ETR Metering

[Ed Erkes]

Its only ETTR if you are adjusting the exposure at base ISO because changing ISO does not add any data to the sensors, it only amplifies what was captured. A proper level of brightness can be obtained with any of the three controls, but you are still only working with what was captured by the aperture and shutter settings (and the latter is even in question form the posts above). People shoot for proper exposure for a variety of reasons rather than ETTR, especially of they do not plan on doing post processing.

--Ken

I'm not using ISO to ETTR . I said I agreed 100% with Steve's first point. I also stated that I am maximizing image data or "signal". Adjusting ISO does not accomplish this.
I'm adjusting shutter speed and aperture for ETTR.

And if you are not post- processing, then you are not getting the best out of your images.

 

[Replytoken]

I'm not using ISO to ETTR . I said I agreed 100% with Steve's first point. I also stated that I am maximizing image data or "signal". Adjusting ISO does not accomplish this.
I'm adjusting shutter speed and aperture for ETTR.

And if you are not post- processing, then you are not getting the best out of your images.

I think that we are getting to roughly the same point with slightly different definitions, and that may be adding to some miscommunications, but yes it now seems clear that when possible, you have been trying to first implement ETTR at base ISO before making other adjustments. And I do agree that post processing allows one to get the most of their images. But there are some photographers, for whatever reasons, who shoot jpegs and shoot their images like they are shooting transparencies (i.e. what they shoot is what they will work with). For them, ETTR is not really an option. Thankfully, many of today's camera bodies offer a lot more control over the recorded image than those from the early days of digital, but I still prefer to post process as it allows me more options.

--Ken

 

[bleirer]

I agree with you 100% about the first point you make above. But I really don't understand the last point at all.

What do you mean by "proper level of brightness"? When I'm capturing an image, my goal is generally to capture as much data, or "signal", as I can. I determine proper exposure during post-processing when I adjust highlights, midtones, and shadows to get the "look" I want for the image. If your definition of proper exposure leaves a good bit of room on the right of the in- camera histogram (whether at base or higher ISOs), then you are not capturing as much signal as you could.

If I try to the place the data as far to the right of histogram, using the zebra stripes to prevent clipping of highlights, how is that not not ETTR? My definition of proper exposure is ETTR. My definition of overexposure is the clipping of important highlights.

Now if I am photographing action against changing light levels and background tonalities, then I may hedge my exposure to the left to avoid clipping highlights. And to counter another argument for ETTR, I don't recall ever noticing a problem with poor color fidelity during post-processing of ETTR images.

I think ettr would be putting the brightest non specular part of the scene as high as possible without clipping, EVEN if that brightest part would not normally be that bright. Normal exposure would place the brights where they fit into the scene, sometimes the brightest thing in a low key image might be upper middle. An ettr shooter would force it to the edge, someone going for normal exposure would let it fall where it falls.

One issue would be culling, some ettr shots have to be adjusted to reveal they are not ruined.

Another would be, at least on my camera, 2 channels have to clip for the blinkies to blink. I notice this with things like macro of red flowers, the zebras never flash even if the red is clipped.

 

[AndoverBob]

I've been thinking about this conversation a bit and one thing I think is happening is that ISO is treated as if it's an exposure control when it's not. I think there's an idea that ISO, Shutter Speed, and F/Stop are all equals in the exposure triangle and the truth is, they're not.

I think it helps to consider the order of how an image is created. Shutter speed and aperture are first and expose the sensor. This is the ONLY place where you can improve your signal-to-noise ratio and lower your noise levels.

So, if you shoot a properly exposed image at base ISO, no ISO gain is added - it's done. However, if you overexpose to the just before point of clipping at base ISO, that can only be done with shutter speed and aperture - so you can increase the SNR here.

However, if the image you have captured at base ISO is too dark, then you use the "volume knob" of ISO to turn up the brightness. The thing is, this is done after the shutter speed and aperture have done their job and the noise patten is already fixed. ISO can't change what's there and it can't improve the SNR - that's already set my the shutter speed and aperture. All ISO can do is can only make what you already have brighter.

