How test for dead/hot pixels?

[bill hansen]

How do all of you test for dead or hot pixels? In the past I've used the Starzen dead pixel test, but when I tried to use that test on my new 50D, I think the application (Starzen) is no longer functional. I downlaoded it again, and the re-downloaded version also does not seem to test the images.

In the past, while the Starzen test was running, I would see a table showing numerical values, and a histogram. Now, the test claims it's "testing", but no data show up. At the end, I do get the message "no dead or hot pixels", but I don't trust it.

I've asked about this on another forum, but I'm not getting answers which help. Is there a test which actually works? Do you all use some other method (for example, someone suggested that just shooting an image with the lens cap on and examining that on the computer monitor is all that's needed)?

Thanks for passing along your experience in testing for dead/hot pixels.

Bill Hansen

 

[Kelly27]

I don't actually test for these, I just look at the images and see what I see. If you cant see them do they matter much?
K.

How do all of you test for dead or hot pixels? In the past I've used
the Starzen dead pixel test, but when I tried to use that test on my
new 50D, I think the application (Starzen) is no longer functional. I
downlaoded it again, and the re-downloaded version also does not seem
to test the images.

In the past, while the Starzen test was running, I would see a table
showing numerical values, and a histogram. Now, the test claims it's
"testing", but no data show up. At the end, I do get the message "no
dead or hot pixels", but I don't trust it.

I've asked about this on another forum, but I'm not getting answers
which help. Is there a test which actually works? Do you all use some
other method (for example, someone suggested that just shooting an
image with the lens cap on and examining that on the computer monitor
is all that's needed)?

Thanks for passing along your experience in testing for dead/hot pixels.

Bill Hansen

 

[bill hansen]

I don't actually test for these, I just look at the images and see
what I see. If you cant see them do they matter much?

I guess they can. For example, most of the time I don't edit pix at 100% mag - only do that if I'm positive I want to make a really large print. I'd be pretty bummed out to find that I have to go through an image and "spot it" like we used to do with large prints in film photography. Dead pixels won't show up easily on a monitor unless you view at full res. Hot pixels are different - they may not show up at ISO 100 or 200, so you might not see them until you need to take an ISO 1600 or 3200 shot some time, and find out that you have bright red "noise" which you can't remove with anything at all.

I'm good now though. A person on another forum suggested that I should repeat my tests at 30 sec exposure. I did that, and at ISO 100 I have no dead or hot pixels (the Starzen test works after all). At ISO 3200, I have no dead pixels but 67 hot pixels, and those show up on the monitor like city lights - terrible!

Of course there's no way I'd ever use ISO 3200 for a 30 sec exposure, but at least I know the test works, and at reasonable ISOs and exposure times, the camera is just fine.

If you ever get interested in testing for dead or hot pixels, the Starzen test is free to download, and it's very quick (takes about 1-2 minutes, no longer than that) and simple to use.

Bill

 

[Mike_PEAT]

How do all of you test for dead or hot pixels?

On my Olympus cameras I just select "Pixel Mapping" and it doesn't only detect stuck/dead pixels, but also maps them out so you don't see them in your pictures.

Unfortunately with most other brands you have to send your camera back to the factory and pay them to do this.

 

[bill hansen]

Well - excuuuuuse me! (Just joking there)

You goys are lucky - I think it's pretty rare to get a significant number of dead or hot pixels though. It seems to me that most people report, at most , 5 or 6 at a higher ISO and exposure of 8 to 10 sec. There have been a few people who have sent cameras back because of unacceptable numbers of dead/hot pixels, or dead/hot ones in an awkward place.

Now on with the day. Maybe I'll get time to take some lower ISO pics with my new toy!

Bill

 

[MPrince]

http://www.starzen.com/imaging/deadpixeltest.htm

 

[bill hansen]

I've had the Starzen test for a few years now. The reason I started this thread is that when I began testing the 50D, it looked like the test wasn't really working. That's because there were no dead/hot pixels at all, up to an 8 sec exposure. But a 30 sec exposure at ISO 1600 showed up plenty of bad pixels.