Checking Light meter accuracy- Did I do something wrong?

Yes, I agree with AjG, I guess I worded it wrong. But that I meant, if a person is wearing a white shirt and a black shirt, it will be impossible to use a spot meter and get the "correct" exposure since it will average the two colors to compensate for a neutral grey, which translate to white is kind of grey and black is kind of grey.... am I correct this time?

I think that you might be trying to express a method to get the correct exposure, if you only had a Spot Meter: you could Spot Meter either the black shirt OR the white shirt and compensate those readings to arrive at the correct exposure.

If you are using a Spot Meter the area being measured is very small, so the Spot Meter does not do any "averaging" - you would have to do the compensation.

If I only had Spot Meter, and I had a person in black trousers and white shirt, then I would probably Spot Meter and area on the person's face and compensate that exposure reading based on the type of the Subject's skin.

I think that Spot Metering is not often used, nowadays.

WW

Yes, they are meant to work that way, but I'm making up a hypothetical scenario where my camera has no meter, and I'm shooting to expose the curtain correctly. I'm putting the dome closely against the curtain, is it not "close metered" as you mentioned?

As an observation, I think that you should consider that these hypothetical scenarios may be adding to confusion, rather than moving you forward in learning Real World Photography.

WW

I'm beginning to wonder ...

I think the OP needs to take more photographs and do a little less theorizing about how things work. The best advice I ever got from someone when I was young and asking these kinds of questions was "Try it and see what you get..."

If you want to check the Nikon FM meter against the Sekonic L358 in incident mode you need to do the following.

1. Use the Sekonic with the lumisphere down.

2. Put an 18% gray card where the subject is.

3. Measure the light with the Sekonic meter at the gray card but facing the camera.

4. Measure the light with the Nikon FM that is close enough to the gray card so the gray card fill the viewfinder. It doesn't matter if the graycard is out of focus. Make sure you or the camera doesn't cast shadlow on the gray card.

5. Compare the reading and the Sekonic should read the same as the Nikon FM.

The Nikon FM doesn't have a built in spot meter. It has a reflective center weighted at 60/40. To eliminate the weighting make sure the fill the frame with a subject with even brightness. Your reading of 3 stops off is about correct.

I think the OP needs to take more photographs and do a little less theorizing about how things work. The best advice I ever got from someone when I was young and asking these kinds of questions was "Try it and see what you get..."

I don't understand why I got so many criticism over a scenario that I'm observing in my bedroom: There is a white/ beige silk curtain backlit by the window, I have camera (pretending with no meter), I have an incidence meter --> how would I meter this curtain to get the right exposure.... is this so remote and "theoretical"???

Anyways, I just measured it, the Sekonic incidence gives consistently 2-2.5 stops under than the spot meter in my camera. And I attribute it to the reflective element of the curtain.

I don't understand why I got so many criticism over a scenario that I'm observing in my bedroom: There is a white/ beige silk curtain backlit by the window, I have camera (pretending with no meter), I have an incidence meter --> how would I meter this curtain to get the right exposure.... is this so remote and "theoretical"???

 

Anyways, I just measured it, the Sekonic incidence gives consistently 2-2.5 stops under than the spot meter in my camera. And I attribute it to the reflective element of the curtain.

You can't measure a backlit curtain with an incident meter. Not criticizing you but that is one of the situation when the incident meter doesn't work.

With an incident meter you use it by aiming it back at the camera not at the subject. That measures the light falling on the subject not the light reflecting off of the subject.

Ergo, if you have the incident meter facing the curtain, you are not using it correctly, are you?

I don't understand why I got so many criticism over a scenario that I'm observing in my bedroom: There is a white/ beige silk curtain backlit by the window, I have camera (pretending with no meter), I have an incidence meter --> how would I meter this curtain to get the right exposure.... is this so remote and "theoretical"???

 

Anyways, I just measured it, the Sekonic incidence gives consistently 2-2.5 stops under than the spot meter in my camera. And I attribute it to the reflective element of the curtain.

All three Sekonic incident meters that I have owned came with a reflected light adapter that can be put in place of the incident dome. I don't know about your specific model, but it is possible that if you bought a used meter that the reflected light adapter is missing. On mine these are small parts and easily lost, so I am careful to keep them in the compartment in the case that came with the meter. If you have the adapter and meter carefully with it you should get a very similar if not identical reading to what you're getting with your Nikon FM.

There is a white/ beige silk curtain backlit by the window, I have camera (pretending with no meter), I have an incidence meter --> how would I meter this curtain to get the right exposure.... is this so remote and "theoretical"???

Yes.

This scenario this is both 'remote' and also, it is well beyond 'theoretical'.

