Incident light meters question

lxdude · Dec 23, 2009

bowzart said:
All this stuff about pointing the incident meter at the light source reminds me of a guy I used to teach with. He was teaching the "reading the palm" method. He insisted that you should move your hand and the meter around until it registered the greatest amount of light and base your exposure on that. Of course, the students all underexposed their film when they did it. And he was a commercial photographer who was (somehow) fairly successful. But then, he hung it up and got himself tenured in a commercial photography school.

I told them to hold their palms parallel to the film plane between them and the subject and suddenly they got it right. I told them not to tell him I did that. It was our secret. I let him take the credit.

Did he tell them to increase exposure one stop from the reading? When I read off my palm (almost 100% of the time), I angle my hand to get the highest reading, then increase from that by one stop.

markbarendt · Dec 23, 2009

Interesting and worthwhile video.

Couple caveats for those just learning about incident meters;

First is the direction the dome is pointed.

His example is essentially a side lit studio portrait where he correctly points the dome at the light source to create the normal high contrast effect expected in a side lit studio shot. This is a special situation not the norm.

I'd imagine that his audience was a bunch of pro wedding & portrait shooters at a convention or seminar where they would have understood that context.

In most any other situation the dome of an incident meter should be pointed squarely at the camera.

Second is we need to understanding the whole process we are using to get to the final product.

If I was using Provia I would use Dean Collins placement of zone V.

If I'm using negatives though, I need to remember that all I'm doing with the exposure is setting myself up for the next step.

If I were using HP-5, I'd personally over expose a bit and maybe even extend development time (compared to box speed and standard directions) for the B&G scene to get more shadow detail on the film and I'd back off on my agitation considerably to protect the highlights in the Bride's dress.

With C-41 I'm going to be placing exposure not only to get the shadow detail but to get the color saturation I want and I will probably use standard development.

I prefer an incident meter over a spot meter to find my camera setting because it is objective and dependable, spot meters are subjective and finicky.

A spot meter for me is simply a tool for judging a subject's brightness when I can't stick my incident meter under their nose or for figuring out the subject brightness range so I know how to develop.

Brandon D. said:
The late photographer/teacher Dean Collins explains "subject tonality" vs. "incident lighting (a.k.a., diffuse exposure) " in very simple terms:
http://www.youtube.com/watch?v=JyzkWxtKWm8

Using incident meters, he demonstrates how a single-toned subject is presented/shaped simply based upon the light falling upon it. Pay close attention to what he says about "relative 3-dimensional contrast" and what he says about "specular highlights vs. shadows."

Using an incident meter has a lot more to do with how the source(s) of light themselves make the subject appear according to the lighting scenario at the time.

eddym · Dec 23, 2009

dfoo said:
Its not all that helpful If you meter the highlight and use that value (as you would if the subject is in direct light) then the shadows will likely be very dark (assuming here negative films not a slide).

Yeah, shadows are funny that way. They tend to be dark... maybe that's why they are called shadows.
Oh, and they tend to be dark in slides, too.

Larry Bullis · Dec 23, 2009

lxdude said:
Did he tell them to increase exposure one stop from the reading? When I read off my palm (almost 100% of the time), I angle my hand to get the highest reading, then increase from that by one stop.

He did that. If you angle your palm to get the highest reading, you are doing just what he told them to do. Good luck.

Larry Bullis · Dec 23, 2009

eddym said:
Oh, and they tend to be dark in slides, too.

Is that what is meant by "dark slide"?

John Koehrer · Dec 23, 2009

Q.G. said:
I must say that i don't know any advanced text on metering at all. Adams probably wrote a bit on the subject.

"The exposure Manual" Dunn & Wakefield
Way beyond what 95% hare need.

Barry06GT · Dec 23, 2009

bowzart said:
Is that what is meant by "dark slide"?

