D500 Overexposure

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For those who don't like clicking on links here are two of the images. Taken with the camera on a tripod, matrix metering. The only change was that the focus point was moved. 3D matrix metering decided that the priority of exposure had to change by two stops for the new 'subject'.

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Hi Ann,
While I do not want to stray too far off topic I feel it important to get our facts correct or at least as close as possible. Perhaps the historical background may not be important but nevertheless wherever possible I believe we should try and report with some accuracy. With respect I feel that you may have missed or be unaware of some of the facts surrounding exposure metering, film speed ratings, and the Zone system

My terms of reference and experiences concerning the Kodak 18% Grey Cards predate the current K factor (as recommended by ANSI/ISO 2720-1974 at 10.6 to 13.4 )—(Previously ANSI PH3.49-1971) — by more than 20 years!
Kodak 18% grey cards were introduced I believe in the early 1950's. They were not particularly designed for photographic purposes having been intended I believe for the graphic arts printing process of the time but nevertheless useful as a known reference value in photography.

Prior to this grey card Kodak rec.
"An Eastman photographic paper envelope should be put in front of the subject, facing the camera. A reading is made by holding the meter close to the envelope without shading it. For average subjects the indicated exposure should be doubled."

The Kodak 18% instructions that were missed out over a period and eventually reintroduced read as follows:
"Meter readings of the gray card should be adjusted as follows- 1) For subjects of normal reflectance increase the indicated exposure by 1/2 stop. 2) For light subjects use the indicated exposure; for very light subjects decrease exposure by 1/2 stop 3) If the subject is dark to very dark increase the indicated exposure by 1 to 1.5 stops"

This increase in exposure effectively recognised that an 'average' scene equates to a 12% value not the stated 18%, therefore adjustment is needed to compensate.

Prior to the 1970s, Kodak 18% Grey Cards were the standard reference that was used to determine exposure levels for Film Processing; and our exposure meters were calibrated, under the earlier ASA standards, to work in conjunction with those cards.
While 18% grey cards were used as a standard reference you still needed to apply the correction factors noted above thereby reducing the 18% value to around a 12% value.

You cannot actually calibrate your meter as it has a fixed value set by the manufacturer. What you can do is effectively calibrate your system which will include your camera, lens, developer etc., to take into account all the variables that constitute to producing a blackening on film or the image formation on a sensor.

Prior to about 1950 exposure meters could be all over the place and report widely varying settings for the same ASA. I do not believe that this actually mattered to the experienced photographer as practical testing as touched on above will have been undertaken to establish the system 'speeds'.

One important milestone occured in 1960 - B&W Film speeds doubled overnight !!!

At this time most B&W emulsions relabelled to double the old film speed. For instance Ilford HP3 and Kodak Tri X speed increased from 200 ASA to 400 ASA - there was no actual change to the product. The original rating of 200 ASA included an exposure safety margin and probably tried to account for the variations in exposure meters of the time. Improvements in light meters saw less need for this safety margin.
Interestingly my own rating for Tri X very many years later was at the old 200 ASA (roll and LF) not the revised 400 ASA
 
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Jim:

I don't need to "document" anything beyond what my copious dark-room processing and printing logs (which date from the mid 1950s!) show very clearly. I have been a full-time working professional photographer (who has always done all of my own Lab work too) for all these years and have actually experienced the changes first hand!

The confusion caused by the new ANSI ratings when they were issued in the early '70s was considerable: almost over-night all film packaging was relabelled with new ratings which appeared to have doubled the speed of the film although the emulsions themselves had not changed at all.

The new ANSI ratings were designed for the exposing of Reversal (slide) film (a burgeoning technology at that time) and set the film to be underexposed by 1 EV compared to the previous ASA rating system. This was a simple way of ensuring that the HLs were not destroyed.

Users of Negative-Positive processes (both colour and B&W) suddenly found that their films were woefully underexposed and had lost shadow details. The more experienced photographers immediately set the Film Speed on their exposure meters to half the value printed on the box.

