What is spot metering...

[stubbsy]

... and do I already know what this is, but not have a name for it.

Phew. I feel embarrased to ask this. AND the Wiki entry for this is wiki-less

[Alpha_7]

I'm not sure I'm the best person to help you with that Peter.... But may I ask if you know what Matrix Metering and Centre Weighted Metering are or if these are foreign to you aswell ?

[owen]

Spot metering gets an area from the middle of the camera (Where the middle af sensor is) and takes an exposure reading from there. The dangers of this is that if you spot meter off a mans black tie, then it will treat the whole image as if it were that colour, and vice versa. I think the area that it meters is 2% - 5% of the whole image square.

Hope this helps stubbsy.

Regards,
Owen.

[pippin88]

It's metering for a small spot rather than trying to meter for the overall image (which is what matrix does).

So the camera gives you the exposure settings to expose whatever is in the small dot (located in the centre) correctly. Very useful if your subjects exposure is all important or matrix isn't exposing what you want correctly.

Also useful to use with the zone system.

[losfp]

Errr....


Lemmeseenow. Spot metering is where the camera meters the exposure from one specific predefined area - on the D70 I think it is the small area inside the active focus point.

Centre-weighted is the same, but the camera looks at the whole centre area. Matrix metering is a complete mystery to all of mankind.

[stubbsy]

Well I'm no less (and no more) confused. See I've heard of spot metering, matrix metering and centre weighted, but all I see in my camera menu is a choice of what SIZE centre weighted - no mention of anything else.

I guess I understand the concepts, just not how to actually do the little $%#$%$# ers

Edit: And thanks Nick - now I'm even stupider than I thought - the zone system???

Better hold off considering a D200 till I know how to use my D70 properly

[christiand]

Hi Peter,

are you referring to menu 11, Center wtd ?
If that is the case, you're right.
The menu allows to set the centre width.
Spot metering can be set on the D70 by choosing a metering mode.

You wil find that on page 75 of the D70 manual.


HTH,
CD

[Alpha_7]

Well I'm no less (and no more) confused. See I've heard of spot metering, matrix metering and centre weighted, but all I see in my camera menu is a choice of what SIZE centre weighted - no mention of anything else.

I guess I understand the concepts, just not how to actually do the little $%#$%$# ers

Edit: And thanks Nick - now I'm even stupider than I thought - the zone system???

Better hold off considering a D200 till I know how to use my D70 properly

Peter,

Near the shutter of the d70 is a Metering button, if you hold it down and scroll with the main command dial, you should scroll through the different metering modes. I have to admit I have very limited knowledge and experience with it, but have experimented with it a little more in the last month or so... otherwise I use Matrix and modify the exposure myself.

[stubbsy]

Christian, Craig - thanks

THAT button - played with it once and forgot about it. I'll just go hide under the table for a while in shame. Good job there was no newbie helping me out (Craig - can't be a newbie since he has waaaay too many posts )

[losfp]

I find that what I end up doing is putting it on spot meter, then using the EL button (set to Exposure lock/hold) to meter exposure, then recomposing and shooting.

Trouble is that sometimes takes too long, so it's the old "shoot raw in matrix mode, then fiddle in post" method that Craig mentions

So far it's either spot or matrix - CW seems to be trying to be both things at once, so I can't ever get it doing what *I* want!!!

[nito]

I find the EL button hard to hold when clicking the shutter button.

[Alpha_7]

Christian, Craig - thanks

THAT button - played with it once and forgot about it. I'll just go hide under the table for a while in shame. Good job there was no newbie helping me out (Craig - can't be a newbie since he has waaaay too many posts )

Not so long ago (as in only weeks), When Nathan (Graphite) was playing with my D70 in preparation for his D50... he handed it back to me.. and the little focus graphic was different on the top LCD display... it took my 5 minutes of pressing lots of buttons to find out how to change it back.... Doug was fairly incredulous when I told him of my discovery about the "D-pad" moving the focus cusor around... up until then I had been using focus lock, or focusing, switching to manual and then recomposing the shot...

I've now in the past 2 weeks or so, have extensively used the focus cursor so its more like second nature to me...

Moral to the story, is we always have more to learn!

[stubbsy]

Moral to the story, is we always have more to learn!

Absolutely. I'll stop learning the day I stop being cognisant of my surroundings.

