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Camera's meter

Lydi2009 10:40pm, 5 October 2009
"This is a tough one to give a definitive answer to. Firstly, simply dialling your camera’s meter to zero doesn’t necessarily mean your exposure is correct. My pages on exposure metering explain some of this. Sometimes your camera’s meter need to show over, or sometimes under, for you to have correct exposure. The essential concept here is that you need to expose for your subject or a specific part of your scene."

Neil, thank you so much for your patience - would appreciate an exposure-for-dummies-explanation, please.

1 I did read your pages carefully, but I am so techonogically disabled, I simply can't get my head around exposure - when is "sometimes over" and "sometimes under"

2 I battle with the 18%grey concept - on a bright sunny day, I dial my D200 to 0 but the image blinks madly - surely, if the camera thought it had to render the scene as 18% grey, it would have been a darker image than the totally blown out image I got?
I remembered you saying that I had to shift the meter 1 to 1.7 stops to the right, and then the image started looking right. So does all this boil down to experience, remembering settings from an information bank?

3 Please recommend a site that explains what I must do with those zonesfrom the zone system to get better exposed pictures?

Many thanks
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Zeroneg1 Posted 10 years ago. Edited by Zeroneg1 (admin) 10 years ago
What Neil is talking about is 'tonal placement'. This means you expose for the most 'important tones' in your scene. This is why just following the meter blindly would lead to wrong tones being captured. This is why most profesionals use Manual Mode because they can place the tones ona 'sliding scale' by changing the shutter and aperture or a combination of both.

This whole metering thing and 18% gray is even more complicated if you use Matrix Metering since now the meter is 'evaluative' and on Nikon DSLR's the 'distance' data is incorporated into the metering as well as the colors of the scene. Overall however it still if prudent to be able to 'place' your tones. Basically what you do is if you have time, spot meter the most important tone in the scene. This can be broken in simple terms as follows:

Textured Higlights (Zone VII-VIII): this would be a white wedding dress or a towel or lace details.

Middle Gray (Zone V): This would be Kodak's greycard aka 18% gray. This is what the meter 'sees'. The meter does not KNOW that the scene before it is 'WHITE' or 'BLACK' or "GRAY'. it just wants to render everything as Middle gray becuase it sees nothing but middle gray. This is why you overexpose +1.7 to +2.0 stops to get white or underexpose -1.7-2.0 stops to get black.

Detailed Shadows (Zone III): This would be the groom's tuxedo or black tie with discernible details in the dark areas.

SO think of it this way as a SCALE with the middlegray as Zone V.

Zone III(-2.0 stops) - ZONE V (Meter Sees)-Zone VII (+2.0 stops)

So this one really goes from:

-Zone I-Zone II-Zone III-Zone IV-(Zone V)-Zone VI-Zone VII-Zone VIII-
(Black)__________________(middle gray)_____(textured highlight)


I hope this is clear. To fully use the Zone System, it is better to spot meter if not Center Weighted since Matrix complicates this because it also checks its database of stored images to compare with the scene you are looking at and judges accordingly.

This is why some DSLRs can render more tones because their 'dynamic response' is more than the competing model or brand. This is evident in the DXOmark databse.

www.dxomark.com/

Some cameras can do more than 12 stops while others can only do 9 or 10 stops. here is a comparison of the D200 vs D90. Dynamic range between them is 1 stop but the low-light capability betwen the two is very wide and tonal range is also different.

www.dxomark.com/index.php/eng/Image-Quality-Database/Comp...|0/(appareil2)/203|0/(onglet)/0/(brand)/Nikon/(brand2)/Nikon


On some newer Nikons the AF indicator also plays an important part in determining your 'most important tone' because the metering system 'WEIGHS' the exposure toward WHERE the AF indicator is placed. I don't know if this is the case with your D200 but on the D90 it definitely is when using Matrix Metering.

Neil however might recommend something else. I could only speak for my experience in Zone System in my film and darkroom days as well as how I apply it to digital.
MOD
@ Zeroneg1:

Outstanding explanation
special year [deleted] 10 years ago
I heard about the Zone System before, is it very useful? Is there a site where I can learn it w/o paying someone for something?
I generally just keep changing EV until the most 'important tones' don't blink in the LCD...
it's not very fast...
MOD
Just do a google on it. Plenty of info out there for free.

But your idea of changing EV really is the way to go, you just got to practice until it is quick for you.
Lydi2009 10 years ago
Zeroneg1 - thanks for your very detailed answer - please help me understand better:

Scenario: Bride in white, groom in black, some trees behind them, their backs towards the bright light - how does it help me to take better pictures by knowing that the white dress is in zone vii-viii? What must I do to my camera to use the zone system?
Thanks a stack
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Zeroneg1 Posted 10 years ago. Edited by Zeroneg1 (admin) 10 years ago
This means you have to meter the most important area you want to HAVE in the image. The Zone VIII and Zone III are the ones you need to have but sometimes due to lighting conditions the number of stops you can capture gets either expanded or contracted. This is where you must decide if you would AUGMENT the existing scene with flash or change the dynamic range with filter (ND filter/Polarizer/Soft FX filters) or expose it as it is.

