What I learned from Gollywop -- and what I wonder

Started Mar 26, 2013 | Discussions
bowportes
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What I learned from Gollywop -- and what I wonder
Mar 26, 2013

As an old fart of a photographer, I thought I knew all about exposure -- you know, aperture, shutter-speed, and ISO.  The point was to nail the proper exposure as given by the camera. Behaving like I had ektachrome loaded in a digital camera, I rarely over- or under-exposed unless I had a situation of backlighting or snow.  The Panny G-series cameras, by shifting the color of the histogram to yellow (caution) if I used the thumb-wheel to increase/lesson exposure, encouraged me to keep it white -- right where the camera automatically exposes.

This may be fine general practice for JPEG shooters, but it turns out it was wrong for capturing raw.

Gollywop's recent post encouraged me to think instead of maximizing the sensor's exposure to light. Rather than accepting the camera's exposure, I should overexpose images just (but not quite) to the point of clipping highlights at base ISO (ETTR). The histogram may go yellow and the image may appear too light in the viewfinder, but as long as the right side of the histogram has not reached the right edge of its axis, go ahead and overexpose.  My raw-processed image will be better for it, in spite of the fact that it doesn't look as good in the EVF at +2/3 exposure as when it's not set to overexpose.  Watching the histogram (or blinkies on an Olympus) is your key for how far to amplify exposure.

Something that's not as clear to me though.  If ISO is at base (160 for most Pannys and 200 for Olympus), the lens is at maximum aperture, and shutter-speed can't be set slower, but the histogram still sits right in the middle -- not overexposed at all -- if I understand correctly, I might get some improvement in image quality by raising the ISO to 400 or 800 in order to overexpose the image, as long as I'm careful not to overexpose to the point where I'm clipping highlights. I'd like confirmation that this is correct.

Another situation that I've commonly encountered in the past is desiring to have the lens wide open in bright daylight. This typically means ISO is at 160 (base), my F1.8 or 2.8 lens is wide open, and shutter speed is as fast as my G5 can take it.  In the past, the EVF still sometimes indicated this gave too much light, so I was compelled to reduce my aperture since ISO couldn't be lowered and SS couldn't be increased, and my goal was to achieve proper exposure for my raw file. But now, if I understand the Gollywop thread correctly, I should be pleased with the overexposure and leave the aperture wide open, as long as it doesn't clip highlights.

So my understanding is that the point is to fully charge the sensor.  Rather than thinking, as I used to, in terms of proper exposure (as my G5's visual indicators still recommend), I should instead think of full exposure, giving the sensor as much light as it can take (without clipping).

I need to stop thinking in film terms; they would never have led me to these conclusions.

Thanks to Gollywop and others who contributed to the discussion. I hope I am getting some of the practical implications right.  If not, please correct me.

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texinwien
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Re: What I learned from Gollywop -- and what I wonder
In reply to bowportes, Mar 26, 2013

bowportes wrote:

Rather than accepting the camera's exposure, I should overexpose images just (but not quite) to the point of clipping highlights at base ISO (ETTR). ... My raw-processed image will be better for it, in spite of the fact that it doesn't look as good in the EVF at +2/3 exposure as when it's not set to overexpose.

Correct

Something that's not as clear to me though. If ISO is at base (160 for most Pannys and 200 for Olympus), the lens is at maximum aperture, and shutter-speed can't be set slower, but the histogram still sits right in the middle -- not overexposed at all -- if I understand correctly, I might get some improvement in image quality by raising the ISO to 400 or 800 in order to overexpose the image, as long as I'm careful not to overexpose to the point where I'm clipping highlights. I'd like confirmation that this is correct.

That's correct.

You'll want to look at sensorgen.info and DxOMark for data on your camera's sensor to figure out which ISOs make sense for you to use. The basic story is that going up in ISO always(?) lowers dynamic range, tonal range and color sensitivity (bad) but sometimes lowers read noise (good). Your task is to balance those positives and negatives out. You could do this in a per-scene basis, but that might be a lot of work, so basic guidelines might be more helpful and easier to remember.

