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DPChallenge Forums >> Hardware and Software >> Dead & hot pixels. Test messed me up
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01/05/2005 02:25:39 PM · #1
I took 3 pictures with my Minolta to test it for dead & hot pixels and got such weird results (settings: ISO 100, 2560*1920, camera is quite cold)
1) Shutter 2 sec - 1 dead / 24 hot;
2) Shutter 7 sec - 0 dead / 0 hot (???)
3) Shutter 1/4 sec - 0 dead / 8 hot.

The test is //www.starzen.com/imaging/deadpixeltest.htm
I examined some of my images and seems not all pixels were ok, I found a couple (I examined portaits, made of course with short shutter speed) - they were much different from other neighbor pixels by its color...

And you - what results do you get with your cameras in this test, guys?
I'd like to know them (the settings of the test are by defaults).

Message edited by author 2005-01-05 14:27:13.
01/05/2005 02:27:06 PM · #2
is this an online test where you upload photos for inspection?
01/05/2005 02:28:35 PM · #3
No, it's not online test. It's a very small program (about 400Kb), that is downloaded and being run. You just have to browse for your images and click "Test" button...
01/05/2005 02:29:43 PM · #4
whats the procedure for taking the photos? what should you be shooting?
01/05/2005 03:18:44 PM · #5
You set minimal ISO (100 or 50, whatever you have got in your cam), manual or aperture priority mode to choose some different shutter speeds (for instance, 8sec, 1sec, 1/4sec), close your lenses with lense cover and take a photo in dark room (as dark as possible ;), with LCD turned off. TIFF or RAW format is required for this test, coz JPEG would add some alghorithm noise to your image, that has nothing to do with actual dead & hot pixels... That's it.
After that you browse for done images with deadpixeltest and press "Test".
Voila!
01/12/2005 05:51:53 AM · #6
Well... nobody tested? :-\
01/12/2005 07:09:10 AM · #7
When does the noise reduction in your camera start working ? Sounds like some point greater than 2 seconds or so.
01/14/2005 10:41:42 AM · #8
Yes, sounds like that... There's no info about this in manual.
However, I got 2 dead pixels, when I tested my cam in some early test. Unfortunatelly, I didn't take a look at shutter and aperture parameters :(
I suppose, that 2 dead pixels showed because of auto mode I used then: so, ISO was high, I guess and shutter speed was something longer, than 2sec, but shorter than the time noise reduction starts working...

BTW, EVERY cam has a noise-reduction system? I just can say, that my cam's lack is it's pretty noisy in comparison with many other 5MP cams. So I have doubt there's NRS implemented there :)
01/14/2005 11:17:55 PM · #9
I tested my 20D some time ago with that program and results were fine for me. I think my first hot pixels were 1 at 15 seconds. I tested to 30 seconds and no dead pixels at all and about 5 hot pixels. I blew the images up to 200% and still couldn't see them at the co-ordinates I was given so I'm happy with that.
01/15/2005 08:34:22 AM · #10
Glad for you, Angie :)
But wow, Canon 20D is not a toy, it's a powerful thing! As far as I can see, you also got another cams. Didn't you test them, too?
Before I chose Minolta 7i I have had Sony F717 as a candidate for buying. How is it now, how long have you been using it? Would be interestring to know its results...
01/15/2005 08:47:02 AM · #11
If you've got a dead pixel you can find them with your own eyes. They are very easy to spot.


01/15/2005 09:17:23 AM · #12
well.. I don't know if it's a condition of having a non-DSLR or whatever, but my fuji s7000 has 49 hot pixels at 3 second exposure, 16 at 1.5 second, and 16 at 1/10 sec.

It also came up with one dead pixel at the 1.5 second.. but no dead pixels on any of the other exposures.

I'm scared to test it at the 15" max exposure. lol
01/15/2005 09:27:09 AM · #13
Originally posted by Nafigator:


But wow, Canon 20D is not a toy, it's a powerful thing! As far as I can see, you also got another cams. Didn't you test them, too?
Before I chose Minolta 7i I have had Sony F717 as a candidate for buying. How is it now, how long have you been using it? Would be interestring to know its results...


I only just realised after posting that I hadn't tested the F717 yet. I'll give it a go. I don't have the 300D anymore. I love the F717, I bought it a few months ago for taking IR shots and now I use it as my take anywhere camera. I'll test it and post the results.
01/15/2005 09:41:11 AM · #14
Originally posted by Nafigator:


I suppose, that 2 dead pixels showed because of auto mode I used then: so, ISO was high, I guess and shutter speed was something longer, than 2sec, but shorter than the time noise reduction starts working...


You know, a dead pixel is a dead pixel. It is dead in every situation with every exposure with any aperture, with any iso. Dead=dead. If the progam finds dead pixels in one situation and none in another situation then either the program is not setup right or the program sucks.


01/15/2005 09:50:54 AM · #15
I tested the F717 ranging from 1/30 sec up to 15 seconds and not a single hot or dead pixel. I've discovered it does take an awfully long time to write TIFF files though. :-S
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