MRomine wrote:
Sorry for my ignorance, not being an electrical engineer, or an engineer of any discipline, just what is or what does a remapping do?
It first performs a blackframe exposure, which identifies which pixels are stuck, then records the list of those pixels in non-volatile camera memory. That list is consulted for every subsequent exposure, which the camera uses to interpolate over the stuck pixels with pixels around it.
James Farrell wrote:
Thom Hogan’s eBook on the Z6 and Z7 addresses this, as you have mentioned, on page 126. Manually activating the Clean Sensor Now does a sensor discharge before the vibration clean. Repeating it a few times, according to Hogan, seems to remove temporary stray electrons. And he does mention that current versions of LR/PS will deal with them in raw files. I am no expert on this stuff. Just repeating what I read.
I'm not sure whether these effects are due to stray electrons or to faulty/weak circuitry on the sensor. Stray electrons would be the result of such circuitry, and I don't think you can somehow remove them. I would assume that you simply repair the effects in the electronic files by mapping the respective pixels. My experience is that there are a number of "hot" pixels that are plain white, as if they were overexposed, but also some "warm" pixels that are less bright and sometimes even show a color (one of the three primary colors, in the pixels I have seen so far). I'm not sure whether raw processing software (LR, PS, Capture One and likely others) would be able to identify all of these "warm" pixels.
For reference here are two 30-minute ISO 100 blackframes I took this morning on my Z6. I allowed the camera to cool for one hour between exposures. To make the wam/hot pixels easier to discern I processed them in RawTherapee, with hot-pixel suppression disabled, and without demosaicing the data (each pixel represents the actual CFA value and is not interpolated). Exposure was adjusted +2EV in post to make all pixels more visible.
You'll have to review the images carefully to discern between hot/warm pixels and read noise.
Thanks for the input to all. I will try to do the consequtive sensor cleanings to see if it remaps.
To answer some of the previous questions
1) The images that triggered this question were during a MW shot, ISO 8k-12k, 20s exposure. No video.
2) The wrappinng in a jacket was just to prevent stray light from getting in. The camera was completely cold, I wrapped it in a jacket, took an exposure at ISO=6400. So no, there was not execssive heating
3) PS is clearly doing some level of hot pixel removal because I can see it in the slight delay when an image is first displayed. If you get lucky there will be a hot pixel in the FOV and you can sometimes see it disapper. That takes care of most but not all hot pixels
The PS scratch fillter does a good job of taking care of any remaining ones, and if used judiciously can be used to somewhat reduce the amount of stars in the sky, which I actually find helpful in emphasizing the MW.
Last but not least, I am not obsessing about these. Was just surprised to see them in the numbers that I did. Had never noticed them on my D800.
MRomine wrote:
Sorry for my ignorance, not being an electrical engineer, or an engineer of any discipline, just what is or what does a remapping do?
In layman's terms, camera sensors are composed of millions of individual sensor pixels. Over time, individual pixels will fail, either being dead or being "stuck", which you can find in the RAW by taking a dark frame and an over-exposed frame with noise reduction off and ideally at base ISO. The remapping process is similar to how denoising in general works, by averaging neighboring pixels.
Happens on every digital camera, and older cameras like the Leica M8 for example don't have built-in auto remapping functions, and require a CLA at Leica AG to remap, so it cost about $500 for me to do it several years ago. I believe it's closer to a thousand nowadays
snapsy wrote:
For reference here are two 30-minute ISO 100 blackframes I took this morning on my Z6. I allowed the camera to cool for one hour between exposures. To make the wam/hot pixels easier to discern I processed them in RawTherapee, with hot-pixel suppression disabled, and without demosaicing the data (each pixel represents the actual CFA value and is not interpolated). Exposure was adjusted +2EV in post to make all pixels more visible.
You'll have to review the images carefully to discern between hot/warm pixels and read noise.
snapsy wrote:
It first performs a blackframe exposure, which identifies which pixels are stuck, then records the list of those pixels in non-volatile camera memory. That list is consulted for every subsequent exposure, which the camera uses to interpolate over the stuck pixels with pixels around it.
Thanks for your reply.
So when does the camera perform the said 'black frame exposure'? Or what induces the camera to perform the 'black frame exposure'?
hans98ko wrote:
sjms
By now you should know that not all changes are listed, this has been going on since the days of DSLRs and not just started since mirrorless.
So how do one explain the higher temperature of the cameras during initial operation compared to that of after firmware release. If no change then why the difference in temperature?
