quick hints on spotmetering ?

Kim Catton · Jun 26, 2007

Hi all.

Im going on a trip to Scotland tommorow and I'm starting to wonder...

When I normally do my photos, which is mostly planned portraitwork I know how to meter the light to get whatever artistic expression im looking for, but when it comes to shooting a lot of B/W film in a lot of different outdoor locations im kind of lost and naturally I want to take precautions before I head of to Scotland. So:

Where should I spotmetre in general? I won´t bring a greycard. Ive heard something about spotmetering in the shadows to get the best results.. ? Also.. would filters of some sort be a good thing?

[Shooting tri-x on 35mm and 120 - Spotmetering via Nikon F80 using various lenses]

Regards, kim

Ian Grant · Jun 26, 2007

It's normal to take readings of the shadows, highlights and midtone so getting a feel for the overall range.

If you know how to meter for portraits then just do the same thing, remember you don't want under exposed shadows or burnt-out highlights (generall skies). Grass serves as a rough 18% grey.

You might try Green, Orange or possibly Red filters.

Ian

Kim Catton · Jun 26, 2007

Ok, but say, I have to compose a picture with ground (grass and stone) and sky. Should I take readings from the sky and from the ground an expose according to the average ?

David Henderson · Jun 26, 2007

I agree with the reply above and its important to recognise that when spot--metering you need to take several readings rather than just one, and indeed that if you want to take just one reading ( as many people prefer to do ) then spot-metering is unlikely to be the right method for you since it turns into a lottery with you trying to guess what a mid-tone might be.

I check readings from around the scene against a notional exposure and see how those parts will be rendered at that exposure-so for example "At f11/125that deep shadow will be three stops under, am I ok with that; the brightest areas of sky will be two stops over, is that what I want?--- and so on. I'll generally make between four and eight readings depending on the complexity of the scene , light wise, and I'm always prepared to revise my notional reading if important elements are going to be lighter or darker than I want.

Just a couple of other points. I use multiple spot-metering because I do a lot of work on contrasty colour transparency film and I want to meter the same way every time. If all my work was on Tri X roll film I might expect to get similar results more simply from incident or matrix metering or even experienced use of a centre-weighted pattern. Lastly I do occasionally need to use a grad with b&w landscapes , not so much to control the sky as to facilitate a longer exposure to keep detail in dense shadow.

Ian Grant · Jun 26, 2007

Kim, using a spotmeter is more often about pre-visualising the image, at the time of composition, and setting the parameters to achieve your desired results.

Now is not the time to radically change the way you work in view of your imminent departure, I hope the UK weather improves in time for you, my mother was just complaining about the cold & rain !

When you get back home have a look at the Zone system, a good book is Ansel Adams, The Negative, and he discusses using the Zone system with folls of film, as opposed to individual sheets in LF cameras.

Have a good trip, Scotland's a wonderful country, and everyone is very friendly.

Ian

Murray@uptowngallery · Jun 26, 2007

Quick & dirty spotmeter

I have heard an anecdotal rule for using general metering with a spotmeter in the absense of a grey card.

Supposedly most human palms held palm up to the sky will give a reading of close to Zone VI, regardless of ethnicity. Spot metering is based on an 'average 18% reflectance' reading indicating Zone V (excluding the few meters that supposedly as set for 13%, but don't worry about that). Obviously this is not an all-inclusive statement. I will not take responsibility for your ruining someone's wedding photography based on this suggestion!

This implies your hand will need 1 stop less exposure than the average scene you may be shooting, and you can set your camera to allow one stop MORE exposure than you read off your palm.

For b/w, you can also meter the darkest item in your scene, and set your exposure to underexpose by two stops. This doesn't guarantee you keep your highlights - only mastering the Zone System to some degree or following the judicial practice of considering the range of the entire scene and deciding what to due will get you closer.

You could also try Sunny-16 (Google it).

My Pentax analog spotmeter was the only thing that was carefully examined and discussed in an airport recently, in a bag of antique and pinhole cameras.

Roger Hicks · Jun 26, 2007

Grey cards are a complete waste of time and money in most cases as no film speeds are keyed to mid tones. Negative films are keyed to the darkest area in which you want texture and detail, and transparency films (and digital, and Polaroids) are keyed to the lightest area you don't want to 'blow' to a featureless white.

