ETTR - Exposing to the right for noise reduction.

[seventythree]

i've read a few articles explaining this technique where you effectively over expose slightly when shooting high ISO.then you pull the photo back using PP. This allegedy helps greatly with reducing noise in the shadows etc. I've had a look back at some of my high ISO shots (at the accidentally overexposed ones),and i must agree that those that need taking back a bit look much better.

Anyone use this technique to good effect, and anyone willing to give any hints on how best to achieve this

cheers, Al

 

[mrtoad]

sounds interesting

there was once a developing technique which gave small grain from high asa film

ffdd was the name

 

[mstphoto]

I have also read articles on Expose to the right.
I tried it and it certainly made a difference as you have seen.
I set my camera to spot metering and manual and exposed for the highlights, in my case the crest of waves, and increased exposure using exp comp to the point just before clipping occurred.

 

[mole2k]

Well the main thing is to expose as far right as you can without clipping the highlights to a level which is unrecoverable from the raw file.

I find that after a while you can tell from the jpeg histogram with a bit of guesswork as to just how overexposed you can go. I guess if you were to do it scientifically then you would spot meter on the brightest bit and experiment to see how many stop over exposed it can be without losing detail.

The reason behind this incase anybody who doesnt know is the sensor data isnt stored linearly over the range from black to white, it's all stored in the brighter sections with less stored in the shadows so if you can compress the range in the highlights you can get less noise because of the improved signal to noise ratio.

Luminous Landscape have a good article on it here.

 

[AliB]

It's one of the things I struggle most with. It's a problem that is made worse at weddings with white dresses and dark clothed grooms. On a few occasions I've had to resort to noise reduction software and I do lack the confidence at times to ignore the camera and shove the exposure right. I'm starting to try to go with it a bit more by shooting a couple of shots, a quick check on the histogram and then try shooting another few more to the right. I think we sometimes worry too much about going too far and blowing whites but I have to say I've seen some awesome images with blown dresses!

Yes, I will be working more on it next year.

 

[Tyke Tiler]

Well the main thing is to expose as far right as you can without clipping the highlights to a level which is unrecoverable from the raw file.

Yup.

 

[HoppyUK]

Well the main thing is to expose as far right as you can without clipping the highlights to a level which is unrecoverable from the raw file.

I find that after a while you can tell from the jpeg histogram with a bit of guesswork as to just how overexposed you can go. I guess if you were to do it scientifically then you would spot meter on the brightest bit and experiment to see how many stop over exposed it can be without losing detail.

The reason behind this incase anybody who doesnt know is the sensor data isnt stored linearly over the range from black to white, it's all stored in the brighter sections with less stored in the shadows so if you can compress the range in the highlights you can get less noise because of the improved signal to noise ratio.

Luminous Landscape have a good article on it here.

Good post and link from Mole

There's a double-benefit from this technique - you get less noise in the shadows because they've been given more exposure, plus there is even more detail in the highlights because of the extra data capture available at the high end.

It's a dangerous game though. I've tried it, and it certainly works in test pics. But in practise I find that unless there is a lot of really important detail in the shadows it doesn't make a huge visible difference and of course you run the risk of blown highlights.

Must be a nighmare for wedding photographers - do you show every crease and subtle tone of the groom's black suit (which nobody cares about) but only at the risk of blowing the bride's dress (which everybody cares about, a lot!)

Edit: I've been using a slighly different technique recently - being guided by blinkies (flashing LCD over-exposure warning) and the histogram in tandem.

I've done some testing, particularly adjusting the contrast level in the Picture Styles pre-sets which shifts the highlight peaks around quite a bit - a lot actually. And now that I know where I am with that, when I have time to fiddle I keep increasing exposure till I get blinkies flashing, then make a judgement about whether they are in important areas or not and either push it a bit more, or back off (I'm a coward, so usually the latter). Of coure it's all on the histogram but I find that with most scenes there is always something spiking off the right hand end and blinkies is the only reliable way of knowing exactly where those over-exposed area are.

