What's the use case for extremely high ISO?

**blues_hawk** · 08-08-2018, 08:26 AM - **1 Like**

Originally posted by victormeldrew

So, you're walking down a dark alley at night with a slow lens and no flash.
You see Britney Spears and J-Lo having an all-out cat fight in the nude.

1) Put it in full auto and high speed continuous.
2) Shoot
3) ???
4) $$$

Best possible use. :P

I also use stacking techniques on AP and night shots when possible, the heart and soul image was puhed and stacked and pushed some more from a stack of 30second exposures using a UHC filter to limit bandwidth and light pollution. I use a 48-52mm adapter on a 2 inch filter to put it on the lens.
I use Siril - in Linux for ap stacking operations.

**UncleVanya** · 08-08-2018, 08:27 AM - **1 Like**

Its also useful to recall that a 1 stop ISO change doubles (or halves) so the numbers get really high really fast. 3200 is 5 stops from 100, another 5 stops is 102400!

**blues_hawk** · 08-08-2018, 08:43 AM - **2 Likes**

It's also a good trade off in situations where you want to keep exposure as short as possible like this really busy butterfly on a Joe-pie in mixed weather.
I set shutter and aperture and let the gain set the levels in this one. Note the dust...so much dust...

iso6400

aitrus3 · 08-08-2018, 12:13 PM - **3 Likes**

As others have said, high ISO is great for checking focus and composition in the dark.
You can also stack high ISO shots, as a few others mentioned, to reduce noise. However, this type of noise reduction is less about "gathering more of the light" and more about: as ISO noise is random, when you stack images of the same subject, the random noise pixels get cancelled out because no two overlap. This improves signal to noise ratio not by increasing the amount of light, but literally decreasing the amount of random noise.

**UncleVanya** · 08-08-2018, 01:33 PM - **1 Like**

Originally posted by aitrus3

As others have said, high ISO is great for checking focus and composition in the dark.
You can also stack high ISO shots, as a few others mentioned, to reduce noise. However, this type of noise reduction is less about "gathering more of the light" and more about: as ISO noise is random, when you stack images of the same subject, the random noise pixels get cancelled out because no two overlap. This improves signal to noise ratio not by increasing the amount of light, but literally decreasing the amount of random noise.

The actual "signal" is reinforced by not being random essentially?

EDIT: Is this composite averaging?

aitrus3 · 08-08-2018, 01:43 PM - **3 Likes**

Originally posted by UncleVanya

The actual "signal" is reinforced by not being random essentially?

EDIT: Is this composite averaging?

Essentially yes. You do gain more signal, but significantly less than if you were to use a long exposure. 10x5 minute exposures at a lower ISO will always look way better than 100x 30s exposures stacked at high ISO. Even though it's the same amount of time, your s/n ratio in the 10x5 minute is already very good, and you improve on it even further by stacking.
Case in point: 2 of my Orion shots from previous years. First is 89x30s shots at ISO 1600 and the best I could do at the time for editing.
Second is a stack of 12 or so, at ISO 800 for 112s taken with my telescope on a proper tracking mount.
I much much prefer the second attempt.
Click on them and view them large in flickr.

---------- Post added 08-08-2018 at 02:03 PM ----------

I'm trying to find the link, but someone over at cloudy nights had a better example of high ISO/shorter exposure vs Low ISO/Longer exposure. While you do get nice noise reduction in the first scenario, it'll just never beat the amount of light captured in the first.

**clackers** · 08-08-2018, 04:34 PM - **2 Likes**

Originally posted by kiwi_jono

Obviously the results look better if you convert to black and white (where some noise can look interesting anyway).
The funny thing is it was a very dull day but I was shooting at 1/8000 and f8!

ISO 800K on the K-1 II looks a lot worse again (no idea why they bothered!)

Well done, Jono.