Take a reading of the darkest area in which you want shadow detail and give about 2-2/3 stops less than indicated by the 'mid-tone' index on a spot meter or use the 'shadow' index or I.R.E. 1

The only reason you would normally bother to read anything other than the deepest shadow in which you want texture and detail is to establish the brightness range of the subject, which you can use to help you determine development time. To do this, you read the brightest area in which you want tone and texture, and see how much brighter it is than the shadow reading.

For an 'average' range (around 6 stops) give normal development; for a longer range, reduce development time; for a shorter range, consider increasing development time.

Any other way of using a spot meter is essentially a fudge. Ths is not to say that it won't work: some fudges are better than other, but many people who think they are being precise are in fact saved by the inherent flexibility of the neg/pos process, especially if they expose generously.

The 'spot' mode in an SLR is a lot less precise than the 1 degree spot of a spot meter, so it is harder to use it properly. Almost any shadow reading, with the appropriate adjustment as above, will however get you pretty close.

Cheers,

Roger (www.rogerandfrances com, where you'll find more about this sort of thing)

Kim Catton · Jun 26, 2007

What about the 10 point "matrix" metering system that is in my nikon F80 - could this be used in situations where taking a shot has to be done fairly quick. ?

Ian Grant · Jun 26, 2007

Yes.

Nice simple quick answer.

Ian

Kim Catton said:
What about the 10 point "matrix" metering system that is in my nikon F80 - could this be used in situations where taking a shot has to be done fairly quick. ?

Roger Hicks · Jun 26, 2007

Kim Catton said:
What about the 10 point "matrix" metering system that is in my nikon F80 - could this be used in situations where taking a shot has to be done fairly quick. ?

Dear Kim,

Yes. Set the film speed 2/3 stop below the ISO and latitude will take care of just about everything.

Cheers,

Roger

Kim Catton · Jun 26, 2007

This seems to be an option and ive before worked with messuaring in shadow...

Sorry if this is a stupid question : When you talk about going down 2-3 stops "stops", are you then talking about the exposure ? say, the meter tells me f8@1/120 - I should go to 1/45-60 ? or... ?

If the object consist of rocks, grass and bright sky... And I meter in the darkest of the rocks and go down 2 steps, what will happen to the bright sky ?

Best regards and thanks, Kim

Roger Hicks said:
Grey cards are a complete waste of time and money in most cases as no film speeds are keyed to mid tones. Negative films are keyed to the darkest area in which you want texture and detail, and transparency films (and digital, and Polaroids) are keyed to the lightest area you don't want to 'blow' to a featureless white.

Take a reading of the darkest area in which you want shadow detail and give about 2-2/3 stops less than indicated by the 'mid-tone' index on a spot meter or use the 'shadow' index or I.R.E. 1

The only reason you would normally bother to read anything other than the deepest shadow in which you want texture and detail is to establish the brightness range of the subject, which you can use to help you determine development time. To do this, you read the brightest area in which you want tone and texture, and see how much brighter it is than the shadow reading.

For an 'average' range (around 6 stops) give normal development; for a longer range, reduce development time; for a shorter range, consider increasing development time.

Any other way of using a spot meter is essentially a fudge. Ths is not to say that it won't work: some fudges are better than other, but many people who think they are being precise are in fact saved by the inherent flexibility of the neg/pos process, especially if they expose generously.

The 'spot' mode in an SLR is a lot less precise than the 1 degree spot of a spot meter, so it is harder to use it properly. Almost any shadow reading, with the appropriate adjustment as above, will however get you pretty close.

Cheers,

Roger (www.rogerandfrances com, where you'll find more about this sort of thing)

Roger Hicks · Jun 26, 2007

Dear Kim,

You can do it either way: instead of f/8 go to f/16-2/3 or instead of 1/125 go to 1/650. Or use both: from your f/8 at 1/125 example, close down 1-2/3 stops (to f/11-2/3), and reduce the shutter speed by 1 step (1/250)

From first principles, if you use the mid-tone index, the meter will try to expose your shadow reading (whatever it is) to give the same density it would normally give a mid-tone. But you don't want that sort of density: you want density that will just comfortably print. You therefore cut your exposure.