My expose to the right technique is not very sophisticated, more quick and dirty, but it works and it helps. It pretty much boils down to this - shall I increase the exposure by one stop, or not? That's it

 

[tdodd]

Here is a white shirt shot raw with an exposure spot metered off the shirt at +4. Wherever it shows as red the pixels are being displayed at 100% saturation. If this was a JPEG file the red bits would be pure, featureless white and impossible to recover....

Here is the same image file after reducing the exposure by 1.5 stops in Lightroom....

That's the power of raw and the ability to recover blown highlights. It is ideal for wedding photography (and everything else ). If that image had been shot to JPEG it would have been toast.

Here is an album showing the more complete story of this little test....

http://picasaweb.google.com/EezyTiger/Exposure?authkey=Gv1sRgCOui54easIX-LQ#

I always shoot raw and I use ETTR a lot. I try strongly to avoid ever underexposing my images. I will usually meter highlights at +3 (white shirt, snow, clouds etc.) and that buys me a 1 stop safety margin while still giving me an ETTR exposure and keeping noise as low as I can reasonably expect. I do check the histogram and I do look for blinkies on my highlights, which warn of clipping. Normally I'm very happy to see just a few hints of clipping, which I am confident that I can pull back a litle if I need to. Of course, I ignore such warnings if they occur over light sources and specular highlights.

Here's an example of a "real world" exposure which as far as I am concerned represents a perfect raw exposure, which maximises data captured and minimises noise. That little bit of clipping is my sign that the exposure is right where I want it to be. This is without edits....

 

[grumpybadger]

The key issue though is that if you "over expose" by 1 stop, you are effectively needing twice the shutter speed (assuming you are light limited and at maximum aperture) so you do run out of space eventually. But, I've certainly found a well handled image at ISO1600 better than one that needs to be pulled up as it is dark at ISO800

The main thing is to get as much light in as possible and it is another factor to consider during low light exposures.

I'm personally a big fan of getting it right in camera (and that doesn't just mean believing the camera's meter)

 

[artyman]

It would be nice to have the luxury of being able to do this, unfortunately birds don't hang in the sky while you reset the camera the only option is best guess beforehand.

 

[tdodd]

It would be nice to have the luxury of being able to do this, unfortunately birds don't hang in the sky while you reset the camera the only option is best guess beforehand.

With respect, I disagree. You can set a manual exposure in advance that is correct for the incident light for the scene you are aiming at. e.g. I seldom shoot birds in anything but fairly good sunlight. My starting exposure will be based on "Sunny 16". That might be 1/1600, f/5.6, 200 ISO. With such an exposure, noise is hardly likely to be a problem and I don't really need to chase a full ETTR. If a white bird comes into view the exposure will be ETTR for the white bits. If a darker bird is my subject I have the option to bump the exposure a bit, but really I don't need to bother. If the ambient is a bit down on full sunshine then I can still have my manual exposure set up ahead of time, maybe to 1/1600, f/5.6, 400 ISO or whatever it needs. This is not guessing. This is being prepared in advance for the prevailing lighting.

I very rarely meter off my subject or my scene. Usually I spot meter off my palm, green grass, the brightest thing of importance or just go by the strength of the sun. I then set up an exposure to suit. Thus, if my scene contains bright things I might meter/expose as follows....

- off green grass at -2/3
- off my own palm at +1 1/3
- off the brightest area of the scene at +3
- "Sunny 16" in bright sunshine

If my subject/scene has nothing bright (e.g. a dark or mid-toned bird/animal/subject against green grass, or blue sky) but I want to maximise my exposure, or nudge it towards the right then typically I may increase the exposure by up to 1 stop from the settings above.

Here's a BIF example, taken on a miserable grey day. From one moment to the next the bird could have been against a background of bright (relatively speaking) sky, or dark green foliage. Regardless of the background the bird had the same light illuminating it from my perspective and the exposure should be the same wherever the bird was. I set up an exposure to just barely see clipping in the sky and I was then set to shoot the bird at any moment with no need for furious knob twirling....

 

[desantnik]

Good advice from tdodd there... I have to say some of your "old school" advice with sunny16 etc has proven to be spot on when I've remembered to use it.