You've done about as good as anyone to keep some texture in the various surfaces (foliage, timber), but of course it's still too grainy even after being downsampled to this little Jpg, and the colour range has been butchered, because dynamic range is affected by ISO just as much as noise.

This is where flash really comes into it, with ISO 400 or less, the way a pro real estate photographer does it (they might have three hidden around a living area).

Hang on, I think I see Britney Spears and J-Lo wrestling behind that fence … nope, just artifacts!

LensBeginner · 08-08-2018, 04:58 PM - **1 Like**

Originally posted by mikeSF

i ran down to Big Sur to shoot bioluminescent algae on a beach under moonless conditions. At ISO 10,000, I was still at a 5 minute exposure to get a dim image. I learned on the shoot that I could even stack 10 images at 20,000 and get a much cleaner image than I had hoped for. I havent had another opportunity to do this since, but am ready for next time.

Thanks.
~3 stops down from ISO 20'000, that would be analogous to using ISO 2'500 or thereabouts.
Unfortunately, diminishing returns come into play, because of how the thing works, but you had a good hunch

LensBeginner · 08-08-2018, 04:59 PM - **3 Likes**

Originally posted by victormeldrew

So, you're walking down a dark alley at night with a slow lens and no flash.
You see Britney Spears and J-Lo having an all-out cat fight in the nude.

1) Put it in full auto and high speed continuous.
2) Shoot
3) ???
4) $$$

Uh... ditch the camera and join the fray?

rawr · 08-08-2018, 08:32 PM - **2 Likes**

My use case for very high ISO is stuff like night time rodeo, where you simply can't use flash because it's a live sports stadium, the light is horribly dim because it's a country-town stadium with only 3 crappy flood-lights illuminating a big area of action, and yet you need to maintain a fast shutter of 1/500 or more to have any hope of freezing action. Plus you need to maintain your lens at f4 on a 70-200 to boost the DOF a tad, given that the subject is 3D and dynamic.

Decent camera performance at ISO 12800 (or above) suddenly becomes essential, because ISO is the only parameter that gives you leeway.

MJKoski · 08-09-2018, 12:49 AM - **1 Like**

ISO has no meaning with ISO invariant camera. You can shoot at low ISO and boost later. With K-1 MK2 this is especially important as you have much less control over noise reduction later.

pxt · 08-25-2018, 10:36 AM - **1 Like**

Theorically it can be switch off.

leekil · 08-25-2018, 12:46 PM - **1 Like**

Originally posted by aitrus3

Case in point: 2 of my Orion shots from previous years. First is 89x30s shots at ISO 1600 and the best I could do at the time for editing.
Second is a stack of 12 or so, at ISO 800 for 112s taken with my telescope on a proper tracking mount.
I much much prefer the second attempt.

Why do you prefer the second one? Because the stars are much sharper?

I suggest a black-point level setting for the second, to make the black blacker and the colors pop more, unless you have a specific reason for not wanting to do that.

aitrus3 · 08-25-2018, 07:44 PM - **3 Likes**

Originally posted by leekil

Why do you prefer the second one? Because the stars are much sharper?

I suggest a black-point level setting for the second, to make the black blacker and the colors pop more, unless you have a specific reason for not wanting to do that.

The second has more nebulosity visible, stars are sharper, and a flat field. First was 89 shots, second was either one of the 12, or the final stack of 12. Near the same amount of time overall i think but longer exposures turn out better.

08-08-2018, 08:43 AM - 2 Likes	#33
blues_hawk Site Supporter Join Date: Jul 2016 Location: Patrick Co. Virginia Photos: Gallery \| Albums Posts: 1,540	It's also a good trade off in situations where you want to keep exposure as short as possible like this really busy butterfly on a Joe-pie in mixed weather. I set shutter and aperture and let the gain set the levels in this one. Note the dust...so much dust... iso6400 Attached Images Last edited by blues_hawk; 08-08-2018 at 08:44 AM. Reason: show iso...

