How good is your meter?

[sirhc55]

I tried an experiment today and was amazed by the results. The two pics below were shot in a light tent with two Bowens Trilites as the source of lighting. The camera was the D2Hs with a 50mm f/1.4 Ais lens. WB was auto for this experiment and an aperture of f/16. I used full manual.

When I take pack shots for clients there is normally a fair bit of fiddling to get a result good enough for print.

What I wanted to try was a comparison between the inbuilt meter on the D2Hs and my new Sekonic L758D. As I am waiting delivery of the test cards from Vanbar the Sekonic has yet to be calibrated to the camera.

Both shots have had absolutely no PP’ing except for resizing, conversion to sRGB and uploading as jpeg.

The first shot is using the inbuilt meter system: average





The next shot was with the Sekonic in incident mode with the lumadisc extended - reading directly off the subject.



Conclusion - I’m glad I purchased the Sekonic

[Steffen]

The first shot is using the inbuilt meter system: average

That's to be expected from a centre weighted meter, with all the white background. I'm guessing that matrix metering would have done better here, because it would have recognised that the background is a lot brighter than the object in focus.

Cheers
Steffen.

[Oz_Beachside]

I found precisely the same. using inbuilt, got those "average" meter readings, then, got a meter (even the basic gossen I have since replaced with the 758D) and its worlds apart.

I read lots about the D200 having good metering, and it does, for lots of applicaitons, but I found for times when I need it to be precise, like white blown background (light tents, or white seamless), its tremendous.

also the physics of the light... the camera meter is looking into the light, the external meter is pointing back at the camera, two very different directions.

interesting post, thanks! PS: have you used the spot meter yet? its soooo narrow, vrey useful when working with natural and fill flash...

[gstark]

I've always found incident light readings to be the best for the images I shoot.

the camera meter is looking into the light, the external meter is pointing back at the camera, two very different directions.

Yes, but no.

The camera meter, in fact, is always looking at your subject, and as such, its view includes the characteristics of that subject, which includes shades and colours. If it happens to be predominantly dark (or light, or deep red, or yellow ... etc) this will have an effect on how your camera interprets what it's "seeing", and as such, any meter reading the camera makes will be influenced by this.

With an incident reading, as you say, the meter is facing back towards the camera, and as such, the meter can (or should be) only reading the light that is falling on the subject. This, IMHO, is exactly what you want in a meter reading.

[ATJ]

also the physics of the light... the camera meter is looking into the light, the external meter is pointing back at the camera, two very different directions.

Or to put it another way, the incident meter is measuring the amount of light falling on the subject whereas the camera is measuring the light falling on the subject and then reflecting in the direction of the camera. The latter will always be influenced by the subject itself - how dark or light it is and also the colours.

You can simulate the an incident meter with your camera's meter by using a grey card. Place the grey card so it is receiving the same light as the subject and meter off the grey card. That would provide a much fairer comparison between the two meters.

In theory, incident metering will be better than camera metering because it isn't influenced by the reflectivity of the subject. If you use the in camera meter to take a photograph of a predominately black subject (a black spider on asphalt), you will end up with a grey image. Similarly, if the subject is predominately white (a snow fox on snow) you will also get a grey image.

I say in theory because incident metering is also not perfect because of the limited dynamic range of the recording media (digital or film). While the incident meter will give you a more accurate reading, dark areas in a photograph may be too dark and lose detail and light areas may be too light and get blown. The second image shows blown highlights on the yellow cable.

In both cases, incident and in camera, you need to use the readings as a guide and then make adjustments based on the subject and what is most important within the subject.

[Kris]

LM vs Matrix in camera? Wouldnt mind seeing that...LM certainly does a good job

[Reschsmooth]

In the absence of incident metering, could you get away with spot metering to basically ignore the white background (I ask because metering is still something I am getting my head around, and would otherwise ask embarrassingly beginner questions)?

[ATJ]

Patrick,

Yes. Ideally, you'd want to spot meter on a grey card or something of similar reflectance. You could probably even use your hand to get a good approximation.

Alternatively, spot meter on the most important area of the subject - the thing you want to be exposed correctly - taking into consideration that a black item would end up over exposed and a white item under exposed if you spot metered on them.

[Steffen]

I found precisely the same. using inbuilt, got those "average" meter readings, then, got a meter (even the basic gossen I have since replaced with the 758D) and its worlds apart.

I may have misinterpreted Chris' use of the word "average"...

Chris, did you mean average as in "less than perfect" or as in "centre-weighed averaging"?

In any case, an incident light meter is by definition correct (unless it's broken), so if you have one and the situation allows for it then use it.

An averaging in-camera meter is only correct if the scene it's averaging over has 18% reflectance. Taking a reading off a green lawn is a good approximation.

A matrix meter takes several reading across the scene and then tries to rationalise what the scene looks like, in order to selectively ignore or emphasise the readings from certain areas in the scene. This works well in a lot of situations, but isn't fool proof. It usually fails with predominantly black or predominantly white objects. Many years back on the Nikon mailing list someone made a joke about Nikon releasing an F5B and an F5W, for shooters of predominantly black, or predominantly white scenes, respectively

Cheers
Steffen.

[ATJ]

An averaging in-camera meter is only correct if the scene it's averaging over has 18% reflectance. Taking a reading off a green lawn is a good approximation.

Assuming your lawn is green - damn drought.

