Incidentally, yours ...

[lars_bergquist]

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I found myself apostrophised recently in this forum by Jaap as "the old man from the age of the oilspot Photometer" as he left me to explain the use of the incident lightmeter. So here we go:

 

The basic problem with any reflected-light meter (as built into cameras) is exactly that they do not meter just light, but reflected light. You have an idea about the subject, but the meter has none. So let us suppose that you want a picture of two white westie dogs on your lawn. If you meter the overall scene, the exposure will probably be about right, because that lawn has a reflectance that is close to the 'ideal' value of 18%, and the dogs won't skew that average too much. But if you go close and meter the dogs, you will get two 18% grey dogs on a greenish-black lawn, because the meter does not 'know' that it is metering two white dogs. Conversely, in the first example, if the background is darkish, the meter will nevertheless 'assume' an 18% subject and increrase the exposure to give that result, changing the dogs into two blown highlights in the process.

 

So you compensate, possibly by using some formulae from the Zone Religion (westies are probably about Zone VII), but basically, you expose by guesswork.

 

With an incident meter, you meter the light that falls on your subject from the direction of the camera, i.e. you hold the meter close to the subject and aimed towards the camera. That white hemisphere is actually an artificial diffuse highlight. When that highlight is nailed down, everything else falls into place. No matte white surface can reflect more than 100% of the light that falls on it, right? The assumption is that it reflects about 80%, i.e. 2 1/3 f-stops above the standard 18% or 'Zone V'. With this correction built into the meter and the exposure indicated, you will use the dynamic range of your sensor or emulsion to the full. That is not 'correct exposure' – there's no such thing – but optimal exposure. An incident meter value can be taken as is, so it is in principle very unproblematic.

 

Now here's a caveat. Your subject may be a clairobscure one, where you actually want an exposure that is skewed towards the left end of the histogram. Look at the picture (I have shown it before, but it is illustrative.) An incident metering would have changed the night into day, probably blowing out parts of the wall with the two candles on the mantelpiece! This is of course a completely non-standard situation, but it shows that you cannot stop thinking. No piece of equipment, however sophisticated, can think for you. But generally, incident metering, made by a hand meter or by an ExpoDisc® over your camera lens, will help solve very hairy situations. It would have solved this one too, if I had dared approach the lady ... an incident metering close to her face would have done the trick. Pardonnez-moi, Madame!

 

The old man from the Age of the Seconic Studio DeLuxe

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[jedi996sps]

I did not see the image when you posted it previously, it is exquisite.

 

I still have my sekonic somewhere, but hve not used it for donkeys. I must therefore fall into the guesswork category, which given the instant nature of digital capture and review, suits my purposes.

 

But, thank you for your interesting and informative post.

 

Ali

[andybarton]

I have moved this to the "Customer" section, as it is applicable to all cameras, not just an M9

[pgk]

Lars

 

I have absolutely no argument with your post other than to say that this is a slower way of working and given this, it might be as effective to take a shot exposed as 'indicated' by the camera meter and then adjust exposure to place the histogram as desired for an 'optimal' exposure. Your concept of 'optimal' exposure is an excellent one because adjustments in exposure at the taking stage can yield rather different results at the post processing stage and as with film these are dictated by the photographer's desired outcome. I find for example that at low ISOs my Leicas yield files with much greater flexibility in their shadow adjustability than my Canon files have and so I will aim at a different optimal exposure depending on what I am using.

[gyoung]

Of course, in the 'old days' we didn't have the benefit of instant image review, so it helped to have a knowledge of sensitometry on ones head.

And instead of histogram we had exp/density curves and quandrant diagrams.

I just bought a refurbished Weston, only a little more than getting my old one repaired (cell failure), spent most of my life in the studio using that with the invercone.

 

Gerry

[pop]

... this is a slower way of working and given this, it might be as effective to take a shot exposed as 'indicated' by the camera meter and then adjust exposure to place the histogram as desired for an 'optimal' exposure ...

 

This is a technique I employ as well from time to time. However, I do not think it's any faster than measuring the incident light. This, of course, applies only to situations where measuring the incident light is applicable.