Exactly how much you cut it is a matter of experience/testing, but it's unlikely to be more than 3 stops and 2 stops would normally result in over-exposure. Two and a half or two and two-third stops are the best starting point. ALWAYS err on the side of over-exposure (or bracket, one exposure at your best guess and one at 1 stop more).

Nothing will happen to the bright sky, incidentally. It'll just be exposed about right. What are you worried might happen? You might even care to check it with your meter, to find out the subject brightness range (BR)

One further thought is that if you do meter the dark side of the rocks, it would be surprising if you got 1/60 at f/8 with ISO 400 film: 1/30 at f/8 or even 1/30 at f/6.6 is more likely.

Finally, note that if the SBR is not great (as it probably won't be in Scotland) exposure is a lot less critical than on a bright sunny say with deep shadows where you want detail -- which is when spot metering comes into its own. On an overcast day, the shady side of even dark rocks is more like a dark mid-tone than a deep shadow.

Cheers,

Roger (you really might find some of www.rogerandfrances.com handy, especially the bits about subject brightness range and grey cards)

Kim Catton · Jun 26, 2007

OK, I seem to get it BUT - how do I define "stops" ? you mentioned going from 8 to 16-2/3 and also going from 125 to 650 ... My nikon says:

125 - 180 - 250 -250 - 500 - 750

5.6 - 6.7 - 8 - 9.5 - 11 - 13 - 16

And what about the 2/3 ?

Am I just being plane stupid again ?

Thx alot for your help, its really useful

Roger Hicks said:
Dear Kim,

You can do it either way: instead of f/8 go to f/16-2/3 or instead of 1/125 go to 1/650. Or use both: from your f/8 at 1/125 example, close down 1-2/3 stops (to f/11-2/3), and reduce the shutter speed by 1 step (1/250)

From first principles, if you use the mid-tone index, the meter will try to expose your shadow reading (whatever it is) to give the same density it would normally give a mid-tone. But you don't want that sort of density: you want density that will just comfortably print. You therefore cut your exposure.

Exactly how much you cut it is a matter of experience/testing, but it's unlikely to be more than 3 stops and 2 stops would normally result in over-exposure. Two and a half or two and two-third stops are the best starting point. ALWAYS err on the side of over-exposure (or bracket, one exposure at your best guess and one at 1 stop more).

Nothing will happen to the bright sky, incidentally. It'll just be exposed about right. What are you worried might happen? You might even care to check it with your meter, to find out the subject brightness range (BR)

One further thought is that if you do meter the dark side of the rocks, it would be surprising if you got 1/60 at f/8 with ISO 400 film: 1/30 at f/8 or even 1/30 at f/6.6 is more likely.

Finally, note that if the SBR is not great (as it probably won't be in Scotland) exposure is a lot less critical than on a bright sunny say with deep shadows where you want detail -- which is when spot metering comes into its own. On an overcast day, the shady side of even dark rocks is more like a dark mid-tone than a deep shadow.

Cheers,

Roger (you really might find some of www.rogerandfrances.com handy, especially the bits about subject brightness range and grey cards)

Roger Hicks · Jun 26, 2007

Kim Catton said:
OK, I seem to get it BUT - how do I define "stops" ? you mentioned going from 8 to 16-2/3 and also going from 125 to 650 ... My nikon says:

125 - 180 - 250 -250 - 500 - 750

5.6 - 6.7 - 8 - 9.5 - 11 - 13 - 16

And what about the 2/3 ?

Am I just being plane stupid again ?

Thx alot for your help, its really useful

Dear Kim,

Okay, you've only got half stops (I think you meant '250-350-500'). If you had 1/3 stops you'd have 125-160-200-250-320-400-500-650-800-1000 and f/5.6 - 6.3 - 7 - 8 - 9 - 10 - 11 - 12.3 (or 12 or 12.5) - 14 - 16 - 18 - 22

So use half stops instead of thirds. The loss of precision is not worth worrying about; just err on the side of over-exposure. Thus, for two and a half stops down from 1/30 at f/8, you could go to 1/180 at f/8 or 1/30 at f/19 (which you don't have on most lenses -- the half stop between f/16 and f/22) or of course 1/125 (2 stops) at f/9.5 (the half stop).

