Pls show examples where increasing brightness in post better than increasing ISO.

Started Oct 1, 2013 | Discussions
Jeff Veteran Member • Posts: 5,087
Re: Pls show examples where increasing brightness in post better than increasing ISO.
1

bobn2 wrote:

ultimitsu wrote:

bobn2 wrote:

So, mostly the metering is checking highlights. The easy technique is to set 2 1/2 or a bit more stops of EC and spot meter off the highlights (if your camera lets you use EC in M). On most camera there are a few ISO settings to be working with, and you know those pretty well anyway.

This sounds quite interesting, can you elaborate a bit on how it works? why 2.5 stops?

Your meter should be calibrated to centre when it gets 18% grey as the nominal exposure (10/ISO lux seconds). So, you need to miscalibrate it to regard 100% as nominal. According to ISO, the ratio of highlight to 18% is 78/10 = 7.8 = 2.96 stops (funny what these discussions can do - I see I miscalculated a long time ago, and have been giving my highlights a bit less than I could - dial in 3 stops). So, if the meter reads highlight and thinks it's 18% grey, it will give 3 stops less exposure than it should - so you correct that with EC, or recalibrating the meter (most will not let you recalibrate that far). In practice if you know how much headroom your camera has, you could dial in more than that.

(Just going back through my working, I realise where the extra half a stop came from, ISO leaves 1/2 stop for specular highlights over white - I must have taken it off somewhere along the line - 3 stops is better)

-- hide signature --

Bob

This is more or less what I've learned to do when shooting in challenging light, but with a small twist.

My E-P5 allows me to adjust the level for shadow and highlight 'blinkies', which I've set at jpeg levels 5 and 250, respectively. In A priority, the rear control wheel adjusts aperture, and the front control wheel adjusts EC.

When taking a shot, exposure is set by keeping an eye on the blinkies while adjusting EC, and while monitoring everything else to be sure I'm not totally killing the shadows. EC will generally fall between -0.5 and -2.5, but the critical issue is watch where the highlights and shadows fall on the live histogram and, via the blinkies, on the image.

The resulting jpeg preview may look off (generally too dark) but this procedure will give me a good raw file for subsequent processing in LR. ISO is a tertiary consideration. I generally try to work at base ISO, but will increase ISO as necessary to keep the viewfinder and jpeg previews usable.

Here are some results http://www.flickr.com/photos/jck_photos/sets/72157635431417147/

It becomes second nature pretty quickly.

texinwien Veteran Member • Posts: 3,326
Re: Pls show examples where increasing brightness in post better than increasing ISO.

Jeff wrote:

bobn2 wrote:

ultimitsu wrote:

bobn2 wrote:

So, mostly the metering is checking highlights. The easy technique is to set 2 1/2 or a bit more stops of EC and spot meter off the highlights (if your camera lets you use EC in M). On most camera there are a few ISO settings to be working with, and you know those pretty well anyway.

This sounds quite interesting, can you elaborate a bit on how it works? why 2.5 stops?

Your meter should be calibrated to centre when it gets 18% grey as the nominal exposure (10/ISO lux seconds). So, you need to miscalibrate it to regard 100% as nominal. According to ISO, the ratio of highlight to 18% is 78/10 = 7.8 = 2.96 stops (funny what these discussions can do - I see I miscalculated a long time ago, and have been giving my highlights a bit less than I could - dial in 3 stops). So, if the meter reads highlight and thinks it's 18% grey, it will give 3 stops less exposure than it should - so you correct that with EC, or recalibrating the meter (most will not let you recalibrate that far). In practice if you know how much headroom your camera has, you could dial in more than that.

(Just going back through my working, I realise where the extra half a stop came from, ISO leaves 1/2 stop for specular highlights over white - I must have taken it off somewhere along the line - 3 stops is better)

-- hide signature --

Bob

This is more or less what I've learned to do when shooting in challenging light, but with a small twist.

My E-P5 allows me to adjust the level for shadow and highlight 'blinkies', which I've set at jpeg levels 5 and 250, respectively. In A priority, the rear control wheel adjusts aperture, and the front control wheel adjusts EC.

When taking a shot, exposure is set by keeping an eye on the blinkies while adjusting EC, and while monitoring everything else to be sure I'm not totally killing the shadows. EC will generally fall between -0.5 and -2.5, but the critical issue is watch where the highlights and shadows fall on the live histogram and, via the blinkies, on the image.