In your scenario I would use the spot meter and meter their faces FIRST, because that what the eye see first and should be well exposed. Next I would meter the white dress and the dark tux. If say the face was at f/8 at 1/60th and the White dress meters at F/8 at 1/250th and the dark tuxedo was meter at f/8 at 1/15th than what you have is a 'NORMAL' scene. Meaning you can go ahead and expose for the face at f/8 at 1/60th since the white dress would fall on Zone VII-VIII because the meter is registering it to be 'two stops' above your 'important face' as well as the dark tux registering at Zone III coming in as (-2.0) two stops under exposure.

Sometimes this is not always the case with say a cloudy day or overly bright sunlight. There is a rule you can follow the so called FINGER RULE:

FLAT SCENE: Three fingers: Three stop difference between 'textured highlight' and 'detailed shadows'

NORMAL SCENE: Four Fingers: There is a four stop range between 'textured highlights' and 'detailed shadows'

CONTRASTY: Five Fingers: There is a five stop ranger between 'textured highlights' and 'detailed shadows'.

In general you can do this by eye too:

NORMAL scenes have vsible but diffuse and soft shadows

FLAT scenes have shadows with little or no definition and form

CONTRASTY scenes have sharp shadow OUTLINES that can be traced.

If you scene is flat you have to create contrast, this is done by either using filters or using flash to overpower the sun. Also when there is too much contrast you can then either use fill flash to 'Brighten up' the shadows areas to push them towards Zone IV from Zone II or Zone III or by using filter like an ND filter to compress the tones.

So after metering you must evaluate what kind of SCENE do you have, is it FLAT? NORMAL or CONTRASTY? How the scene is captured and metered would depend on your lens as well as in your camera. Different cameras have different dynamic and tonal range depending on the ISO and lens used.

All of this is 'SHIFTING' where the existing tones on the scene are PLACED. This are controlled by your aperture and shutter speed as well as any flash or filter you use. Essentially you should consider the EXISTING tones in the scene as being on a "SLIDING SCALE" of Zones where you can move the tones UP or DOWN depending you how you expose them. Your 'baseline' would always be the Zone V or middle gray. Some people meter only the 'textured hightlights' and 'detailed shadows' and extrapolate the middle gray based on the Zone VII-VIII and Zone III placement on the scene.

These tones and how they are rendered can also be altered in Photoshop using the CURVES and LEVELS but that has a limit. You do want you most important TONES to fall closer to Zone V (middle gray) than outwards to Zone IX and Zone II because it is harder to 'recover' those tones even if you shoot RAW. Shooting in RAW could only save you so much so proper exposure is still preferable to doing everything in post-production.

Finally the workflow is:

1) METER: The most important tones you desire and ignore the others.

2) EVALUATE: the scene before you based on the meter readings. Which tonality is more important than the others?

3) DECIDE: How you will expose the most important tones in the scene. Will you WEIGH or LEAN your exposure towards the 'Textured Hightlights or towards the 'Detailed Shadows'? Deciding on this depends on your exposure and your camera and lens.

EDIT: In Neil's blog this is a great example of him placing tones:

www.planetneil.com/tangents/2009/10/01/workshop-view-phil...

The regular shot he had is pretty normal without much contrast or PUNCH. He choses to UNDEREXPOSE so that there is now contrast and then ENHANCE the shot by making the Flash the dominant or KEY light.


Notice that in the regular shots, the building and the columns behind in the background registered at Zone VI to Zone VII (light gray to textured white highlights), by underexposing it he pushed them to Zone V-Zone VI which is much darker. The rest of the tones in the building which were Zone IV-V in the regular shot were now pushed down to Zone III-IV. He dealt with the 'Detailed shadows' FIRST and took care of the important tones (SKIN and clothing) using flash.

www.planetneil.com/tangents/2009/05/28/shutter-speed-cont...

By Neil changing shutter speed from 1/40th to 1/100th, the tonalities in Zone VI-VII is PUSHED DOWN to Zone IV-V (almost 3 stops really more like -2.7). The upper highlights of Zone VIII-IX also get toned down to Zone V-VI (the Veil)
Lydi2009 10 years ago
Zeroneg1 - this is mind-blowing, but I'll go through it until everything clicks into place for me - thank you so much for your time and patience.
MOD
Again

@ Zeroneg1:

Outstanding explanation

Practice and experience and working this out mentally is really the key to go along with what Zeroneg1 said
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Zeroneg1 Posted 10 years ago. Edited by Zeroneg1 (admin) 10 years ago
In practice for me this is how I do it.

