A7rii Hot pixels during long exposure.

Started Aug 9, 2015 | Discussions
Maple888 Regular Member • Posts: 178
A7rii Hot pixels during long exposure.

I was just testing the camera doing long exposures ready for a trip to Iceland and found i was getting these results. This seems to be a similar problem that people complained about when they upgraded from the Olympus OM-D E-M5 to the Olympus em1, the em1 had this hot pixel problem in the shots unless LE NR was set to on, where as the em5 was much cleaner without having to have the NR on.

I did shots at iso 800 with shutter speeds from 2 to 30 seconds and LE NR off and found that the problem starts to get bad at around 5s onwards.Turning LE NR on gave a clean file.I then did the same test with my A7r and found that it was no where near as bad.

This is a bit disappointing as i was planing to use this for night timelapses now you are able to power from usb.

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Astrophotographer 10 Forum Pro • Posts: 13,235
Re: A7rii Hot pixels during long exposure.

That is definitely worse than a7R. I have never seen an a7R 30 second shot like that with that many hot pixels. I am a bit shocked. I thought it was supposed to be cleaner.

What was the temperature when you took this 30 second shot? Was it RAW, auto white balance?

What about an ISO6400 30 second night shot?

You could make a dark and a bias and used scaled darks so you set it up once and then subtract the master dark (say 12 x 30 second darks at the ISO you intend to use and make a master dark).

Same with a bias - shortest exposure with cap on to get a snapshot of the electronic noise. You need a bias for scaled darks which scale a base master dark to match the measured image which varies with temperatures and exposure lengths.

LENR is fine but it doubles the length of time to take the shots. Not a problem when its only 6 x 30 seconds but  time lapse. Unless you allow 35 seconds between time lapse shots to allow for the LENR to occur after every image taken in the time lapse.

Greg.

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OP Maple888 Regular Member • Posts: 178
Re: A7rii Hot pixels during long exposure.

It was about 15c outside.The iso doesnt seem to be a factor its the shutter speed as the time increases the hot pixels increase.

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Magnar W
Magnar W Senior Member • Posts: 4,155
Re: A7rii Hot pixels during long exposure.

Maple888 wrote:

I did shots at iso 800 with shutter speeds from 2 to 30 seconds and LE NR off and found that the problem starts to get bad at around 5s onwards. Turning LE NR on gave a clean file.

What was the temperature when you made the test shots? Temperature highly affects long exposure noise.

Also, why not use long exposure noise reduction if this is a problem, or make your own dark frames that are subtracted from the "light frames" (the exposures) at post processing?

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OP Maple888 Regular Member • Posts: 178
Re: A7rii Hot pixels during long exposure.

Astrophotographer 10 wrote:

That is definitely worse than a7R. I have never seen an a7R 30 second shot like that with that many hot pixels. I am a bit shocked. I thought it was supposed to be cleaner.

What was the temperature when you took this 30 second shot? Was it RAW, auto white balance?

What about an ISO6400 30 second night shot?

You could make a dark and a bias and used scaled darks so you set it up once and then subtract the master dark (say 12 x 30 second darks at the ISO you intend to use and make a master dark).

Same with a bias - shortest exposure with cap on to get a snapshot of the electronic noise. You need a bias for scaled darks which scale a base master dark to match the measured image which varies with temperatures and exposure lengths.

LENR is fine but it doubles the length of time to take the shots. Not a problem when its only 6 x 30 seconds but time lapse. Unless you allow 35 seconds between time lapse shots to allow for the LENR to occur after every image taken in the time lapse.

Greg.

yes for singles shots its not really a big deal i would use the LE NR set to on, i would usually take multiple shots and then merge them together to average the noise out anyway.But for long timelapses its not ideal.

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Astrophotographer 10 Forum Pro • Posts: 13,235
Re: A7rii Hot pixels during long exposure.

That's quite cool so ambient air temperature wasn't a factor.

Greg.

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Astrophotographer 10 Forum Pro • Posts: 13,235
Re: A7rii Hot pixels during long exposure.

No its not ideal and something you don't need to do with the a7R. Are you sure there is no setting turned on that is making this worse? Not sure what that would be though.

Greg.

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Astrophotographer 10 Forum Pro • Posts: 13,235
Re: A7rii Hot pixels during long exposure.

I guess the point here is this is worse than the a7R in performance. Now you have to do something to clean it up whereas it is not necessary with a7R. And that is only ISO800 which is way low for nightscapes or night time lapses. They are more done at ISO6400 or minimum ISO3200. I was hoping a7Rii ISO12800 was clean as ISO6400 is on a7R.