The resulting jpeg preview may look off (generally too dark) but this procedure will give me a good raw file for subsequent processing in LR. ISO is a tertiary consideration. I generally try to work at base ISO, but will increase ISO as necessary to keep the viewfinder and jpeg previews usable.

Here are some results http://www.flickr.com/photos/jck_photos/sets/72157635431417147/

It becomes second nature pretty quickly.

I started typing a similar reply, took a break, and here you've gone and done the work, yourself!

The live-view 'blinkies' overexposure indicators are a boon to ETTR raw photogs. Add sufficient controls (i.e. Olympus E-M5, E-P5, E-M1) and you have an ETTR dream machine.

I, too, started out in A mode, mostly, but since Anders W convinced me that there was little advantage to A or S over M when using the blinkies method of ETTR, I have switched, and stay in M 99% of the time.

What comes out are images that are usually within a (<1/3) fraction of a stop from optimal ETTR. As much light as possible collected without blowing any important highlights - consistently.

Since the E-M5 (and E-P5) sensor is not 100% ISO-invariant, I do switch between ISO 200, 400 and 800 (rarely 1600). My sincere hope is that the next generation of OM-D models will be truly ISO-invariant, so I can forget that useless (to me) throwback to ancient history and get on with making properly-exposed photographs - one less useless variable to have to keep in mind.

 texinwien's gear list:texinwien's gear list
Panasonic Lumix DMC-GM5 Olympus E-M5 II Olympus 12-40mm F2.8 OnePlus One Canon EOS 300D +20 more
ProfHankD
ProfHankD Veteran Member • Posts: 5,291
The meaning of ISO, NEX-7 vs. EOS 7D
1

Jeff wrote:

PhilPreston3072 wrote:

With the latest sensors, some have been proclaiming it's better to shoot at base ISO and increase brightness in post rather than increase ISO in camera.

I would like to see some examples of this. Are there any examples where increasing brightness in post delivers better IQ than increasing ISO in camera? And please, disable all NR settings.

Here's a comparative example from Pierre Sottas comparing the same exposure made at ISO 100 and ISO 6400. http://www.dpreview.com/forums/post/36903045 Note the difference in how the highlights have been captured.

ISO film speed is a bit of a judgement call for sensors used in digital cameras. Basically, the notion of ISO change is implemented by two things:

  • Change of the exposure settings (aperture and shutter speed)
  • Change of the sensor gain

The comparison being made in http://www.dpreview.com/forums/post/36903045 is keeping the exposure settings of the higher ISO, just comparing changing the sensor gain in camera (which is presumed to be a change in analog amplification) with changing the gain in digital post-processing. Depending on noise/dynamic range in the values out of the ADC, the raw difference can be tiny. The Magic Lantern folks have repeatedly claimed that Sony-made sensors are "ISO-less" in that there is very little difference between the two methods for changing gain, but their dual ISO hack for several Canon DSLRs shows a claimed 3-stop improvement in dynamic range by setting the analog gains differently for the two interleaved sensor readout channels.

I think what's going on is that Sony's sensors have exceptionally low noise in their analog processing -- for example, compare the DxOMark scores of the NEX-7 and EOS 7D. Color depth is 24.1 vs. 22 bits and dynamic range is 13.4 vs. 11.7. In short, the Sony sensor is about 2 stops "cleaner" as the data comes off the sensor at low ISO. Even more interesting is the dynamic range curve comparison of the two cameras as ISO setting is changed. Dynamic range decreases for both cameras as ISO is increased, generally decreasing about 1 stop per stop increase in ISO -- which would mean increasing ISO basically adds nothing. However, the Canon sensor doesn't decrease dynamic range much until ISO 400 -- whereas the Sony sensor drops steadily, but isn't as bad as the Canon at 100 until it reaches 400. Both sensors perform identically at 800.

What does all that mean? Basically, it says that the claim of Sony sensors being ISO-less is well justified (although there is a little bump in the dynamic range that gives about 1/2 stop improvement at 6400, probably due to raw noise reduction kicking in). The Canon sensor, however, just doesn't have enough analog headroom to get all the dynamic range the lowest few ISOs could have provided, so it can get somewhat more than 2 stops improvement by bumping the ISO to something around 400 or 800.

Anyway, this is an interesting phenomenon, and perhaps I'll have the students in my "Cameras as Computing Systems" course do a little project on this....

