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Forum: Pentax K-1 & K-1 II
12-27-2017, 03:30 PM
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I still haven't made it to capturing any outdoor night shots (nasty weather here), but in the meantime, you might find interest in this thread unless you've already read it. Good luck with Precision Camera. Let us know how that goes.
Detected hot pixels - PentaxForums.com |
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Forum: Pentax K-1 & K-1 II
12-25-2017, 09:29 AM
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Not my intention to have you drink lemonade. I completely understand your frustration and would do the same. Just wanted to be sure it's not a post-processing issue rather than a camera issue but if other cameras on same settings/subject did not exhibit problem, it's camera.
Last night I would have gotten a whole lot of white dots, even with a film camera. We got dumped on with a Christmas eve snow storm and I didn't get any chance to take outdoor shots. I'll try again tonight since there's supposed to be some clearing and a chance for stars maybe.
What were all the settings you used when you got your dot problem? I will attempt to duplicate those when I take a test shot. I know you were using 30s and an ISO of 1600 or above - what aperture? Did your image fill most of the histogram with the exposure you used? Will use converted RAW this time to see if any dots are present.
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Forum: Pentax K-1 & K-1 II
12-24-2017, 03:24 PM
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I'll have to wait for dark and will try to take some shots tonight and post the results. Last night would have been ideal to shoot some star fields but tonight is going to be overcast. I will find a suitable target nonetheless. I would anticipate seeing a small number of white specks since there are always a few defective pixels in any given sensor (hence the two I observed last night).
Are you seeing these white dots on the LCD when you take the pictures, or is it after (or during) post processing? It occurred to me that folks seeing the white dots may be capturing an underexposed frame and then stretching the noise floor with a post processing tool so that naturally occurring noise is being seen. That would be expected since a lot of gain has already been applied to the image by using a high ISO. The frames I took were observed directly on the LCD (which did show the few individual "stuck" pixels clearly). I would anticipate they would appear very similar if brought up in a program like Photoshop but if I had an inadequate exposure and stretched the blacks (using curves) it could well produce what you're observing (not that I've tried that).
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Forum: Pentax K-1 & K-1 II
12-23-2017, 10:03 PM
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When I did it for my previous post, my K-1 was in AUTO for long exposure noise reduction (and yes, it doubles the exposure time to 1 minute). I just repeated the process at 128000 ISO and long exposure noise reduction off, and still no specks. With AUTO, there may have been some additional noise reduction, but with the LCD image, it wasn't obvious. This is the first low light photography I've done with the K-1 and it's pretty impressive. I can barely see the wall (by eye) which I used as a test shot, but the 30 second f5.6 exposure brings out all the colors and is reasonably sharp and well exposed. In any case, I really thought I'd see more noise than I did. but to answer your question, no, I didn't see any white spots either way.
Addenda: I got to thinking about what you said and went back to a white/black target for testing. With 12800 ISO I did see 2 white pixels in the black target but they are pixel events and could be easily retouched. I then reshot with 51200 ISO at f11 (30s), thinking I would see all kinds of noise, but still only the 2 white pixels and a relatively quiet reproduction of the black area (noise reduction turned OFF in both instances). I'm even more impressed.
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Forum: Pentax K-1 & K-1 II
12-23-2017, 04:44 PM
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Since they are in the same locations, it's not a noise problem and is definitely sensor related (or some failure in subtracting the reference background). There could be an adjustment for "black clip" which would mask the dots, but it seems that in your case, it is likely a sensor issue requiring replacement.
Hope you can get this problem fixed to your satisfaction. At least you know how to verify the problem has been fixed.
I did a quick test with my K-1 last night at 3200 and 12800 ISO shooting into a darkened room (just enough light to produce an image in 30 seconds) with no specks visible so that's what you can expect when you get this issue resolved. Too bad, but there are some defects that slip through quality assurance and plague customers like yourself.
Have a good Christmas and let us know how this comes out.
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Forum: Pentax K-1 & K-1 II
12-22-2017, 09:52 PM
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Your white dot problem (illustrated by MJKoski) appears to be "dark noise" and I don't think any "calibration" is going to address it (unless there's an adjustment for noise reduction downstream). It could be the sensor or the amplifier which reads the sensor before that information is digitized (not sure if that would be integral to the sensor or a separate component). It's random noise common to a bad sensor, amplifier, or some type of electrical interference (any high power radio/cell/television transmission or other electrical equipment nearby?) and appears when image gain is increased at higher ISOs. It could just be a noisy sensor.
The cure will most likely lead to the replacement of the offending component. Your long exposure/high ISO/dark background is a good test to see if the problem is remedied. You can also look at the liveview presentation with a high ISO and low lighting to get an idea of how much noise is present (don't be alarmed, some noise is normal).
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