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No, that is from the movie _Star Wars_.
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Larry Bullis · Dec 23, 2009

I thought that was Dark Side! Oh well, I'm culturally illiterate.

lxdude · Dec 23, 2009

bowzart said:
He did that. If you angle your palm to get the highest reading, you are doing just what he told them to do. Good luck.

Don't need the luck. 35 years of Kodachromes perfectly exposed are good enough for me. I have no idea for the discrepancy. All I can say is it always worked fine for me. What about a gray card? Do you advocate holding it the same way?

You say to hold it parallel to the film plane. What if you're pointing the lens downward at a 45 degree angle to take a picture of something on the ground and in the next shot level to take a shot of something in front of you, then in the next 45 degrees above you? If you meter the subject above you at noon, won't the reference (hand or card) be in full shadow? The incident light is the same, the exposure is the same. The light reflected off a hand or card will vary.

If you're not finding the maximum reflectance off a known reference, how does the reference accurately replicate the scene, which will likely have elements reflecting at maximum?

One mistake made when metering off a reference is to not watch for reflection off the surface of the reference. That is, my hand has some shininess to it, as does the gray card I use. I do have to make sure to angle the reference so the shininess is not picked up as part of the reading.

The reason I like incident so much is that it protects the highlights with transparency film. I can meter incident, set the exposure, and take a picture of a white wall, and it won't be overexposed. Sometimes though, I will reduce exposure further to hold more detail. Either way shadows have to follow, so will appear dark to some. With negative film, I can see how more exposure than indicated can be desired, making a maximum reflectance reference reading appear to underexpose.

Larry Bullis · Dec 23, 2009

Well, carry on. If it works for you, what can I say?

lxdude · Dec 23, 2009

bowzart said:
Well, carry on. If it works for you, what can I say?

I'm curious as to how his advice failed. It should have worked, IMO, and I'm trying to understand why it didn't. I can see that with negative film it might not give the most desirable exposure, even if technically accurate. Picking up surface reflections off a gray card can skew toward underexposure by a full stop or a little more; off a hand, almost as much.

I guess the students didn't take too much to his "offhand" approach.

df cardwell · Dec 23, 2009

If one has become in the habit of metering from the toe, as we do with Zone-ish spot metering, an incident meter can seem unreliable and confusing.

But if you think about placing your midtones in the middle of the useful range of your film and developer combination, incident reading is a snap. You can trust your eye (or, TRAIN your eye) to notice if your subject is evenly lit with nor direct sunlight, or struck by sunlight, or if the day is completely overcast.

It can be VERY easy, extremely accurate, and totally reliable. Unless you are going for a special effect,
you measure the light as the camera will see it. That's all there is to it.

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BetterSense · Dec 23, 2009

Someone mentioned that in overcast conditions, he would take an incident reading, then reduce exposure and increase development by some amount to correct for the flat contrast.

In harsh direct sunlight conditions, shouldn't it then make sense to take an incident reading in sunlight, but then increase exposure from the reading and then possibly reduce development? Since since "sunlight is sunlight", how much correction would be good?

In sunny texas, I pull my film one stop pretty much all the time in the sun, when using sunny-16. I just got an incident meter and I'm trying to figure out if I should increase exposure and reduce development after taking a reading in sunlight, or if the incident meter is going to magically take care of indicating some extra exposure for me. The meter gives sunny-16 in the sun, so I think I need to be adding some exposure on the side.

Larry Bullis · Dec 23, 2009

lxdude said:
I'm curious as to how his advice failed. It should have worked, IMO, and I'm trying to understand why it didn't. I can see that with negative film it might not give the most desirable exposure, even if technically accurate. Picking up surface reflections off a gray card can skew toward underexposure by a full stop or a little more; off a hand, almost as much.

I guess the students didn't take too much to his "offhand" approach.