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08-08-2018, 08:26 AM - 1 Like	#31
blues_hawk Site Supporter Join Date: Jul 2016 Location: Patrick Co. Virginia Photos: Gallery \| Albums Posts: 1,540	Originally posted by victormeldrew So, you're walking down a dark alley at night with a slow lens and no flash. You see Britney Spears and J-Lo having an all-out cat fight in the nude. 1) Put it in full auto and high speed continuous. 2) Shoot 3) ??? 4) $$$ Best possible use. :P I also use stacking techniques on AP and night shots when possible, the heart and soul image was puhed and stacked and pushed some more from a stack of 30second exposures using a UHC filter to limit bandwidth and light pollution. I use a 48-52mm adapter on a 2 inch filter to put it on the lens. I use Siril - in Linux for ap stacking operations.

08-08-2018, 08:27 AM - 1 Like	#32
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,459	Its also useful to recall that a 1 stop ISO change doubles (or halves) so the numbers get really high really fast. 3200 is 5 stops from 100, another 5 stops is 102400!

08-08-2018, 12:13 PM - 3 Likes	#34
aitrus3 Pentaxian Join Date: Mar 2010 Location: Kamloops B.C. Photos: Gallery \| Albums Posts: 1,432	As others have said, high ISO is great for checking focus and composition in the dark. You can also stack high ISO shots, as a few others mentioned, to reduce noise. However, this type of noise reduction is less about "gathering more of the light" and more about: as ISO noise is random, when you stack images of the same subject, the random noise pixels get cancelled out because no two overlap. This improves signal to noise ratio not by increasing the amount of light, but literally decreasing the amount of random noise.

08-08-2018, 01:33 PM - 1 Like	#35
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,459	Originally posted by aitrus3 As others have said, high ISO is great for checking focus and composition in the dark. You can also stack high ISO shots, as a few others mentioned, to reduce noise. However, this type of noise reduction is less about "gathering more of the light" and more about: as ISO noise is random, when you stack images of the same subject, the random noise pixels get cancelled out because no two overlap. This improves signal to noise ratio not by increasing the amount of light, but literally decreasing the amount of random noise. The actual "signal" is reinforced by not being random essentially? EDIT: Is this composite averaging?

08-08-2018, 01:43 PM - 3 Likes	#36
aitrus3 Pentaxian Join Date: Mar 2010 Location: Kamloops B.C. Photos: Gallery \| Albums Posts: 1,432	Originally posted by UncleVanya The actual "signal" is reinforced by not being random essentially? EDIT: Is this composite averaging? Essentially yes. You do gain more signal, but significantly less than if you were to use a long exposure. 10x5 minute exposures at a lower ISO will always look way better than 100x 30s exposures stacked at high ISO. Even though it's the same amount of time, your s/n ratio in the 10x5 minute is already very good, and you improve on it even further by stacking. Case in point: 2 of my Orion shots from previous years. First is 89x30s shots at ISO 1600 and the best I could do at the time for editing. Second is a stack of 12 or so, at ISO 800 for 112s taken with my telescope on a proper tracking mount. I much much prefer the second attempt. Click on them and view them large in flickr. ---------- Post added 08-08-2018 at 02:03 PM ---------- I'm trying to find the link, but someone over at cloudy nights had a better example of high ISO/shorter exposure vs Low ISO/Longer exposure. While you do get nice noise reduction in the first scenario, it'll just never beat the amount of light captured in the first.

08-08-2018, 04:34 PM - 2 Likes	#37
clackers Otis Memorial Pentaxian Join Date: Jul 2013 Location: Melbourne Photos: Albums Posts: 16,397	Originally posted by kiwi_jono Obviously the results look better if you convert to black and white (where some noise can look interesting anyway). The funny thing is it was a very dull day but I was shooting at 1/8000 and f8! ISO 800K on the K-1 II looks a lot worse again (no idea why they bothered!) Well done, Jono. You've done about as good as anyone to keep some texture in the various surfaces (foliage, timber), but of course it's still too grainy even after being downsampled to this little Jpg, and the colour range has been butchered, because dynamic range is affected by ISO just as much as noise. This is where flash really comes into it, with ISO 400 or less, the way a pro real estate photographer does it (they might have three hidden around a living area). Hang on, I think I see Britney Spears and J-Lo wrestling behind that fence … nope, just artifacts!