Greg.

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OP Maple888 Regular Member • Posts: 178
Re: A7rii Hot pixels during long exposure.

Astrophotographer 10 wrote:

I guess the point here is this is worse than the a7R in performance. Now you have to do something to clean it up whereas it is not necessary with a7R. And that is only ISO800 which is way low for nightscapes or night time lapses. They are more done at ISO6400 or minimum ISO3200. I was hoping a7Rii ISO12800 was clean as ISO6400 is on a7R.

Greg.

No all setting checked and as i say did the same with the a7r which didnt show anywhere near the amount of hot pixels at the same settings looks like it may well be a trait of the new sensor.When i first got it i did a few shots in my room at iso12800 to compare to my D750 and it was on par with the Nikon if not a hair better but that was probably shot at around 1/4s.Ill do a few more with a full range of iso settings latter after work.

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Esstee
Esstee Contributing Member • Posts: 649
Re: A7rii Hot pixels during long exposure.

Maple888 wrote:

I was just testing the camera doing long exposures ready for a trip to Iceland and found i was getting these results. This seems to be a similar problem that people complained about when they upgraded from the Olympus OM-D E-M5 to the Olympus em1, the em1 had this hot pixel problem in the shots unless LE NR was set to on, where as the em5 was much cleaner without having to have the NR on.

I did shots at iso 800 with shutter speeds from 2 to 30 seconds and LE NR off and found that the problem starts to get bad at around 5s onwards.Turning LE NR on gave a clean file.I then did the same test with my A7r and found that it was no where near as bad.

This is a bit disappointing as i was planing to use this for night timelapses now you are able to power from usb.

It looks as though the camera isn't applying long shutter NR
Which btw. all camera's do (automatically) as all sensors produce hot pixel noise in such conditions. Though the difference being, the A7R II may not address the noise automatically.

That said, you can however use a software like Raw Therapee or Capture One which offers hot pixel control tools to clean-up the image while you wait for Sony to issue a FW update to address this.

Also are you sure you can't toggle this function on or off in camera?

seachicken2000
seachicken2000 Veteran Member • Posts: 3,237
Re: A7rii Hot pixels during long exposure.

Was IBIS on? If it was I'd be interested to know if turning it off improves things, as IBIS may generate heat. It would also explain things, since the A7r has no IBIS.

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Mlenny
Mlenny New Member • Posts: 23
Re: A7rii Hot pixels during long exposure.
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OP Maple888 Regular Member • Posts: 178
Re: A7rii Hot pixels during long exposure.

seachicken2000 wrote:

Was IBIS on? If it was I'd be interested to know if turning it off improves things, as IBIS may generate heat. It would also explain things, since the A7r has no IBIS.

It was off

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Graham Best Veteran Member • Posts: 3,426
Re: A7rii Hot pixels during long exposure.

Esstee wrote:

It looks as though the camera isn't applying long shutter NR
Which btw. all camera's do (automatically) as all sensors produce hot pixel noise in such conditions. Though the difference being, the A7R II may not address the noise automatically.

With all the Sony cameras I've had, long exposure NR isn't performed "automatically", but is an option.

Edit:

All digital cameras do perform an automatic mapping of the sensor to remove hot pixels, usually monthly (and having nothing to do with long exposure NR). These hot pixels are normal to all sensors, and are a result of the manufacturing process. You might move your camera's date up to next month and see if you have any change.

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Ketan G Regular Member • Posts: 325
Re: A7rii Hot pixels during long exposure.

I'm seeing hot pixels as well. The issue is not that there are hot pixels, but that, as I understand, using Long Exposure Noise Reduction reduces the bit depth from "14 bits" to 12. Below is an enlarged crop (since these are individual pixels to see) from a 15 second exposure at ISO 100 exposed 1 stop under to protect for highlights. You may need to click on it to see as the preview doesn't show them on my screen:

I don't think this is a major issue, but it does force a trade off between noise reduction for these and bit depth. As I understand Sony's NR kicks in in ways you don't expect so the practical difference may be minimal. Still, it would be nice not to have that trade off.

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Esstee
Esstee Contributing Member • Posts: 649
Re: A7rii Hot pixels during long exposure.

Graham Best wrote:

Esstee wrote:

It looks as though the camera isn't applying long shutter NR
Which btw. all camera's do (automatically) as all sensors produce hot pixel noise in such conditions. Though the difference being, the A7R II may not address the noise automatically.

With all the Sony cameras I've had, long exposure NR isn't performed "automatically", but is an option.