The basic reason is that if you modify the position of your hand, you actually aren't metering the light that is illuminating the subject at all. Let's take a backlit scene for an example, at the extreme. If you read the greatest amount of light you can get off your hand, you'd be setting your exposure to be about right if you turned 180 degrees away from the scene. The scene you are shooting is in shadow. If you read your hand with the sun lighting its back while you read the front, you will have much more relevant information. Not all situations are so extreme; I hope you can interpolate for the intermediate situations - which are nearly infinite. The incident meter or the hand, if used correctly, will neutralize all of the variables.

As df says a couple of posts back "...you measure the light as the camera will see it. That's all there is to it." That is all there is to it. Reading light the camera doesn't see can't be very reliable.

I have to wonder how consistent your exposures are. I don't know you, so I have no way of knowing what you consider to be a well exposed image. You certainly are right about the gray card reflections; must take care, there.

One thing is possible; in reading for slides it is more important not to overexpose.

Chuck_P · Dec 23, 2009

BetterSense said:
Someone mentioned that in overcast conditions, he would take an incident reading, then reduce exposure and increase development by some amount to correct for the flat contrast.

Click to expand...

That was me.

In harsh direct sunlight conditions, shouldn't it then make sense to take an incident reading in sunlight, but then increase exposure from the reading and then possibly reduce development? Since since "sunlight is sunlight", how much correction would be good?

Click to expand...

Taking an incident reading in the sun will underexpose the shadow areas, so yes a correction would have to be made to account for that, then a reduction in development could provide some control in the highlight densities. I've used 35 mm for general outdoor snapshot photography and I pulled Tri-X or Plus-X one stop (to preserve detail in the shadows a majority of the time) by rating it at 200 or 64, then reduced development to an what I considered an n-1 for highlight control. Contrast in the final print can be manipulated with VC papers and contrast filters most effectively.

But I would never do this for anything that I considered to be critical, because, IMO, the incident meter is not as an effective tool in strong sun/shade conditions (but there again, folks that do BTZS system of exposure and development will differ with that, I'm not familier with it). In my 4x5 work, I will always use a reflective spot reading to ensure positively 100% of the time my important shadow area was adequately exposed to my visualization, then I plan development for the highlights accordingly.

In sunny texas, I pull my film one stop pretty much all the time in the sun, when using sunny-16. I just got an incident meter and I'm trying to figure out if I should increase exposure and reduce development after taking a reading in sunlight, or if the incident meter is going to magically take care of indicating some extra exposure for me.

Click to expand...

Like I mentioned above, pulling the rating one stop will add more shadow density (but they can be printed down if needed), I would then reduce development, absolutely. There are no magic bullets with this stuff, boils down to intelligent use of the particular metering method you use.

df cardwell · Dec 23, 2009

shouldn't it then make sense to take an incident reading in sunlight, but then increase exposure from the reading and then possibly reduce development? Since since "sunlight is sunlight", how much correction would be good?

It depends completely on the film and developer you were using !

A film like Tri X or, even better, TMY2, in XTOL or D-76, and you wouldn't need any corrections unless you were aiming for perfection. If the light was flat, (if the scale of the image was short) simply increasing the contrast as you printed it would be sufficient. If the scale was long, from direct sunlight striking the subject, or falling on the background, the film can record it in a way that it can easily be printed by split filtering, pre-exposure, or some other method of your choosing. TMY (TX, PX, and FP4) hold a range of 14 to 16 zones in a linear manner, making them ideal for shooting roll film under a variety of lighting conditions. A film like TXP, with a long toe and strong highlight separation, being off a little is being off a lot, and punishment is severe. (Insert head banging rant here about folks who insist on using TXP and HC-110 to try to record a long scale image, and spend their lives and energy trying to burning in murderously dense negatives !).

We can establish whatever standards we need by simple testing. The idea, sitting up here in snowy Michigan, the idea of sunny-16 is charming. Find your ideal day, shoot at f/16 and find your perfect shutter speed, and that is your EI for incident meters.

