"Do the Nikon have the function to find and map out stuck pixels?"... 🙄
Strictly speaking it is (singular) "Does the Nikon have the function to find and map out stuck pixels?"
But you could say (plural) "Do the Nikons have the function to find and map out stuck pixels?"
It's complicated, even English people get muddled. 😀
Anyhow, back on-topic, this is what I have found out from the manual:
I really don't know what it all means. But I think that high ISO and long exposure means noise even if noise reduction is on.
By default I have turned on NR. But I have heard that astronomers recommend turning it off. Maybe that is the next thing to try?
Apparently you can do things with MS Windows Nikon software and RAW images to fix it too, But I can only handle jpeg in linux.
Strictly speaking it is (singular) "Does the Nikon have the function to find and map out stuck pixels?"
But you could say (plural) "Do the Nikons have the function to find and map out stuck pixels?"
It's complicated, even English people get muddled. 😀
Anyhow, back on-topic, this is what I have found out from the manual:
I really don't know what it all means. But I think that high ISO and long exposure means noise even if noise reduction is on.
By default I have turned on NR. But I have heard that astronomers recommend turning it off. Maybe that is the next thing to try?
Apparently you can do things with MS Windows Nikon software and RAW images to fix it too, But I can only handle jpeg in linux.
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Terrible problems getting my nightly snap of the hoped-for Nova.
I made a hash of Focussing in darkness, well, you can imagine. You can't SEE anything! The nearby parked car roofs were not low and flat enough to balance a tripod easily too.
Street lights hardly make for dark skies either. I really must write to the Local Councillor. Not that he'd know light pollution from a hole in the ground. 🙁
Thought I'd try the V1+ setting that make supposedly colours more vivid, and turned off noise reduction:
Another bust!
My mood was hardly lightened on reading about the problems local residents in Pembrokeshire are creating about our new Space Radar station, designed to keep us, the US and Australia safe from marauding enemy satellites:
https://www.bbc.co.uk/news/articles/c51y89ne1l7o
Usual NIMBY whatnot from ill-informed locals. Talk of migrating Shearwater and Chuff birds being confused by the installation of 27 antennas. They'll be mentioning newts in local ponds next!
Some claim the spot is "Magical". Some are worried about lights. Well, this is radar. It doesn't use lights.
Ignorant comparisons of cancer risks from "Iron Dome" missile radars (which can probably microwave an egg at a 1000 yards) and this one which points up at the sky. I know a bit about radars, more than I can tell you.
These chaps at RAF Fylingdales don't look worried about health issues:
Civilians really shouldn't interfere with things that are best left to Physicists and Engineers. 😡
Sorry to rant.
I made a hash of Focussing in darkness, well, you can imagine. You can't SEE anything! The nearby parked car roofs were not low and flat enough to balance a tripod easily too.
Street lights hardly make for dark skies either. I really must write to the Local Councillor. Not that he'd know light pollution from a hole in the ground. 🙁
Thought I'd try the V1+ setting that make supposedly colours more vivid, and turned off noise reduction:
Another bust!
My mood was hardly lightened on reading about the problems local residents in Pembrokeshire are creating about our new Space Radar station, designed to keep us, the US and Australia safe from marauding enemy satellites:
https://www.bbc.co.uk/news/articles/c51y89ne1l7o
Usual NIMBY whatnot from ill-informed locals. Talk of migrating Shearwater and Chuff birds being confused by the installation of 27 antennas. They'll be mentioning newts in local ponds next!
Some claim the spot is "Magical". Some are worried about lights. Well, this is radar. It doesn't use lights.
Ignorant comparisons of cancer risks from "Iron Dome" missile radars (which can probably microwave an egg at a 1000 yards) and this one which points up at the sky. I know a bit about radars, more than I can tell you.
These chaps at RAF Fylingdales don't look worried about health issues:
Civilians really shouldn't interfere with things that are best left to Physicists and Engineers. 😡
Sorry to rant.
"Hot" pixels are a bit of a misnomer for pixels with above usual charge leakage for the sensor. Sensor temperature has it's own set of problems which is why we use cooled cameras. The best thing to do is take images with the sensor covered and then subtract that from the final image, plus stack many shorter exposures with a little positional dither, then bad pixels, noise and other issues tend to average out when aligned, as in the case of bad pixels they are not in the same place wrt the target object on each exposure. You should also take flats -- images of an even light source that will allow correction for vignetting, uneven sensitivity etc.