The sensors on Digital cameras behave similarly to Reversal film in that saturated pixels and over-exposed highlights will lose all detail which cannot be recovered.

The 12% standard is appropriate for digital cameras when used to shoot JPGs.

Those of us who shoot RAW need to adjust our meter-settings (and understand their correct use) if we are to take full advantage of the available DR.
 
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3D matrix metering has to decide at some what what the subject is. Much of this is decided by the focus distance and where the active focus point is. In a high contrast scene like yours where the majority of the scene is in the shade it has to ignore blown highlights at some stage. Have a look at some tests I did with my D90 and 3D matrix metering. I don't see over-exposure in your 'subject' at the centre of the frame - if the camera exposed for the bright corners then the majority of the scene would be very dark indeed.
As per my blog in the link I provided the active focus point tells the camera which part of the scene gets priority and if the subject is somewhere around the 3-5m mark and the bright background is beyond that mark it will concentrate on the 3-5m part of the scene.
That's very interesting! I will test it next time I'm on a hike, thank you :).
Only problem I see is with scenes like the one above where there isn't really a good point to aim to...
 
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That's very interesting! I will test it next time I'm on a hike, thank you :).
Only problem I see is with scenes like the one above where there isn't really a good point to aim to...
It's also going to depend on the body you have - matrix metering changes between bodies like operating system updates on computers.
 
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still plowing through the manual and have seen there is an exposure fine tine option which allows a stop either way. may come in useful. didnt see that on a d7200 so not sure if its a new thing.
 

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still plowing through the manual and have seen there is an exposure fine tine option which allows a stop either way. may come in useful. didnt see that on a d7200 so not sure if its a new thing.
I don't know about the D7200....but this feature has been on several Nikon bodies in the past.
 
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This is by far the best explanation that I have yet to read about the whole science of correct metering for digital cameras.

https://photographylife.com/how-to-use-the-full-dynamic-range-of-your-camera

I recommend that you read this very carefully and follow along by doing your own matching tests as you read.

And then re-read the whole thing again!

But be aware that Iliah Borg is using readings from an Incident-light exposure meter for the preliminary tests before he explains how that translates into setting and using the in-camera exposure meters.

[You can safely ignore most of the ill-informed comments which follow the main article because they will totally confuse you!]
 
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This is by far the best explanation that I have yet to read about the whole science of correct metering for digital cameras.

https://photographylife.com/how-to-use-the-full-dynamic-range-of-your-camera

I recommend that you read this very carefully and follow along by doing your own matching tests as you read.

And then re-read the whole thing again!

But be aware that Iliah Borg is using readings from an Incident-light exposure meter for the preliminary tests before he explains how that translates into setting and using the in-camera exposure meters.

[You can safely ignore most of the ill-informed comments which follow the main article because they will totally confuse you!]
I read Iliah's article yesterday afternoon before Ann brought it to our attention. I didn't read that he is using an incident light meter - my interpretation is that he was using the camera's meter in spot-metering mode: "For each shot, we spot-metered one of those neutral grey patches at the bottom row, starting from the white patch, setting the exposure according to the recommendations of the spot meter."

I understand the theory of his approach, but his writing is confusing because the figure numbers in the text do not correspond to the figure numbers on the graphics. Nevertheless, I found it to be an interesting and worthwhile contribution to our knowledge. Unfortunately I don't have a color checker chart to calibrate my own cameras.
 
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Jim:
You might want to get a ColorChecker Passport and then use it to build your own Camera Profiles (separate ones for each camera body as well as profiles for the different light-sources under which you shoot).

The canned profiles which ship with the software are only generic ones and every camera sensor may differ considerably from another one.

I can't tell you how much building your own Camera Profiles will both simplify and speed-up your post processing.
 
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I read Iliah's article yesterday afternoon before Ann brought it to our attention. I didn't read that he is using an incident light meter - my interpretation is that he was using the camera's meter in spot-metering mode: "For each shot, we spot-metered one of those neutral grey patches at the bottom row, starting from the white patch, setting the exposure according to the recommendations of the spot meter."