 ProfHankD's gear list:ProfHankD's gear list
Canon PowerShot A640 Canon PowerShot A720 IS Canon PowerShot S70 Canon PowerShot G1 Canon PowerShot G5 +27 more
Jeff Veteran Member • Posts: 5,087
Re: Pls show examples where increasing brightness in post better than increasing ISO.

texinwien wrote:

Jeff wrote:

bobn2 wrote:

ultimitsu wrote:

bobn2 wrote:

So, mostly the metering is checking highlights. The easy technique is to set 2 1/2 or a bit more stops of EC and spot meter off the highlights (if your camera lets you use EC in M). On most camera there are a few ISO settings to be working with, and you know those pretty well anyway.

This sounds quite interesting, can you elaborate a bit on how it works? why 2.5 stops?

Your meter should be calibrated to centre when it gets 18% grey as the nominal exposure (10/ISO lux seconds). So, you need to miscalibrate it to regard 100% as nominal. According to ISO, the ratio of highlight to 18% is 78/10 = 7.8 = 2.96 stops (funny what these discussions can do - I see I miscalculated a long time ago, and have been giving my highlights a bit less than I could - dial in 3 stops). So, if the meter reads highlight and thinks it's 18% grey, it will give 3 stops less exposure than it should - so you correct that with EC, or recalibrating the meter (most will not let you recalibrate that far). In practice if you know how much headroom your camera has, you could dial in more than that.

(Just going back through my working, I realise where the extra half a stop came from, ISO leaves 1/2 stop for specular highlights over white - I must have taken it off somewhere along the line - 3 stops is better)

-- hide signature --

Bob

This is more or less what I've learned to do when shooting in challenging light, but with a small twist.

My E-P5 allows me to adjust the level for shadow and highlight 'blinkies', which I've set at jpeg levels 5 and 250, respectively. In A priority, the rear control wheel adjusts aperture, and the front control wheel adjusts EC.

When taking a shot, exposure is set by keeping an eye on the blinkies while adjusting EC, and while monitoring everything else to be sure I'm not totally killing the shadows. EC will generally fall between -0.5 and -2.5, but the critical issue is watch where the highlights and shadows fall on the live histogram and, via the blinkies, on the image.

The resulting jpeg preview may look off (generally too dark) but this procedure will give me a good raw file for subsequent processing in LR. ISO is a tertiary consideration. I generally try to work at base ISO, but will increase ISO as necessary to keep the viewfinder and jpeg previews usable.

Here are some results http://www.flickr.com/photos/jck_photos/sets/72157635431417147/

It becomes second nature pretty quickly.

I started typing a similar reply, took a break, and here you've gone and done the work, yourself!

The live-view 'blinkies' overexposure indicators are a boon to ETTR raw photogs. Add sufficient controls (i.e. Olympus E-M5, E-P5, E-M1) and you have an ETTR dream machine.

I, too, started out in A mode, mostly, but since Anders W convinced me that there was little advantage to A or S over M when using the blinkies method of ETTR, I have switched, and stay in M 99% of the time.

What comes out are images that are usually within a (<1/3) fraction of a stop from optimal ETTR. As much light as possible collected without blowing any important highlights - consistently.

Since the E-M5 (and E-P5) sensor is not 100% ISO-invariant, I do switch between ISO 200, 400 and 800 (rarely 1600). My sincere hope is that the next generation of OM-D models will be truly ISO-invariant, so I can forget that useless (to me) throwback to ancient history and get on with making properly-exposed photographs - one less useless variable to have to keep in mind.

Couldn't agree more.  I've been experimenting a bit with the level settings for the blinkies. 5 and 250 may be unnecessarily conservative, but produce good files.  2 and 253

Anders W is probably right (as usual), but I just like how the controls work in A mode.  Back wheel A, front wheel EC, and it's totally second nature.  Flick the 2x2 control and then ISO is on the front wheel.  I am using M mode more often, but A mode just feels more intuitive to me.  Admittedly, this is a personal quirk.

Oly could really own this with a few more tweaks of their UI. They're pretty close now.

rubank Contributing Member • Posts: 923
Re: Examples
1

The simple fact is
that you have to choose: will you sacrifice the highlights or the shadows. With a scene where the DR is beyond what your camera can capture in a single exposure, this choice is of greater importance than what ISO routine you prefer.

Do you want to preserve highlights it is often better to choose underexposure at low ISO, at the cost of shadow colour and noise (esp. banding). If shadows are more important it is often better to choose high ISO, at the cost of highlight rendering.

Heavy shadow lifting commonly leeds to colour shift and banding noise, at least with badly lit scenery where major parts of the image is in deep shadow.
In daylight situations with minor parts of the image in deep shadow, lifting in post is mostly not a problem (unless you have an ISO-full camera).

