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How do you test for dead pixels on your sensor?


Indecisive

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I was in Red Dot the other day and trying out a lens that I eventually bought.

 

However on taking a photo of the owner .. I found a blue dot on the shot (which should be grey .. the colour of the wall). How do I ascertain whether it is a dead pixel or just some other odd thing happening? What I am saying is that I don't know how to test for dead pixels on sensors. Can you tell me a simple way to do it?

 

OR is it just easier to send the body off to be evaluated by Leica? Which I can do tomorrow as I am in their london shop.

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  • 2 weeks later...
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"Blue dot" sounds familiar.

 

More than likely a dead or stuck pixel AFAIK.

Zoom in and see if there is also a vertical line above and below running through it.

Although ... long time exposures can sometimes cause hot pixels (normal).

 

Maybe shoot a plain surface in low light at high ISO. Check it then at 100% for dots and lines.

 

Dead pixels often show up best on the LCD in the first stage of preview resolution. Its gone in a second or two so be quick to look.

 

Mike :(

 

You could also do a fix with this software (until the hardware gets repaired).

www.pixelfixer.org

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Indecisive,

 

I haven't experienced the phenomenon you describe. But, given that you are going to Leica tomorrow, presumably to attend a short course, why not take it and ask the resident expert? You may find reassurance on the spot!

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I tried that one, Brent, and I would not base any conclusions on it. It works on JPGs and counts JPG artefacts as hot or dead pixels. According to it my new M9 has 5204 hot pixels and 19685 dead pixels....

 

You'd better get rid of that thing quick. Ok, I'll give you $1,000 for it just because I'm a nice guy.

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I tried that one, Brent, and I would not base any conclusions on it. It works on JPGs and counts JPG artefacts as hot or dead pixels. According to it my new M9 has 5204 hot pixels and 19685 dead pixels....

 

That's 205,111 cold pixels with dodgy or dead neighbours. M9 sounds like a pretty mean district.

 

;)

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Guest EarlBurrellPhoto

What still irks me is that my long-gone Epson R-D1 ("s" firmware) had a simple utility for mapping out bad pixels, whilst the M8 and M9 require sending it back.

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Thanks for the advice!

 

I think it will be easiest to send it back to Leica to check it. The camera also has that brown ring problem so I think I will get them to look at it and repair under warranty if they can.

 

There should be no problem with rectifying these faults under Passport... time to get that camera checked out whilst you can?

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