It's so annoying when bad pixels simply pop up at random!
I take my lens cap off to you for your explanation, gpauk.
P.S. I knew I'd flush you out eventually! 😀
I take my lens cap off to you for your explanation, gpauk.
P.S. I knew I'd flush you out eventually! 😀
Space War is becoming a reality, but not quite as I once envisaged it!
Instead it's about cyber warfare, electronic attacks, and ground-to-orbit missiles capable of destroying satellites.
https://www.abc.net.au/news/2024-05...world-is-preparing-for-war-in-space/103634106
Indeed, I was inwardly quite excited at the prospect of Space War! We may need to develop our skills if the Klingons attack, never mind The Usual Suspects. 🤣
I tried 15s photos with the lens cap on at ISO 400 and ISO 1600.
Totally black screen with the exception of a double grey pixel that appeared near the bottom at ISO 1600:
I think the jpeg compression has anti-aliased them.
A total over-exposure to white was just that. No black pixels.
About 10 consistent rogue red pixels appear in long exposures of the sky at both ISO's. I suppose this is some sort of over-sensitivity.
I do know the Nikon D40 with 6M pixels was considered a better camera with a base ISO of 100, whereas the D60 at 10M is ISO 200.
I really don't know, but I assume sensor heating is aggravating this over-sensitivity in long exposures.
Considering the sensor is 3872 X 2592 small format, this is really quite impressive quality control by Nikon. Old LED screens used to be worse!
I have finished "Quanta and Fields" by Sean Carroll. I certainly can't argue with The Standard Model. All is waves!
The last Chapter (Appendix) was on Fourier Transform. I know that subject.
The more you confine a wave function to a small space (position), the more spread out the frequencies (momenta) become. This is the Uncertainty Principle!
The correct mathematical description is that Momentum is the Fourier Transform of Position. It's just maths, though quite why Planck's Constant (6 X 10^-34 J.s) is what it is remains a mystery.
Amongst talk of Fermions, Sean also pointed out that the Binding Energy of a Hydrogen Molecule is only 4.5eV which must be a photon verging from blue to low ultraviolet. It is the 2 electrons that pull it together over the repulsive force of the protons, and they have opposite spin.
Other interesting bits of chemistry involve how the gas Helium works with two electrons, and metal Lithium with three, though the outer one is the main event.
Overall, an interesting if difficult read. 🙂
I tried 15s photos with the lens cap on at ISO 400 and ISO 1600.
Totally black screen with the exception of a double grey pixel that appeared near the bottom at ISO 1600:
I think the jpeg compression has anti-aliased them.
A total over-exposure to white was just that. No black pixels.
About 10 consistent rogue red pixels appear in long exposures of the sky at both ISO's. I suppose this is some sort of over-sensitivity.
I do know the Nikon D40 with 6M pixels was considered a better camera with a base ISO of 100, whereas the D60 at 10M is ISO 200.
I really don't know, but I assume sensor heating is aggravating this over-sensitivity in long exposures.
Considering the sensor is 3872 X 2592 small format, this is really quite impressive quality control by Nikon. Old LED screens used to be worse!
I have finished "Quanta and Fields" by Sean Carroll. I certainly can't argue with The Standard Model. All is waves!
The last Chapter (Appendix) was on Fourier Transform. I know that subject.
The more you confine a wave function to a small space (position), the more spread out the frequencies (momenta) become. This is the Uncertainty Principle!
The correct mathematical description is that Momentum is the Fourier Transform of Position. It's just maths, though quite why Planck's Constant (6 X 10^-34 J.s) is what it is remains a mystery.
Amongst talk of Fermions, Sean also pointed out that the Binding Energy of a Hydrogen Molecule is only 4.5eV which must be a photon verging from blue to low ultraviolet. It is the 2 electrons that pull it together over the repulsive force of the protons, and they have opposite spin.
Other interesting bits of chemistry involve how the gas Helium works with two electrons, and metal Lithium with three, though the outer one is the main event.