I understand the theory of his approach, but his writing is confusing because the figure numbers in the text do not correspond to the figure numbers on the graphics. Nevertheless, I found it to be an interesting and worthwhile contribution to our knowledge. Unfortunately I don't have a color checker chart to calibrate my own cameras.
Yes, he was using a spotmeter (Sekonic 758DR probably same as shown in the image) the first image being shown having a DR of over 11 stops. The spot reading taken from the white dome of the 758 in the image and compared to matrix metering

Incident metering was used as a comparison indicating the degree of underexposure both this and in camera metering (matrix) can give

As mentioned earlier there is no 18% used in camera metering or seperates AFAIK 18% has never been used. They will be all calibrated between 10.6% - 14% regardless of film, JPEG or raw. This requires that the photographer if reading an 18% grey card apply around +1/2 EV to bring the metered reading up to the equivalent of 18% to get closer to a correct rendition of the card without post processing.

I believe for the colour checker shots he would be using the in camera spot meter to measure each grey tone to set exposure.

In real terms the differences in exposure depends on the factors laid out in the article which in turn is dependent on the manufacturers take and application of the ANSI ISO standards

Roughly a meter calibrated to 12.5% Nikon/Canon/Pentax will require a +0.5EV to equate to 18% and a meter calibrated to 10% will require +0.8EV.

Question is does this +1/2 stop make a difference as we can easily manipulate tonal values in post often without much in the way of cost re. noise? Well, if we are just shooting 18% grey cards then perhaps not and for many other subject that equate to the an average scene value of 12% again perhaps not. But when small errors of exposure get compounded you can get much larger than desirable shifts from optimum exposure

To try and clarify any confusion about standards and why they were introduced:

The ASA standard (later to become ANSI) underwent a major revision in 1960 with ASA PH2.5-1960. This related to B&W film only where the quoted speed doubled overnight, without a change to formulation of the film stock.

Colour speeds quoted by manufacturers did not change other than by newer film coatings.
Colour negative film standards were not introduced until 1965 (ASA PH2.27-1965)
Colour reversal film speeds were defined much later in 1983 (ANSI PH2.21-1983)
 
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I didn't read that he is using an incident light meter - my interpretation is that he was using the camera's meter in spot-metering mode: "For each shot, we spot-metered one of those neutral grey patches at the bottom row, starting from the white patch, setting the exposure according to the recommendations of the spot meter."
I believe for the colour checker shots he would be using the in camera spot meter to measure each grey tone to set exposure.
That's what I meant, though I may not have explained it well.

Though I understand all this theory about exact exposure to the upper limit of the camera's dynamic range, I don't see that it has much application outside the studio.

Suppose you are on a game drive in Africa under moderately bright sun. You have just been photographing zebras in the sunlight when you suddenly see a lion family lying in the shade in perfect pose. You have to get the shot now. Do you remember and apply all of the principles you've learned to get exactly the optimum exposure? If it's me, I'm going to make an educated guess and hope to fix my mistakes on the computer. That's where the large dynamic range of the newest cameras gives us such an advantage.
 
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If it's me, I'm going to make an educated guess and hope to fix my mistakes on the computer. That's where the large dynamic range of the newest cameras gives us such an advantage.
I agree - based on all the tests I've done with matrix metering and the many variables involved it's best to just shoot away and make exposure compensation adjustments for the occasional scene that is confusing for the meter. There is no one adjustment that will make the metering accurate for every scene.
 
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That's what I meant, though I may not have explained it well.
Guess I was trying to reinforce what you thought about the methodology

Though I understand all this theory about exact exposure to the upper limit of the camera's dynamic range, I don't see that it has much application outside the studio.

Suppose you are on a game drive in Africa under moderately bright sun. You have just been photographing zebras in the sunlight when you suddenly see a lion family lying in the shade in perfect pose. You have to get the shot now. Do you remember and apply all of the principles you've learned to get exactly the optimum exposure? If it's me, I'm going to make an educated guess and hope to fix my mistakes on the computer. That's where the large dynamic range of the newest cameras gives us such an advantage.
I agree that mostly this type of exposure correction is for more contemplative work e.g. landscape or studio work.