AS long as your testing is well thought out, and your approach consistent, it doesn't matter whether you build your exposures upon Zone I or Zone V. One can be as precise with an incident meter as a spot meter, in either case, being limited only by the mind of its owner.

markbarendt · Dec 23, 2009

CPorter said:
Taking an incident reading in the sun will underexpose the shadow areas, so yes a correction would have to be made to account for that, ...

I think this statement is a bit misleading.

Incident meters don't suggest underexposing the shadows, or for that matter, overexposing the highlights; they simply measure the light falling on the subject and they suggest an exposure setting that would place the scene's mid-tones as midtones on the film. Caucasian faces will fall properly in zone VI or so. A gray card will fall in zone V perfectly. Black cats will be black, blah, blah, blah...

It is important to note that to get good results from any meter, incident or reflective, film testing and processing tests and printing tests are important.

Q.G. · Dec 23, 2009

CPorter said:
Taking an incident reading in the sun will underexpose the shadow areas

This is (still ) not an incident light metering issue. It is a general light metering issue: if the contrast range is too large, you get both underexposed shadows and overexposed highlights.
Meter the bit lit by the strongest light, and the error will indeed be in the shadows.

If you use a reflected light meter, and point it at something of known reflectivity, and adjust the resulting reading for that reflectivity, you get the exact same result as you would using an incident light reading.

The trick is in knowing when the range might be too much for the film to capture.
You can meter to find out (both using incident or reflected light metering), or know from experience.

Using a reflected light meter, an obvious solution would appear to be to meter both highlight and shadow (or even only the shadow), to find a middle value and use that for exposure.
But then you would start blowing out the highlights. As well as keeping the shadows underexposed.
(You could do the same using an incident light meter, though for some - perhaps valid - reason, that would not appear as 'natural' as pointing a reflected light meter at different parts of the scene.)
So the solution to this problem really lies in knowing what to do, not in the metering method.

Mike1234 · Dec 23, 2009

Similar thread here: (there was a url link here which no longer exists)

BetterSense · Dec 23, 2009

It is a general light metering issue: if the contrast range is too large, you get both underexposed shadows and overexposed highlights.

(emphasis mine)

This is what I'm not 100% understanding.
If you take an incident meter reading in bright sunshine, I can imagine that shadows you might care about would be underexposed, because they could be more than 1-2 stops less than middle grey. It makes sense to me that shadows under trees, etc. could be deeper when you take a reading in open sunlight, compared to when you take a reading in open overcast light.

What doesn't makes sense to me is that you could take a reading in sunshine and there would be any change in the highlights. Things have different reflectivies, to be sure, but even something with 99% reflectivity should end up the same amount (in stops) above zone 5 regardless of whether you measured sunlight falling on it or weak room light falling on it. If a white T-shirt is 2-stops brighter than middle grey in overcast conditions, I don't understand why it still isn't exactly 2-stops brighter than grey in sunny conditions.

Chuck_P · Dec 24, 2009

markbarendt said:
I think this statement is a bit misleading.

I don't think so. It's pretty basic stuff. Now I have done this and verified for myself with my incident meter and it is true. What I have been saying is simply fact----basic incident metering facts. From left to right, as indicated in the text, the photos were taken using the indicated meter reading---it's a poor scan but you get the point:

-Alan Ross has the dome of the incident meter placed in sunlight, you can see that the shadows are underexposed. (my interpretaion of the text: this should be painfully obvious to you---the exposures recommended by the meter aim to reduce the density on the negative in the sunlit area to that which will print closer to a middle gray, thus underexposing the shadows.

-Next, the dome of the incident meter is moved just a few inches up into a very narrow beam of shadow, you can see that the sunlit portions are blocked. (my interpretation of the text: this should be painfully obvious to you---the exposures recommended by the meter aim to increase the density on the negative to render the shadow middle gray, thus blocking the sunlit areas.)