For instance, on the G3 you should avoid ISO 200 - you'll have lower dynamic range, tonal range and color sensitivity than at ISO 160, and you'll have HIGHER read noise. E-M5 users should avoid ISO 250 and 320 for similar reasons.

E-M5 rule of thumb: Use ISO 200, where possible. Skip 250 and 320. ISO 400 and 800 will net you a reasonable reduction in read noise. ISO 1600 will net you a tiny reduction in read noise. After that, the sensor is pretty much ISO-less, and it won't pay off to use higher ISOs. Short rule: 200 when you can, 400 or 800 are ok if you can't ETTR at 200, 1600 isn't all bad. Anything higher than that should be avoided.

G3 rule of thumb: Very similar to the E-M5 - 160 when you can. Avoid 200. 400 and 800 are ok if you can't ETTR at 160. 1600 isn't all bad. Anything higher than that should be avoided.

These rules of thumb also apply in cases where things are really dark. It can make more sense to 'underexpose' at ISO 800 than bump up your ISO to 3200 or 6400. I shoot like this some times, using a maximum ISO of 800 or 1600 and shutter speed priority to freeze motion at parties or indoor events. Here's one I 'underexposed' by a couple of stops at ISO 1600, then brightened in post:

Available light. Underexposed by a couple of stops at ISO 1600. Brightened in post.

But now, if I understand the Gollywop thread correctly, I should be pleased with the overexposure and leave the aperture wide open, as long as it doesn't clip highlights.

Correct - as long as you're not blowing important highlights, you're in good shape.

So my understanding is that the point is to fully charge the sensor. Rather than thinking, as I used to, in terms of proper exposure (as my G5's visual indicators still recommend), I should instead think of full exposure, giving the sensor as much light as it can take (without clipping).

Right.

I need to stop thinking in film terms; they would never have led me to these conclusions.

Mostly right, I think. If you were developing your own film, however, and knew its characteristics, it could have also made sense to use a similar strategy - get as much exposure as you can without blowing highlights and process accordingly when you develop.

For the most part, though, I think film-shooters were primarily concerned about protecting highlights, especially if they weren't developing them film, themselves.

tex

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LincolnB
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Re: What I learned from Gollywop -- and what I wonder
In reply to bowportes, Mar 26, 2013

bowportes wrote:

Something that's not as clear to me though. If ISO is at base (160 for most Pannys and 200 for Olympus), the lens is at maximum aperture, and shutter-speed can't be set slower, but the histogram still sits right in the middle -- not overexposed at all -- if I understand correctly, I might get some improvement in image quality by raising the ISO to 400 or 800 in order to overexpose the image, as long as I'm careful not to overexpose to the point where I'm clipping highlights. I'd like confirmation that this is correct.

You might get less highlight clipping and less shadow noise but you'll get more sensor noise overall. There is a trade-off.

The shutter speed can almost always be set slower, unless you're photographing movement. Bulb mode on my G3 is something like 2 minutes.

Another situation that I've commonly encountered in the past is desiring to have the lens wide open in bright daylight. This typically means ISO is at 160 (base), my F1.8 or 2.8 lens is wide open, and shutter speed is as fast as my G5 can take it. In the past, the EVF still sometimes indicated this gave too much light, so I was compelled to reduce my aperture since ISO couldn't be lowered and SS couldn't be increased, and my goal was to achieve proper exposure for my raw file. But now, if I understand the Gollywop thread correctly, I should be pleased with the overexposure and leave the aperture wide open, as long as it doesn't clip highlights.

Yes, Expose To The Right and then adjust the exposure to taste (i.e. "correct") in post.

So my understanding is that the point is to fully charge the sensor. Rather than thinking, as I used to, in terms of proper exposure (as my G5's visual indicators still recommend), I should instead think of full exposure, giving the sensor as much light as it can take (without clipping).

Yes, without clipping. That is the essence of ETTR.

I need to stop thinking in film terms; they would never have led me to these conclusions.

Yes - It's possible to do edits in post with digital that weren't easy with film. Take advantage of them.