[Matt. K]

Spot metering is where the camera reads only the light reflected from a very small area of the viewfinder. It is useful under the following circumstances...a man sitting in a car at night and the interior light is on...or a man on a stage with a small spotlight lighting only his face, or a person standing under a street lamp at night. The camera ignores the vast areas of darkness and only considers the light on the face of your subject, providing that is where you have the spot meter aimed. The area read by the spotmeter should approximate an 18% gray card in reflectance...otherwise the photgrapher will have to interpret the reading and add compensation. Plus 1 or 2 stops for white and minus 1 or 2 stops for black subject.

Center weighted metering is similar but the circle is much larger and the tones being read are not so critical. It works well where you want the camera to ignore bright backgrounds such as on the beach or in the snow...or a subject that is backlighted by light coming through a window or door etc. Both of these metering systems are very useful under the conditions that I just mentioned. Matrix metering should be used for everything else because it is very very good.

[losfp]

I find the EL button hard to hold when clicking the shutter button.

Which is why I have switched it to EL lock/hold One tap, and it freezes the exposure until I tell it otherwise.

Usually I forget

[avkomp]

spot metering?? isnt that when you take a light reading off the dog ??
sorry!!

[leek]

I've been using spot & centre weighted a lot up here in the UK... The sky is so bright in comparison with the illumination that it provides on the ground that if you use matrix, then your images will be underexposed... I have been spot metering off my actual subject and then bracketing to get a usable sky on another shot.

[BBJ]

Peter, i use metering abit mainly spot and matrix, spot is ok depending on the day when i am chasing bikes, i could spot meter on the bike then the rest of the fram is either under exposed etc.. so sometimes on a bright day i might shoot matrix so i have an even light between bike and rest of the frame, it is something you have to try and you will see a differance.
I think the others have covered most of it, but have a play you will see the dif.
Cheers
John
BBJ

[Onyx]

Peter, and others, here's an example of when you might like to use spot metering.



I spotted this hawt girl with piercings (yeah yeah, each to their own - I like pierced girls) onboard the ferry during the Nov micro meet. Spot metered her face, with the sky exposure blown and the interior as dark as the cat in Schrodinger's box. Her face is exposed as intended... In fact this image is a tight crop with a much larger area of blackness that is the interior of the ferry which would have messed up the exposure if I had used another form of metering. AFAIK, the spot being metered corresponds to the active AF point. So that may bring unpleasant surprises if one uses closest focus priority or dynamic area AF (ie. AF point not being as intended).

[stubbsy]

Thanks Chi. That's a great example. So if I have spot metering on and move the focus using the D pad then the spot metering is based on my focus point. That's pretty cool since if you move the focus point presumably it's on what you want to meter off.

[Steffen]

Matt made an important point about spot metering, that is often overlooked. One has to develop the skill of guessing subject reflectance. If you use a lot of spot metering you'll know how to correct exposure for various skin types, sky, sand, rock, grass etc.

If you were to simply spot meter a caucasian face without compensation it'll come out underexposed in most cases.

I rarely use spot metering for auto exposure, since I find that matrix metering gives very good results in most cases, and for tricky lighting that may confuse the matrix there's always centre weighted. I do use it sometimes when I've got lot of time (like with landscape shots) to sample a scene and determine whether it can be shot without drowning or overblowing any area. Or for posed portraits, when I can ask the subject to hold a gray card up to their face for me to meter off.

Both spot and center weighted will give accurate exposure assuming the metered subject area has 18% reflectance, like a Kodak gray card. Or a lush green lawn or tree top (in very good approximation).

Centre weighted metering behaves slightly differently depending on the body. It will always take the whole frame into account, giving the central circle an increased weight in the overall average (hence the name). Some bodies (like the F3) are fairly agressive and assign 75% priority (IIRC) to the centre. I think the majority are using a 60/40 split, or thereabouts. Modern bodies (like most DSLR's) also allow the size of the central circle to be customised. The important thing to remember is that the high-priority circle is always in the centre, hence metering with the important bit centered, then re-composing, may be necessary.

With spot metering on modern and digital bodies one can sometimes customise the size of the spot. Interestingly, a 1% spot isn't usually available, although it was once considered the only "true" spot meter in pro bodies...

On my D2H the metering spot isn't always central but appears to follow the chosen AF sensor.

Cheers
Steffen.

[Steffen]

Her face is exposed as intended...

It is, technically, underexposed though.