Overall, an interesting if difficult read. 🙂
I was planning a blockbuster post about the "Fourier Transform in Quantum Mechanics" but this is now on hold.
Why? Because I had a truly strange experience yesterday. This could only happen to a person "On the Spectrum" as high-functioning autistic people like myself say.
Being naturally insensitive to people's feelings, I want to tell you about it.
Taking a break from heavy books about Gravity and Science, I have started reading John Green's book "Turtles All The Way Down".
I also picked up an interesting looking Astronomy book in our generally mediocre local library's science section, which generally is limited to books by pop star Prof. Brian Cox and the lovely Prof. Lisa Randall, who does digress a bit away from science into philosophy sometimes, IMO.
TBH it's a bit teenagerish, like his famous and moving book "The Fault In Our Stars". But one of the protagonists is extremely OCD and her boyfriend is an Asperger's syndrome Astronomer, so I can relate.
It's a whodunnit, when the boy Davis Pickett's millionaire father mysteriously disappears off the scene hours before the Cops are about to arrest him for criminal activity.
Davis is quizzed by the Cops about his father's disappearance, and we suspect he knows more than he is letting on:
I happen to know a bit about Vega and Epsilon Lyrae, even have a photograph I took:
You can see that Epsilon Lyrae, at the top, is a double star. It is, in fact a "double-double" in a telescope.
Vega is an extraordinarily interesting star too, and will be the brightest star in the sky in 150,000 years as well as being the pole star.
So Davis' statement has some credibility IMO.
Imagine my astonishment in opening the first chapter of my star book to find that Vega is also mentioned:
The stars Vega (Hikoboshi) and Altair (Orihime) are famous in Japanese culture. They even have a day to celebrate them, July 7th.
Just so you can understand the fable of Hikoboshi and Orihime, who were so in love they got very little cow herding or weaving work done, thus were only allowed by the chief gods to fly across the heavenly river one day a year to meet, here is a picture of the Summer sky. Epsilon is (coincidentally, it seems, but there is no such thing as coincidence to a good detective like Harry Bosch...) on the line to Deneb below Vega.
And there was you thinking Vega in the Lyre was all about the myth of Orpheus and Eurodyce (who were also in love) in the underworld!
I find this an extraordinary example of the "Synchronicity" that Psychiatrist Carl Jung and Physicist Wolfgang Pauli would so often discuss.
Indeed, it is "Turtles All The Way Down"! You follow? 😎
Why? Because I had a truly strange experience yesterday. This could only happen to a person "On the Spectrum" as high-functioning autistic people like myself say.
Being naturally insensitive to people's feelings, I want to tell you about it.
Taking a break from heavy books about Gravity and Science, I have started reading John Green's book "Turtles All The Way Down".
I also picked up an interesting looking Astronomy book in our generally mediocre local library's science section, which generally is limited to books by pop star Prof. Brian Cox and the lovely Prof. Lisa Randall, who does digress a bit away from science into philosophy sometimes, IMO.
TBH it's a bit teenagerish, like his famous and moving book "The Fault In Our Stars". But one of the protagonists is extremely OCD and her boyfriend is an Asperger's syndrome Astronomer, so I can relate.
It's a whodunnit, when the boy Davis Pickett's millionaire father mysteriously disappears off the scene hours before the Cops are about to arrest him for criminal activity.
Davis is quizzed by the Cops about his father's disappearance, and we suspect he knows more than he is letting on:
I happen to know a bit about Vega and Epsilon Lyrae, even have a photograph I took:
You can see that Epsilon Lyrae, at the top, is a double star. It is, in fact a "double-double" in a telescope.
Vega is an extraordinarily interesting star too, and will be the brightest star in the sky in 150,000 years as well as being the pole star.
So Davis' statement has some credibility IMO.
Imagine my astonishment in opening the first chapter of my star book to find that Vega is also mentioned:
The stars Vega (Hikoboshi) and Altair (Orihime) are famous in Japanese culture. They even have a day to celebrate them, July 7th.
Just so you can understand the fable of Hikoboshi and Orihime, who were so in love they got very little cow herding or weaving work done, thus were only allowed by the chief gods to fly across the heavenly river one day a year to meet, here is a picture of the Summer sky. Epsilon is (coincidentally, it seems, but there is no such thing as coincidence to a good detective like Harry Bosch...) on the line to Deneb below Vega.