That's why I keep saying ETTR is really only effective at base ISO (or, in the case of dual gain sensors, you can see an advantage once the secondary amp kicks in). That's also why I say that, unless you're at base ISO (or at the ISO just before the second gain circuit kicks in), there's nothing to be gained by deliberately overexposing your shot. Just shoot a proper level of brightness and it's all good

Hi Steve, long time lurker, 1st post.

I understand all the physics here, but I am still confused about how this transfers to my field work. I shoot birds primarily, hand held. So if they are stationary, with the 200-500 on my D7500 I need a high shutter speed (1/1500 and up) just to keep the image stable. Of course, for BIF the shutter speed will higher. As a consequence, base ISO is rarely going to fill the histogram. But if all I am doing is adjusting the gain, I don't see where it matters if it's in the camera or post; it will all be the same as there is no change to SNR with increased ISO. So why bother with the ISO adjustments in the field? I am having trouble wrapping my head around this.

Sorry if this is a dumb question.

Bob

 

[Replytoken]

Hi Steve, long time lurker, 1st post.

I understand all the physics here, but I am still confused about how this transfers to my field work. I shoot birds primarily, hand held. So if they are stationary, with the 200-500 on my D7500 I need a high shutter speed (1/1500 and up) just to keep the image stable. Of course, for BIF the shutter speed will higher. As a consequence, base ISO is rarely going to fill the histogram. But if all I am doing is adjusting the gain, I don't see where it matters if it's in the camera or post; it will all be the same as there is no change to SNR with increased ISO. So why bother with the ISO adjustments in the field? I am having trouble wrapping my head around this.

Sorry if this is a dumb question.

Bob

It will depend on our camera, shooting preference and post processing software. With good software and a camera that is ISO invariant, you can make the adjustments in post processing rather than at the time of shooting and you should get the same or similar results. But not all cameras are invariant, and not everybody has good post processing skills and/or good software, so dealing with it in camera might make more sense.

--Ken

 

[Steve]

Hi Steve, long time lurker, 1st post.

I understand all the physics here, but I am still confused about how this transfers to my field work. I shoot birds primarily, hand held. So if they are stationary, with the 200-500 on my D7500 I need a high shutter speed (1/1500 and up) just to keep the image stable. Of course, for BIF the shutter speed will higher. As a consequence, base ISO is rarely going to fill the histogram. But if all I am doing is adjusting the gain, I don't see where it matters if it's in the camera or post; it will all be the same as there is no change to SNR with increased ISO. So why bother with the ISO adjustments in the field? I am having trouble wrapping my head around this.

Sorry if this is a dumb question.

Bob

What Ken said is spot on.

In addition, I think there are times the camera may do a better job of balancing A/D conversion than RAW processing software, although it's rare to see it. Most of the time all I do is maximize the amount of light hitting the sensor via shutter speed and F/stop and then adjust ISO for the proper brightness level. Yes, you can just shoot at base ISO or where the extra amp kicks in and brighten in post with the same results as had you shot the proper ISO in the field.

However, I think there is value in getting it right in-camera for two reasons - first, when I'm evaluating images in the field to see if I "got it" looking at a three stop underexposure isn't reassuring. Second, when I use the proper brightness, I have verification of the ISO. If I'm just shooting at base ISO and brightening in post, I'm only guessing how far I'm going to have to push the exposure. If I expose properly in the field, I can see - for sure - where my ISO is, and if it's too high, try to make adjustments.

The bottom line with everything I've posted here is really simple - just shoot a proper exposure in the field and don't spend mental resources worrying if your histogram is far enough to the right. Just get a proper exposure and do what you can to maximize the amount of light hitting the sensor (i.e keep Iso as low as you can). That's what I do and have done for years now. So far, it's worked out pretty well.

 

[bleirer]

Hi Steve, long time lurker, 1st post.

I understand all the physics here, but I am still confused about how this transfers to my field work. I shoot birds primarily, hand held. So if they are stationary, with the 200-500 on my D7500 I need a high shutter speed (1/1500 and up) just to keep the image stable. Of course, for BIF the shutter speed will higher. As a consequence, base ISO is rarely going to fill the histogram. But if all I am doing is adjusting the gain, I don't see where it matters if it's in the camera or post; it will all be the same as there is no change to SNR with increased ISO. So why bother with the ISO adjustments in the field? I am having trouble wrapping my head around this.