Set the camera in A mode (Aperture Priority)

Set the metering to Spot.

Set the AF indicator to the important part of the scene.

Take a shot.

Evaluate the picture. The picture taken with Aperture priority is your BASELINE. Sometimes I take more than one shot with the AF indicator set to the 'textured highlights' and another at the 'detailed shadows'.

Now switch to M mode (Manual) and change the shutter speed or Aperture and expose the scene as you like. This part is HOW you actually SLIDE the exposure based on how much you change your exposure FROM the BASELINE. In most cases once you are happy wiht the tonality you got, you stick to that setting unless the light changes.

If you have flash on you have to adjust the flash output as well during the scene stage. This is easier to do if youre using a Nikon DLSR because of the I-TTL/CLS. I use TTL for indoors and TTL-BL for outdoors both with flash exposure compensation set depending on the ambient light levels and direction/quality of light I want to dominate.

Starting with A mode then switching to M mode is so automatic for me now that I dont even think I do it. And I rarely post-process any shots anymore unless I am doing some 'stylized' images.


For really tricky shots I also rely on a Flash Meter with a flat diffuser. Using an incident light meter is much better since that measures LIGHT FALLING ON' the subject instead of the built-in meter of the camera which measures 'REFLECTED LIGHT' which is affected by the subject's materials like shiny clothing or dull textile. But this i mostly use for tricky light situations or when using multiple manual flash setup.
Lydi2009 10 years ago
Zeroneg said; "This is why you overexpose +1.7 to +2.0 stops to get white or underexpose -1.7-2.0 stops to get black. "

When I overexpose a white object, from the 0 reading (where it is already blown-out) it makes an even bigger mess of the white, so please tell me what I'm still missing.

Please help me understand: Why do you refer to 1.7 stops if there are only 3 spaces in a stop, set to 1/3 increments - the only other setting is 1/2 increments, not so?
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Zeroneg1 Posted 10 years ago. Edited by Zeroneg1 (admin) 10 years ago
Ok If your using Matrix Metering which is 'EVALUATIVE' It already 'perceives' it as white in 'SOME' instances. 'Some' because this depends on the surroundings and environment where this 'white' subject is. On some DSLRs this also depends on WHERE you place the AF indicator, since it PRIORITIZES that area when doing Matrix Metering/Segmented/Evaluative.

The +1.7-2.0 Zone placement is really for Spot and Centerweighted metering. Matrix Metering or Segmented metering is something else because it judges the tones on the scenes based on its surroundings as well as based on camera ORIENTATION (horizontal vs vertical) and in Nikon cameras the 'camera orientation' is taken into account by the Matrix Metering as well as adjusts its evaluation accordingly since it can judge if the bright spot above is the 'sky' or something else because it has an internal image database (converted as an algorithm) where it compares the scene before you and tries to guess what kind of picture are you taking.

read:

www.mir.com.my/rb/photography/hardwares/classics/nikonf4/...

That's from a 20 year old technology camera from the 80s, The Matrix Metering in the new Nikon DSLRs uses a more complex algorithm (3D Color Matrix Metering II) and actually reads 'spectral response' (color,hue and tint) as well as distance information. Nikon claims in F5 that the Matrix Metering there can read fluorescent and incandescent and other spectra. I have no doubt this is also present in the DSLRs now.

imaging.nikon.com/products/imaging/technology/scene/14/

As for the 1.7 stops instead of counting 2.0 that's for subtleties in tonal rendition. Ok let me explain. On most cases if I do a FULL stop exposure compensation by doing Zone placement, the 'captured' tones do not register in 'desirable tonality' hence a TWEAK of 1/3 stop sometimes is enough to bring the tones correct. This is also probably why Neil refers to +-1.7-2.0 sometimes +.3 or +.7 stops adjustments in his flash or ambient exposure.

Having your f/stop increments in 1/3 offers you a more subtle way of rendering tonalities compared to say 1/2 stop or even full stops. This also makes working with Aperture Priority and Manual mode much easier. 1/3 stop increments offers enough tonal change that has observable effects without a HUGE SHIFT in the way the tones are rendered across the image.
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zesty reward [deleted] 10 years ago
Zeroneg1 .. fantastic explanation. Very clear. Thanks! :)
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Zeroneg1 10 years ago
Ahh I hope I didn't step on your toes Neil :) Thanks.
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zesty reward [deleted] 10 years ago
naaah .. that's what this group is for .. everyone can climb in at any time.
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zesty reward [deleted] 10 years ago
The info on this page has been extended, and now appears as a guest blog post on my site ...

www.planetneil.com/tangents/2009/10/23/zones-of-light/
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