Cheers,

Roger

Kim Catton · Jun 26, 2007

NICE

That should be about it. Using this should help me in getting what Im pursuing. When it comes to where to meassure, should I just go for the darkest part in the composition - aim for that - adjust to what the spotmeter tell me is correct. Then make my adjustment (going down 2-1/2 stops and expose? The meter will then most likely tell me im off 5 half-stops right ? which I should of course just ignore ?

Kim,

Once again, thanks for taking your time helping me. Really, your making my trip to Scotland much more easier

Roger Hicks said:
Dear Kim,

Okay, you've only got half stops (I think you meant '250-350-500'). If you had 1/3 stops you'd have 125-160-200-250-320-400-500-650-800-1000 and f/5.6 - 6.3 - 7 - 8 - 9 - 10 - 11 - 12.3 (or 12 or 12.5) - 14 - 16 - 18 - 22

So use half stops instead of thirds. The loss of precision is not worth worrying about; just err on the side of over-exposure. Thus, for two and a half stops down from 1/30 at f/8, you could go to 1/180 at f/8 or 1/30 at f/19 (which you don't have on most lenses -- the half stop between f/16 and f/22) or of course 1/125 (2 stops) at f/9.5 (the half stop).

Cheers,

Roger

Roger Hicks · Jun 26, 2007

Kim Catton said:
NICE
The meter will then most likely tell me im off 5 half-stops right ? which I should of course just ignore ?

Dear Kim,

The meter reading should only be a stop different at most, because you'll be reading the broad area (average reflectance about 13 per cent) again, instead of the shadow area (reflectance maybe 1-2 per cent).

It might even be identical. And if it's more -- use the broad area reading.

In other words, if your broad area reading is 1/250 at f/11, and your shadow-adjusted reading is 1/175 at f/11, use 1/175. But if the shadow-adjusted reading is 1/350, use the 1/250 second broad-area reading.

Used like this, spot metering is a way of getting enough detail in the shadows: when Ansel Adams got a spot meter, he is reputed to have said that his exposures increased by a stop.

The other two ways to use a spot meter are to stop highlights 'blowing' (in trannies, Polaroids and digi) and to keep a constant exposure for a chosen key-tone (traditionally a skin highlight in the heroine's complexion in movies). But neither of these affects you here.

Have fun in Scotland!

Cheers,

Roger

Kim Catton · Jun 26, 2007

OK - So now im confused again It might be the new introduction to broad area reading and shadow adjusted readings and the fact that the meter reading should be a stop different at most ? a ... I shouldnt alwas just go down 2 1/2 stops from what the meter tells me ?
This might be more complicated than I thought

sorry

Kim

Roger Hicks said:
Dear Kim,

The meter reading should only be a stop different at most, because you'll be reading the broad area (average reflectance about 13 per cent) again, instead of the shadow area (reflectance maybe 1-2 per cent).

It might even be identical. And if it's more -- use the broad area reading.

In other words, if your broad area reading is 1/250 at f/11, and your shadow-adjusted reading is 1/175 at f/11, use 1/175. But if the shadow-adjusted reading is 1/350, use the 1/250 second broad-area reading.

Used like this, spot metering is a way of getting enough detail in the shadows: when Ansel Adams got a spot meter, he is reputed to have said that his exposures increased by a stop.

The other two ways to use a spot meter are to stop highlights 'blowing' (in trannies, Polaroids and digi) and to keep a constant exposure for a chosen key-tone (traditionally a skin highlight in the heroine's complexion in movies). But neither of these affects you here.

Have fun in Scotland!

Cheers,

Roger

dachs · Jun 26, 2007

Gents
No-one has mentioned it apart from one incident light note ealier;
Not trusting the simple part area average meter built into my M6 when I first got it, I bought a Gossen meter with a wee diffuser dome for incident light.
directed at the light source it worked perfectly every time (slides 100ASA very contrasty subjects rright sun dep shadows + water eflections) Then I began to notice that, intelligently pointed, the camera never disagreed with the incident meter anyway. I only rarely check these days by meter - eg thru a doorway into sunlight. How you point the meter and work out what you want - as has been said - is the essence of it. Take loads of film and enjoy Scotland rain & all!

