I just wanted to share this with you all...

I was out and about yesterday testing my 24~70/2.8 along with the singh-ray variable ND+Polarizer bla bla bla...

BTW, the lens is AWESOME. PERIOD.

The Singh-Ray works great, but does do a tag vignetting at 2.4.

So I get home, and check out the shots, especially the long exposures.

What?! There is a very large persistence black dot on my pics! All on the long exposures.

So I start testing and testing and testing.

It *must* be dirt on the sensor as the dot changes color and intensity the longer I expose...not a dead pixel!

So I say, cool, let me clean it. Thats when everything went down hill. I not only did not remove the dot, but added about 10 billion more! The more I cleaned the more it worsened.

And yes, I was using qtips. NEVER EVER EVER EVER <billion time more> use qtips.

Least to say, I did not sleep.

This morning, I drove down the a pro shop, got some Eclipse solution, a box of Sensor Swabs (12 per box), a large blower and went to work.

7 swabs later, 1 hour of cleaning, testing, cleaning, testing, I got down to 2 very small dots at the extreme corners at 22 second shot.

I'm going to leave it at that!

Needless to say, don't use qtips...BTW, very easy to do!

Phew, scared the #### out of me!

Thats it, just wanted to share my pain and joy!

~Kam

Visit my Nikonians gallery.

Glad you found Eclipse and sensor swabs but sorry you found it the hard way! As you go forward, try just two or three cleanings before taking a break. It becomes an endless cycle of removing some dust and adding more in different places. Often the couple of outlier dust bunnies will fall off once you let the camera sit a bit.

As for testing the cleanliness of your sensor, the exposure TIME does not matter. Just stop down the aperture to f/22 and defocus completely. You can then shoot a clear blue or overcast sky without a flash or instead I use a flash and a white wall...hard to miss the dust spots. Shutter speed won't matter though as the dust bunnies are moving with the sensor.

-Alex Rosen
www.flickr.com/photos/klrbee25/

Visit my Nikonians gallery.

I never thought of defocusing! I tested at f22+ on a white background.

Phew! and once more, phew!

Btw, the 24/70 f2.8 is an absolutely awesome lens.

Visit my Nikonians gallery.

>I never thought of defocusing! I tested at f22+ on a white
>background.
>
>Phew! and once more, phew!
>
>Btw, the 24/70 f2.8 is an absolutely awesome lens.
I have to agree... The 24-70 IS an awesome lens!

Kam,
I need to clean mine too, but haven't done it yet. I came across this website that has a great compilation of information about cleaning sensors. Very solid information - not marketing any particular products at all. Check it out -

http://www.cleaningdigitalcameras.com/index.html

Also, Thom Hogan has an excellent aticle of the same subject.
http://www.bythom.com/cleaning.htm

Thanks for sharing you experience - I'm glad everything turned out good!

Dave