On Sat, 02 May 2009 10:14:23 +1200, "Colin.D"
wrote:

tony cooper wrote:

snip

On this subject...There are three spots that show up in my images if I
shoot so the sky is in the background. They are circled in red on the
linked image. (Forget the subject; I'm just using it to show the
spots)

They are not noticeable with any other background. So far. Always in
the same place, so they are something on the lens or the mirror of my
Nikon D40. I can't see them looking at the lens or the mirror. I've
cleaned both with isopropyl alcohol, but it doesn't help.

Suggestions?

http://i48.photobucket.com/albums/f2...r213/spots.jpg


Not on the lens or the mirror. Cannot be the mirror as it is up when
the exposure is made, and any dust or marks on a lens element is totally
out of focus and will have no effect on the image.

The spots are actually on the sensor, or the AA filter in front of the
sensor. You need to clean the sensor, or get it cleaned. Tons of info
on how to do this on google.

Colin D.

Found this on the web in a forum responding to a problem just like
mine:


Sounds like you found the "sensor", really a filter or glass over the
sensor. When you remove the lens, you see the mirror. Put the camera
in bulb mode and lock the shutter open, and that's the "sensor".
Ensure that you have plenty of battery power (or are hooked up to the
AC/DC adapter) before you stick anything into the sensor cavity. If
the shutter closes while you have something in the cavity, the shutter
will break, and you will need an expensive repair.

I have to clean my cameras often, since I shoot outdoors and change
lenses many times a day. I have found that compressed air takes care
of most problems, and a $10 bulb, like Mark mentioned, is the best way
to go for field work. If you are willing to put a little more $$ into
it, get an oil-less diaphragm compressor for an airbrush, ~$100. The
other nice thing about air is that you don't put anything in the
shutter cavity.

DO NOT use "canned air", these little cans with compressed air in
them. They contain isobutane and other hydrocarbon propellants which
can "spit" out of the can and leave spots on the sensor that will
require a liquid cleaning to remove.



--
Tony Cooper - Orlando, Florida