Dust on my D70

LonelyTraveler · Jan 13, 2008

Apologies if this is the wrong area for this, but it seemed most appropiate.

My friend, a semi-professional photographer recently purchased a Nikon D300, and put his D70 up for sale for $300, with a 28-300mm lens. I figured it'd be the boost in photography I was looking for and so far I've been very satisfied.

My issue is this...He told me there's a few specks of dust on the image sensor, but it's only viewable at f/20 and up (according to him). I tried to find the dust by taking pictures of a blank wall with the f/20 settings, and I can't find anything. But now that he's said something I wanna get it off before I realize its where I don't want it to be on a very nice shot.

Question is: Can I safely clean this off with some for of light air or something without worrying about screwing stuff up, or should I find a local camera shop and see what they say? I know people who are into photography with SLR's so they may be able to help me, but I wanted a 2nd opinion before I did anything else.

Thanks.

TATTRAT · Jan 13, 2008

sensor cleaners, 20$. Just be careful and do NOT apply too much pressure.

Just my $.02

Garbz · Jan 14, 2008

If they are only viewable at f/20 and up then they are in the lens and not the sensor. If they were on the sensor they wouldn't be affected by aperture.

Even if they were on the sensor I would try putting the camera into cleaning mode so that the shutter opens and hold it upside down and gently blow in first. That gets all but the most stickiest of dust out.

LonelyTraveler · Jan 14, 2008

Thanks for the quick replies. I put the camera into cleaning mode and gently blew it out. Seemed to do the trick. :mrgreen:

Big Mike · Jan 14, 2008

If they are only viewable at f/20 and up then they are in the lens and not the sensor. If they were on the sensor they wouldn't be affected by aperture.

Sorry Garbz....but that's wrong. Spots in the image, from dust on the sensor, are greatly affected by the aperture of the lens. A smaller aperture will give you more DOF...and the closer to being in focus the dust is, the worse the spots will be.

When shooting at large apertures...the dust is still there...but it's so out of focus that it is virtually impossible to see it.
That's why you test for sensor dust by shooting at a very small aperture.

Actually, dust on the lens is less likely to show up in images than dust on the sensor.

Garbz · Jan 15, 2008

Ok but what I don't understand is that your not changing the depth of field inside the camera aren't you? The image is projected through the aperture and then onto the sensor plane. If there is dust sitting directly on the sensor plane it would look just as sharp (dark black spec) regardless if the incoming light has been scattered by the edges of the lens elements (small DOF large aperture) or if the light is pin sharp, and by the same token the dust shouldn't be affected by the focus. How do you adjust the focus of something with a lens when a) the subject is between the lens and sensor, and b) how do you adjust focus at all if the subject is 1mm from the sensor plane. Since DOF is a function of differences between distance to subject to background. How could a subject 1mm from the sensor possibly compare to even a near focusing lens that focuses 1m away?

Mind you I am talking about dust sitting on the sensor itself, the effect of aperture would be minor in comparison to a sizeable dust spec on the lens.

Regardless if it's right or wrong I would like to know a reason if anyone can explain it.