Hot pixel or dust - DPChallenge Forums

Canon EF 17-40mm f/4.0L USM

11/29/2007 10:10:46 PM · #1

Can you guys tell if this is a hot pixel or dust on my sensor.

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Thanks for the help, Jeremy

david_c

Canon EOS-7D

11/29/2007 10:12:17 PM · #2

Dead pixel, I'd say.

edit: Hot pixels are variable in colour, from what I've seen and read. Dust spots aren't usually quite so defined or contained.

Message edited by author 2007-11-29 22:15:02.

PGerst

Canon EOS-20D

Tamron SP AF 28-75mm f/2.8 XR Di for Canon

11/29/2007 10:15:08 PM · #3

Its probably dust. Generally hot pixels are red, green, or blue, and generally not seen at that resolution.

1) Look at other images, see if it appears. If so, it could be dust that hasn't moved, or a group of hotpixels. If it goes away, it was probably dust that moved. Hot pixels will generally exist always as it is a defect in the sensor.

2) Examine each channel in photoshop. If you see the spot in one channel, but not the others, its probably a hot pixel. Given that it is white, its probably dust.

The key will be to look at other images, before and after that one was taken.

Message edited by author 2007-11-29 22:15:51.

Tamron SP AF 28-75mm f/2.8 XR Di for Canon

11/29/2007 10:15:46 PM · #4

now what do I do, send it in. The camera is brand new.

PGerst

Canon EOS-20D

11/29/2007 10:17:08 PM · #5

Go through the troubleshooting I gave you. Its important information to give tech support.

Originally posted by rupypug:

now what do I do, send it in. The camera is brand new.

kenskid

Nikon D700

Nikon AF-S NIKKOR 24-70mm f/2.8G ED

11/29/2007 10:17:17 PM · #6

Need to see more samples of other shots.

Originally posted by rupypug:

now what do I do, send it in. The camera is brand new.

david_c

Canon EOS-7D

Canon EF 17-40mm f/4.0L USM

11/29/2007 10:19:28 PM · #7

Originally posted by rupypug:

now what do I do, send it in. The camera is brand new.

Take a picture of your lens cap. If it's dust, it will not be illuminated. If the pixel appears in the same spot, return the camera to the location where it was purchased, and ask for an exchange. Tell them the sensor has a dead pixel and you can show them the evidence if necessary. Of course, there's no guarantee that the next one won't have a dead pixel, too.

11/29/2007 10:41:52 PM · #8

I ran the test and it said 0 dead pixels and 3797187 hot pixels. Is this good or bad.

Thanks Jeremy

Canon EF 17-40mm f/4.0L USM

11/29/2007 11:21:09 PM · #9

I did notice that in the raw form the dead pixels or whatever they are, are not showing up.

Thanks, Jeremy

david_c

Canon EOS-7D

11/29/2007 11:25:50 PM · #10

Originally posted by rupypug:

I ran the test and it said 0 dead pixels and 3797187 hot pixels. Is this good or bad.

Thanks Jeremy

What test? That dead pixel test thingie? I dunno, but 3.7 million hot pixels seems high....1 out of 3 on your sensor would indicate a serious issue with the sensor. Did you take a shot of your lens cap? Is the bright, white pixel there? Is this the only image you have that shows the pixel?

dickwilhelm

Canon EOS-30D

Canon EF 75-300mm f/4.0-5.6 IS USM

11/29/2007 11:37:16 PM · #11

I may be missing something but doesn't dust on the sensor show itself as a gray or black spot since it prevents light from reaching that part of the sensor. Certainly wouldn't show as white.