Do I have a dirty lens?

archaeopteryx said:

Hi folks,

I've got a D60 with a 24-85mm f/3.5-4.5 lens. I did some "still
life" shots against a white sheet recently, and noticed a
persistent spot on the images. I've been trying to figure out if
it's the lens or the CMOS image sensor, but I think it's the
former; the problem is worse at high aperatures (f/27) and fades
considerably at about f/9.5.

Here are some shots I did against a COMPLETELY white board (except
for the word "focus") at f/27. The first image has a couple of
spots, most notably toward the topmost middle area (see arrow).
The 2nd image shows the extent of the problem, after running the
same image through autolevels in PS. Incidently, these are
grayscale.





My questions:

1) Are these spots due to a dirty lens (and not the CMOS)? I don't
have another lens to swap out to test my theory.

2) Can the lens be cleaned? About how much will this set me back?

3) I hear that the "L" lenses are sealed against dust and moisture.
Would this take care of the problem? (this is probably the result
of a wind storm while shooting in Arches NP).

Click to expand...

archaeopteryx said:

Hi folks,

I've got a D60 with a 24-85mm f/3.5-4.5 lens. I did some "still
life" shots against a white sheet recently, and noticed a
persistent spot on the images. I've been trying to figure out if
it's the lens or the CMOS image sensor, but I think it's the
former; the problem is worse at high aperatures (f/27) and fades
considerably at about f/9.5.

Here are some shots I did against a COMPLETELY white board (except
for the word "focus") at f/27. The first image has a couple of
spots, most notably toward the topmost middle area (see arrow).
The 2nd image shows the extent of the problem, after running the
same image through autolevels in PS. Incidently, these are
grayscale.





My questions:

1) Are these spots due to a dirty lens (and not the CMOS)? I don't
have another lens to swap out to test my theory.

2) Can the lens be cleaned? About how much will this set me back?

3) I hear that the "L" lenses are sealed against dust and moisture.
Would this take care of the problem? (this is probably the result
of a wind storm while shooting in Arches NP).

Click to expand...

archaeopteryx said:

Hi folks,

I've got a D60 with a 24-85mm f/3.5-4.5 lens. I did some "still
life" shots against a white sheet recently, and noticed a
persistent spot on the images. I've been trying to figure out if
it's the lens or the CMOS image sensor, but I think it's the
former; the problem is worse at high aperatures (f/27) and fades
considerably at about f/9.5.

Here are some shots I did against a COMPLETELY white board (except
for the word "focus") at f/27. The first image has a couple of
spots, most notably toward the topmost middle area (see arrow).
The 2nd image shows the extent of the problem, after running the
same image through autolevels in PS. Incidently, these are
grayscale.





My questions:

1) Are these spots due to a dirty lens (and not the CMOS)? I don't
have another lens to swap out to test my theory.

2) Can the lens be cleaned? About how much will this set me back?

3) I hear that the "L" lenses are sealed against dust and moisture.
Would this take care of the problem? (this is probably the result
of a wind storm while shooting in Arches NP).

Click to expand...

Andrew Cawte said:

Do a search for 'sensor dust' or 'sensor cleaning' - there's loads
of stuff about how to do it. I favour Q-tips with Eclipse fluid
myself

Andy.

archaeopteryx said:

Hi folks,

I've got a D60 with a 24-85mm f/3.5-4.5 lens. I did some "still
life" shots against a white sheet recently, and noticed a
persistent spot on the images. I've been trying to figure out if
it's the lens or the CMOS image sensor, but I think it's the
former; the problem is worse at high aperatures (f/27) and fades
considerably at about f/9.5.

Here are some shots I did against a COMPLETELY white board (except
for the word "focus") at f/27. The first image has a couple of
spots, most notably toward the topmost middle area (see arrow).
The 2nd image shows the extent of the problem, after running the
same image through autolevels in PS. Incidently, these are
grayscale.

My questions:

1) Are these spots due to a dirty lens (and not the CMOS)? I don't
have another lens to swap out to test my theory.

2) Can the lens be cleaned? About how much will this set me back?

3) I hear that the "L" lenses are sealed against dust and moisture.
Would this take care of the problem? (this is probably the result
of a wind storm while shooting in Arches NP).

Click to expand...

Click to expand...