As has been mentioned many times using an Incident Meter to meter a backlit curtain is using the wrong tool. We might as well be discussing how to drive a nail into hardwood with a screwdriver.

Anyways, I just measured it, the Sekonic incidence gives consistently 2-2.5 stops under than the spot meter in my camera. And I attribute it to the reflective element of the curtain.

Secondly, as has been also mentioned, your camera has no spot meter.

Thirdly, also as has been previously explained, your conclusion that the curtain's reflective element causes the metering difference between the camera's meter and the Sekonic meter, is simply wrong.

***

I don't understand why I got so many criticism over a scenario that I'm observing in my bedroom:

I have re-read every response: I read no criticism of you whatsoever.

I do read many responses which provide accurate technical information; advice based on experience and knowledge to see you progress in your knowledge; or both.

Moreover, this conversation has bounced around, for whatever reason, across a few different topics and the responses have attempted to correct your inaccurate assumptions and steer you to better understanding at each new bounce.

Also, in is well worth noting, contrary to your opinion "valuable lesson learnt, again for free through the internet" - the lessons you are being provided in this conversation are not free, they come at the cost of the generosity of the time, given by many very experienced folk, who have contributed to this conversation, simply, in attempt to assist you.

Here is a LINK where you can find the User Manual for the Sekonic 358 and in that manual I am reasonably confident that you will find how that light meter can be used to make reflected light meter readings: and a lot more information, also.

M. Butkus provides many of these manuals for out of production photographic gear and asks for a small donation (I think it is US$3.00) for those who use his service.

WW

Reflected light meter readings are affected by the colour and saturation of the object from which the light is reflected:Incident light meter readings are not.

 

Because the curtain is white, or close to white: see the above explanation. If the curtain were black the SLR's meter would indicate about F/2.8.

 

WW

Yes.

 

This scenario this is both 'remote' and also, it is well beyond 'theoretical'.

 

As has been mentioned many times using an Incident Meter to meter a backlit curtain is using the wrong tool. We might as well be discussing how to drive a nail into hardwood with a screwdriver.

 

Thirdly, also as has been previously explained, your conclusion that the curtain's reflective element causes the metering difference between the camera's meter and the Sekonic meter, is simply wrong.

.....

it is unlikely that you would want to photograph a curtain with light shining through it. Perhaps a close example would be a stained glass window, from inside a building with the sun illuminating the glass from the outside.

 

WW

1) Your previous post as quoted before said the reflective meter is affected by color, so I'm reasoning the meter in the camera is affected by the curtain being white, therefore F stops lower by 2/3 stops. why is this wrong?

2)Could you explain why my scenario is remote and well beyond 'theoretical'? Why is a backlit curtain is remote but a stained glass window is "close example"

3) When people tell me something is wrong or not supposed to used for that, I just couldn't take that as an answer. I have re-read every single post people has take the time to write, but here is my follow up questions still. They are basically asking the same thing.

a)Why can't I used an incidence meter for backlit subject?

b) What dictates a spot meter only measures reflected light, and an incidence measures lighting falling on the subject?

c) They are both essentially a calculator with a light sensor, one is with a 1% 3% lens, one with a dome/ sphere But both are measuring light falling on the sensor... so how come when I point a spot meter at the backlit curtain it is ok, and when I point the incidence it is not?

As a matter of fact, as mentioned Sekonic meters have accesories/adpaters to turn incidence meter into a spot. So could someone explain to me in fundamental terms, instead of the conclusive:

With an incident meter you use it by aiming it back at the camera not at the subject. That measures the light falling on the subject not the light reflecting off of the subject.

As has been mentioned many times using an Incident Meter to meter a backlit curtain is using the wrong tool. We might as well be discussing how to drive a nail into hardwood with a screwdriver.

WW

What I'm after is why are you not supposed to "drive a nail into hardwood with a screwdriver.", because it will strip the wood, because the nail has no notches for the screwdriver?

I'm here to learn, and that's all

What I'm after is why are you not supposed to "drive a nail into hardwood with a screwdriver.", because it will strip the wood, because the nail has no notches for the screwdriver? I'm here to learn, and that's all

Because it is the screwdriver is the incorrect tool to use for that job: as is an incident light meter the incorrect tool to use to meter a backlit curtain

Why you ask? Because an Incident Light meter is designed to do a different job and that job and how to use an Incident Light Meter (and also how to use a Reflected Light Meter) has been outlined several times, by several respondents.

WW

2)Could you explain why my scenario is remote and well beyond 'theoretical'? Why is a backlit curtain is remote but a stained glass window is "close example"

You are quoting out of context to advance an argument by either mistakenly combining two vastly different points, or worse, using this form of questioning as a baiting technique.

In either case: please don't do that.

The former is irritating, please note that the latter is against forum rules.