Listen to him

 

[DiddyDave]

It's one of the things I struggle most with. It's a problem that is made worse at weddings with white dresses and dark clothed grooms. On a few occasions I've had to resort to noise reduction software and I do lack the confidence at times to ignore the camera and shove the exposure right. I'm starting to try to go with it a bit more by shooting a couple of shots, a quick check on the histogram and then try shooting another few more to the right. I think we sometimes worry too much about going too far and blowing whites but I have to say I've seen some awesome images with blown dresses!

Yes, I will be working more on it next year.

I'm taken to my blinkies for getting it right at Weddings

I use them to show me that bits of the dress are starting to blow (as in tdodd's swan image) and go with that - works every time

For me - the ONLY thing that matters for correct exposure is the main subject and in a Wedding this is the Bride & her dress. I do try to avoid losing an entire background to white by the positioning of the shot, and by using higher ISO to avoid solid blacks indoors, but if either happens so long as the Bride looks great I'm happy

I do of course tell potential couples NOT to wear black for him if white for her - but few listen

Blinkies are your friend

DD

 

[artyman]

I perhaps should say my comment about 'best guess' was more flippant than actual I follow much the same approach as tdodd when setting manually.

 

[tdodd]

Here's a "Sunny 16" example. To be honest I would have great difficulty shooting this in any autoexposure mode because I would really struggle to know how the camera would interpret this scene and where it would position the exposure. Clearly the swan is of paramount importance, but despite the dark and shady background I could see the swan was lit by sunlight, so I set a "Sunny 16" manual exposure of 1/1000, f/7.1, 200 ISO. One needs to take care that reflective water (or snow) does not cause the subject to overexpose, but in this case the exposure was bang on. This is with no edits and it is just at the right hand edge of the histogram without clipping...

 

[DiddyDave]

"Sunny 16" ???

Where does that come from

DD

 

[AliB]

What a great little thread this is turning into, theory and how people best put it into practice in varying conditions. TP just rocks

Sunny 16 for anyone interested http://en.wikipedia.org/wiki/Sunny_16_rule


I do have the cameras set to both histogram and blinkies so it works for me both indoors and out. I sometimes find the histo more use outdoors or with a wide angle, I suppose I've just learned to read it but the blinkies are great as they show me WHERE the overexposure is. Between them I can see how much and where. I still cock it up though! :bang:

 

[Suvv]

"Sunny 16" ???

Where does that come from

DD

California IIRC

 

[seriousrikk]

"Sunny 16" ???

Where does that come from

DD

In good sunlight you can be pretty sure that an aperture of F16 and a shutter speed matching your ISO wil give a nicely exposed image.

The shift the values to get the aperture/shutter speed you want.

Not sure of it's benefits in the UK. Maybe we should come up with something like a Rainy 4

 

[tdodd]

Dave, surely you jest. In case you don't - http://en.wikipedia.org/wiki/Sunny_16_rule

Of course, you can mix and match apertures against shutter speed and/or ISO. e.g. a "Sunny 16" exposure of f/16, 1/100, 100 ISO is the same as f/8, 1/400, 100 ISO is the same as f/5.6, 1/1600, 200 ISO and so on. They are all equivalent to a "Sunny 16" exposure.

In truth, "Sunny 16" proves to be a very useful starting point, on a sunny day, but may need fine tuning if there is a little haze, or some extra reflectance from the environment (water, snow, white sand). Usually when I go off shooting birdies on a sunny day I can have my manual exposure set up before I even get to my location, because "Sunny 16" will be pretty darned close to where I need to be.

 

[Kev M]

Sooooooooo slooooooow.

Bunch of smart arses

 

[tdodd]

Actually, Kev, your post (before you edited it) was useful. I agree that winter sun is pretty weedy and may need a helping hand, so "Sunny 16" might need a little extra added on top.

 

[DiddyDave]

Dave, surely you jest. In case you don't - http://en.wikipedia.org/wiki/Sunny_16_rule

Of course, you can mix and match apertures against shutter speed and/or ISO. e.g. a "Sunny 16" exposure of f/16, 1/100, 100 ISO is the same as f/8, 1/400, 100 ISO is the same as f/5.6, 1/1600, 200 ISO and so on. They are all equivalent to a "Sunny 16" exposure.