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richarddd
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Re: What I learned from Gollywop -- and what I wonder
In reply to bowportes, Mar 26, 2013

The idea is to get as much light on the sensor as possible, consistent with (1) not having such a wide aperture that you don't have enough DOF, (2) not having such a slow shutter speed that you have motion blur and (3) not clipping highlights in which you want to preserve detail.

Blinkies are much more useful than the histogram for checking the last point.

If you still aren't at clipping, then you should consider increasing ISO if it will decrease noise and not give you too little dynamic range.  The effect of ISO on noise and dynamic range on your camera can be checked at sensorgen.info

You might have to dial back brightness and make other adjustments in processing.

You should experiment to make sure it all works well for you with your camera. For example, check if the blinkies correlate well enough with clipping and check the effects of increasing ISO

All this assumes you're shooting RAW

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texinwien
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Re: What I learned from Gollywop -- and what I wonder
In reply to LincolnB, Mar 26, 2013

LincolnB wrote:

bowportes wrote:

Something that's not as clear to me though. If ISO is at base (160 for most Pannys and 200 for Olympus), the lens is at maximum aperture, and shutter-speed can't be set slower, but the histogram still sits right in the middle -- not overexposed at all -- if I understand correctly, I might get some improvement in image quality by raising the ISO to 400 or 800 in order to overexpose the image, as long as I'm careful not to overexpose to the point where I'm clipping highlights. I'd like confirmation that this is correct.

You might get less highlight clipping and less shadow noise but you'll get more sensor noise overall. There is a trade-off.

I believe that is incorrect. Assuming exposure stays the same (same luminance, aperture and shutter speed), going from a lower ISO with higher read noise to a higher ISO with lower read noise (say, from ISO 200 to ISO 400 on the E-M5) will net you less noise.

It will, however, also net you less dynamic range, tonal range and color sensitivity. That's where the tradeoff comes into play with this strategy. You have to decide whether the drop in read noise is worth the tradeoff in the loss of dynamic range, tonal range and color sensitivity that comes along with it (when bumping ISO from 200 to 400 on the E-M5 and keeping exposure the same, as an example).

tex

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richarddd
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Re: What I learned from Gollywop -- and what I wonder
In reply to richarddd, Mar 26, 2013

Another good source of information is this thread http://forums.dpreview.com/forums/post/42595072

See the links in the first post. You may have to click on the camera name in the right pane. The linked chart clearly shows the noise issue on the E-M5 between ISO 200 and 400.

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Michael Meissner
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Re: What I learned from Gollywop -- and what I wonder
In reply to richarddd, Mar 26, 2013

richarddd wrote:

Another good source of information is this thread http://forums.dpreview.com/forums/post/42595072

See the links in the first post. You may have to click on the camera name in the right pane. The linked chart clearly shows the noise issue on the E-M5 between ISO 200 and 400.

Various posts over the years have said that the Panasonic sensor used by the earlier Pens tends to have less noise when you use the full stop ISO's (200, 400, 800, 1600, 3200) rather than the intermediate versions.  There is an option to only use whole stops in auto ISO.  It sounds like the same is probably true of the Sony sensor used in the E-M5, E-PL5, and E-PM2.

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Vlad S
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Make sure to test it
In reply to bowportes, Mar 26, 2013

Go ahead with the rules suggested above, but try to test it for your typical scenes. In the past we had threads with test images, and everyone saw what they wanted to see. I think this indicates that the difference is not that big, but everybody has their own criteria what's important and what's not. At any rate, I would encourage you to do your own tests, with your own style of processing, rather than take anyone's word for it.

Vlad

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bowportes
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Re: What I learned from Gollywop -- and what I wonder
In reply to Michael Meissner, Mar 26, 2013

Michael Meissner wrote:

richarddd wrote:

Another good source of information is this thread http://forums.dpreview.com/forums/post/42595072

See the links in the first post. You may have to click on the camera name in the right pane. The linked chart clearly shows the noise issue on the E-M5 between ISO 200 and 400.