***

That stated, the following two points addresses the question at hand:

1. Your scenario is remote and well beyond theoretical because you insist that it be done by using the incorrect tools for the job.

2. The task of measuring the exposure of a Back Lit Curtain is a close example to the task of measuring the exposure for a stained glass window and (importantly) when that similarity was made in Post #10, a method of how to achieve that task was clearly outlined and noted that method did NOT include using an Incident Meter.

WW

Because it is the screwdriver is the incorrect tool to use for that job: as is an incident light meter the incorrect tool to use to meter a backlit curtain

 

Why you ask? Because an Incident Light meter is designed to do a different job and that job and how to use an Incident Light Meter (and also how to use a Reflected Light Meter) has been outlined several times, by several respondents.

 

WW

Sometimes it's easier to just admit that you don't know...

you are turning this whole thing into a gospel truth from the church... "You are not supposed to have sex untill you get married" Why? you are just not supposed to because that's what this manual said called holy bible!

MODERATOR NOTE:

Sometimes it's easier to just admit that you don't know...

you are turning this whole thing into a gospel truth from the church... "You are not supposed to have sex untill you get married" Why? you are just not supposed to because that's what this manual said called holy bible!

Please step very carefully and think hard before you publish your commentary here.

On the face of this commentary, it could easily be interpreted as a personal attack and/or purposefully directing the thread off track: both actions are also against forum rules.

Please also note: it is against forum rules to comment on Moderation within the forums.

If a member has issue with Moderation they may contact the Moderator concerned or any other Moderator by PM.

William

I have revisited post #10 as you mentioned.

if you see the video, I have measured using incidence meter both towards the window as well as pointing into the room, none of the reading is less than 3 stops over.

Certainly the camera meter is measuring both reflective light off the curtain as well as see-through light from the window behind. But as I mentioned in the video I have measured with incidence to both direction. And I thought I cleared the question myself by saying, the incidence meter ignored the reflective reading as being a white curtain. hence the 2-3 stops difference.

But then I was just plainly shoved with comments from you "You are just not supposed to". And I have explained myself that there is a reason why you are not supposed to use a screwdriver for the nails, requesting the similiar explanation for this metering situation. And you refused to answer me in this manner.

Personally, I don't consider any object in real life situation "theoretical" or "remote", let alone shooting a curtain with an incidence meter. Art is made when rules are broken. I don;t know what "Real world photography" you are referring to, is it a place where students of the subject are not allowed to question how instrument works and why passing a certain point?

As I said, spot meter or incidence meter they are both equipped with a light sensor, eventually measuring light falling onto the senors. ButI have yet received any explanation as to why by mounting a dome vs lens, will determine whether I could or could not meter a curtain against a window... But I no longer have any hope in getting answers here. Everyone can just let this post sink and die like any child's innocence....

1)

3) When people tell me something is wrong or not supposed to used for that, I just couldn't take that as an answer. I have re-read every single post people has take the time to write, but here is my follow up questions still. They are basically asking the same thing.

 

a)Why can't I used an incidence meter for backlit subject?

b) What dictates a spot meter only measures reflected light, and an incidence measures lighting falling on the subject?

c) They are both essentially a calculator with a light sensor, one is with a 1% 3% lens, one with a dome/ sphere But both are measuring light falling on the sensor... so how come when I point a spot meter at the backlit curtain it is ok, and when I point the incidence it is not?

As a matter of fact, as mentioned Sekonic meters have accesories/adpaters to turn incidence meter into a spot. So could someone explain to me in fundamental terms, instead of the conclusive:

 

 

I did tell you that you can't measure a backlit curtain with an incident light meter and you couldn't take that as an answer I am not so sure that you don't criticize me for giving bad answer.

So before I attempt to answer your a, b and c questions may I ask that are you really here to learn?

I did tell you that you can't measure a backlit curtain with an incident light meter

I'm sorry I didn't mean to direct it to you, I was just asking why "you that you can't measure a backlit curtain with an incident light meter".

But I just got my answers in a different forum. thank you

But I just got my answers in a different forum. thank you

Care to share that answer with us ? ... was it: "Because a dome on an incident light meter provides a diffused light for the cell in the meter to read, therefore if you point the incident meter straight at the curtain, all you get is an average diffused reading of the window light and not particularly of the curtain itself"

but I'm making up a hypothetical scenario where my camera has no meter, and I'm shooting to expose the curtain correctly. I'm putting the dome closely against the curtain, is it not "close metered" as you mentioned?

No. Your hypothesis is wrong!

An incident meter's dome gives an incorrect reading when used as you suggest. You need to use the meter in reflective mode, the same as the camera meter works.

Incident light is the light falling on, or illuminating, the subject. Reflected light is the portion of that incident light that's reflected back from the subject. Two completely different things, and needing two different metering modes.