These are my findings, based on extensive practice and not on science.

Jeff Veteran Member • Posts: 5,087
Re: The meaning of ISO, NEX-7 vs. EOS 7D

ProfHankD wrote:

Jeff wrote:

PhilPreston3072 wrote:

With the latest sensors, some have been proclaiming it's better to shoot at base ISO and increase brightness in post rather than increase ISO in camera.

I would like to see some examples of this. Are there any examples where increasing brightness in post delivers better IQ than increasing ISO in camera? And please, disable all NR settings.

Here's a comparative example from Pierre Sottas comparing the same exposure made at ISO 100 and ISO 6400. http://www.dpreview.com/forums/post/36903045 Note the difference in how the highlights have been captured.

ISO film speed is a bit of a judgement call for sensors used in digital cameras. Basically, the notion of ISO change is implemented by two things:

  • Change of the exposure settings (aperture and shutter speed)
  • Change of the sensor gain

The comparison being made in http://www.dpreview.com/forums/post/36903045 is keeping the exposure settings of the higher ISO, just comparing changing the sensor gain in camera (which is presumed to be a change in analog amplification) with changing the gain in digital post-processing. Depending on noise/dynamic range in the values out of the ADC, the raw difference can be tiny. The Magic Lantern folks have repeatedly claimed that Sony-made sensors are "ISO-less" in that there is very little difference between the two methods for changing gain, but their dual ISO hack for several Canon DSLRs shows a claimed 3-stop improvement in dynamic range by setting the analog gains differently for the two interleaved sensor readout channels.

I think what's going on is that Sony's sensors have exceptionally low noise in their analog processing -- for example, compare the DxOMark scores of the NEX-7 and EOS 7D. Color depth is 24.1 vs. 22 bits and dynamic range is 13.4 vs. 11.7. In short, the Sony sensor is about 2 stops "cleaner" as the data comes off the sensor at low ISO. Even more interesting is the dynamic range curve comparison of the two cameras as ISO setting is changed. Dynamic range decreases for both cameras as ISO is increased, generally decreasing about 1 stop per stop increase in ISO -- which would mean increasing ISO basically adds nothing. However, the Canon sensor doesn't decrease dynamic range much until ISO 400 -- whereas the Sony sensor drops steadily, but isn't as bad as the Canon at 100 until it reaches 400. Both sensors perform identically at 800.

What does all that mean? Basically, it says that the claim of Sony sensors being ISO-less is well justified (although there is a little bump in the dynamic range that gives about 1/2 stop improvement at 6400, probably due to raw noise reduction kicking in). The Canon sensor, however, just doesn't have enough analog headroom to get all the dynamic range the lowest few ISOs could have provided, so it can get somewhat more than 2 stops improvement by bumping the ISO to something around 400 or 800.

Anyway, this is an interesting phenomenon, and perhaps I'll have the students in my "Cameras as Computing Systems" course do a little project on this....

There are others that can speak much more authoritatively about in-camera analog versus digital processing of the sensor data. And I'm not a Canon shooter so can't say much about that, either. But by simple E-P5 behaves as one would expect from iso-less perspective, which so far has been good enough for me.

Sound's like an interesting course.  With that source of 'free labor', it might be fun to do some controlled tests under typical shooting conditions.

I assume you've seen the sensor gen site http://www.sensorgen.info/?

Jeff Veteran Member • Posts: 5,087
Re: Examples
1

rubank wrote:

The simple fact is
that you have to choose: will you sacrifice the highlights or the shadows. With a scene where the DR is beyond what your camera can capture in a single exposure, this choice is of greater importance than what ISO routine you prefer.

Do you want to preserve highlights it is often better to choose underexposure at low ISO, at the cost of shadow colour and noise (esp. banding). If shadows are more important it is often better to choose high ISO, at the cost of highlight rendering.

Heavy shadow lifting commonly leeds to colour shift and banding noise, at least with badly lit scenery where major parts of the image is in deep shadow.
In daylight situations with minor parts of the image in deep shadow, lifting in post is mostly not a problem (unless you have an ISO-full camera).

These are my findings, based on extensive practice and not on science.

The color shifts can be a function of the processing software you use. What are you using?

