Spot metering in practice

[aMac]

Well after what seemed like a good deal on a new camera turned out to be a scam, I was so in-the-zone for a new piece of equipment that I went ahead and just bought a 30D from a store anyway.

It's an amazing jump to go from a 300D and I'm over the moon with it, but that's for another time and another thread. What I'm here for is to ask about spot metering. I've done some searches and what I find seems to be explanations of how the different metering modes work and compare, rather than specific use guidelines.

What's the normal process for using spot metering and where is it appropriate? So far what I understand and from having a play is that I can use the spot meter to get a reading on a piece of scene, and then adjust the shutter/aperture while looking at the meter reading to set it's exposure how I'd like, up to +/-2 stops (after that it goes outside the meter range and is flashing so it's a guess up to +/-3 stops). I seem to be getting acceptable results so far but what kind of objects should I be taking readings from for example?

I've never studied photography in a learning environment, having instead learned what I needed to know from hands-on experience or from knowing other photographers so forgive me if this is basic stuff.

 

[Big Mike]

Congrats on the new camera.

what kind of objects should I be taking readings from for example?

There are different ways to go about metering for a scene. You could use the spot meter to meter the dark & light areas separately, then pick an exposure that is somewhere in the middle.

A spot meter is also good if you know the reflectivity of somthing in the scene...and you can use that reading for the shot. For example, you could meter green grass, which is about the same as 18% grey...and that should give you an exposure that is pretty close to accurate.

Let's take a step back...Do you understand how a camera's meter works? It wants to turn what it sees into the tone of 18% grey. So if you meter snow...it will make it look grey. If you meter a dark shadow, the meter will give you settings to make it grey. To get an accurate exposure, you need to recognize what the meter is reading and adjust the exposure accordingly. That's where the spot meter is good...because you can meter something specific and adjust accordingly. For example, you could meter the palm of your hand...and open up about one stop. You could meter something that is white...and then open up (add exposure) about two stops. It's not something that you learn over night...but once you know how to use your meter...it's a great tool.

 

[hawee99]

k so if I was to meter snow and I line it up and the camera says correct exposure, I take the picture and the snow should turn up 18 percent more grey? so If I want the snow to look white, I would open up a little more...? Right?

 

[Big Mike]

so If I want the snow to look white, I would open up a little more...? Right?

That's correct.

 

[aMac]

Thanks for the input, Mike. Is that metering on the grass tip for grass in direct sunlight or in shadow/overcast?

Yes I know about 18% grey and the basics of what the camera metering is trying to achieve from constantly having to adjust the exposure compensation when shooting on the 300D, but that was still relying on the camera to do most of the work. I'm looking forward to be able to understand exposure a lot more now and not having to tweak the raw settings so much.

 

[Big Mike]

I believe it works best (or at all) in direct sunlight...although as long as the same light is hitting it, as your subject...you should be OK.

 

[TheLostPhotographer]

I use spot metering all the time (when time allows). It's excellent for landscapes. Look for the darkest area - take a reading. Look for the lightest area - take a reading. Look for the 'grey card' area - take a reading and expose for the mean value.

I rarely use digital mind and find that the metering on my film cameras when taking center weighted average are pretty much spot on most of the time. However, in landscape scenes with big contrast spot metering is good.


It is also good if you want to expose for a very selective area of a scene. Perhaps in a dark room/environment where you want to pick out a highlight without burning out. Maybe an old plough blade catching the rays of leaking sunlight in an old barn for example. You know that most of the scene is next to pitch black and your eyes adjust accordingly. Your camera doesn't. It would normally take an average reading and over expose the area you want accurately exposed. So, you point your spot reading at the plough blade and ignore the darkness around you.

There are many useful applications for taking spot readings.

 

[Chas]

It's been a while since I've used my spot meter, but the idea is that it lets you "place" important bits of the scene (any bit that you like) into a particular light "value", or degree of brightness in the final image. I recommend some of Ansel Adams' classic books on his "Zone System" in black & white photography, they're fun to read as well as educational because you get the benefit of his great wisdom and experience. Of course you can only really "place" a single spot in a given scene, and then everywhere else in the field of view will just fall onto whatever brightness level it happens to have in the given light conditions with that particular exposure setting. The beauty of the spot meter is that after you've made a provisional decision about exposure based on a first reading (f/4 at 1/250th, say, based on a reading of the face and giving it a certain brightness level), you can find out exactly what brightness levels ("Zones") other parts of the scene will fall into - which might or might not cause you to rethink your exposure decision. With time, you will develop a feel for what different exposure "Zones" (standard gray = Zone V) will look like in the final image or print, and then you're cooking with gas.

As was said, the meter reads for 18% gray or "Zone V" - if you shoot at the exact exposure setting indicated by the meter (after inputting the ISO speed of course), you'll get that certain standard gray in that specific spot in the final image, under standard conditions of post-exposure processing. Generally speaking (but not always - that's the whole point really), in black & white photography you want someone's face to be at around brightness Zone VI or VII for the right look, which means that if you take a spot meter reading on someone's face it's often good to use an exposure one or two stops above that indicated by the meter (which again, always assigns a brightness of Zone V or 18% to whatever it's looking at). This means you might need 1-2 stops larger aperture or 2-4 times the exposure length or some combination of these two. You also can find out if an area of important but rather deep shadow will show any detail in the final print (allowing for digital processing of course), by taking a reading after provisionally picking your exposure setting. You will also find out what areas are likely to be completely whited out through over-exposure (or "blown out") with loss of important detail in the high end - how do you want the final print to look, in your imagination? Maybe the face should be exposed a little more (Zone 8, say), to bring out more detail in this shadowy area without blowing out this bright area over here.

