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Photography Question 
Nadia kronfli

Mark on photos

I recently purchased a Canon Rebel XTI. This is my first SLR and I am learning to use it. I have noted that when I take photos in sunshine I am getting a mark on the photo almost. This is more obvious where I have used an Ultraviolet filter on the lens (almost like a reflection of the filter). Could there be something wrong with the camera or is this a technique problem. All the photos I am talking about are exposure between 200-250 & f8-f10. I am attaching four images to illustrate and have circled the mark in red.

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10/22/2007 12:29:51 PM

It looks like a smudge on the sensor to me, Nadia. One that turns visible with less UV light.
Try cleaning your sensor (but very carefully).

Good luck!

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10/22/2007 1:34:17 PM

Christopher A. Vedros
BetterPhoto Member Since: 3/14/2005
  Dirt on the sensor will typically show up as a dark spot in the same place in each photo. I don't think UV light should have anything to do with it.

I think the spot on the middle two photos taken with the filter were caused by a speck or a water spot on the filter itself.

Remember, the XTi has a self-cleaning sensor. I wouldn't recommend cleaning it unless you are absolutely sure it needs cleaning.

Chris Vedros

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10/22/2007 4:16:35 PM

Carlton Ward
BetterPhoto Member Since: 12/13/2005
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  Hello Nadia, I switch lenses a lot and am constantly fighting with particles of dust on my sensor. I use the Giotto blower to blow the dust off my sensor since my 20D is not self cleaning. Just be careful to not touch the sensor and never use compressed air unless you want to turn your camera into a paperweight. I cant wait to get the 40D that has a self cleaning sensor.
I am assuming you know how to remove spots using Photoshop (clone & healing brush tools) - if not please reply and I will tell you how.
I usually do not use filters because I use I dont want another optic obstructing or detracting from my lens capabilities (I will sometimes use a circular polarizer) and am careful to keep my lens & filters as clean as possible.

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10/23/2007 10:08:58 AM

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