Exposing to the right with high ISO

Started Apr 14, 2012 | Discussions
twald
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Exposing to the right with high ISO
Apr 14, 2012

Following is an image shot at ISO 25,000 with the NEX-5N. I took this RAW, opened in LR4 to adjust levels and exported. I did not apply noise reduction.

I know, it's nothing artistic but I tried something new (to me)

I did a bit of experimenting and found that raising the ISO does not really raise the image noise--if you lower the exposure in PP. With that said, you should use the highest ISO possible without blowing the highlights.

According to an article on Luminous Landscape on "Exposing to the Right," shooting like this gives you better color information because up to half of the camera's bit depth is used in the top 1/5 of the histogram. If that is so, using higher ISO should, in theory, give you a better signal/noise ratio in certain situations than a lower ISO. They did not talk about using this method with high ISO, so I tried it myself.

Would anyone care to try this? Take a low-light picture using your usual ISO, shutter, and aperture (raw, of course). Then take another picture, leaving the shutter and aperture where it is and increasing the ISO so that you almost blow the highlights. Finally, open them in LR or equivalent and make the exposure equal.

Note that the in-camera histogram is based on jpeg and the raw has quite a bit of headroom over the jpeg (ie. the histogram will sometimes show clipping when the raw is a full stop away from clipping). To get the most out of the raw, set the camera to portrait and set both contrast and saturation to -3. You could also try to intentionally clip some highlights and see how the raw compares.

Sony Alpha NEX-5N
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twald
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Re: Exposing to the right with high ISO
In reply to twald, Apr 14, 2012

Also, this image is not downsized; it is cropped. Here's a 100% center crop:

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uuronl
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Re: Exposing to the right with high ISO
In reply to twald, Apr 14, 2012

That's pretty astounding quality.

With that said, I think you'd have far less light in a situation where you'd intentionally select ISO 25600. You'd really only want to think about using 25600 to speed up the shutter, and exposing to the right is going to slow down your shutter speed (meaning you could select a lower ISO at regular exposure and the same shutter and get as good or better quality).

Also, if the shutter gets slow enough, you'll have to steady the camera (and be shooting a subject that is stationary) so it's going to be hard to find a situation where this is called for.

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Mark Weston
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In reply to twald, Apr 14, 2012

Thank you for sharing with your example. I shoot raw only and generally ignore the everything other than aperture, shutter speed, ISO exposure compensation and focus. I had not thought about the cameras settings such as portrait impacting my raw file.

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RussellInCincinnati
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never realized histogram was based on jpeg
In reply to twald, Apr 14, 2012

Guess it's plausible. Switched my camera to Portrait mode, saturation and contrast minimal, didn't notice a huge difference immediately, will investigate further when have time. Thanks.

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twald
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Re: never realized histogram was based on jpeg
In reply to RussellInCincinnati, Apr 14, 2012

Note that the portrait, or any other style, does not effect the raw file. It only changes the in-camera display of the image, including the histogram.

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twald
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Re: Exposing to the right with high ISO
In reply to uuronl, Apr 14, 2012

uuronl wrote:

That's pretty astounding quality.

With that said, I think you'd have far less light in a situation where you'd intentionally select ISO 25600. You'd really only want to think about using 25600 to speed up the shutter, and exposing to the right is going to slow down your shutter speed (meaning you could select a lower ISO at regular exposure and the same shutter and get as good or better quality).

Also, if the shutter gets slow enough, you'll have to steady the camera (and be shooting a subject that is stationary) so it's going to be hard to find a situation where this is called for.

I agree with what you are saying. However, where this might be useful is when shooting, say, 3200 ISO. Move it up to 6400 or 12000 so that it almost clips the highlights and adjust the exposure in PP. This approach definitely works better than trying to lift shadows because shadow noise can quickly become a problem--much more so than overexposure at a higher ISO.

I do realize that this approach has drawbacks. The most significant one is that dynamic range is fairly limited.

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villebon
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Re: Exposing to the right with high ISO
In reply to twald, Apr 14, 2012

twald wrote:

To get the most out of the raw, set the camera to portrait and set both contrast and saturation to -3. You could also try to intentionally clip some highlights and see how the raw compares.

Raw is affected by contrast and saturation settings now? When did that come to be?

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Villebon

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Philip Corlis
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Re: Exposing to the right with high ISO
In reply to twald, Apr 14, 2012

Boy I wish I understood how the ETTR concept applies to the latest generation of Sony sensors better.

I have read that many consider the Luminous Landscape article out of date, applying more to the last generation of sensors than the modern ones. In short, it may not work as described. The danger of this technique (I think) is that it significantly reduces the dynamic range of the sensor. So, Sony's latest batch of sensors may capture 11 - 12 stops of contrast at ISO 100, but they are only capable of capturing 7 stops at 3200.

