How many "bad" pixels is acceptable?

[andysaj]

I have a new D80, and I ran the bad pixel test. I found 2 red pixels and 2 white. I am wondering if this is acceptable? I am guessing this is something I never would have noticed, had I not run this test, but is this something I should exchange the camera over? Or, will pretty much all of them have some amount of bad pixels?

If I were to do nothing, I assume that those pixels will always show up as red and white in my pictures, correct? However, I'd have to zoom way in to see them, and even then I may not be able to, is this correct?

Thanks,
Andy

 

[andysaj]

To clarify, I took a 5 sec shot at ISO 1600 with the lens cap on, and then scrolled through the picture on the camera, zoomed in. I only really saw the pixels at the most zoomed setting and one less. If I zoomed out further, they disappeared, which leads me to believe I would never notice these in a real world picture, especially if I don't do prints over 8x10, is that correct?

I also have to believe that every camera will have some of these if the test is performed, or am I wrong.

Andy

 

[tdkd13]

I think almost all cameras will exhibit this in the circumstances you mentioned.
Ted
--
http://photobucket.com/albums/y260/tdkd13/

 

[flakko]

If you are planning on shooting with the lens cap on this is definetly a problem otherwise you will never see them.

My D80 had something similar but hasn't showed up in any of the several hundred photos I have taken.

 

[andysaj]

I hear you on the shooting with the lens cap on thing. I was thinking the same thing myself. I have only taken a few "real" pictures so far. I'll take a look at them on my PC and see if I can even see the pixels. I know I won't be able to see the white ones, and I am curious as to whether or not I can even see the red ones.

Figured even if I exchanged it, there's a good chance I'd end up with one that is worse off.

Thanks for the advice,
Andy

 

[paulwilko]

After reading about these "hot pixels" i decided to try this myself.

I took a 30 sec exposure at ISO 1600 with the lens cap on.

I was horrified what i saw. There were more hot pixels than blackness.

I thought, this can't be right, so i took a pic of my beige wall at iso 1600 1/8th sec and there is not one hot pixel. I certainly have not noticed any hot pixels in my everyday shooting.

I think this is getting a bit silly now where we are trying to re-create problems that arn't really there instead of going out and shotting real everyday things.

 

[andysaj]

Agreed. Seems like this happens with all the new cameras to some extent. Reminds me of the dreaded backfocus issue when the D70 came out....

 

[e268]

I did the test with 2 seconds. I got a faint white pixel. I think 30 sec is too long. It will heat up the sensor.

 

[Oery]

NONE

 

[andysaj]

Well, I am going to do another test with a quicker shutter speed, and then look through my "real" photos. If I don't see anything in those, then I am satisfied.

 

[Vandyu]

Post back what you come up with. I wish Phil would evaluate this in his review so we would know if it really is a problem worth worrying about.

 

[amadeomk]

Here is my story... I ran the lens cap test at multiple ISO's and shuter speeds. I found that yes, at 1600 30 secs, there were quite a few... but would I ever or have I ever used those settings, no. At ISO 100 things seemed OK from 1/4 to 30s.

I went out to do some real photography. At iso 100 and something like 250 speed I got a couple fairly visible hot pixels, then upon closer examination I started seeing smaller less visible spots in the picture.

The camera went back, now I'm waiting a few months to see if this is something you've got to live with with a D80 or if it will be fixed. If it is something I have to live with, I'll skip this model. I tried the reasonable approach and do real picture taking but the results were not acceptable. I've never had problems with my D70. I guess it won't be going on ebay after all (not just yet).

Amadeo

 

[andysaj]

If I end up being able to see them in my pics, I will definitely exchange the camera. I'll check it out tonight and post my results.

 

[flakko]

Have you done the same test with the D70 and what was the result?

 

[CoreyAllen]

I thought I had seen in various posts here that the problem "goes away". My impression (just what's formed in my mind, not based on any evidence) is that the firmware in the camera detects these and edits them out over time. Apparently they can (and do) the same step at the factory.

It's possible we're exceeding the conditions under which the test is done at the factory. It's possible that over time the sensor has subtle fluctuations that cause new hot pixels that weren't evident at the factory. As a software developer, I can imagine several algorithms to automatically detect and correct hot pixels that are visible in any way on a typical exposure.

I'd even go so far as to request that people who have taken the time to do these tests with the lens cap on at long exposures and high ISO do it multiple times over the course of longer periods and to see whether some of the original pixels get "fixed" by the firmware automatically.

But since I can imagine about a billion better things to do with my own time, and since I'm sure the good people on this forum would rather be taking pictures than doing tests, I don't expect anyone to "prove" this one way or another.

I personally would only go by whether I can find the hot pixels in typical exposures that I wanted to keep anyway. I would do the "lens cap" test to find the regions where the hot pixels may be, then check a typical picture to be sure they're not there.

I'd rather spend hours shooting more perfectly good pictures than waste the time to do an exchange to fix hot pixels I'll never see in a keeper.

 

[andysaj]

I sold the D70 a while back, and I never performed the test.

 

[andysaj]

Good suggestions. Actually, that's what I am going to do, look back through the pictures I took, in the region where the most noticable pixel was, and see if I can locate it. If not, then I am done worrying about it.

I'll update this evening.

 

[FRC]

Ouoting Mike Pasini, Editor
Imaging Resource Newsletter

You just bought a thousand dollar digicam with full manual control and you want to show off. You take some long exposure night shots and are horrified to see a bright spot in the same part of every picture -- and it isn't a star. It's the infamous hot pixel.

Is your CCD defective?

Actually, no. More than a defect, hot pixels are a fact of life. Understanding them will make you feel better, certainly, and may even suggest when you should return your digicam. So let's take an in-depth look at them.

http://www.imaging-resource.com/ARTS/HOT/HOT.HTM

 

[raymondox]

Any you can see which are not corrected in camera during normal use. So redo your test in normal conditions and if you can still see any then worry about it.

I must admit any pictures I take with the lens cap on make me look like a real fool. Especially by the people I am taking a picture of. Its absolutely amazing looking at the expressions of people where you've taken their picture with the lens cap on.

--
Bluenose

 

[andysaj]

Yep, just took a few pictures and I can't see any pixels in them, so I am done with this issue. Really reminds me of the D70 backfocus thing when it came out, and everyone was up in arms, and doing all sorts of tests...