In truth, "Sunny 16" proves to be a very useful starting point, on a sunny day, but may need fine tuning if there is a little haze, or some extra reflectance from the environment (water, snow, white sand). Usually when I go off shooting birdies on a sunny day I can have my manual exposure set up before I even get to my location, because "Sunny 16" will be pretty darned close to where I need to be.

Twas indeed a jest



Perhaps bizarrely I've just never heard or thought of it like that, but I did think it harkened back to the Sunny, Shade etc. examples on my old film boxes

I had nearly 30 years of using them and it never clicked like that :bonk:

DD

 

[RobertP]

Tim (or anyone else)....

Stuff like this would be a welcome addition to the TP tutorials section if you feel like adapting what you have posted into one

We need a simple explanation of what benefit there is in using raw and the job is almost done above (maybe with a blown camera jpeg too for comparison). And this ETTR and sunny 16 stuff is all good too

 

[DiddyDave]

Tim (or anyone else)....

Stuff like this would be a welcome addition to the TP tutorials section if you feel like adapting what you have posted into one

We need a simple explanation of what benefit there is in using raw and the job is almost done above (maybe with a blown camera jpeg too for comparison). And this ETTR and sunny 16 stuff is all good too

Ha - that'll teach him to not be overly-helpful

DD

 

[david357]

There is a HUGE amount of information available on TP for anyone who needs it, and this thread is a brilliant example.

There are several articles on the net re ettr, (the luminous landscape one is excellent), but the examples and explanation given by guys like tdodd on this thread are what actually helps people understand the principles, and make the difference between having heard about ettr and actually trying it!

This thread (and plenty of others, written by people with great depth of knowledge on subjects but with an ability to write in a way that is understandable by anyone) should be required reading by anyone with a real desire to improve their photography!

 

[morbidorbits]

Hello, this is an interesting thread but not the first time that I have come across the subject (Luminous Landscape). I have specific question about how to correctly expose a photo where the sun is in frame, such as in a sunset? I have never been able to correctly expose this (on 400d) and if anyone has any advice it would be greatly appreciated.

I shoot RAW and I often suffer from 'unrecoverably over exposed' sunsets.

I don't have any linear gradient filters so I hope they are not going to be required


Ta, Jeff

 

[martsharm]

Here is a white shirt shot raw with an exposure spot metered off the shirt at +4. Wherever it shows as red the pixels are being displayed at 100% saturation. If this was a JPEG file the red bits would be pure, featureless white and impossible to recover.... [snip]

Tim, that's an excellent example of ETTR with raw. You mention in your little slideshow that ETTR with JPG isn't a good idea and I agree with this - JPG simply carries a final image and not the "hidden" info of raw. Blown whites are lost and that's that. I've heard shooting JPG compared to shooting slide film - everything must be right at the moment of capture.

My question is... if you compare your ETTR+compensation raw converted to JPG with a JPG exposed "properly" (ie no white clipping) out of the camera, would there be any detectable image quality difference? Doesn't JPG carry "just enough" info to recreate the image as it was taken? (Only falling over when we ask it to recreate lost info such as lightening shadows or pulling out blown whites).

What I'm getting at here is - yes I understand the ability of raw to correct afterwards. I also understand that ETTR puts more information in the shadows. But in the example above with the shirt - with raw you can recover the whites in the shirt if they are blown, but blowing is a mistake in itself. Can you actually tell the difference between an ETTR raw conversion and a properly exposed out of camera JPG?

 

[jgs001]

Tim, thanks again for all the great information your passing on... and everyone else.

Jeff whilst I'm no expert... I don't think you can expose both the sun and the foreground correctly. The dynamic range for that would be enormous. I think you have to settle for either a burnt out sun, or silhouetted foreground..

Be very very very careful shooting the sun, it will damage your eyes, camera or both when focused. I've seen pictures of melted astro eyepieces, and whilst I've not met them, I know there are people who have lost eyes on improperly protected equipment.

 

[morbidorbits]

Tim, thanks again for all the great information your passing on... and everyone else.

Jeff whilst I'm no expert... I don't think you can expose both the sun and the foreground correctly. The dynamic range for that would be enormous. I think you have to settle for either a burnt out sun, or silhouetted foreground..