It's a lot of fun if you're into B&W photography particularly, but it takes much more time to set up a shot of course - which is often A Good Thing. Usually, photograph shouldn't be rushed - unless you're going to miss the key action of course.

Sorry if I've confused you. I'll dig up a book title or two if you're really interested. You will find that using a spot meter greatly enhances your control of the final result and hence enjoyment, if you've got the time and interest do it right. It will become second nature with practice, and photos will become less a matter or luck (or clever software in the camera making "decisions" for you based on a database of other people's photographs), and more the result of conscious decisions on your part. By definition then, it's more creative. Not forgetting that a lot can be done on the computer afterwards as well, but only to a certain point .....

 

[hawee99]

I'll dig up a book title or two if you're really interested. ....

I'd be down for a few recommended book titles on this please

 

[TheLostPhotographer]

snip, snip, snip...Zone system...snip, snip...

Hi Chas,

Do you use the Zone System whilst shooting B&W digital? Have you noticed any difference to film?

An ignorant question possibly. If you do use digital; how tolerant is it compared to film? Do you think the Zone System is still relevant in these modern times of tolerant film and RAW?

 

[ann]

it is a system that works very well with LF negatives, as each negative can be custom made (so to speak)
it can also be used with roll film , but one must commit the whole roll to a specific exposure and development combination.

I think it is relevant with black and white film or digital with regard to learning about the tonal values and brighest ranges.

however, i hope this doesn't end up with a war about the system, it is just a tool, nothing more, nothing less.

Most traditional black and white photographers have figured out a method for exposure and development of their films, there are many methods and ways to do this. It comes down to what works the best for each individual.

 

[Chas]

Hi Chas,

Do you use the Zone System whilst shooting B&W digital? Have you noticed any difference to film?

I'm a complete newbie on DSLR (i.e. don't own one yet!), which is why I decided to spend time on the forum and get advice to help me decide which one to buy. I'm getting plenty of good stuff already, this is a great forum. No, all my B&W work has been in either 35 mm (Spotmatic or Canon A2) or in 4X5 (Tachihara field camera with Schneider lenses) - it was with the latter that I really got into the zone as it were. Used to have my own basement darkroom with all the 4X5 gear - sigh. So I can't answer your question, but I'm very much looking forward to hearing from someone who can. All I've done to date is compare sensitivity curves between different sensors and with my old B&W films - digital B&W is all theory to me at the moment, but of course the principles of exposure control (in-camera) don't change. This thread is getting me excited about eventually making large B&W prints with a quality DSLR, taking full advantage of the new technology. Old neurones, long dormant, are firing again ....

Old exposure control techniques + new lens/body technology = something pretty marvelous! There's still nothing quite like B&W, IMHO, for mood ........

--------------------
Ann: "however, i hope this doesn't end up with a war about the system, it is just a tool, nothing more, nothing less. etc"

I couldn't agree with you more. It isn't for everyone, and I'm not even sure if it's for me with auto-bracketing, 11-point evaluation and all the rest of it. My judgement may be somewhat affected by the wave of nostalgia that has now engulfed me but which will recede - we shall see. Anyway, it's all good.


p.s. when are they coming out with an "affordable" digital back for my 4X5, answer me that someone please .............. ? I know, I dont' wanna know.

 

[aMac]

Thanks for the great replies! That's just what I needed. It goes without saying that I'll pick up a lot more when I get out there and practice, but a trip to the library will be great too, so a recommendation will be well appreciated. I've been meaning to look up something on lighting in general for a while now anyway but I've been putting it off.

 

[Chas]

I'd be down for a few recommended book titles on this please

After dusting off the relevant shelf, here you go:

1) "Examples. The Making of 40 Photographs." Ansel Adams. (Little, Brown & Co). I must reread this book, he talks you through his thinking very carefully on each of these remarkable prints, which are all shown next to the text of course. Still a classic.
2) "The Negative." Ansel Adams. Book 2 of the famous set of 3. Forget that it's about film, here's where he discusses exposure control, much of which is still relevant. The photosensitive medium has change, but so what? It may be electronic, but it still has upper and lower limits does it not? And if the data aren't there in the bytes after the exposure, no amount of fancy software work is going to bring it back .....
3) "Zone VI workshop." Fred Picker. Amphoto books. I like Fred, he explains things well and is very down-to-earth.

Of course, histogram displays in DSLRs must also give a lot of useful information, but without the necessary detailed mapping. An "isozonogram" [my neologism] display on the monitor would be nice - can they do this yet? I love histograms - work with them in statistical analysis of clinical trial biochemistry data all the time. Very useful I imagine, especially to alert you that areas might be blocked or underexposed I would assume. I want this very badly ....

 

[Big Mike]

Very useful I imagine, especially to alert you that areas might be blocked or underexposed I would assume

Yes, the histogram is indeed a wonderful feedback tool on digital cameras. Rather than alerting you about underexposed areas however, most cameras will warn you about overexposure. With digital photography, the shadow detail is more 'recoverable' than detail that has been blown out. However, there is more detail/information in the upper end of the range. This is where we get the technique called 'Expose to the right'. Basically, it means the the best exposure will give you a histogram that is as close to the right (bright) side but without actually clipping the right edge.

Check this out...http://www.luminous-landscape.com/tutorials/expose-right.shtml