[gyoung]

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And thank you Lars, can't do that simply on the mobile version of the forum

 

Gerry

[lars_bergquist]

Hi all. Using a hand meter – any hand meter – is slower than the 'quick&dirty' reflected method, simply because you have to get the meter out! I do in fact take most of my pictures using the in-camera meter because it is a good one and gives useful results in most situations.

 

The point however is to be exposure-savvy enough to know when the straight reflected method will fail. This is where you haul out your trump card and save the day. The situation where the camera meter fails is invariably one where the subject does not have an even distribution of reflectances. This leads us to the question of the spot meter – if anybody still uses that instrument.

 

I have used various spot meters (meters with an acceptance angle of 1–2°). My experience is that they create more problems than they solve. You may pinpoint the exposure that renders any detail as a mid-gray (or mid-green or mid-purple or whatever) tone, but just what is the reflectance of that detail? Unless you know that, your overall exposure may be badly off. You can of course do a thorough analysis of the scene, probing every bright thing and every dark corner to get at the luminance distribution, but that is a slow and laborious process. This is what a matrix metering system tries to do, but while the results may be better than that of a mechanically and thoughtlessly applied averaged or center-weighted one, all the ifs and buts are still there.

 

The advantage of the incident method is that it is independent on the vagaries of the subject. It will correctly expose both the baker in the proverbial snowdrift and the chimney-sweep in the coalhole, both of which would be 18% grey (the hue of a Kodak Gray Card) if exposed by the reflected method. Giving the physical nature of objects, a metering of the absolute light level will nail down where the famous Zone V is, and where the maximum diffuse highlight is, two reference points that are as important with digital cameras as with slide film in the past. (Negative film with its long shoulder on the characteristic curve can be quite brutally over-exposed). On a bright day with steady light, I don't even need to meter different subjects when I have established a basic exposure, like f:8 at 1/1000 and ISO250 – really 'sunny sixteen' in a different guise.

 

In a case like that of the picture I showed, lighted by four candles only, the rules are different however. It was taken in the autumn of 2010 with a M9 and a brand new Summilux-M 1:1.4/35mm ASPH. FLE at f:1.4 and 1/15th of a second. ISO was 1000. I just guessed the exposure, checked the histogram and the result was acceptable; I didn't want to try 1/8 offhand. The candle flames were allowed to burn out of course. During our darkroom days we learned to print both point sources of light, and specular highlights (which are mirror images of a source of light like the sun) to the maximum white of the paper. Such things are simply off any scale of normal reflected luminances, because they are not reflected!

 

Ye olde manne from the Age B.E.M. (Before Exposure Meters)

[dhsimmonds]

Lars, I must be much older then, as I was using the Weston Mk IV with invercone attachment before Seconic were even heard of! In fact I still have mine, the photocell is still as good as new and the meter is very accurate. However like you I very rarely use it, just admire it in the drawer in it's original leather case!

 

Modern camera meters are very accurate if used intelligently. But there is nothing more accurate than incident light readings as we always used for portraiture and virtually a necessity with film slides! It was excellent basic training when I come to think about it for using a modern digital camera intelligently!

[Jeff S]

In a case like that of the picture I showed, lighted by four candles only, the rules are different however....(snipped)...I just guessed the exposure...

 

Not incidentally, quite a nice guess, reflecting your years of experience.

 

Jeff

[NZDavid]

Careful metering still makes sense even in the digital era. Many photographers now seem to think exposure has to be only approximate and it can be adjusted later in PP. While there is a lot of latitude in a digital file, I still prefer getting a shot as right as possible in camera. Otherwise you get lots of wasted images, and spend a lot more time! There is often a surprising difference between incident and reflected readings: not just in low light but bright sun. As a handheld meter, the Sekonic 308b is compact, accurate, and easy to use.

[jaapv]

Added to M9 FAQ :)

[pico]

Like many of you I have been using meters from the early Westons (I have many, and four that work), and the latest and greatest for LF work.

 

However, using the M7 or M9 I scan the scene to get readings from shadows, midrange, highlight and if necessary go full Manual. It is faster than taking out the light meter.