However, it may still have been exposed as intended, in a shot like this one has to make sacrifices, the scene totally overwhelmed the film's/sensor's latitude.

Cheers
Steffen.

[christiand]

Hi Steffen,

This is a tricky exposure.
The face is slightly under exposed but the shoulder needs
a little bit less ?
Is this a matter of fill flash ?
So what do you do ?
You may have to compromise or decide to not take that kind of photo
in that kind of lighting conditions.
But how often do you not have a choice ?

Cheers,
CD

[Sheetshooter]

Spot metering is an especially useful function to determine the subject brightness range of a scene which can be a very useful check and, in application of the Zone System, a means of determining both exposure and development data.

In all of the characteristic curves I have plotted with both Canon & Nikon DSLR cameras of late I can assure you that an increase of exposure of just ONE stop would be about the safe limit. On the Canon there is useful tone to well over more than two-stops (but certainly not three) but the Nikon (D70s) peaked at just on the two-stop mark. (Zone VII for those who might know).

In film practice it was de rigueur for people to test, calibrtate and adjust their exposure and development regimes from meter to meter, shutter to shutter and film/developer combination to filmn/developer combination. That level of application seems absent in many quarters with digital practice but is still most beneficial for those with the inclination and interest to do it.

With digital capture it is, in fact even more important - especiually where low values are concerned. With film the scale of lightness and darkness (density) is a logarithmic progression whereas with digital it is arithmatic. With the varying curve of the toe and shoulder of a logarithmic curve the low and high tones condense at a given rate. With digital capture you have a scale of 0 to 255 and once values dip below 0 there is no data to recvover.

Cheers,

[stubbsy]

I just want to say that for a dumb question I'm getting lot's of very smart and informative replies. Thank you one and all.

[HappyFotographer]

Christian, Craig - thanks

THAT button - played with it once and forgot about it. I'll just go hide under the table for a while in shame. Good job there was no newbie helping me out (Craig - can't be a newbie since he has waaaay too many posts )

I haven't read all this thread yet, but Stubbsy.....thanks for asking. I couldn't work out how to get the options to change (and yes, I did look through the manual....quickly).

[Sheetshooter]

Might I suggest a simple test for anyone wishing to use in-camera spot-metering - or even dedicated spot metering.

In a darkened room (doesn't need to be pitch dark) set up a lit candle or a torch that is a confined area of light that does not fully illuminate the entire space.

Preferably with the camera fitted with a normalish lens placed on a tripod, pan the field of view left and right and make a mental note of just where the exposure indicator starts to show a significant shift. The do the same with an up and down tilting. That way you will get a fair idea of where the spot-meter is reading on YOUR camera. I would then repeat the test with a wide angle lens and a longer lens to see if the area is constant or variable dependent on focal length.

With spot-metering it is just as important to be certain of what IS NOT included as what IS included.

Another very useful test to determine IR sensitivity with any sort of reflected light meter (LUMINANCE meter) including an in-camera meter in any mode is to point the sensor at an electric stove element in a darkened kitchen. The element is turned of at this stage. Make a note of the exposure. Now turn the element on. Watch the exposure reading and if it begins to alter BEFORE there is a visible shift in brightness or 'glow' then there is an issue with the IR shielding of the metering cell.

Cheers,

[Onyx]

Hi Steffen,

This is a tricky exposure.
The face is slightly under exposed but the shoulder needs
a little bit less ?

Christian, the shot had quite a bit of negative exposure comp applied in post to recover her shoulder - it was more blown in the original capture. As Steffen correctly pointed out - her face is technically underexposed, the lighting conditions having overwhelmed the latitude of the sensor. Fill flash would have helped - but not knowing how her more punked up boyfriend would have reached to me taking the pic, its use may not be practical in this case, for my personal safety.

I agree with Steffen and Walter, using the spot meter does require knowing that it assumes reflected middle grey (and knowing how to compensate for lighter/darker tones), and knowing precisely which spot is being metered. Also be aware that on the D70 body the EV range of spot metering is more restricted than CW or matrix. (EV2 minimum according to the manual IIRC, matrix goes to EV0).

It was such a huge discussion point that the lower than 1 series Canon bodies not supporting spot metering - when it seems quite a number of Nikon shooters have thus far compiled fantastic images without the need for it. More ammunition for the argument that the gear doesn't matter. Extra features don't matter. The photographer matters.