Edit:

All digital cameras do perform an automatic mapping of the sensor to remove hot pixels, usually monthly (and having nothing to do with long exposure NR). These hot pixels are normal to all sensors, and are a result of the manufacturing process. You might move your camera's date up to next month and see if you have any change.

Most all camera's in existence perform long shutter NR to mitigate the noise created from the additional heat in the process. In most all systems, this is built-in and cannot be turned on or off.

Graham Best Veteran Member • Posts: 3,426
Re: A7rii Hot pixels during long exposure.

Esstee wrote:

Graham Best wrote:

Esstee wrote:

It looks as though the camera isn't applying long shutter NR
Which btw. all camera's do (automatically) as all sensors produce hot pixel noise in such conditions. Though the difference being, the A7R II may not address the noise automatically.

With all the Sony cameras I've had, long exposure NR isn't performed "automatically", but is an option.

Edit:

All digital cameras do perform an automatic mapping of the sensor to remove hot pixels, usually monthly (and having nothing to do with long exposure NR). These hot pixels are normal to all sensors, and are a result of the manufacturing process. You might move your camera's date up to next month and see if you have any change.

Most all camera's in existence perform long shutter NR to mitigate the noise created from the additional heat in the process. In most all systems, this is built-in and cannot be turned on or off.

That's interesting but what does that have to do with Sony camera's long exposure NR or this thread? As I said, it's a menu option (camera menu, pg. 5 on the a7r) on Sony cameras.

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Esstee
Esstee Contributing Member • Posts: 649
Re: A7rii Hot pixels during long exposure.

Graham Best wrote:

Esstee wrote:

Graham Best wrote:

Esstee wrote:

It looks as though the camera isn't applying long shutter NR
Which btw. all camera's do (automatically) as all sensors produce hot pixel noise in such conditions. Though the difference being, the A7R II may not address the noise automatically.

With all the Sony cameras I've had, long exposure NR isn't performed "automatically", but is an option.

Edit:

All digital cameras do perform an automatic mapping of the sensor to remove hot pixels, usually monthly (and having nothing to do with long exposure NR). These hot pixels are normal to all sensors, and are a result of the manufacturing process. You might move your camera's date up to next month and see if you have any change.

Most all camera's in existence perform long shutter NR to mitigate the noise created from the additional heat in the process. In most all systems, this is built-in and cannot be turned on or off.

That's interesting but what does that have to do with Sony camera's long exposure NR or this thread? As I said, it's a menu option (camera menu, pg. 5 on the a7r) on Sony cameras.

Because this would leave two options in my view:

1. the system is present but none functional (needs FW to correct)

2. the system can be toggle on or off by the user.

SQLGuy Veteran Member • Posts: 7,658
Re: A7rii Hot pixels during long exposure.

Esstee wrote:

Graham Best wrote:

Esstee wrote:

Graham Best wrote:

Esstee wrote:

It looks as though the camera isn't applying long shutter NR
Which btw. all camera's do (automatically) as all sensors produce hot pixel noise in such conditions. Though the difference being, the A7R II may not address the noise automatically.

With all the Sony cameras I've had, long exposure NR isn't performed "automatically", but is an option.

Edit:

All digital cameras do perform an automatic mapping of the sensor to remove hot pixels, usually monthly (and having nothing to do with long exposure NR). These hot pixels are normal to all sensors, and are a result of the manufacturing process. You might move your camera's date up to next month and see if you have any change.

Most all camera's in existence perform long shutter NR to mitigate the noise created from the additional heat in the process. In most all systems, this is built-in and cannot be turned on or off.

That's interesting but what does that have to do with Sony camera's long exposure NR or this thread? As I said, it's a menu option (camera menu, pg. 5 on the a7r) on Sony cameras.

Because this would leave two options in my view:

1. the system is present but none functional (needs FW to correct)

2. the system can be toggle on or off by the user.

It's 2. And the OP already stated that he doesn't want to use it, and has disabled it.

His main issue is that Long Exposure NR seems to be more needed with the A7RII than it is with the A7R. It's a more sensitive sensor, built on a different process, and apparently using some different analog gain as well, so it's not surprising to me that it behaves differently than the A7R sensor does under these conditions.

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Esstee
Esstee Contributing Member • Posts: 649
Re: A7rii Hot pixels during long exposure.

SQLGuy wrote:

It's 2. And the OP already stated that he doesn't want to use it, and has disabled it.

Then I see no issue here whatsoever.
Either the user chooses to turn on long shutter NR so as to have what other camera's have or he doesn't and deals with the effects of heat alternatively. Which isn't all bad if/when you think of it as I find most RAW developers address hot pixels better than in camera systems to begin with.

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