Sorry if this is a dumb question.

Bob

Good question, actually. Looking at how your camera responds to iso in the chart linked below. You can see that it improves with in camera iso up to 400 then stays at the same level at all the higher iso settings. So that is info you could use to devise a personal strategy if you wanted to bother with ettr. For example if your ettr exposure left you at iso 400 or below, then maybe go for ettr, but above 400 then don't worry about ettr and just meter it straight or else see if you can safely give a little on shutter speed or f number to get to 400 or below. Above 400 give up on ettr and maybe start trading off iso with shutter speed or f number if you have anything left to give, or just go with iso once you are as wide and slow as you comfortably want to go. At that point the in camera iso is not hurting you at least if you have gotten your shutter as slow as you're willing to risk and the aperture as wide as you're willing to accept.. That article i posted earlier about optimizing image quality is a good read as far as the various trade offs go.

Shadow Improvement of Photographic Dynamic Range versus ISO Setting

.

 

[Woodyg3]

The bottom line with everything I've posted here is really simple - just shoot a proper exposure in the field and don't spend mental resources worrying if your histogram is far enough to the right. Just get a proper exposure and do what you can to maximize the amount of light hitting the sensor (i.e keep Iso as low as you can). That's what I do and have done for years now. So far, it's worked out pretty well.

Exactly the way I feel, as well.

 

[AndoverBob]

Good question, actually. Looking at how your camera responds to iso in the chart linked below. You can see that it improves with in camera iso up to 400 then stays at the same level at all the higher iso settings. So that is info you could use to devise a personal strategy if you wanted to bother with ettr. For example if your ettr exposure left you at iso 400 or below, then maybe go for ettr, but above 400 then don't worry about ettr and just meter it straight or else see if you can safely give a little on shutter speed or f number to get to 400 or below. Above 400 give up on ettr and maybe start trading off iso with shutter speed or f number if you have anything left to give, or just go with iso once you are as wide and slow as you comfortably want to go. At that point the in camera iso is not hurting you at least if you have gotten your shutter as slow as you're willing to risk and the aperture as wide as you're willing to accept.. That article i posted earlier about optimizing image quality is a good read as far as the various trade offs go.

Shadow Improvement of Photographic Dynamic Range versus ISO Setting

.

Interesting site. Thanks

Bob

 

[Nextlife1]

Am I interpreting this correctly for the Z9? Overall, dynamic range is highest and relatively flat from native up to maybe 1200, then decreases. However, shadow recovery is given added dynamic range of 1 from about 1200 on. However, as ISO increases above a certain point (say 1200), so will noise and so is the danger for blowing out highlights.

I don't shoot in low light, so my biggest concern has always been losing the sky. Is lowest ISO still my best bet for maximum DR but I'm "safe" shooting up to say 800-1,000 at dusk? RAW and LR/PS.

I have similar questions, though I don't understand your comment about DR being flat up to 1200. This is the Z9 curve I see for DR vs. ISO:

Looing at this curve I have assumed that if I am going to be below ISO 500 I really want to be all the way down to 200 or below, as values in between are suboptimal (and like shooting at ISOs higher than 500). But then I look at the shadow recovery curve:

Which suggest to me that anything at 400 and below is where I want to be. My rudimentary understanding of these concepts won't let me reconcile these two things. Can someone explain it to me? Thanks!

 

[Nimi]

I have similar questions, though I don't understand your comment about DR being flat up to 1200. This is the Z9 curve I see for DR vs. ISO:
View attachment 30831

Looing at this curve I have assumed that if I am going to be below ISO 500 I really want to be all the way down to 200 or below, as values in between are suboptimal (and like shooting at ISOs higher than 500). But then I look at the shadow recovery curve:
View attachment 30832

Which suggest to me that anything at 400 and below is where I want to be. My rudimentary understanding of these concepts won't let me reconcile these two things. Can someone explain it to me? Thanks!

That was an error on my part, which is why I deleted my question. Lower iso=higher DR. EXCEPT that there is a bump in shadow DR recovery as ISO increases.