Various posts over the years have said that the Panasonic sensor used by the earlier Pens tends to have less noise when you use the full stop ISO's (200, 400, 800, 1600, 3200) rather than the intermediate versions. There is an option to only use whole stops in auto ISO. It sounds like the same is probably true of the Sony sensor used in the E-M5, E-PL5, and E-PM2.

I may remember poorly, but I think I read once (somewhere in the forum) that 160, 320, 640, 1280, etc. Were the appropriate full stops on the GH2. And I had inferred from that that those were the ones to focus upon on the G5. If this is wrong, I'd like clear word on that

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Pedagydusz
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Re: What I learned from Gollywop -- and what I wonder
In reply to texinwien, Mar 26, 2013

texinwien wrote:

[...] It will, however, also net you less dynamic range, tonal range and color sensitivity. [...]

I don't understand this part. Why, in ISOless situations, do you get less DR, for example, or color sensitivity? It does not make sense to what I thought I had understood!

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gollywop
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Re: What I learned from Gollywop -- and what I wonder
In reply to bowportes, Mar 26, 2013

bowportes wrote:

As an old fart of a photographer, I thought I knew all about exposure -- you know, aperture, shutter-speed, and ISO. The point was to nail the proper exposure as given by the camera. Behaving like I had ektachrome loaded in a digital camera, I rarely over- or under-exposed unless I had a situation of backlighting or snow. The Panny G-series cameras, by shifting the color of the histogram to yellow (caution) if I used the thumb-wheel to increase/lesson exposure, encouraged me to keep it white -- right where the camera automatically exposes.

This may be fine general practice for JPEG shooters, but it turns out it was wrong for capturing raw.

Gollywop's recent post encouraged me to think instead of maximizing the sensor's exposure to light. Rather than accepting the camera's exposure, I should overexpose images just (but not quite) to the point of clipping highlights at base ISO (ETTR). The histogram may go yellow and the image may appear too light in the viewfinder, but as long as the right side of the histogram has not reached the right edge of its axis, go ahead and overexpose. My raw-processed image will be better for it, in spite of the fact that it doesn't look as good in the EVF at +2/3 exposure as when it's not set to overexpose. Watching the histogram (or blinkies on an Olympus) is your key for how far to amplify exposure.

texinwien's post just under your OP pretty much answers your questions on the button. Now all I have to do is get you to not use the term over-expose as you have above

Over-exposre is when you blow out the sensor at base ISO. You can be excused for a confusion on this score, because in my post Exposure vs. Brightening, I used the term over-saturate for this. But it was agreed by many that the term saturation should be reserved for its meaning in describing color intensity. Thus, in my revision I am reclaiming the term over-exposure to mean the situation when so much light falls on the sensor that some photosites (sensels) are gifted with more electrons than they can hold -- blown, in the vernacular.

So rather than "I should overexpose images just (but not quite) to the point of clipping highlights at base ISO (ETTR)" you would think "I should expose at base ISO to just below the point where raw clipping occurs, ETTR." This is not over-exposure, it's just plain ETTR.

Something that's not as clear to me though. If ISO is at base (160 for most Pannys and 200 for Olympus), the lens is at maximum aperture, and shutter-speed can't be set slower, but the histogram still sits right in the middle -- not overexposed at all -- if I understand correctly, I might get some improvement in image quality by raising the ISO to 400 or 800 in order to (overexpose -> brighten) the image, as long as I'm careful not to (overexpose to the point where I'm clipping highlights -> overexpose). I'd like confirmation that this is correct.

Again here. In the above, I've altered the verbiage that has been bold-faced. The boldface regular is the original text. The boldface italics is my suggested replacement. In the second change, note that overexposure to the point of clipping is redundant.

The G5 appears to be a very slightly semi-ISOless camera. Read noise does fall up to 800 or without commensurate loss in DR -- but the read noise is pretty low across the board. So it would appear you could exploit some ISO increases with relative impunity if they otherwise worked to your advantage when you are unable to ETTR.