Be very very very careful shooting the sun, it will damage your eyes, camera or both when focused. I've seen pictures of melted astro eyepieces, and whilst I've not met them, I know there are people who have lost eyes on improperly protected equipment.

Thanks John. I will be careful in the field but I guess I am trying to understand the general principles of photography, without the need to experiment with everything (and frazzle my retina!).

So to shoot a sunset, with sun will require a multiple exposure (HDR) in order to get both the sun highlights and the foreground correctly exposed?

 

[DiddyDave]

Thanks John. I will be careful in the field but I guess I am trying to understand the general principles of photography, without the need to experiment with everything (and frazzle my retina!).

So to shoot a sunset, with sun will require a multiple exposure (HDR) in order to get both the sun highlights and the foreground correctly exposed?

Sunrises/Sunsets are one of the most common things newbies try to shoot as they look amazing to our eyes - and crap to the camera

As has been said the dynamic range (difference from light to dark) is so great that the camera cannot record it in a single image. So if you expose for the foreground you blow the sky, expose for the sky and you block-up the foreground

Blending exposures (if you have no filters) the is way forwards here and doesn't necessarily need HDR programs, though they do make it simpler

DD

 

[desantnik]

So to shoot a sunset, with sun will require a multiple exposure (HDR) in order to get both the sun highlights and the foreground correctly exposed?

No, less hi-tech than that... a graduated filter... perhaps even one called a "sunset filter".

Job done.

 

[DiddyDave]

No, less hi-tech than that... a graduated filter... perhaps even one called a "sunset filter".

Job done.

And unless you shoot a seascape some of the landscape will be affected by the filter and need correction in PP - which is why I don't 'do' filters

I even had Joe Cornish admitting to that as a 'failing' in that department when he came to the talk I arranged here in Barnsley last year

DD

 

[tdodd]

Mart, since I never shoot JPEG (except with my stupid point and shoot) I have no frame of reference for directly comparing raws that have been slightly overexposed and then recovered vs JPEGs that were exposed "correctly" in the first place. If you want to shoot some test shots and make such comparisons please feel free

The thing is, there is a lot more to shooting raw than recovering blown highlights, and as far as I am concerned, slightly blown highlights in raw are not a mistake, they are pushing the envelope to the max in order to optimise the maximum amount of data captured. As far as I am concerned, you don't shoot raw to record images. You shoot raw to record data. You craft your image afterwards.

Benefits of raw, off the top of my head.....

- You can record more image data and decide later how best to make use of it;
- You can sort out your WB after taking the shot and fine tune the aesthetics;
- You have freedom to apply as little or as much sharpening as you wish, depending on the exact needs of the subject/scene;
- You have freedom to apply as little or as much noise reduction as you wish, depending on the exact needs of the subject/scene;
- You can fine tune black and white points and the tone curve that joins them, while still having all the recorded image data to play with;
- You have 12-14 bits of data per channel, and not just 8;
- You can choose your preferred colour space after taking the shot;
- You can crop your files and produce JPEGs (or TIFFs) of any dimensions you like, without suffering the losses of double JPEG compression.
- In short, you get to tailor the image processing to the needs of each shot individually rather than having the camera apply sweeping general adjustments to every image, regardless of need.

Of course, people can produce very nice looking JPEGs straight out of camera, but shooting raw gives you the freedom to make some kinds of adjustments without penalty to IQ and can also give you a margin of safety when shooting in an uncontrolled environment (not the studio) and needing to shoot quickly without the opportunity for practice shots.

I'm not good enough to shoot perfectly, every time, and nature seldom provides lighting that is exactly perfect for one's needs, so shooting raw allows me that extra leeway for my own mistakes and to tweak the image for optimum appeal. If I were to shoot JPEG the cake would already be baked and I'd have my options significantly reduced. I like options.

p.s. I may be a bit anal about this, but in my mind, given that we know JPEG to be a lossy format, I do not like the idea of applying any sort of editing to a JPEG file and then resaving again as a JPEG. Even if all you do is to resize for the web then that is still a double JPEG save - once within the camera and once without - and, of course, after downsizing you need to sharpen again, so editing is inevitable. I'd rather only save to JPEG once.

