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01-22-2014, 06:52 AM   #1
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Hot Pixels query

I took my K5-II out a couple of nights ago to have a play with it at night having just got a remote shutter. Took about 50 pictures and on just over 20 of them, several red dots can be seen. I'd not heard of this before so contacted the shop I bought it from to ask for their advice, they suggested it was probably a hot pixel but that I should send it in to be checked under warranty (bought in August). Happy to do this but before I accept the 4-6 weeks without my camera, I thought I'd post here and see what your thoughts are. Index of /pics/hotpixel


I've attached a link with three of the pictures from the other night(large files, sorry). Of the two most persistent dots, one can be seen towards the top left and the other about two thirds down towards the middle (a third can be seen above this, towards the top of the image- there are various others in other pictures). The final image is a 3.5 hour exposure in a cupboard- is that a normal outcome? I was quite surprised by how red it looks..


I'd really appreciate your thoughts on this, as to whether I should send it off for a check-up, and apologies if I should have posted this in the beginners forum- wasn't sure which was more relevant.


Cheers

01-22-2014, 07:09 AM   #2
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Have you ran the pixel mapping function on the cameras menu yet? We ran it on all of our cameras and that took care of any issues.

David
01-22-2014, 07:16 AM   #3
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I did give that a try after Googling hot pixels- the two persistent ones I described above remained in most long exposure shots..
01-22-2014, 08:07 AM - 1 Like   #4
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Ah, I see. Yep, time to contact your service company.

01-22-2014, 08:39 AM   #5
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OK great, thanks for confirming that then. Just didn't want to send it off for six weeks for them to turn around and say it's standard.
01-22-2014, 11:19 AM   #6
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Andrew,

Do you have dark-frame subtraction turned on? I don't know what it's called in the k5 series, but it's the function that when you take a long exposure, it takes another exposure with the shutter closed and subracts that dark frame from the photograph to reduce noise and hot pixels. This is noticeable as in the following scenario: If you take a 30-second exposure, after the shutter closes after 30 seconds, the camera is "busy" for ANOTHER 30 seconds while it acquires the dark frame.

If you don't have that turned on, try with it on and see if that cleans up your picture.

-Joe-
01-22-2014, 11:25 AM   #7
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Hi Joe,


I do have that on, yes- I was wondering why there was such a delay. I'll figure out how to turn it off and give it a try. Thanks.
01-22-2014, 11:26 AM   #8
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OP I just re-read you first post and I was wondering about your 3 1/2 hour exposure: did you mean to say the entire frame was red? If so with that long an exposure I believe the red is infrared sensitivity because of the extreme length of the exposure. Please disregard if that was not what you meant!<br />
<br />
David

01-22-2014, 11:29 AM   #9
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You can see it here David: http://andrew.vu/pics/hotpixel/IMGP1668.JPG - it's lots and lots of red dots that show.
01-22-2014, 11:35 AM   #10
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Andrew,

It will be worse with it off. It SHOULD be on, so you had it correct to begin with.

It's a bummer that you might have to send your camera for repair!

By the way, the hot pixels are worse at high ISO. If you are shooting at high ISO, drop the ISO to 200 or 400 and try it again.

-Joe-

QuoteOriginally posted by andrewvu Quote
Hi Joe,


I do have that on, yes- I was wondering why there was such a delay. I'll figure out how to turn it off and give it a try. Thanks.
01-22-2014, 12:05 PM   #11
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Turned off slow shutter speed noise reduction which got rid of the pause after long exposures- the red dot problem seems to have ceased. Now the question is, should I have to turn this off to remove the dots or should these dots just not be there in the first place? Also when I took a 300 second shot with the lens cap on, the image has a sort of purple / pinkish haze rather than being pure blackness- is that normal?


Thanks for all your help so far
01-22-2014, 12:34 PM   #12
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QuoteOriginally posted by andrewvu Quote
I took my K5-II out a couple of nights ago to have a play with it at night having just got a remote shutter. Took about 50 pictures and on just over 20 of them, several red dots can be seen. I'd not heard of this before so contacted the shop I bought it from to ask for their advice, they suggested it was probably a hot pixel but that I should send it in to be checked under warranty (bought in August). Happy to do this but before I accept the 4-6 weeks without my camera, I thought I'd post here and see what your thoughts are. Index of /pics/hotpixel


I've attached a link with three of the pictures from the other night(large files, sorry). Of the two most persistent dots, one can be seen towards the top left and the other about two thirds down towards the middle (a third can be seen above this, towards the top of the image- there are various others in other pictures). The final image is a 3.5 hour exposure in a cupboard- is that a normal outcome? I was quite surprised by how red it looks..


I'd really appreciate your thoughts on this, as to whether I should send it off for a check-up, and apologies if I should have posted this in the beginners forum- wasn't sure which was more relevant.


Cheers
Hot pixels are normal on long exposures like that. My rule of thumb is if you're going to go out of your way to get a 5-minute exposure, waiting another 5 minutes for noise reduction isn't a big deal. Though having two camera bodies in that situation is very nice

So, to recap, there's probably nothing wrong with your camera. Pixel mapping should take care of any hot pixels that are always there, while the slow shutter speed noise reduction will nuke all the long-exposure hot pixels, since they're more likely to occur when the sensor is warm.

Adam
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