Roger Hicks · Jun 26, 2007

Dear Kim,

First principles again:

Read the broad area. This gives you let us say) 1/500 at f/11 (ISO 400 film on a sunny day).

Read the shadow. This gives you, let us say, 1/60 at f/11 (under the same conditions).

Obviously the two readings both refer to the same subject, but the shadow reading is recommending 3 stops more. Factor in the 2-1/2 stop adjustment and it is now recommending just 1/2 stop more. Use that.

Typically, on a bright, sunny day with deep shadow, you will end up giving 1/2 to 1 stop more than the broad area reading recommends. It can go higher: a couple of stops, even.

On an overcast day without deep shadows, your shadow reading (after the 2.5 stop adjustment) may actually recommend less exposure than the broad area meter, because your shadows aren't really very dark -- they are not 2.5 stops darker than the mid-point of your 'average' scene. Again, you'll still get a reading that works, but you'll probably like the tonality better in the one that is more generously exposed.

Does that make it clearer?

Cheers,

roger

Roger Hicks · Jun 26, 2007

dachs said:
Gents
No-one has mentioned it apart from one incident light note ealier;
Not trusting the simple part area average meter built into my M6 when I first got it, I bought a Gossen meter with a wee diffuser dome for incident light.
directed at the light source it worked perfectly every time (slides 100ASA very contrasty subjects rright sun dep shadows + water eflections)

Yes, that's fine with slides, because exposures for slide film (and digi and Polaroids) are keyed to the highlights, as noted above, and the old name for incident light reading is the 'artificial highlight' system.

You simply have to discard any shadows that are more than about 5 stops darker than the highlights, because that's the maximum range slide film can record before it 'blows' at the light end or 'blocks up' at the dark end.

With negs, though, the exposure is keyed to the shadows, and there is no telling how much darker the shadows are than the 'artificial highlight' On an overcast day, with a flat, dull subject, they might be as little as 2 stops darker, so they'll be generously exposed. On a bright, sunny day with deep shadows, they might be as much as 7 stops darker (unusual, but far from impossible if there are overhanging rocks and cave entrances, for example), so they will be underexposed if you use the incident reading.

The easy way around this is to give extra exposure on sunny days, but that's a rule of thumb based on experience, not an exposure measurement. The only way to know how much exposure the shadows actually need is to measure their brightness.

Cheers,

Roger

noseoil · Jun 26, 2007

"Grey cards are a complete waste of time and money in most cases as no film speeds are keyed to mid tones." Roger

Roger, in general I tend to disagree with this statement. Perhaps I'm going out on a limb here, but I've found that with roll film and "normal" development, a grey card will work very well in most situations. The problem people have with B&W film is that they haven't done their homework when it comes to film speed, exposure and development. Since roll film is a one shot development, it is nice to have consistency with respect to exposure. This will at least give similar print times, if nothing else.

I've given up on trying to work SBR numbers with roll film, because there is no way to tweak development anyway, unless the entire roll is shot under similar lighting conditions. In this case, you are basically working in controlled lighting, almost in a studio setting, as it were. The easiest way to get consistency in exposures is with a gray card, because it takes away the subjective portion of metering a shadow, or more specifically, where do you meter? Is it under the rock, under the tree, under the car, against the cliff face or the unlit side of a portrait?

I tend to agree with Dachs in this case. The meter in a 35mm camera is actually pretty amazing. Think about shooting a roll of slide film in a 35mm camera. With a basic meter which is really fairly crude, one is able to take some great images, bracket for exposure and get excellent results. This is all done with a zone 5 placement, 18% grayscale or whatever you wish to call it. I find that a gray card works pretty well in most situations. tim

Kim Catton · Jun 26, 2007

That does it

VERY LAST question:

The Broad area Means ? average metering of the non-shadow area in the composition or reading the sky ?

kim

Roger Hicks said:
Dear Kim,

First principles again:

Read the broad area. This gives you let us say) 1/500 at f/11 (ISO 400 film on a sunny day).