 

[desantnik]

I even had Joe Cornish admitting to that as a 'failing' in that department when he came to the talk I arranged here in Barnsley last year

The people buying the postcards of "Brighton Pier during a thermonuclear war" don't care though

 

[HoppyUK]

DANGER!

Since the histogram is derived from an in-camera JPEG, it changes a lot according to the Picture Styles applied. There's a one stop difference depending on settings.

The contrast setting in particular makes a big difference - more than a stop between -4 to +4. It shifts the graph both right and left, and also affects the level at which blinkies flash.

Just shoot two images, identical exposure and framing, with the contrast set to max and min. The two images will look very different on the LCD, and the histogram will shift right/left by about one vertical bar on the histogram (Canon). At the right hand end, one bar is about one stop.

If you are using the histogram to set optimum exposure, you need to know what you are basing your assumptions on.

 

[DiddyDave]

DANGER!

Since the histogram is derived from an in-camera JPEG, it changes a lot according to the Picture Styles applied. There's a one stop difference depending on settings.

The contrast setting in particular makes a big difference - more than a stop between -4 to +4. It shifts the graph both right and left, and also affects the level at which blinkies flash.

Just shoot two images, identical exposure and framing, with the contrast set to max and min. The two images will look very different on the LCD, and the histogram will shift right/left by about one vertical bar on the histogram (Canon). At the right hand end, one bar is about one stop.

If you are using the histogram to set optimum exposure, you need to know what you are basing your assumptions on.

Good point

Which is why I don't use it

In t'olden days, I knew that my cameras would always meter some conditions 'wrongly' and so I adjusted accordingly - so long as it's always 'wrong' by a similar amount anything can be worked around with a little brain-power & experimentation

DD

 

[psenior1]

Good point

Which is why I don't use it

In t'olden days, I knew that my cameras would always meter some conditions 'wrongly' and so I adjusted accordingly - so long as it's always 'wrong' by a similar amount anything can be worked around with a little brain-power & experimentation

DD

isn't this where uniwb comes in, not tried it myself yet but gives you a histogram based on raw image rather than the jpeg from what I understand

 

[tdodd]

I use Neutral picture style and leave the settings for that style at default. I agree that if you lark about with different picture styles, while trying to judge your raw exposure, then beware of dragons.

Mind you, if we are to evaluate RGB histograms in camera, for shooting raw, then your choice of white balance setting is equally (or perhaps more) significant. There is no point neutralising the colour bias from the lighting, by setting the "correct" WB for the scene, if you want to know what is happening to your pixels at the raw level. What you need is UniWB if you are really serious about these things.

An easier UniWB for Canon Shooters.

The problem with having the "right" WB set in the camera - http://www.youtube.com/user/eezytiger#p/u/8/FLXoznsvEvI.

I tried it but gave up with it. Now I usually just leave the camera on Daylight WB and Neutral PS and I have a pretty good handle on where I'm at. Of course, the pictures SOOC often look like crap, but that's why I stick them through my raw processor to sort out WB and apply a suitable tone curve, sharpening etc..

 

[HoppyUK]

Just to emphasise the point on how Picture Styles affect the position of the histogram. Yes they do, and Contrast does it quite a lot. However, the Raw image captured is not affected by Picture Styles - only the exposure level changes that. Sorry to repeat, but it's important, which is why you need to check your Contrast setting before making Expose-To-The-Right judgements.

I think the RGB histogram is a red herring (haha ). Seriously, what's the point? Is it a 'marketing' feature?

I would also suggest that white balance changes can effectively be ignored as far as overall exposure is concerned. It hardly changes the histogram at all, and has no effect on the Raw capture of course.

Why do you need to set White Balance to Neutral, everything to zero, or use UniWB when shooting Raw, when trying to optimise exposure? I think you can use any method or combination of pre-set parameters, so long as you know what they are and so have a known reference point to work to.

Edit: If you change the Picture Styles pre-sets significantly, perhaps because you are intending to work off the Raw file anyway, bear in mind that you will then have ruined the in-camera JPEG and rendered it useless. Just in case you wanted to use it after all, or use it for proofing or whatever.