"Spotting" Issue with EF 10-22

Greetings,

I've been noticing some strange spotting issues when shooting the sky with my EF 10-22. It only occurs when stopped down to f/11 or greater. Is this normal or is there something wrong with my technique? My return window with B&H is coming up fast so I need to make a decision soon.

Here are the pics (EXIFS available)

Looks like dust on sensor.

Looks to me like you have dust on your sensor and you need to clean it. Typically you'll see dust when you are in the f/11 - f/32 range.... Suggest you clean it before it gets worse... Start with a blower and if that doesn't do it (IMO it usually gets rid of most but not all) you can then proceed to use "Sensor Swabs" and WILL get the job done... You can do a search on "sensor cleaning" and find a million posts on it... No big deal though, dust on a sensor is something EVERYONE deals with....

This is classic sensor dust. It's more likely to show on pictures taken with an ultra wide angle because of the extreme depth of field. Try a rocket blower brush.

sensor dust, as explained above

It can't be dust on the mirror because the specs are in the photos... its dust physically ON the sensor.

It is dust on your sensor. Get a Rocket blower and clean that thing. A good way to check for dust set it at f/16 or so and point at a clear sky with the focus at infinety. It will bring out all the dust on your sensor...

Good luck
Mike

Honeybee wrote in post #3171412
Looks like dust on mirror.

Dust on the mirror wouldn't show up in the images as the mirror flips up and out of the light path when the shutter is open and the sensor is exposed. In fact, dust on the mirror is so far out of the plane of focus, you won't even see it in the viewfinder when composing the photo.

As other have indicated, this is a classic case of a dirty sensor, i.e. small dust particles on the sensor filter just behind the shutter. You won't see these small particles at larger apertures, but when you stop down they create these distinct shadows on the image.

Time to clean the sensor.

Mark

I appreciate the responses! Whew! I thought it was a problem with the lens. I will focus the lens at the sky at infinity and verify if it's dust on the sensor.

Thanks,

Syd

OK, I confirmed it. Time to crack out the rocket blower! I take it compressed air is too strong?

off wrote in post #3171481
OK, I confirmed it. Time to crack out the rocket blower! I take it compressed air is too strong?

Liquid is the issue with compressed air. The rocket blower most likely won't work. Definately give it a try, but you'll probably have to break down and buy a kit, or send it to canon. Or just deal with it and use the healing brush in PS to fix it.

Here is a pic after judicious use of the rocket blower:

Dust happens.
Yes, you need to clean the sensor periodically, but the best way to avoid snot on your pictures is to avoid using narrow apertures when you don't need to.

Wide angle lenses will give you extreme DOF, even at moderate apertures. Play around with a DOF calculator and you'll see what I mean. The two shots in your first post could have been done at f/4 with no losss in sharpness.

That looks great now. Don't look too close, you will go insane.

Curtis N wrote in post #3171679
Dust happens.
Yes, you need to clean the sensor periodically, but the best way to avoid snot on your pictures is to avoid using narrow apertures when you don't need to.

Wide angle lenses will give you extreme DOF, even at moderate apertures. Play around with a DOF calculator and you'll see what I mean. The two shots in your first post could have been done at f/4 with no losss in sharpness.

Curtis,

I am in complete agreement with you. I took those shots for testing purposes. Rarely do I ever stop down over f/8.

Thanks,

Syd