Railfan Technology > "Blue Dots" in My Digital Images

I noticed there were some blue dots in the upper left corner on my digital images which I take using a Nikon D50. I took the lens off and cleaned the mirrors. The two images are the first two photos I took after I cleaned the mirrors. The first one does not have the dots, the second one does. Any ideas? Thanks for your help. 

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The sensor needs cleaning.

Is that something I can do or do I need to take it to a repair shop? 

The manual that came with your camera should tell you all about doing that or you can Google it.
 

Cleaned the mirrors? There should only be one mirror... and one sensor. If you touch/clean either one of those you need to be absolutely sure you've got every speck of dust off of them. You can do this yourself with wipes/cleaning fluid (mirror) but I'd only use a blower brush on the sensor.
 
​If that doesn't work, you've possibly got some bits stuck in your lens.

The specks maybe didn't appear in the first image becuse maybe your depth of focus was shallower and they were out of focus.

I'd bring it to someone qualified to clean DLSR sensors. It can be somewhat tricky.

Sensor swabs and a solution were sold.  Sometimes it would require several passesas  After a while the dust can become baked on.

Online search will give you info.  Surprised with a camera that age that it did not appear before.  Usually comes with changing lenses.
Problem with  sending in, it can appear again shortly.  Newer cameras have some shake dust removal built in.

Bob

I get that too, every once in a great while.  But it's intermittent.  I drive a Canon 5D III and it has a feature that cleans the sensor every time it's turned ON or OFF, so I guess that's working?   If so, that points to dirt on the sensor rather than the lens because I usually discover it well after the fact- no while I'm out in the field. 
SR

It's not the mirror, the mirror gets out of the way when you release the shutter, right?

BoilingMan Wrote:
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> I get that too, every once in a great while.  But
> it's intermittent.  I drive a Canon 5D III and it
> has a feature that cleans the sensor every time
> it's turned ON or OFF, so I guess that's
> working?   If so, that points to dirt on the
> sensor rather than the lens because I usually
> discover it well after the fact- no while I'm out
> in the field. 
> SR
>
> It's not the mirror, the mirror gets out of the
> way when you release the shutter, right?

Oh yes, spot on, I forgot that! Lol.

Ha!
Spot On
SR

(pun)

BoilingMan Wrote:
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> Ha!
> Spot On
> SR
>
> (pun)

;-)

Dust on the sensor should appear in every picture in the same place on the image.  Try shooting a clear sky or a white wall to test (but be aware of any dimples on the wall if you choose that route).  If spots happen only now and then, I suspect the cause is somewhere else, maybe dust or lint on the rear element of the lens?