That doesn't look at all what I get with my NEX-5N or A7R after I set the date ahead by a year, switch camera off, hear the shutter movement, switch camera back on, set correct date, switch camera off, then on, and shoot 30 second images with lens cap on and LENR OFF.
k-h.a.w wrote:
That doesn't look at all what I get with my NEX-5N or A7R after I set the date ahead by a year, switch camera off, hear the shutter movement, switch camera back on, set correct date, switch camera off, then on, and shoot 30 second images with lens cap on and LENR OFF.
Maybe there is something wrong with your camera?
That's what I'm wondering. Has any other A7RII users checked their camera for hot pixels?
yunjo wrote:
So, after doing the pixel remapping per Snapsy's instruction, this is what I get. Lens cap on, ISO 100, f/22, 30 sec exposure. First image is pushing 2 stops and shadows +100. As one can see, still with hot pixels.
Second image is pushing 5 stops to exaggerate and show all the hot pixels. Kind of looks like Christmas to me.
Here's what I get on the A7s and D810 using your same exposure and LR settings:
The 5DSR looks great, Snapsy. The A7S looks better than D810. At +2 EV, I don't think the A7S hot pixels would be noticeable. +5EV is quite exaggerated and if my images are off by +5EV, it's user error and not camera/sensor issue. But when hot pixels are noticeable at +1.5-2 EV, I would think our modern day sensors on $3K cameras should be able to tolerate that.
yunjo wrote:
The 5DSR looks great, Snapsy. The A7S looks better than D810. At +2 EV, I don't think the A7S hot pixels would be noticeable. +5EV is quite exaggerated and if my images are off by +5EV, it's user error and not camera/sensor issue. But when hot pixels are noticeable at +1.5-2 EV, I would think our modern day sensors on $3K cameras should be able to tolerate that.
The A7s is about the same as your A7rII when you account for the fact it's 12MP and so you're looking at fewer total pixels at the same 4x magnification. Something to keep in mind is that there are "hot pixels" and "warm pixels"; hot pixels are visible without PP +exposure adjustment, warm pixels require +exposure adjustment to see. They're both the same underlying thermal phenomenon - the only difference is how far off the std dev. the affected pixels are. I mention this because if we're going to compare long exposure performance across cameras we should start using the same PP settings.
Agree about the 5DSR. According to Roger Clark Canon is performing dark current noise reduction on the 6D/7DM2 and I presume the 5DS/R as well (6D and 7DM2).
6D article quote:
"The constant dark level with long exposure time indicates the camera has on-sensor dark current suppression. This, however, does not suppress noise from dark current. But it results in a uniformly dark level that needs no post processing correction. No long exposure dark frames are needed when making long exposures if recording raw."
7DM2 article quotes:
"The 7D Mark II results are compared to other cameras in Figure 3, where it is seen that the 7D Mark II dark current is about a factor of 10 lower that other cameras. That low dark current makes the 7D Mark II a game changer for long exposure low light photography."
"The dark current in the 7D Mark II doubles about every 4.8 degrees C on average. Note too that the lower the temperature, the fewer hot pixels show in the image. This makes long exposure night imaging more difficult in hot environments in general, but the 7D Mark II is the best in the Canon lineup. For example, the 7D Mark II in the 23 C range has dark current similar to other cameras, like the 7D Mark 1) working at 3 C."
Btw, here are 8-minute exposures on the 5DSR @ ISO 100 with no LENR. I presume the 5DS/R got the same long-exposure noise improvements as the 7DM2 that Roger mentioned in his article.
Guys if you have a single hot pixel eg it's always on viewfinder. Change the date of your camera back in time and power on. You will hear shutter go off and voila no more hot pixel!
davewolfs wrote:
Guys if you have a single hot pixel eg it's always on viewfinder. Change the date of your camera back in time and power on. You will hear shutter go off and voila no more hot pixel!
Tried that and didn't work. I believe that works only for stuck pixels and not hot pixels.
yunjo wrote:
Shadow noise I can handle and expect, hot pixels, not so much.
But cleaning excessive shadow noise has more detrimental effect on the picture than cleaning those hot pixels. I have tried a bunch of NR methods. Even the best, Topaz Denoise, would give visibly softened look to the image when I have to deal with excessive shadow noise. Masking only works for out of focus area or otherwise you have a soft part of a picture right next to a sharp/slightly noisy part. Hot pixels are more visible at first look, but after correcting them, I don't see any degradation to the original image.
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davewolfs wrote:
Guys if you have a single hot pixel eg it's always on viewfinder....
I think that is called stuck pixel since it's always present at one place. Hot pixel is supposed to be random. That is why it's better to take more than one dark frame to eliminate most hot pixels.
poses wrote:
Yunjo, i get the same hot pixels on my a7rii. gonna see if store copy does it too. would like to know if these are isolated defects we have!
Fred Miranda wrote:
It should actually work with most cameras.
Fred, I think this action would benefit with an extra step of color noise reduction. That would turn most of the red/blue hot pixels into monochromatic pixel, then dust&scratches would work better.