Another situation that I've commonly encountered in the past is desiring to have the lens wide open in bright daylight. This typically means ISO is at 160 (base), my F1.8 or 2.8 lens is wide open, and shutter speed is as fast as my G5 can take it. In the past, the EVF still sometimes indicated this gave too much light, so I was compelled to reduce my aperture since ISO couldn't be lowered and SS couldn't be increased, and my goal was to achieve proper (exposure -> brightness) for my raw file. But now, if I understand the Gollywop thread correctly, I should be pleased with the (overexposure -> exposure) and leave the aperture wide open, as long as (it doesn't clip highlights -> highlights aren't clipped).

Again, just sayin'.

So my understanding is that the point is to fully charge the sensor. Rather than thinking, as I used to, in terms of proper exposure (as my G5's visual indicators still recommend), I should instead think of full exposure, giving the sensor as much light as it can take (without clipping).

Yup -- whatever "proper" means

I need to stop thinking in film terms; they would never have led me to these conclusions.

Thanks to Gollywop and others who contributed to the discussion. I hope I am getting some of the practical implications right. If not, please correct me.

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Re: What I learned from Gollywop -- and what I wonder
In reply to Pedagydusz, Mar 26, 2013

Pedagydusz wrote:

texinwien wrote:

[...] It will, however, also net you less dynamic range, tonal range and color sensitivity. [...]

I don't understand this part. Why, in ISOless situations, do you get less DR, for example, or color sensitivity? It does not make sense to what I thought I had understood!

The sensor's saturation capacity always drops with increased ISO, and with it the largest signal able to be captured.  Thus, even if noise remains constant with ISO, DR will fall.  DR is the number of stops in SatCapacity/ReadNoise.

Check out www.sensorg.com to see these relations for a number of different cameras.

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richarddd
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Re: What I learned from Gollywop -- and what I wonder
In reply to Michael Meissner, Mar 26, 2013

Michael Meissner wrote:

richarddd wrote:

Another good source of information is this thread http://forums.dpreview.com/forums/post/42595072

See the links in the first post. You may have to click on the camera name in the right pane. The linked chart clearly shows the noise issue on the E-M5 between ISO 200 and 400.

Various posts over the years have said that the Panasonic sensor used by the earlier Pens tends to have less noise when you use the full stop ISO's (200, 400, 800, 1600, 3200) rather than the intermediate versions. There is an option to only use whole stops in auto ISO. It sounds like the same is probably true of the Sony sensor used in the E-M5, E-PL5, and E-PM2.

For the E-M5, ISOs between 200 and 400 have higher noise than 200 or 400, but above 400 intermediate values are fine.  Noise stops decreasing in the 800-1600 range.

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richarddd
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Re: What I learned from Gollywop -- and what I wonder
In reply to gollywop, Mar 26, 2013

gollywop wrote:

Pedagydusz wrote:

texinwien wrote:

[...] It will, however, also net you less dynamic range, tonal range and color sensitivity. [...]

I don't understand this part. Why, in ISOless situations, do you get less DR, for example, or color sensitivity? It does not make sense to what I thought I had understood!

The sensor's saturation capacity always drops with increased ISO, and with it the largest signal able to be captured. Thus, even if noise remains constant with ISO, DR will fall. DR is the number of stops in SatCapacity/ReadNoise.

Check out www.sensorg.com to see these relations for a number of different cameras.

That link doesn't work. See the link in my post above, http://forums.dpreview.com/forums/post/51163548

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bowportes
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Re: Make sure to test it
In reply to Vlad S, Mar 26, 2013

Vlad S wrote:

Go ahead with the rules suggested above, but try to test it for your typical scenes. In the past we had threads with test images, and everyone saw what they wanted to see. I think this indicates that the difference is not that big, but everybody has their own criteria what's important and what's not. At any rate, I would encourage you to do your own tests, with your own style of processing, rather than take anyone's word for it.

Vlad

Vlad, I don't know whether the "testing" you are referring to is specific to the question of raising ISO beyond base, or if it refers to the entire idea of going for "full exposure".  ??