And there was you thinking Vega in the Lyre was all about the myth of Orpheus and Eurodyce (who were also in love) in the underworld!
I find this an extraordinary example of the "Synchronicity" that Psychiatrist Carl Jung and Physicist Wolfgang Pauli would so often discuss.
Indeed, it is "Turtles All The Way Down"! You follow? 😎
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Interestingly, Altair is one of the few stars whose images have been resolved beyond a point source.
Direct image of Altair taken by CHARA array optical interferometer
Altair is not spherical, but bulges at the equator due to its high rate of rotation: https://en.wikipedia.org/wiki/Altair
It was on planet Altair IV that the starship Bellerophon landed, and was subsequently vaporised, in the movie Forbidden Planet.
And it was on Altair IV that the crew of United Planets starship C-57D discovered the only survivors, Dr. Morbius and his daughter Altaira.
Wait a minute. If the spaceship gets vaporised, how did the spacemen get home? Or are they stuck on a planet with only one girl? 🤣
Unsurprisingly, I muddled up the Cowherd and the Weaver Girl... 🙁
Altair is the Cowherd Hikoboshi, and Vega is Orihime. We know this because Hikoboshi looks after the two kids, who are the bright Beta and Gamma stars either side of him and Altair.
Here eagerly awaiting mum's annual return across the Heavenly River lifted by magpies.
Stars seem to look very small indeed. Altair is 3.2 mas (milli arc seconds).
For comparison Hubble can resolve 100 mas directly or 0.1".
Antares and Betelgeuse are about 40 mas. These are measured by specialist satellites AFAIK, and ground based interferometry on large telesopes.
I know my 55mm camera can resolve about 2 arc minutes or 2' by comparison when I look at double stars.
A good 5" aperture telescope refractor at X300 can resolve 2" or 2 arc seconds. Thus can do this with image enhancing techniques:
This wiki chart is quite useful as a comparison of bigger solar system objects:
Unsurprisingly, I muddled up the Cowherd and the Weaver Girl... 🙁
Altair is the Cowherd Hikoboshi, and Vega is Orihime. We know this because Hikoboshi looks after the two kids, who are the bright Beta and Gamma stars either side of him and Altair.
Here eagerly awaiting mum's annual return across the Heavenly River lifted by magpies.
Stars seem to look very small indeed. Altair is 3.2 mas (milli arc seconds).
For comparison Hubble can resolve 100 mas directly or 0.1".
Antares and Betelgeuse are about 40 mas. These are measured by specialist satellites AFAIK, and ground based interferometry on large telesopes.
I know my 55mm camera can resolve about 2 arc minutes or 2' by comparison when I look at double stars.
A good 5" aperture telescope refractor at X300 can resolve 2" or 2 arc seconds. Thus can do this with image enhancing techniques:
This wiki chart is quite useful as a comparison of bigger solar system objects:
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It's quite incredible how Astronomers and Mathematicians discovered things like Pluto. At magnitude 15 you can hardly see them even with modern equipment.
Ace mathematician Urban Le Verrier, you will recall, calculated its position from oddities in the orbit of Neptune (Which looks 20X wider) around 1840:
This is dwarf planet Eris, imaged by Hubble, and it's about the same size (2000 miles across) as Pluto but 3X further away usually, so magnitude 18 and only discovered in 1954:
We said Hubble can resolve 0.1", so this looks reasonable. After that, it's long exposure and stability of the platform.
What are we up against here? The QUANTUM MECHANICS of the photon in the end!
I can do a mere 2' with my cheapish DSLR camera and 18-55mm f3.5-5.6 for Nu1 and Nu2 Bootis which is about 10' :
What I want is a proper 5" telescope and camera attachment and computer tracking mount, but that's about $5000!
https://www.astropix.com/html/equipment/sva130t.html
But attaching a camera is a pain, because you need a field flattener lens too. Telescopes don't make a planar flat image unassisted.