08-08-2018, 04:58 PM - 1 Like	#38
LensBeginner Veteran Member Join Date: Sep 2014 Photos: Albums Posts: 4,696	Originally posted by mikeSF i ran down to Big Sur to shoot bioluminescent algae on a beach under moonless conditions. At ISO 10,000, I was still at a 5 minute exposure to get a dim image. I learned on the shoot that I could even stack 10 images at 20,000 and get a much cleaner image than I had hoped for. I havent had another opportunity to do this since, but am ready for next time. Thanks. ~3 stops down from ISO 20'000, that would be analogous to using ISO 2'500 or thereabouts. Unfortunately, diminishing returns come into play, because of how the thing works, but you had a good hunch

08-08-2018, 04:59 PM - 3 Likes	#39
LensBeginner Veteran Member Join Date: Sep 2014 Photos: Albums Posts: 4,696	Originally posted by victormeldrew So, you're walking down a dark alley at night with a slow lens and no flash. You see Britney Spears and J-Lo having an all-out cat fight in the nude. 1) Put it in full auto and high speed continuous. 2) Shoot 3) ??? 4) $$$ Uh... ditch the camera and join the fray?

08-08-2018, 08:32 PM - 2 Likes	#40
rawr Veteran Member Join Date: Jun 2009 Posts: 11,913	My use case for very high ISO is stuff like night time rodeo, where you simply can't use flash because it's a live sports stadium, the light is horribly dim because it's a country-town stadium with only 3 crappy flood-lights illuminating a big area of action, and yet you need to maintain a fast shutter of 1/500 or more to have any hope of freezing action. Plus you need to maintain your lens at f4 on a 70-200 to boost the DOF a tad, given that the subject is 3D and dynamic. Decent camera performance at ISO 12800 (or above) suddenly becomes essential, because ISO is the only parameter that gives you leeway.

08-09-2018, 12:49 AM - 1 Like	#41
MJKoski Veteran Member Join Date: Aug 2016 Posts: 1,784	ISO has no meaning with ISO invariant camera. You can shoot at low ISO and boost later. With K-1 MK2 this is especially important as you have much less control over noise reduction later.

08-25-2018, 10:36 AM - 1 Like	#42
pxt Senior Member Join Date: Jul 2018 Posts: 290	Theorically it can be switch off.

08-25-2018, 12:46 PM - 1 Like	#43
leekil Pentaxian Join Date: May 2016 Photos: Albums Posts: 2,003	Originally posted by aitrus3 Case in point: 2 of my Orion shots from previous years. First is 89x30s shots at ISO 1600 and the best I could do at the time for editing. Second is a stack of 12 or so, at ISO 800 for 112s taken with my telescope on a proper tracking mount. I much much prefer the second attempt. Why do you prefer the second one? Because the stars are much sharper? I suggest a black-point level setting for the second, to make the black blacker and the colors pop more, unless you have a specific reason for not wanting to do that.

08-25-2018, 07:44 PM - 3 Likes	#44
aitrus3 Pentaxian Join Date: Mar 2010 Location: Kamloops B.C. Photos: Gallery \| Albums Posts: 1,432	Originally posted by leekil Why do you prefer the second one? Because the stars are much sharper? I suggest a black-point level setting for the second, to make the black blacker and the colors pop more, unless you have a specific reason for not wanting to do that. The second has more nebulosity visible, stars are sharper, and a flat field. First was 89 shots, second was either one of the 12, or the final stack of 12. Near the same amount of time overall i think but longer exposures turn out better.