What do you think is the problem

I love to take pictures of the sea. But my 75-300 i think is not clean at all. Do you see like this thing in the middle of the picture. What do you think it is. My other lenses are clean. the only one i have the little dust in this 75-300. I need to clean that.

What do you advice me to do?

http://img244.imagesha​ck.us/img244/1528/mark​a5.jpg

the place is a little dangerus and the ocean is salty

You have a hair and some dust bunnies on your sensor (or more accurately, your sensor cover...)

Time for a cleaning...

I would believe that dirt/dust is on your sensor, and would show up with all lenses assuming you shot at f32 like you did with this pic. You need to clean that sensor!

Dave

the sensor cleaning is like in the book .I think i saw how to clean that. thas true??

tracknut wrote in post #5465111
I would believe that dirt/dust is on your sensor, and would show up with all lenses assuming you shot at f32 like you did with this pic. You need to clean that sensor!

Dave

no to tell you i dont see the dust with others.

well i need to clean but the humidity right now and the rain is kind of crazy right now is raining a lot in my town

Take a photo with any of your lenses, set at f32, of a blank white wall, or of the sky. That should make it more obvious, but of course if this dust is on your sensor, it will be there regardless of the lens you have on.

I don't think the Canon user manual has information on cleaning your sensor, other than how to raise the mirror up, which you do need to do. Search this site for "Sensor cleaning" and you'll find tons of information.

Dave

First off, just get a 'rocket-blower' or similar, This should shift most things. - DON'T blow on the sensor or use compressed air!

I agree with most of the others here that is is probably a "sensor dust" issue. Dust in the lens is so far out of the focus plane that you'll never see it on your image. A large spec of dust on the outside of the rear element could possibly cause image degradation, but you wouldn't see a sharp edged shadow like you see there.

Moniphoto wrote in post #5465092
the place is a little dangerus and the ocean is salty

Plus, there are flying worms there!

Moniphoto wrote in post #5465134
no to tell you i dont see the dust with others.

well i need to clean but the humidity right now and the rain is kind of crazy right now is raining a lot in my town

Just to drive the point home to overkill you probably didn't shoot your other lenses at f32 like that shot so you don't see the stuff (I would think the hair would be seen wide open though). High humidity is a good time to clean the sensor as there will be less static around. And do what was suggested and use a blower first to get the big stuff off so you don't scratch things. The blower might get that hair and the other spots will not show up at wider stops.

F32 BTW is not a good place to be shooting as it will give you more DOF but a softer image overall as diffraction is affecting the image.

UFO of course!

Try shooting at f14....
I am sure that the dirt is on your sensor.
Check out the copper hill method. http://www.copperhilli​mages.com/index.php?pr​=Tutorials

I am learning a lot. I already clean the sensor. I dont know why the machine says clean clean. Of course is very high the humidity in my house and very hot in the afternoon. I use a blower etc etc and the temperature of the room was ok.

Do you know the sensor swab 2? i saw that is very good for sensor cleaning.

Thanks guys.

Monica

Which camera do you have? The "automatic sensor clean" of the 40D is only a "static electricty" effect ... it is not a true Sensor Clean - where you would use a liquid solution & a pad to swipe the physical sensor... Like other suggested, do a search on Sensor Cleaning ... there is a ton of great info out here... good luck - get rid of that crud on your sensor...