-Next, the dome is placed in "lightly spotted sunlight", the exposure is much more satisfactory. (my interpretation of the text: I'm not going to be searching for just the right mix of sun and shade with my dome, when a reflected reading is simpler, more reliable, IMO in these situations)

-Lastly, a reflective reading with the exposure made using the camera's built- in meter gives the same exposure as as the previous example. (my interpretation of the text: the distribution of light versus dark areas of the scene are obviously pretty even because the in-camera meter (that also assumes the subject is middle gray) rendered a negative with well proportioned densities that printed very well, no manipulation of the meter was used.) Once the distribution of light vs. dark areas of the scene become heavy in either direction, the in-camera meter, or a hand held wide area reflective meter will get fooled and the photographer has to adjust in that instance.

Like I said, pretty basic stuff.

Chuck_P · Dec 24, 2009

Q.G. said:
This is (still ) not an incident light metering issue.

O.G., IMO, I was addressing "Better Sense's" comments about incident metering and going back to read the OP, it's pretty much in line with the discussion, IMHO. I realize these threads take on a life of their own sometimes, nature of the beast.

Brandon D. · Dec 24, 2009

Subjectively speaking, the "proper exposure (or relative exposure)" for a shadow can be "underexposure" in many cases.

In real life, most shadows probably aren't Zone V or VI; many shadows are truly IV, III, II, or etc. And, if incident metering leads to a recommended exposure which puts shadows that are truly Zone II on Zone II in your image, then the incident meter did its job. But, of course, dynamic range capabilities also play a major role in this.

I think people get way too hung up on underexposure and overexposure in photography. There is no right or wrong way to respond/handle these extremes. It's an aesthetic decision. If the photographer wants to interpret the scene differently, then they could change the exposure or make changes during the developing/printing process to suit their vision.

But, there are no rules, or objective methods, for interpreting the scene or for responding to underexposure and/or overexposure in the scene. For instance, some photographers may want the "underexposed shadows" on the door to go even darker in the final print (in CPorter's example above).

FRANOL · Dec 24, 2009

Using incident light meter by Bill Smith, link http://photo.net/bboard/q-and-a-fetch-msg?topic_id=23&msg_id=001IXA

Brandon D. · Dec 24, 2009

CPorter said:
O.G., IMO, I was addressing "Better Sense's" comments about incident metering and going back to read the OP, it's pretty much in line with the discussion, IMHO. I realize these threads take on a life of their own sometimes, nature of the beast.

I think you took his post the wrong way.

To help clarify, his point wasn't that you weren't in line with the discussion. His point was that the dilemma you brought up, "Taking an incident reading in the sun will underexpose the shadow areas" is a not a result of metering (be it incident or reflective). But, it's actually a result of extremely high contrast inherent in the scene and also a lack in our photographic process's ability to capture and show an extremely high dynamic range.

In a contrasty lighting scenario, it isn't an incident meter's job to recommend a "perfect exposure" for the entire scene simply based on one meter reading. It seems that sometimes people don't realize that it isn't the meter's "fault" that some lighting scenarios are too contrasty for the meter to recommend a useful exposure for the entire scene (with just one meter reading). That's part of the reason why I recommend that people begin learning how to use an incident meter in even lighting until they get a sense of how it functions (i.e., what it does and what it can't do, capabilities and limitations). Meters certainly cannot compress all of the inherent dynamic range in scenes into fully visible detail on film, allowing our cameras to capture more detail in the shadows and specular highlights. If meters could, then metering and photography would be easy, .

What's in the scene is in the scene. But, if the range of brightness in the scene is extreme, then we can't just solely rely upon the meter or blame it. When the contrast is inherently high, then it's best to do extensive metering and to go through trial-and-error until you get desired results. It's up to the photographer to evaluate the whole scene with precise metering, and then to make aesthetic exposure decisions based on that info and his/her tastes.

Incident light meters question

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