Jack Hogan Veteran Member • Posts: 6,160
Re: Examples
1

rubank wrote:

Heavy shadow lifting commonly leeds to colour shift

My experience is that with moderate lifts (say 3-4 stops) in an otherwise decently exposed image if 'color' shifts are observed the raw converter is usually at fault.  What raw converter do you use?  Try free RawTherapeeand see if you still get them. ┬áIf not, you know where they came from

ProfHankD
ProfHankD Veteran Member • Posts: 5,291
Re: The meaning of ISO, NEX-7 vs. EOS 7D

Jeff wrote: I assume you've seen the sensor gen site http://www.sensorgen.info/?

I had not.  Great site!

 ProfHankD's gear list:ProfHankD's gear list
Canon PowerShot A640 Canon PowerShot A720 IS Canon PowerShot S70 Canon PowerShot G1 Canon PowerShot G5 +27 more
rubank Contributing Member • Posts: 923
Re: Examples

Jack Hogan wrote:

rubank wrote:

Heavy shadow lifting commonly leeds to colour shift

My experience is that with moderate lifts (say 3-4 stops) in an otherwise decently exposed image if 'color' shifts are observed the raw converter is usually at fault. What raw converter do you use? Try free RawTherapeeand see if you still get them. If not, you know where they came from

I´ve been using RT for many years, thank you. It is really not the best tool for shadow lifting, at least for me it gives severe colour shifts.

I don´t know what convereter was used in the famous D7000 pics (above in this thread) but the colour shift is obvious, as is the shadow banding in the ISO 100 shot.

bobn2
bobn2 Forum Pro • Posts: 53,182
Re: Examples
1

rubank wrote:

The simple fact is
that you have to choose: will you sacrifice the highlights or the shadows. With a scene where the DR is beyond what your camera can capture in a single exposure, this choice is of greater importance than what ISO routine you prefer.

Do you want to preserve highlights it is often better to choose underexposure at low ISO, at the cost of shadow colour and noise (esp. banding). If shadows are more important it is often better to choose high ISO, at the cost of highlight rendering.

Heavy shadow lifting commonly leeds to colour shift and banding noise, at least with badly lit scenery where major parts of the image is in deep shadow.
In daylight situations with minor parts of the image in deep shadow, lifting in post is mostly not a problem (unless you have an ISO-full camera).

These are my findings, based on extensive practice and not on science.

The point about knowing the science is that it lets you take out of the loop a lot of the 'extensive practice'. That is, if you know what's going on, you have a fir idea what's going to work in the first place, and particularly, how do you choose between this 'highlight' and 'shadow' DR. The answer is quite simple in the end, you meter the highlights to take them just up to the limit and then get as much shadow legroom as you need. Essentially, with exposure management, thge science turns a black art into simple and regular procedures. No more 'correct is when you get the result you want' or 'the important thing is to nail exposure, but you just have to learn how by experience'.

-- hide signature --

Bob

boardsy Senior Member • Posts: 2,215
My example!
1

Copy/paste from Open Talk > "ISO is a polyseme" thread:

It seems that I previously had not realised a few basic things about photography:

1) exposure is just the amount of light hitting the sensor (or I suppose more correctly, read by the sensor?) from a combination of shutter time and aperture size - regardless of ISO selected. This is not an esoteric scientific definition that doesn't affect us, nor a debatable philosophical or language definition - it's simply what happens every time you take a photo!

2) ISO is not a boosting of the sensor's sensitivity, nor of the registered light "signal" received in either analog or digital terms, as I and apparently others previously believed. It is a re-mapping of the exposure information (see 1) above) after the photo is taken, to affect the viewed brightness of the JPG, and/or a re-setting of the RAW so that the mis-named "exposure" (=brightness) slider's 0 setting is now higher than the original exposure, making the RAW appear brighter in your RAW processing software.

3) "High ISO noise" is not due to an ISO gain/boost, which doesn't actually happen - see 2) above - it's due to under-exposure which is due to less light available (from the lighting conditions, or from shutter time or aperture settings). There was a lower signal to noise ratio on exposure, and subsequently on increasing the brightness (either by high ISO setting or boosting "exposure," brightness, levels etc in software, which all amount to the same thing) there is less information in the shadows to "turn up" so the viewed image falls apart (= "ISO noise"). Fewer bits of data are presumably being used across a larger range of the brightness spectrum (these terms may be making Bobn, GB & DM cringe by now. I hope they are at least notionally correct!).

4) Another consequence of raising ISO to influence the exposure (= shutter time & aperture) is the increased likelihood of blowing highlights to compensate for better shadow exposure. If that's a good compromise for the conditions and your desired result, fine, but it's often safer to under-expose at low ISO and carefully raise shadows later in RAW if you value your highlights.