Read the shadow. This gives you, let us say, 1/60 at f/11 (under the same conditions).

Obviously the two readings both refer to the same subject, but the shadow reading is recommending 3 stops more. Factor in the 2-1/2 stop adjustment and it is now recommending just 1/2 stop more. Use that.

Typically, on a bright, sunny day with deep shadow, you will end up giving 1/2 to 1 stop more than the broad area reading recommends. It can go higher: a couple of stops, even.

On an overcast day without deep shadows, your shadow reading (after the 2.5 stop adjustment) may actually recommend less exposure than the broad area meter, because your shadows aren't really very dark -- they are not 2.5 stops darker than the mid-point of your 'average' scene. Again, you'll still get a reading that works, but you'll probably like the tonality better in the one that is more generously exposed.

Does that make it clearer?

Cheers,

roger

Roger Hicks · Jun 26, 2007

Dear Tim,

Well, actually, pretty much anything works astonishingly well, because, as noted, pos/neg photography is extremely flexible.

But grey cards are only a variant on the 'artificial highlight' method (a fixed tone that is an unknown amount lighter than the deepest shadows) and are therefore subject to exactly the same theoretical objections as noted in my previous post. Those theoretical objections become a matter of practical importance as soon as the SBR is greater than about 5 or 6 stops.

I fully take your point about SBRs and using an 'average' development time, but if you're going to meter a small, known area, why not measure the shadows, to which the exposure is keyed?

No subjectivity is needed in metering the darkest shadow in which you want texture and detail: it's the darkest shadow in which you want texture and detail. The only judgement call lies in recognizing when those shadows are so light, compared with the overall scene, that a shadow reading will give you a reduced exposure. Even that is easily (and objectively) overcome. Take a broad-area reading (no grey card) and take a shadow reading (no grey card -- but of course apply the 2.5/2.67 stop correction factor). Use whichever reading recommends more exposure.

Why carry around a piece of plastic or cardboard which is at best a compromise, and at worst (under very contrasty lighting) misleading?

Cheers,

Roger

Kim Catton · Jun 26, 2007

Edit -

My last question was just : how do you make the Broad Area reading ?

Roger Hicks · Jun 26, 2007

Kim Catton said:
That does it

VERY LAST question:

The Broad area Means ? average metering of the non-shadow area in the composition or reading the sky ?

kim

Dear Kim,

'Broad area' means the subject you're photographing, from the camera position, with either the camera itself in one of its full-frame-reading modes or a hand-held, non-spot meter.

Reading the sky is wonderfully misleading. A deep blue sky is a tolerable mid-tone; a white sky (I have one outside at the moment) is typically around 4 stops brighter than grass (another tolerable mid-tone).

Now consider a scene with big puffy white clouds in a blue sky (clouds maybe 4 stops brighter than a mid-tone) and a mediaeval arcaded street with the shops 3 or 4 metres back from the street, under the overhang of the building above. Dark areas of the shop-fronts are quite likely to be 4 stops darker than a mid-tone. That's an 8-stop range. The only way to be sure of giving enough exposure, and no more, is to measure the dark areas of the shop-fronts: the darkest areas in which you want texture, in fact.

Yes, you can get the same reading in a number of other ways. A broad-area reading will give you an identical reading, at a given angle and distance from the shops -- but step back, or angle it up towards the puffy white clouds, and it'll recommend less exposure, or step forward, or angle it down, and it'll recommend more. Likewise, an incident-light or grey-card reading will give exactly the same reading -- for a very limited range of positions and angles. With experience, you can learn what those positions and angles are, which is why people get good readings that way, but there's a lot more experience and judgement involved in doing it that way than there is in taking a spot reading of the darkest area in which you want texture and detail.

Until I understood the simple fact that metering for negs is metering for the darkest area in which you want texture and detail, I wasted a lot of time with spot meters and grey cards, which is why I'm a bit evangelical about it now.

It's worth remembering that the first commercially successful spot meter (the SEI Photometer, still highly sought after today) didn't even have a mid-tone index, just shadow (for neg) and highlight (for movie). I'm not sure why they were added to later meters, because they really are of very limited usefulness.

Cheers,

Roger

quick hints on spotmetering ?

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