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richarddd
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Re: Make sure to test it
In reply to bowportes, Mar 26, 2013

bowportes wrote:

Vlad S wrote:

Go ahead with the rules suggested above, but try to test it for your typical scenes. In the past we had threads with test images, and everyone saw what they wanted to see. I think this indicates that the difference is not that big, but everybody has their own criteria what's important and what's not. At any rate, I would encourage you to do your own tests, with your own style of processing, rather than take anyone's word for it.

Vlad

Vlad, I don't know whether the "testing" you are referring to is specific to the question of raising ISO beyond base, or if it refers to the entire idea of going for "full exposure". ??

I don't know anyone disagrees with maximum light on the sensor (within constraints of DOF and motion blur), so ISO testing is more important, but why not test everything?

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Prokyon
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Re: What I learned from Gollywop -- and what I wonder
In reply to texinwien, Mar 26, 2013

texinwien wrote:

Assuming exposure stays the same (same luminance, aperture and shutter speed), going from a lower ISO with higher read noise to a higher ISO with lower read noise (say, from ISO 200 to ISO 400 on the E-M5) will net you less noise.

It will, however, also net you less dynamic range, tonal range and color sensitivity.

isn't this misleading ? if exposure stays the same and ISO 400 is not overexposed, ISO 200 would not be fully saturated by at least one stop and because of the lower read noise at ISO 400 the dynamic range can be increased

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texinwien
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Re: What I learned from Gollywop -- and what I wonder
In reply to Prokyon, Mar 26, 2013

Prokyon wrote:

texinwien wrote:

Assuming exposure stays the same (same luminance, aperture and shutter speed), going from a lower ISO with higher read noise to a higher ISO with lower read noise (say, from ISO 200 to ISO 400 on the E-M5) will net you less noise.

It will, however, also net you less dynamic range, tonal range and color sensitivity.

isn't this misleading ? if exposure stays the same and ISO 400 is not overexposed, ISO 200 would not be fully saturated by at least one stop and because of the lower read noise at ISO 400 the dynamic range can be increased

That's a good point. The maximum possible DR will fall as you raise the ISO. As long as you're still not experiencing unwanted highlight clipping at the higher ISO with the exact same exposure, you will get more DR out of that same exposure at the higher ISO, because of the decrease in read noise.

Which is the whole reason for recommending that one raise ISO if they've reached the max exposure at base ISO (the max allowed by their desired aperture and shutter speed) but still have plenty of highlight headroom.

How about a correction of the above sentence to: It will, however, also net you less lower maximum dynamic range, tonal range and color sensitivity.

Sound good? Thanks for pointing it out.

tex

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Macx
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Re: What I learned from Gollywop -- and what I wonder
In reply to gollywop, Mar 26, 2013

gollywop wrote:

bowportes wrote:

As an old fart of a photographer, I thought I knew all about exposure -- you know, aperture, shutter-speed, and ISO. The point was to nail the proper exposure as given by the camera. Behaving like I had ektachrome loaded in a digital camera, I rarely over- or under-exposed unless I had a situation of backlighting or snow. The Panny G-series cameras, by shifting the color of the histogram to yellow (caution) if I used the thumb-wheel to increase/lesson exposure, encouraged me to keep it white -- right where the camera automatically exposes.

This may be fine general practice for JPEG shooters, but it turns out it was wrong for capturing raw.

Gollywop's recent post encouraged me to think instead of maximizing the sensor's exposure to light. Rather than accepting the camera's exposure, I should overexpose images just (but not quite) to the point of clipping highlights at base ISO (ETTR). The histogram may go yellow and the image may appear too light in the viewfinder, but as long as the right side of the histogram has not reached the right edge of its axis, go ahead and overexpose. My raw-processed image will be better for it, in spite of the fact that it doesn't look as good in the EVF at +2/3 exposure as when it's not set to overexpose. Watching the histogram (or blinkies on an Olympus) is your key for how far to amplify exposure.

texinwien's post just under your OP pretty much answers your questions on the button. Now all I have to do is get you to not use the term over-expose as you have above

Over-exposre is when you blow out the sensor at base ISO. You can be excused for a confusion on this score, because in my post Exposure vs. Brightening, I used the term over-saturate for this. But it was agreed by many that the term saturation should be reserved for its meaning in describing color intensity. Thus, in my revision I am reclaiming the term over-exposure to mean the situation when so much light falls on the sensor that some photosites (sensels) are gifted with more electrons than they can hold -- blown, in the vernacular.