I applied this "theory" on Monday taking this:

View: original size

http://www.flickr.com/photos/59079068@N02/10028975555/

Instead of raising ISO to "get a better exposure at the expense of some ISO noise" as I mistakenly would have previously in A mode, I used S mode, kept ISO at base (200 on my camera, a NEX F3), set my aperture at f2 (manually on a Canon FD 35/2 with a Lens Turbo "speed booster" focal reducer adapter lens), and used I think 1/30 second shutter time (as long as I could get away with hand-held), and accepted the under-exposure. This kept the highlights intact and allowed me to massage the shadows and overall brightness in RAW. Yes it's a bit dark, but it reflects the scene and is clean enough.

This is a practical example of how understanding what exposure and ISO really are can help your photography! I thank Bobn and Great Bustard for persevering with this, and I hope that I have understood correctly!

-- hide signature --

Regards,
Alan
my Flickr

rubank Contributing Member • Posts: 923
Re: Examples
1

bobn2 wrote:

rubank wrote:

The simple fact is
that you have to choose: will you sacrifice the highlights or the shadows. With a scene where the DR is beyond what your camera can capture in a single exposure, this choice is of greater importance than what ISO routine you prefer.

Do you want to preserve highlights it is often better to choose underexposure at low ISO, at the cost of shadow colour and noise (esp. banding). If shadows are more important it is often better to choose high ISO, at the cost of highlight rendering.

Heavy shadow lifting commonly leeds to colour shift and banding noise, at least with badly lit scenery where major parts of the image is in deep shadow.
In daylight situations with minor parts of the image in deep shadow, lifting in post is mostly not a problem (unless you have an ISO-full camera).

These are my findings, based on extensive practice and not on science.

The point about knowing the science is that it lets you take out of the loop a lot of the 'extensive practice'.

Extensive practice has a lot of other benefits. You need 10 000 hours of practice (whatever you engage in) to get proficient. Try it.

That is, if you know what's going on, you have a fir idea what's going to work in the first place,

I do.

and particularly, how do you choose between this 'highlight' and 'shadow' DR.

The answer is quite simple in the end, you meter the highlights to take them just up to the limit and then get as much shadow legroom as you need.

The point of my post was that sometimes the scene DR is beyond the capacity of a single exposure and you do not always want to favour the highlights. Shadow footroom or highlight headroom is, in such a case, a matter of preference and choice. ETTR might not be the answer.

I´m sure you´ll get better with practice too:)

boardsy Senior Member • Posts: 2,215
Re: Examples
1

rubank wrote:

bobn2 wrote:

rubank wrote:

The simple fact is
that you have to choose: will you sacrifice the highlights or the shadows. With a scene where the DR is beyond what your camera can capture in a single exposure, this choice is of greater importance than what ISO routine you prefer.

Do you want to preserve highlights it is often better to choose underexposure at low ISO, at the cost of shadow colour and noise (esp. banding). If shadows are more important it is often better to choose high ISO, at the cost of highlight rendering.

Heavy shadow lifting commonly leeds to colour shift and banding noise, at least with badly lit scenery where major parts of the image is in deep shadow.
In daylight situations with minor parts of the image in deep shadow, lifting in post is mostly not a problem (unless you have an ISO-full camera).

These are my findings, based on extensive practice and not on science.

The point about knowing the science is that it lets you take out of the loop a lot of the 'extensive practice'.

Extensive practice has a lot of other benefits. You need 10 000 hours of practice (whatever you engage in) to get proficient. Try it.

That is, if you know what's going on, you have a fir idea what's going to work in the first place,

I do.

and particularly, how do you choose between this 'highlight' and 'shadow' DR.

The answer is quite simple in the end, you meter the highlights to take them just up to the limit and then get as much shadow legroom as you need.

The point of my post was that sometimes the scene DR is beyond the capacity of a single exposure and you do not always want to favour the highlights. Shadow footroom or highlight headroom is, in such a case, a matter of preference and choice. ETTR might not be the answer.

I´m sure you´ll get better with practice too:)

But surely one will get better faster, and probably ultimately better, by knowing how things work from the start? Just look at this randomly googled tutorial:

"Turning the ISO rating up will allow more light in. You can then increase the shutter speed or shrink the aperture while maintaining the proper exposure - the right amount of light coming in."

Completely wrong!