According to John Shaw, you can also use sky on a clear day to check your meter using the "sunny f/16 rule". With the sunny f/16 rule, the correct exposure under sunny conditions is f/16 and 1 over the ISO. For ISO 200, the correct sunny exposure is f/16 and 1/200" (which also means f/11 and 1/400, etc.). So, if you were to point the camera to a clear south sky (Shaw says north, but he's American) about 45º above the horizon, the correct exposure should be f/16 & 1/200" @ ISO 200.

I haven't tried this with my D70, but did it (some years ago) with my FE2 and F801s to determine that they always overexposed. With film it was easy as the ISO for film was fairly accurate. I would set the ISO on the camera to the calibrated value rather than the ISO for the film. For example, for Kodachrome 64, I set the FE2 to ISO 80.

With digital, the added complication is that the stated ISO may not be correct, rather than the meter itself. If the sunny f/16 test doesn't give you the right results it could either be the meter or the stated ISO. What I mean is that the meter may be accurate for the ISO - so you get well exposed pictures - but the ISO itself may be wrong.

[Reschsmooth]

According to John Shaw, you can also use sky on a clear day to check your meter using the "sunny f/16 rule". With the sunny f/16 rule, the correct exposure under sunny conditions is f/16 and 1 over the ISO. For ISO 200, the correct sunny exposure is f/16 and 1/200" (which also means f/11 and 1/400, etc.). So, if you were to point the camera to a clear south sky (Shaw says north, but he's American) about 45º above the horizon, the correct exposure should be f/16 & 1/200" @ ISO 200.

I have a table, based on the sunny f/16 rule, which gives the +/- EV for different lighting, eg. candlelight maybe 1/ISO @ 16 +, say, 3 stops or something, and morning light maybe +1/2 stops. I may try to find the table and copy it onto a post.

[ATJ]

I have a table, based on the sunny f/16 rule, which gives the +/- EV for different lighting, eg. candlelight maybe 1/ISO @ 16 +, say, 3 stops or something, and morning light maybe +1/2 stops. I may try to find the table and copy it onto a post.

For a moment I thought you were talking about the tables that used to come in or on the packaging for Kodak (and maybe others) film. Note, these were also based around sunny f/16.

[sirhc55]

Try this:

For portraits

http://mysite.verizon.net/jayandriot/Loop.htm

[Matt. K]

With a bright background as shown in the products shot opening up 1 or 2 stops with a reflective reading would be mandatory. This would achieve the same result as the incident meter.

[Reschsmooth]

Further to ATJ's post above, below is a table based on the f/16 @ 1/ISO ("Basic Daylight Exposure" - BDE) guideline.

Sunlight - normal subject in sunlight: BDE
Sunlight - silhouette: -2 stops
Sunlight - bright snow or sand: -1 stop
Sunlight - backlight, exposing for shadow: +2
Overcast - weak, hazy: +1
Overcast - normal, cloudy, bright: +2
Overcast - heavy or open shade: +3
Neon, lighted signs: +5
Stage Shows: +5-7
Flood Light Acts: +6
Flood-lit Acts: +7
Brightly-lit theatre districts: +6
Store windows at night: +6
Fireworks: +6
Night football, boxing, etc: +6
Office - flourescents: +6
Brightly lit downtown - night: +7
Fairs, amusement parks: +8
Swimming pool - indoor tungsten lights: +8
Home interior - at night: +8
School, church - stage and auditorium: +9
Christmas lighting at night: +10
City skyline at night: +13

This is courtesy of Brooks Institute of Photography care of "Photographic Global Notes" (Vol 1&2) [Silver Pixel Press] 1994

Use this as you will

[Matt. K]

Patrick
Tables like that are very useful. Everyone should carry a copy in their camera bag.

[the foto fanatic]

As I am waiting delivery of the test cards from Vanbar the Sekonic has yet to be calibrated to the camera.

Hi Chris

Have the target cards arrived, and if so have you profiled your camera?

What cards did you buy?

What is your verdict on the Sekonic now?

[sirhc55]

Cricketfan - yes I did receive my ”Perfect Pix” targets from Vanbar. Actually, for the price of $118 delivered, it’s a wee bit of a rip-off. You get:

1 An 8 colour target card
2 A 3 tone card - white, grey and black
3 A target grey card
4 A zone card
5 Patches card
6 A RGB-CYMK natural colour card.

50¢ worth of card IMHO

I plan on doing the profiling in the coming weeks. I have been totally involved recently on the audio/video side of my life.

As far as the Sekonic is concerned I’m still wrapped with it and since the dollar has improved it’s now even better value.

[the foto fanatic]

Cricketfan - yes I did receive my ”Perfect Pix” targets from Vanbar. Actually, for the price of $118 delivered, it’s a wee bit of a rip-off. You get:

1 An 8 colour target card
2 A 3 tone card - white, grey and black
3 A target grey card
4 A zone card
5 Patches card
6 A RGB-CYMK natural colour card.

50¢ worth of card IMHO

I plan on doing the profiling in the coming weeks. I have been totally involved recently on the audio/video side of my life.

As far as the Sekonic is concerned I’m still wrapped with it and since the dollar has improved it’s now even better value.

I notice the Sekonic card is US$99, and that's for only one 10X8 B&W card!

[sirhc55]

Trevor

They are all ripp-offs. Much the same as printers. The inks will normally cost more than the printer after 2 refills

[Grev]

I do think that you can also get used to the feel of the particular camera's in built meter.

For example, for me, I'm so used to the D70's metering, I know how much to compensate depending on what type of scene it is, and I don't particularly have any rules to govern it, just by 'feel'. And I mainly use centre weighed metering with the smallest radius.