Like I said, I don't prevent to understand this concept fully - but what I've read suggests this is an idea that has come and gone.

I may be completely wrong so I hope someone can clear this up for me.
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twald
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Re: Exposing to the right with high ISO
In reply to villebon, Apr 14, 2012

villebon wrote:

twald wrote:

To get the most out of the raw, set the camera to portrait and set both contrast and saturation to -3. You could also try to intentionally clip some highlights and see how the raw compares.

Raw is affected by contrast and saturation settings now? When did that come to be?

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Villebon

I specifically said that it does not affect the raw file. I said that it affects the in-camera jpeg that the histogram is based on.

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villebon
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Re: Exposing to the right with high ISO
In reply to Philip Corlis, Apr 14, 2012

Philip Corlis wrote:

Like I said, I don't prevent to understand this concept fully - but what I've read suggests this is an idea that has come and gone.

What works even better is MFNR (multiple frame noise reduction) which is available in some Sony cameras. Set ISO at 25600, mode to MFNR (jpegs only) and press shutter button once. The camera will take several shots in a burst, do in camera noise reduction and give you a pratically noise free image.

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Villebon

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probert500
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Re: Exposing to the right with high ISO
In reply to twald, Apr 14, 2012

twald wrote:

Following is an image shot at ISO 25,000 with the NEX-5N. I took this RAW, opened in LR4 to adjust levels and exported. I did not apply noise reduction.

I know, it's nothing artistic but I tried something new (to me)

I did a bit of experimenting and found that raising the ISO does not really raise the image noise--if you lower the exposure in PP. With that said, you should use the highest ISO possible without blowing the highlights.

According to an article on Luminous Landscape on "Exposing to the Right," shooting like this gives you better color information because up to half of the camera's bit depth is used in the top 1/5 of the histogram. If that is so, using higher ISO should, in theory, give you a better signal/noise ratio in certain situations than a lower ISO. They did not talk about using this method with high ISO, so I tried it myself.

Would anyone care to try this? Take a low-light picture using your usual ISO, shutter, and aperture (raw, of course). Then take another picture, leaving the shutter and aperture where it is and increasing the ISO so that you almost blow the highlights. Finally, open them in LR or equivalent and make the exposure equal.

Note that the in-camera histogram is based on jpeg and the raw has quite a bit of headroom over the jpeg (ie. the histogram will sometimes show clipping when the raw is a full stop away from clipping). To get the most out of the raw, set the camera to portrait and set both contrast and saturation to -3. You could also try to intentionally clip some highlights and see how the raw compares.

Interesting. - Instinctively I've always tried to avoid boosting exposure in shadow areas. Conversely, if the situation is very contrasty I'm willing to let the shadows go black rather than have blown highlights. Rarely do blown highlights read right but dark shadow areas do. Although, to some degree its contextual.

Have you also tried the anti motion blur and twilight modes? You will have a jpeg but the resultant image has shadow detail and is noise free at iso6400 with no loss of detail. Pretty amazing.

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twald
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Re: Exposing to the right with high ISO
In reply to Philip Corlis, Apr 14, 2012

OK, so I just debunked my own theory.

Following are two images, the only difference between them being the ISO setting on the camera. I took the first one at ISO 3200 and let the camera determine the metering. I set camera to manual and took the second one at ISO 25600, making sure the shutter and aperture stays the same as the first one. I then lowered the exposure of the second one in LR by 3.5 EV.

While the second one shows remarkable noise control at ISO 25600 on an APS-C sensor, the first one is slightly better.

What this does prove is that simple ISO comparisons don't necessarily show which system will perform better in low light.

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Philip Corlis
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Re: Exposing to the right with high ISO
In reply to villebon, Apr 14, 2012

Thanks for the reply! It sounds like yet another jpeg only slick trick available in some cameras... BTW, isn't that the basic idea behind the NEX Hand Held Twilight mode or am I quacking up the wrong tree?

Thanks Again!
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flint-hill
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Bravo!
In reply to twald, Apr 14, 2012

Good for you for doing the experiment and reporting results. You're doing real science when you debunk your own theory!

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rakurai
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Re: Exposing to the right with high ISO
In reply to twald, Apr 15, 2012

Simply brilliant!

I'm seeing this as an alternative of HHT and AMB, for shooting handheld in low light.

Did some test here, 1st ISO 25600, 2nd ISO 12800. Both handheld 1/50 sec, F1.8, EV-2.5 in PP, same level of noise reduction, purple fringing everywhere haha

Notice that the level of details almost the same, but of course 25600 is twice brighter.
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