The mathematics, which is Spatial Fourier Transform:
You have seen that before, of course, in the Sinc function, which is the unrectified version:
Rectangular or circular apertures like lenses are not necessarily the best way to do things. The Gaussian transform maps onto itself so less diffraction:
This is the sort of thing you consider with arrays of receivers as in some radar setups or arrayed radio telescopes. Say, you had three speakers in a row, as in some home-theatre centre setups.
The middle one should be twice as loud as the two side ones for less diffraction problems. 1:2:1 being the simplest binomial coefficients. It will probably work with vertical tweeter arrays too.
I amaze myself sometimes. 🙂
Ace mathematician Urban Le Verrier, you will recall, calculated its position from oddities in the orbit of Neptune (Which looks 20X wider) around 1840:
This is dwarf planet Eris, imaged by Hubble, and it's about the same size (2000 miles across) as Pluto but 3X further away usually, so magnitude 18 and only discovered in 1954:
We said Hubble can resolve 0.1", so this looks reasonable. After that, it's long exposure and stability of the platform.
What are we up against here? The QUANTUM MECHANICS of the photon in the end!
I can do a mere 2' with my cheapish DSLR camera and 18-55mm f3.5-5.6 for Nu1 and Nu2 Bootis which is about 10' :
What I want is a proper 5" telescope and camera attachment and computer tracking mount, but that's about $5000!
https://www.astropix.com/html/equipment/sva130t.html
But attaching a camera is a pain, because you need a field flattener lens too. Telescopes don't make a planar flat image unassisted.
The mathematics, which is Spatial Fourier Transform:
You have seen that before, of course, in the Sinc function, which is the unrectified version:
Rectangular or circular apertures like lenses are not necessarily the best way to do things. The Gaussian transform maps onto itself so less diffraction:
This is the sort of thing you consider with arrays of receivers as in some radar setups or arrayed radio telescopes. Say, you had three speakers in a row, as in some home-theatre centre setups.
The middle one should be twice as loud as the two side ones for less diffraction problems. 1:2:1 being the simplest binomial coefficients. It will probably work with vertical tweeter arrays too.
I amaze myself sometimes. 🙂
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You should go RAW really as it will give you added quality with a proper developer...
//
I'm not sure that unprocessed RAW images will help a lot. The resolution is largely lens limited, rather than sensor limited AFAIK.
And RAW causes me some issues in Linux PC operating system. But of course, Nikon provide some class leading software in Nikon Suite for the UTTER HORROR that is MS WINDOWS, which I really only use for speaker simulation. 🤣
And RAW is presumably huge in size. Even the Nikon jpegs are actually about 5 MB, way beyond Forum storage capabilities. 10.2 million pixels at 12 bit resolution in my case, do the math. This forum even compresses jpegs more than I upload.
Which is reasonable, and why I try to limit to about 100kB uploads.
My main gripe when I venture into the multiway speaker forum is that most people don't understand the limiting mathematics of all our efforts to reach perfection. So it's endless... almost a total waste of time! 🙁
And RAW causes me some issues in Linux PC operating system. But of course, Nikon provide some class leading software in Nikon Suite for the UTTER HORROR that is MS WINDOWS, which I really only use for speaker simulation. 🤣
And RAW is presumably huge in size. Even the Nikon jpegs are actually about 5 MB, way beyond Forum storage capabilities. 10.2 million pixels at 12 bit resolution in my case, do the math. This forum even compresses jpegs more than I upload.
Which is reasonable, and why I try to limit to about 100kB uploads.
My main gripe when I venture into the multiway speaker forum is that most people don't understand the limiting mathematics of all our efforts to reach perfection. So it's endless... almost a total waste of time! 🙁
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To put that into context:
At a resolution of 0.1 arc-seconds, the JWST could resolve a penny 24 miles away or a football 340 miles away.
You normally have a lot more tools available for processing RAW images so I’d say it’s the way to go. I was very surprised at the difference in post processed image quality between RAW which I now shoot and JPEG. I use Lightroom, but there may be specific astrophotography tools out there for noise reduction and image stacking.
You can always export post processed RAW to JPEG.
You can always export post processed RAW to JPEG.
Incredible image of plasma plumes on the Sun
https://x.com/konstructivizm/status/1808502706497007730
https://x.com/konstructivizm/status/1808502706497007730