-- hide signature --

Regards,
Alan
my Flickr

bobn2
bobn2 Forum Pro • Posts: 53,182
Re: Examples

rubank wrote:

bobn2 wrote:

rubank wrote:

The simple fact is
that you have to choose: will you sacrifice the highlights or the shadows. With a scene where the DR is beyond what your camera can capture in a single exposure, this choice is of greater importance than what ISO routine you prefer.

Do you want to preserve highlights it is often better to choose underexposure at low ISO, at the cost of shadow colour and noise (esp. banding). If shadows are more important it is often better to choose high ISO, at the cost of highlight rendering.

Heavy shadow lifting commonly leeds to colour shift and banding noise, at least with badly lit scenery where major parts of the image is in deep shadow.
In daylight situations with minor parts of the image in deep shadow, lifting in post is mostly not a problem (unless you have an ISO-full camera).

These are my findings, based on extensive practice and not on science.

The point about knowing the science is that it lets you take out of the loop a lot of the 'extensive practice'.

Extensive practice has a lot of other benefits. You need 10 000 hours of practice (whatever you engage in) to get proficient. Try it.

That's afigure plucked out of the air with no evidence. The point is that science provides direction much faster than trial and error. That's the reason for the increasing pace of technology - if we wee still developing by trial and error, we'd still be in the bronze age.

That is, if you know what's going on, you have a fir idea what's going to work in the first place,

I do.

But not as good as if you sat down and understood what's going on underneath.

and particularly, how do you choose between this 'highlight' and 'shadow' DR.

The answer is quite simple in the end, you meter the highlights to take them just up to the limit and then get as much shadow legroom as you need.

The point of my post was that sometimes the scene DR is beyond the capacity of a single exposure and you do not always want to favour the highlights. Shadow footroom or highlight headroom is, in such a case, a matter of preference and choice. ETTR might not be the answer.

Sure, and in those situations, knowing what's happening gives you better information to make the compromise

I´m sure you´ll get better with practice too:)

You never know, I might be better than you already.

-- hide signature --

Bob

(unknown member) Senior Member • Posts: 1,321
Re: The meaning of ISO, NEX-7 vs. EOS 7D

ProfHankD wrote:

ISO film speed is a bit of a judgement call for sensors used in digital cameras. Basically, the notion of ISO change is implemented by two things:

  • Change of the exposure settings (aperture and shutter speed)
  • Change of the sensor gain

It is physically impossible to increase or decrease the sensor gain.

All sensors operate at a single gain value. Any change in gain (electronic or digital) occurs after the shutter closes.

In principle, there should be no difference between increasing brightness (not exposure) by increasing (ISO) using electronic amplification or digital multiplication during post-processing. However the actual results will be highly dependent on the specific camera being used. Besides the convenience of viewing results immediately, the primary reason to use in-camera gain is to get the most out the analog-to-digital converter. Some cameras have ADCs that require no electronic gain to accommodate the ADC technology. The Nikon D7000 and Phase One digital backs are just two examples.

OP PhilPreston3072 Senior Member • Posts: 2,553
Re: examples where increasing brightness in post is better than increasing ISO.
1

bobn2 wrote:

Ah, well - that would have produced far from the same settings. The highlights seem to be about three stops above saturation for 1600, so he'd have reduced the exposure to say 1/250 at f/2.0 to protect the highlights at 1600, then he'd have switched to 100 and had three stops less exposure (and more noise) than Pierre did. What he should have done is what Pierre did, give it the longest exposure and widest aperture and shot at the optimum ISO for read noise (actually not quite, 200 is better than 100 on the D7000).

-- hide signature --

Bob

I was only referring to the highlights in the windows and verandah which are really only slightly clipped.  No point in saving highlights in the light bulbs since there's really no detail of interest there.  I estimate 1 stop less exposure would have been enough to capture detail in the windows and verandah.  2 stops at most.

In any case, any knowledgeable photographer who is blowing critical highlights at ISO6400 and is already at lowest practical shutter speed and widest practical aperture knows that lowering ISO is the only thing needed to rescue highlights.  If Pierre wanted to do a proper comparison between high ISO and base ISO then he should have lowered the ISO so that the highlights in the window and verandah didn't clip.

 PhilPreston3072's gear list:PhilPreston3072's gear list
Canon EOS 450D Canon EF-S 18-200mm f/3.5-5.6 IS +1 more
OP PhilPreston3072 Senior Member • Posts: 2,553
Re: examples where increasing brightness in post is better than increasing ISO.

ultimitsu wrote:

PhilPreston3072 wrote:

I'm afraid you are still missing the point. If you're testing ISO6400 performance and finding that highlights are clipping then of course you have to reduce exposure.

it is you who is missing the point. it is well arguable that both shots got the right brightness - the sky is black and the walls is lit. the fact that inside the building detail preserved is a bonus. reduce ISO to 100 without any in-computer brightening (which is what you are advocating) would give you detail in the building but no details at all on the walls.

