lens to the sensor isn’t parallel. Take the lens off the camera (don’t forget to put a body cap on your camera to keep dust out =D) and look through it with your eye at about the same distance as the sensor would be. You should see a big circle of light. That circle of light is what an individual pixel on the sensor is gathering light from. One piece of dust in that circle, even fairly close to the sensor, isn’t going to block that entire circle of light, so at larger apertures dust won’t affect the picture much (remember with the lens off the camera the aperture will be wide open).

However, at smaller apertures that circle gets smaller, so a piece of dust is covering up more of that circle and affecting the picture more.

I’ve got a boatload of dust on my sensor, but I do all my shooting at f/8 and larger so I never see it. Macro photographers who stop down a ton for depth of field tend to need to worry more about dust.

[Claff]

I was shooting trackside last weekend and while I usually shoot at a stupid fast shutter with fast aperture, I was experimenting with slower shutter (1/125ish) for more of a sense of speed. I had to crank the aperture up (down?) to around 11 to 14 and the junk that showed up on those pics ruined the whole batch for me. I gotta do that sensor cleaning before the next time out and I’m a little skittish about doing it cause I’ve never done it before.

As you can see, the junk on the sensor wound up smack dab in the middle of the car’s hood in most cases, and that’s a tough place to try and fix things.

[Analogy]

Claff, if you can shoot a white wall at the same aperture setting, you can probably use that as a mask to photoshop the dust away. Worth a shot.

[Curious]

I’m a little skittish about doing it cause I’ve never done it before.

nor had i but the link i have above got me past that. i used the cheapy blower that came with the camera and it got 90% of the dust and reduced the small bit that was left. i need to get to a camera store and get the blower in the article.

[Author]

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