The smaller the aperture, the smaller the transition in shadow from light to dark.
This also applies to the focal length. The longer it is, the smaller the transitional shadow and thus more visible.
Just try a white wall as I wrote before. Or a peace of white paper. As you can see the dust is dark for there’s no light going to the sensor. So on a white back ground most visible.
George
I remember those lensrentals articles about “extraneous stuff inside the lens” (and the lack of effect it has on the images). If they don’t convince anyone that it’s always dust on the sensor… nothing else can!
First principles.
Good luck!
I have been away for a while. I had a very ill son (age 35 who just passed away). I waited until I was in my 40s to start a family as I did not want to it while I was in the Navy (Submarine duty), so it has been a bit hard on me.
I did get a loupe and a sensor cleaning kit, as per all yall’s fine advice and sure enough, under the right light and magnification there those little dust critters were. Now it is a matter of me either having the courage to clean it myself or as I mentioned before, taking it to Houston. The people that I was going to take it to in my earlier posting flat said “NO, send it to Nikon. . .”; however; sense then I found an actual camera cleaning pro in Houston.
I have yet to contact him, but I am hoping that he will do the job and show me how seeing as how he is over an hour away, and I suspect that given the coastal winds around here, dust on the sensor is going to be a regular problem
Again, Thank you all.
trav (Old Sub Sailor)
Condolences for the unimaginable grief of passing of your child. It feels completely wrong, but we’ll all go and don’t know when.
As for sensor cleaning, I’ve used the pentax cleaning kit with a sticky tip that took all the dust off in a few iterative steps.
I’m sorry for your loss, and the saying “there’s no logical order who will leave this world and when” is no comfort for you.
I agree with @platypus on the sticky cushion on a stick - for “just dust, no oil involved” it’s the best. Mine is no Pentax but from eyelead – same principle.
You need to be careful if your sensor is in a camera body with “in-body-stabilisation”, to not damage the drives and fixings of the sensor. Also, it’s not very practical, but holding the camera with the mount towards the Earth can reduce the chance to let new particles settle on the sensor. But usually we’re holding the body with the bottom plate downwards. So all durst particles coming in will likely settle on the lower half of the sensor and since it’s recording the images upside down, we see the results quickly in the skies.