So rather than "I should overexpose images just (but not quite) to the point of clipping highlights at base ISO (ETTR)" you would think "I should expose at base ISO to just below the point where raw clipping occurs, ETTR." This is not over-exposure, it's just plain ETTR.

Something that's not as clear to me though. If ISO is at base (160 for most Pannys and 200 for Olympus), the lens is at maximum aperture, and shutter-speed can't be set slower, but the histogram still sits right in the middle -- not overexposed at all -- if I understand correctly, I might get some improvement in image quality by raising the ISO to 400 or 800 in order to (overexpose -> brighten) the image, as long as I'm careful not to (overexpose to the point where I'm clipping highlights -> overexpose). I'd like confirmation that this is correct.

Again here. In the above, I've altered the verbiage that has been bold-faced. The boldface regular is the original text. The boldface italics is my suggested replacement. In the second change, note that overexposure to the point of clipping is redundant.

Don't use "brighten" in this sense, though. You're raising ISO to 400 or 800 to reduce read noise and maximise available camera dynamic range, NOT because it brightens the raw file (which it can't) nor because of what it does to final image after the raw file has been developed, which would be unwanted.

The G5 appears to be a very slightly semi-ISOless camera. Read noise does fall up to 800 or without commensurate loss in DR -- but the read noise is pretty low across the board. So it would appear you could exploit some ISO increases with relative impunity if they otherwise worked to your advantage when you are unable to ETTR.

Another situation that I've commonly encountered in the past is desiring to have the lens wide open in bright daylight. This typically means ISO is at 160 (base), my F1.8 or 2.8 lens is wide open, and shutter speed is as fast as my G5 can take it. In the past, the EVF still sometimes indicated this gave too much light, so I was compelled to reduce my aperture since ISO couldn't be lowered and SS couldn't be increased, and my goal was to achieve proper (exposure -> brightness) for my raw file. But now, if I understand the Gollywop thread correctly, I should be pleased with the (overexposure -> exposure) and leave the aperture wide open, as long as (it doesn't clip highlights -> highlights aren't clipped).

Again, just sayin'.

And again, it's meaningless to use "brightness" to describe a raw file. Your final image may be bright or not, but the raw file isn't, and final image brightness has nothing to do with your camera settings.

I'm in full agreement with everything else

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Hen3ry
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Many thanks to Golly, Bowie, and Tex -- very illuminating!
In reply to bowportes, Mar 26, 2013

I have to (shamefacedly) admit that Golly's post left me floundering. About a quarter of the way through, I staggered to halt, blamed it all on the fact that he was talking ab out RAW when I am a JPEG shooter, and went outside to take a picture -- a nice simple one with lots of light around!

My apologies, Golly, I should have tried harder.

Now that Bowie has interpreted it and Tex polished it a little, I grok it. Thanks to you both.

In fact, it is right on the money of what I have been thinking about and doing more and more of with my E-PL3 -- paying a lot of attention to the histogram and to getting the highlights up to the right end since the E-PL3 doesn’t take kindly at all to under exposure (and is pretty desperate at 800 ISO in my view -- not that that worries me at all).

I can then mess with the histogram (or even -- extreme, edgy stuff -- the curves!!!) in PP to darken the pic a bit or whatever.

Something my focus on the highlights has made me more conscious of is which highlights I might be clipping. Do they matter? From time to time I had been disappointed by results in "correctly" exposed pix where preserving the highlights had pushed more important stuff into nether world of Oly 12 MPX JPEG shadows.

I have now learned to scan the pic for highlights and shadows -- and on occasion, to let those highlights blow so important matter is lifted out of the shadows into the mid tones.

Thanks again all three -- I see more clearly now (but I will continue in JPEG where possible!)

Cheers, geoff

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