 

[Ed Erkes]

I notice this with things like macro of red flowers, the zebras never flash even if the red is clipped.

If your zebras aren't even flashing then you haven't set the zebras for the proper level.
These 2 videos explain it well.

Zebra 109+ for Sony Raw Photographers - Mark Galer

Choose the most appropriate exposure using Sony’s Zebra feature. Photographers shooting in the Raw file format have a little highlight recovery headroom, so the optimum level for being warned of overexposed highlights (that cannot be recovered in Raw editing software) is to create a Custom level...

www.markgaler.com

 

[KimM]

If your zebras aren't even flashing then you haven't set the zebras for the proper level.
These 2 videos explain it well.

Zebra 109+ for Sony Raw Photographers - Mark Galer

Choose the most appropriate exposure using Sony’s Zebra feature. Photographers shooting in the Raw file format have a little highlight recovery headroom, so the optimum level for being warned of overexposed highlights (that cannot be recovered in Raw editing software) is to create a Custom level...

www.markgaler.com

Thank you for these tutorials Ed. I have been using 109 but there is a recommendation for 107 on the R4... so I will experiment with this.

 

[John Woodworth]

That was an error on my part, which is why I deleted my question. Lower iso=higher DR. EXCEPT that there is a bump in shadow DR recovery as ISO increases.

The ability to see detail in low light depends on how close to the inherent noise floor of the sensor system (detector + amplifier + ADC) is the signal from a pixel.

Taking the Z9 as an example, the noise floor of the detector system takes a step downwards by about 1.2 EV at about ISO 400. This is done by switching to a different amplification chain at that ISO.

So that means you can recover (see more detail) in the darkest shadows at ISO 500 than you can at ISO 400 by about 1.2 EV.

 

[Nimi]

The ability to see detail in low light depends on how close to the inherent noise floor of the sensor system (detector + amplifier + ADC) is the signal from a pixel.

Taking the Z9 as an example, the noise floor of the detector system takes a step downwards by about 1.2 EV at about ISO 400. This is done by switching to a different amplification chain at that ISO.

So that means you can recover (see more detail) in the darkest shadows at ISO 500 than you can at ISO 400 by about 1.2 EV.

Thanks, so if I want maximum DR and maximum shadow recovery what's the optimal ISO for the Z9?

 

[bleirer]

If your zebras aren't even flashing then you haven't set the zebras for the proper level.
These 2 videos explain it well.

Zebra 109+ for Sony Raw Photographers - Mark Galer

Choose the most appropriate exposure using Sony’s Zebra feature. Photographers shooting in the Raw file format have a little highlight recovery headroom, so the optimum level for being warned of overexposed highlights (that cannot be recovered in Raw editing software) is to create a Custom level...

www.markgaler.com

Those zebras in the viewfinder look cool. On my canon i have to take a test shot. And the ability to set the levels something my Canon doesn't do either.

However, what I was taking about was the color channels, not luminosity. Might be worth checking out see how your camera responds. On mine two colors have to be blown to get any blinkies. Usually no issue, but it proves that a single color can be badly blown yet the blinkies don't blink. If I shoot something totally red, a rose for example, the color histogram for red might be far up the right wall, but if a 2nd color is not over the limit the blinkies don't blink.

 

[John Woodworth]

Thanks, so if I want maximum DR and maximum shadow recovery what's the optimal ISO for the Z9?

ISO 64.

 

[jhorsch]

I was taught the reason to ETTR was that the further right you move on the histogram, short of blowing it out, the more data is captured. As a result you can correct the exposure (move the histogram left) in post and keep all the data for better IQ, whereas if you underexpose you lose IQ when correcting the exposure in post (move the histogram to the right) because there's less data. Is that no longer true with newer cameras, such as Nikon Zs?

 

[Replytoken]

I was taught the reason to ETTR was that the further right you move on the histogram, short of blowing it out, the more data is captured. As a result you can correct the exposure (move the histogram left) in post and keep all the data for better IQ, whereas if you underexpose you lose IQ when correcting the exposure in post (move the histogram to the right) because there's less data. Is that no longer true with newer cameras, such as Nikon Zs?

In general, I do not believe things have changed, so what you have briefly described is still a good summary of ETTR.

--Ken