Put it this way, did the poster do all he possibly can to preserve highlights when using high ISO?  If he did not then I don't know why he's complaining about lost highlight detail.  When it comes to lowlight shooting, highlights are much easier to preserve than deep shadows.

 PhilPreston3072's gear list:PhilPreston3072's gear list
Canon EOS 450D Canon EF-S 18-200mm f/3.5-5.6 IS +1 more
Jack Hogan Veteran Member • Posts: 6,160
Re: Examples

rubank wrote:

Jack Hogan wrote:

rubank wrote:

Heavy shadow lifting commonly leeds to colour shift

My experience is that with moderate lifts (say 3-4 stops) in an otherwise decently exposed image if 'color' shifts are observed the raw converter is usually at fault. What raw converter do you use? Try free RawTherapeeand see if you still get them. If not, you know where they came from

I´ve been using RT for many years, thank you. It is really not the best tool for shadow lifting, at least for me it gives severe colour shifts.

You are welcome. If the sensor is linear in the shadows, so will RT's results be if one applies exposure compensation.  This is not true of all converters.

I don´t know what convereter was used in the famous D7000 pics (above in this thread) but the colour shift is obvious, as is the shadow banding in the ISO 100 shot.

The converter was RPP. There is no way the two images could look exactly the same, given the fact that one of them has several channels clipped to smithereens - not just inside the house - and the other possibly some blacked to zero undithered. In that sense, I believe that the one you think has the 'correct' colors is not the same one I'm thinking.

Here is another good example of color shift from the same thread, this time pushed 6 stops. And another here, this time a lower exposure rescued 6 stops. Major shifts in the effectively 8-bit raw files

In fact, if I were to look at these images without knowing that they had been pushed I would simply think that they lacked a little saturation and contrast compared to their relative references. As for color shifts...

rubank Contributing Member • Posts: 923
Re: Examples

bobn2 wrote:

rubank wrote:

bobn2 wrote:

rubank wrote:

The simple fact is
that you have to choose: will you sacrifice the highlights or the shadows. With a scene where the DR is beyond what your camera can capture in a single exposure, this choice is of greater importance than what ISO routine you prefer.

Do you want to preserve highlights it is often better to choose underexposure at low ISO, at the cost of shadow colour and noise (esp. banding). If shadows are more important it is often better to choose high ISO, at the cost of highlight rendering.

Heavy shadow lifting commonly leeds to colour shift and banding noise, at least with badly lit scenery where major parts of the image is in deep shadow.
In daylight situations with minor parts of the image in deep shadow, lifting in post is mostly not a problem (unless you have an ISO-full camera).

These are my findings, based on extensive practice and not on science.

The point about knowing the science is that it lets you take out of the loop a lot of the 'extensive practice'.

Extensive practice has a lot of other benefits. You need 10 000 hours of practice (whatever you engage in) to get proficient. Try it.

That's afigure plucked out of the air with no evidence.

Actually not
http://www.wisdomgroup.com/blog/10000-hours-of-practice/

The point is that science provides direction much faster than trial and error.

There is no such contradiction. Most science is based on trial and error.

That's the reason for the increasing pace of technology - if we wee still developing by trial and error, we'd still be in the bronze age.

That is, if you know what's going on, you have a fir idea what's going to work in the first place,

I do.

But not as good as if you sat down and understood what's going on underneath.

You jump to conclusions about my understanding. Keep your comments to what you know.

and particularly, how do you choose between this 'highlight' and 'shadow' DR.

The answer is quite simple in the end, you meter the highlights to take them just up to the limit and then get as much shadow legroom as you need.

The point of my post was that sometimes the scene DR is beyond the capacity of a single exposure and you do not always want to favour the highlights. Shadow footroom or highlight headroom is, in such a case, a matter of preference and choice. ETTR might not be the answer.

Sure, and in those situations, knowing what's happening gives you better information to make the compromise

From simple answer to compromise requiring good information. You´re going forward, good.

I´m sure you´ll get better with practice too:)

You never know,

Yes, I know. You will get better with practice.

I might be better than you already.

Of course you might, but I have serious doubts.

Keyboard shortcuts:
FForum MMy threads