It is not always possible in the circumstances you describe to spot meter accurately and make exposure adjustments but you do carry about with you at all times a known reflectance value i.e. the palm of your hand (probably a reflectance of around 36%). So you would probably get a pretty good exposure by metering the palm and increasing by 1 full stop in bright sunlight or if subject in shade it possible to cast a shadow on your hand and read accordingly.

Having just seen a video of a Chinese lady being grabbed by a tiger in China (she got out of the car in a game reserve) and eaten I am unlikely to find myself looking at these cats from anything other than the confines of a good zoo - so I should have adequate time to set exposure :eek:
 
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>>>
Suppose you are on a game drive in Africa under moderately bright sun. You have just been photographing zebras in the sunlight when you suddenly see a lion family lying in the shade in perfect pose. You have to get the shot now. Do you remember and apply all of the principles you've learned to get exactly the optimum exposure? >>>>

Those are exactly the situations under which I frequently shoot — and why pre-programming my in-camera exposure meters means that I am already pre-set to ETTR . . . to the max!
You probably noticed how seldom I even glance at my LCD while actually shooting? That is because I am confident that the camera is nailing the exposure. And it is!

I use the ±EV button to over-ride the meter-settings on the fly when a specific situation needs that sort of treatment. You learn to judge situations instinctively and I just change my EV setting without taking your eye from the viewfinder.
 
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I'm a bit confused here after reading... what should the spot meter be targeted at? 18% grey after the +EV compenstation?
And if so, does that mean that I need to have a colorchecker with me everywhere? (got a bit lost there on the last part)
 
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I'm a bit confused here after reading... what should the spot meter be targeted at? 18% grey after the +EV compenstation?
And if so, does that mean that I need to have a colorchecker with me everywhere? (got a bit lost there on the last part)
When you point your camera at your subject the internal metering assumes that the object is at 12.5% reflectance (particularly spot metering) if you use that value then whatever the meter has measured will be seen as a mid grey value (regardless of it being either white or black or any in between shade) but that value will be 12.5% not 18%.

To equate to 18% grey card (if that is what you are metering) to place the value precisely you would need to open up by 1/2 stop.

IMO spot reading is the most precise way to get an accurate exposure but it must be born in mind that you will need to correct either + or - EV depending on the subject tone under the focus point - which will always be rendered as a mid grey of a 12.5% reflectance value regardless of actual tone. Centre weighted and Matrix operate in a different way with matrix being the most mysterious (and probably least documented) ;). IME Nikon matrix does a pretty good job most of the time - just point and shoot.

Quite often we may find that the value that needs careful placement are the highlight values (non specular) at least those where we desire tonality and texture. So these need to be metered and the exposure adjusted to place these values to the right on the histogram (raw histo. not JPEG). Now this may mean you need to increase the cameras suggested exposure by +2EV - 3.5EV - but you will not know the actual safe value until you undertake some testing.

Metering and adjusting exposure for highlights means you have placed the important highlight values as far to the right as possible (prior to clipping) and the shadow values will fall where they may - hopefully within the DR of your camera system.

You certainly do not need to carry around a Color Checker card with you but it is nice to have if handy. From an exposure point of view as long as you have a known reference to meter off then you should be good to go.

One thing you will carry with you at all times is your hand - just meter off your palm and increase the indicated exposure by 1 stop, making sure you orientate your palm to the same plane of the subject and that you are in the same lighting conditions - this should get you close to a 'correct' exposure in most circumstances

As to colour balance using a Color Checker can be very handy just set the white or grey patch to neutral and you will have colour balanced the image to represent colour without the influence of the prevailing light colour. Just be aware that this is not necessarily correct or even desirable for many common situations or subjects and correcting white balance by eye and feeling may be more appropriate to convey your visualisation at the time of capture
 
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