If you can't get your head around that, then you've just wasted however much money you spent on that Sekonic L358.

Art is made when rules are broken.

Or a complete and hopeless mess is made. Sorry, but that's just pretentious guff.

No. Your hypothesis is wrong!

An incident meter's dome gives an incorrect reading when used as you suggest. You need to use the meter in reflective mode, the same as the camera meter works.

 

Incident light is the light falling on, or illuminating, the subject. Reflected light is the portion of that incident light that's reflected back from the subject. Two completely different things, and needing two different metering modes.

 

If you can't get your head around that, then you've just wasted however much money you spent on that Sekonic L358.

 

Or a complete and hopeless mess is made. Sorry, but that's just pretentious guff.

As I tell my students, Picasso could and did make portrait paintings that were conventional in every way when he was young. He was perfectly capable of perspective drawing, etc., but chose not to later in his career. But he knew how to do it if he had chosen to make paintings that way. I think the same thing applies to photography--knowing the rules allows the photographer to decide when breaking the rules in a particular way will make for a more interesting result. Not knowing them condemns the photographer to endless experimentation with multiple variables in the expectation that once in a while something good will happen. I've never liked those odds...

As I tell my students, Picasso could and did make portrait paintings that were conventional in every way when he was young. He was perfectly capable of perspective drawing, etc., but chose not to later in his career. But he knew how to do it if he had chosen to make paintings that way. I think the same thing applies to photography--knowing the rules allows the photographer to decide when breaking the rules in a particular way will make for a more interesting result. Not knowing them condemns the photographer to endless experimentation with multiple variables in the expectation that once in a while something good will happen. I've never liked those odds...

The bottom line is that you can't break the rules unless you know the rules.

The Sekonic meter I have, has the dome and also a disk (with hole) to be used for reflected metering.

The case has a place to hold the disk, but not the dome, so the only way to store it is with the dome on.

Incident light means "light shining on" something. It doesn't work for objects that have light other than

the light shining on them. Curtains, stained glass windows, and projected images are some examples.

In the beginning there were only averaging meters, which worked (and still work) surprisingly well.

(Especially with negative film with a one stop or so tolerance.)

Many typical scenes are close to the "standard" 18%. If the subject wears a black or white shirt,

but the background is gray (at least in black and white) it works well.

I first got my FM (new) after using a rangefinder with external meter. The manual exposure

settings are especially convenient for metering. Point the camera at different parts of the subject,

and see what the meter reads. Pick one somewhere in between. Most often, I find that the

exposure doesn't change much pointing around the subject.

A spot meter might read about 5% of the center of the field of view of the lens.

An averaging meter should, ideally, average over the whole field of view and not outside.

The usual selenium cell meter (from about 50 or 60 years ago) has a lens array in front

to approximate the average over the scene. Some have a white plastic diffuser to

place in front for incident reading.

If you have a reflected light meter, and want incident readings, read the reflection off

an 18% gray card, or something close. Some common skin colors reflect about 36%,

so you can read that and adjust one stop.

The important part of using a light meter is to know what it can and can't do.

In the case of back-lit objects, with an incident or reflected meter, you have to

use it carefully. In a common case, you photograph a person standing in front

of a window. In this case, an incident reading at the person's face works well.

The background will be overexposed, but the person should come out fine.

If I did actually want to photograph a backlit curtain with an incident meter, I would

read from behind the curtain, and then adjust based on how much light comes through

relative to how much might be reflected from a typical (18%) object. I suspect I

might stop down one or two stops, for darkish or lightish curtain.

I suspect reading from outside (incident light) on a stained-glass window might

be about right. Note that, as mentioned above, in theory you should not adjust

exposure for the reflectance of the subject. You want dark subjects to be dark,

and light subjects to be light. That is why incident meters are often best.

However, theory isn't always right. Sometimes you do want to adjust for the subject

reflectance, but not completely. You want dark gray subjects to come out dark gray,

and light gray subjects to come out light gray.

When using the FM with a backlit scene, when you are not specifically shooting

the backlight, increase the exposure by a stop or two. (Some cameras have

a backlight correction button to do this. But the manual setting of the FM makes

it very easy.) This is part of what you "learn" when learning photography.

When to trust the meter, when not, and how to adjust for those meter fooling scenes.

As above, the FM is especially good for these cases. You specifically have to adjust

the shutter speed and (more usually) aperture to center the meter. You then have

an opportunity to adjust as needed.

Autoexposure cameras make this more complicated. Some have exposure lock,

where you point at something that is appropriately lit, lock the exposure. But often

enough there isn't an appropriate object. There is, then, exposure offset where

you can adjust relative to the meter reading. And then not forget to reset to 0

before the next shot that doesn't need it.