Do you remember anywhere stated that after firmware update will bar the use of 3rd party batteries?
from the day i got the Z6 i really felt no temp difference in use. and i use it a lot. the only part that got warm was the XQD card as it did in all previous cameras i have owned that use it.
the prevention of the use of 3rd party batts is rather a weak example. a lot of garbage batteries out there the have real poor construction. its almost impossible to keep up with the "blocking" that is so easily circumvented. this is childs play for a code monkey. its a simple setup linked to the internal driver for battery condition/information.
so in reality you are using the assumption engine theory right?
if they make a statement like this for a rather arcane fix:
• Improved autofocus performance for photos and movies shot under low light: -3.5 – 19 EV (low light autofocus -6 – 19 EV), measured in photo mode with single-servo AF (AF-S) at ISO 100 and 20°C with an f/2 lens.
whats the point of not saying anything. a lot of people here (and thats just here which is a small sampling to say the least) use this camera. yet this is a one off at the moment from one particular source.
So when does the camera perform the said 'black frame exposure'? Or what induces the camera to perform the 'black frame exposure'?
It does a hot-pixel remapping whenever you perform two menu-based sensor cleanings back-to-back. It's not documented but has been in Nikon cameras for several generations. Sony cameras do it automatically once a month - you can also trigger it manually on those cameras by advancing the clock forward by a month.
In regards to hot pixels on your Z6, you should see no hot pixels at all when using the camera's. I would recommend to send the Z6 in for service once the service center reopens back up.
sjms wrote:
from the day i got the Z6 i really felt no temp difference in use. and i use it a lot. the only part that got warm was the XQD card as it did in all previous cameras i have owned that use it.
the prevention of the use of 3rd party batts is rather a weak example. a lot of garbage batteries out there the have real poor construction. its almost impossible to keep up with the "blocking" that is so easily circumvented. this is childs play for a code monkey. its a simple setup linked to the internal driver for battery condition/information.
so in reality you are using the assumption engine theory right?
if they make a statement like this for a rather arcane fix:
• Improved autofocus performance for photos and movies shot under low light: -3.5 – 19 EV (low light autofocus -6 – 19 EV), measured in photo mode with single-servo AF (AF-S) at ISO 100 and 20°C with an f/2 lens.
whats the point of not saying anything. a lot of people here (and thats just here which is a small sampling to say the least) use this camera. yet this is a one off at the moment from one particular source.
So what do a code monkey 🙊 like you know about internal functioning of the camera compare to people who works in the field and have access to the information.
That link you posted was on nikonrumors a couple of weeks ago and is nothing new to people like us because it is not the first time astrophotographers has been doing it. I even mentioned the use in some of my posts.
Maybe is time for you to join some of your street activities now. Don't miss it, it is hard to come by to have the opportunity of getting some memorable shots. But don't get shot. 🤣
These type of scenes can only be found in Afghanistan, Hong Kong, Iraq, Lebanon, Libya, Somalia, Syria...Oh! Always with the involvement of you know who! 🙊
hans98ko wrote:
So what do a code monkey 🙊 like you know about internal functioning of the camera compare to people who works in the field and have access to the information.
That link you posted was on nikonrumors a couple of weeks ago and is nothing new to people like us because it is not the first time astrophotographers has been doing it. I even mentioned the use in some of my posts.
Maybe is time for you to join some of your street activities now. Don't miss it, it is hard to come by to have the opportunity of getting some memorable shots. But don't get shot. 🤣
These type of scenes can only be found in Afghanistan, Hong Kong, Iraq, Lebanon, Libya, Somalia, Syria...Oh! Always with the involvement of you know who! 🙊...Show more →
GroovyGeek wrote:
Thanks for the input to all. I will try to do the consequtive sensor cleanings to see if it remaps.
To answer some of the previous questions
1) The images that triggered this question were during a MW shot, ISO 8k-12k, 20s exposure. No video.
2) The wrappinng in a jacket was just to prevent stray light from getting in. The camera was completely cold, I wrapped it in a jacket, took an exposure at ISO=6400. So no, there was not execssive heating
3) PS is clearly doing some level of hot pixel removal because I can see it in the slight delay when an image is first displayed. If you get lucky there will be a hot pixel in the FOV and you can sometimes see it disapper. That takes care of most but not all hot pixels
The PS scratch fillter does a good job of taking care of any remaining ones, and if used judiciously can be used to somewhat reduce the amount of stars in the sky, which I actually find helpful in emphasizing the MW.
Last but not least, I am not obsessing about these. Was just surprised to see them in the numbers that I did. Had never noticed them on my D800.
Does the Pixel Mapping function on Nikon mirrorless bodies cause any harm to the sensor over time? IOW, can you initiate the remapping function as often as you need?
