help with auto levels in PS and sensor

quiddity · Feb 15, 2011

Here are 2 photos of blue sky and moon. Noticed a spot on left and thought I would do a PS autolevel which I read helps make spotting sensor dust easy.

The first is a plain JPG cut from RAW no processing done

DSC_0241 by tshesse, on Flickr

The second is a copy of the first with auto levels applied.

DSC_0241_AutoLevel by tshesse, on Flickr

Can someone explain what all the black stuff is and whether I need to be concerned?
And I just had my semsor cleaned 2 weeks ago by the local camera shop.

Thanks.
Tim

Big Mike · Feb 15, 2011

That looks like dust on the sensor to me.

When cleaning the sensor, I always do a before & after test shot. Fairly often, all the dust isn't gone with the first or second attempt, so I keep cleaning it until I get as rid of as much dust/spots as possible.

It's quite easy to do, I would suggest learning to do it yourself, rather than paying a camera shop flunky to do it.

By the way, you don't need Auto Levels to see the dust spots. Just use levels or curves and adjust it to have lots of contrast. But more importantly, take your test shots with a very small aperture (high F number)...that will really show you were the dust is.

Overread · Feb 15, 2011

Considering the massive amount of noise and the dark shadows appearing in the top corners I'd also say that you've probably taken things a wee bit too far in editing. You might well benefit using the layer mask/selection wizard and doing the levels adjustment on the moon and then on the background as separate stages - that way you can balance the levels for the moon and then balance them for the best possible background - rather than both at the same time.