[bocaburger]

If shooting (for example) the shaded side of a street while standing on the sunny side, an incident reading is inaccurate unless you run across the street, take the reading, and then run back to take the shot. Likewise example, standing in a canopied strand of trees shooting a sunlit mountainside across a valley, an incident meter is useless. Otherwords, any time the photographer can't get into the same light as is falling upon the subject, incident metering requires at the very least, the same sort of compensation guesstimate as a reflected reading. For me, judging reflectance tonality is no big deal. If I can't find a mid-tone to occupy the metering circle, I can simply meter anything from black to white, and subtract or add exposure accordingly. And, to get an effective incident reading anytime, anyplace, I have simply to point my lens at the palm of my hand and add 1.5 stops to the camera's reading (or it can be done in AE by setting comp to +1.5 and lock the close-up reading of the palm). Thus even though I own a couple incident meters and have used them in portrait settings both indoors and out, I never found them any quicker or more trustworthy than an reflected meter + my brain.

[Jeff S]

I never found them any quicker or more trustworthy than an reflected meter + my brain.

 

Easier to use your palm, I think.

 

Jeff

[roguewave]

Lars, I very much appreciate the time & effort you brought to bear here. Having been shooting in a very dark jazz club for the last 7 months I've had to make lots of adjustments. With the metering sophistication afforded by modern cameras such as the M9, my "used" Nikon D3 and few Canons I have had the pleasure to use, there are several strong strategies that are indeed based on your post, but extended more into the digital world.

 

As an example, my Nikon D3 allows me to shoot the frame at various exposures and combinations to test and review & then save those combinations that render the images I prefer. The digital DNG's are real mirrors of how I would be working in film, bracketing in various ways.

 

It's imperative to woodshed with your tools, regardless of analog or digital. The digital world of these very sophisticated computers-cameras open new worlds of imaging, but it stands on all the important lessons of light's affect on a "film", be it chemical or electrical.

 

Thanks again for the image & your informative words. All the Best.

[MarkP]

Lars,

thanks for starting this thread.

 

The histogram is useful for assessing the exposure of the whole image, and assessing for over- or under-exposure. However, unless I'm missing the bleeding obvious there is no histogram pattern that provides information as to whether the subject or area of interest is optimally exposed, and if not it is that much harder to get optimal tonal quality in PP. I not infrequently have an 'optimal' histogram but a 'sub-optimal' subject exposure.

 

The internal reflectance meter of the M9 obviously works most of the time, and there are clearly situations where using an external light meter is inconvenient or impossible. However, I don't see it as a problem in a lot of more considered photography.

 

I went out this morning and bought my first external light meter (a basic model, a Sekonic L-308S). Trying it out this afternoon I don't know why I didn't get one years ago. Not only are the exposures improved with better subject tones, but it's a great teaching tool.

 

 

Mark

[pgk]

However, unless I'm missing the bleeding obvious there is no histogram pattern that provides information as to whether the subject or area of interest is optimally exposed, and if not it is that much harder to get optimal tonal quality in PP. I not infrequently have an 'optimal' histogram but a 'sub-optimal' subject exposure.

Just zoom in to the relevant image and select 'info'.

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[theendlesshouse]

Develop your instincts then trust them.

[lars_bergquist]

Lars,

thanks for starting this thread.

 

[ ... ]

 

I went out this morning and bought my first external light meter (a basic model, a Sekonic L-308S). Trying it out this afternoon I don't know why I didn't get one years ago. Not only are the exposures improved with better subject tones, but it's a great teaching tool.

 

 

Mark

 

Mark, that is an important point. There are two things about light that we are very badly equipped by nature to judge accurately, light intensity and colour temperature, because Old Lady Evolution has put in some very good compensating equipment – for eminently practical reasons, and these are the only reasons she is interested in. I have learned a lot using light meters of different kinds, both spot, reflected and incident (got my first incident-capable meter, a Gossen Sixtomat, around 1959) and also light temperature meters. My practical conclusion was that the type I could use productively was the incident one.

 

Use your incident meter, and do at the same time carefully observe the state of the sky (bright? hazy? cloudy? heavily overcast?), where the light is coming from, anything masking the source(s) of light, such as threes, house walls – everything that seems to influence exposure. The knowhow you gain will be invaluable, if you have an incident meter, ot just a reflected-type meter, or no meter at all. No meter absolves us from thinking. This knowledge helps us to think.

 

The old man from the Selenium Age