Spot metering difficulty

oldnewandblue · Dec 7, 2011

Hi all, new on here.. I have been shooting on evaluative metering mode on my 5d mk1 for sometime now, but I want to use the spot metering mode. I understand that it covers about 3% of the centre, but I find it really hard to set the exposure (shooting manual of course) because the metering is so sensitive ... Anyone got any tips on this ?? Many thanks xx

Ysarex · Dec 7, 2011

Put the camera into one of its semi-auto modes like P, Tv or Av.

Joe

Robin Usagani · Dec 7, 2011

I dont advise using spot with semi auto. Your exposures will jump and down quite a bit between shots.

Ysarex said:
Put the camera into one of its semi-auto modes like P, Tv or Av.

Joe

Of course it is sensitive, it is only pointing a little spot. You can be on someones hair, forehead, sky etc. The key is to know where to put the exposure of what you are metering. For example if I shoot a bride, I probably point it at the bright spot of her dress and put it at +2 or +1 2/3. Or I can point at the forehead and put it at 0 (assuming her skin isnt dark or fair).

oldnewandblue · Dec 7, 2011

Thanks guys .. @ joe.. I don't shoot on semi auto. If I did, I probably wouldn't be interested in shooting with spot.@schwetty... Yup I get this.. But in the time that I compose, meter, & change the +/- etc, the subject will have moved, or I will have moved, and it's too late! I was just wondering if there is a secret to doing this fast enough to overcome the sensitivity.. Or is it enough to stay @ 9% with evaluative. Never had problems there, but with improving my skill in mind, I hoped to master 'the sport'. Also, schwetty, I take it your a wedding photographer.. Would youind if I asked you a post production/presentation question? Xx

Robin Usagani · Dec 7, 2011

sure ... I dont mind.

You want to point something that is big and it is OK if you arent accurate. RAW is very forgiving. As long as you are as close as 1 stop or sometimes more, you are fine. More than likely if you point it at the skin and set it to 0, your photo will be workable. Just dont point it at the shiney part of the forehead or something.

pgriz · Dec 7, 2011

Well, use the spot meter as a probe. Ideally, you should point it at the brightest spot where you want to see detail and get a reading. Say it is 1/1000sec at f/8 at ISO 200. Then you see what the darkest spot reads. Say it is 1/4 sec at f/8 at ISO 200. That means that the lightest and darkest parts of your image are about 8 stops apart. Now meter something in the scene that is at the midpoint of brightness. It might be 1/125sec at f/8 at ISO 200. Chances are, if you go to evaluative metering for this scene, you'll get something close to 1/125sec (f/8, ISO 200). Now you know that your highlight is about 3 stops above the midpoint, and your detailed shadows are 5 stops below the midpoint. For most DSLR cameras, the image will be within the dynamic range of the camera, and you will get detail in both the highlights and the shadows.

However, suppose the highlight read at 1/4000 sec, everything else being equal (ie, two stops brighter). Now, your camera may not be able to extract detail in the highlights as they risk being "blown". So as a photographer, you make the decision about what is more important to you - the highlight detail or the shadow detail, and bias your exposure accordingly. It should also be clear that the exposure will be set manually because you are overriding the reading that the camera makes and you set an intelligently-derived exposure that will give you the photo you want.

The exception to the above is when the point of interest is very small (relative to the size of the frame), and the exposure of that point of interest has to be right - then I will go with the camera's reading on that spot. An example of this would be shooting a performer on stage, lit by bright floodlights, but surrounded by black (or very dark) background. The spot reading on his/her face would give me a much better exposure reading than an "evaluative" or averaging reading. The same applies if you are shooting a person surrounded by very bright background (snow or sand), and the averaging exposure will usually drastically underexpose the person.

Derrel · Dec 7, 2011

^^^^^^^EXCELLENT post, pgriz!!!

Ysarex · Dec 7, 2011

You asked if there's a way to use the spot metering function and at the same time work fairly quickly....OK.

As Pgriz noted you can use the spot meter to measure the dynamic range of the scene. That means multiple readings and calculations and time. Nobody can do that quickly. So if you're trying to use the spot meter in that manner then your question doesn't make sense.

How else can a spot meter be useful? You can use it to determine the exposure from a point in the photo where you have assessed -- based on your extensive experience -- there is a middle grey. If you're thinking about spot reading off something other than a middle grey then you're back to calculations and working slow -- you could possibly plan to meter off skin tones that are typically one stop brighter than middle grey and if so dial in an appropriate EC.

So, one precise reading and then recompose and click. How to do that as fast as possible? I would have earlier set an ISO that I had assessed was appropriate to the general illumination level. Then I'd place the camera in Tv or Av mode based on my preference for the circumstance (fast shutter hand held for example). Ready to go in TV mode:

1. Assess the scene and find the meter spot.
2. Place meter zone over spot.
3. Press AEL button on camera while verifying camera selected f/stop.
(Once AEL button pressed no jumping of exposure will take place.)
4. Recompose.
5. Click.

That would be the fastest possible way to do that in a way that makes sense. Otherwise you could put the camera in M and work more slowly.

Joe

MLeeK · Dec 7, 2011

Sending you something to help...

Robin Usagani · Dec 7, 2011

There are many ways to do it i guess, AEL is one of them. Unfortunately some canon cameras you cant lock it for several shots. Not sure if my 5D II can lock it for multiple frames. I havent tried.

I like matching spot metering to where I think it should be. For example if I want the blue sky to be blue on my raw file, I just point it to the blue sky and set my meter to around +1, + 1 2/3.

Big Mike · Dec 7, 2011

Yup I get this.. But in the time that I compose, meter, & change the +/- etc, the subject will have moved, or I will have moved, and it's too late! I was just wondering if there is a secret to doing this fast enough to overcome the sensitivity..

One of the advantages of shooting in manual, is that your exposure won't change (unless you change it). So as long as you're shooting in the same light, you only need to set your exposure once, and then you don't have to worry about exposure for subsequent shots (provided the light doesn't change and you want to maintain the exposure you've set).

So for example, you might look at your scene and choose something that you could guess the brightness of, for metering. A common one is green grass or foliage...it's often very close to middle grey (middle grey, being what your camera's meter is calibrated for). So you would meter on the grass, get to zero on your scale...and then recompose and start shooting, not having to worry about your exposure. In this case, spot may not be ideal, because grass/foliage isn't uniform...so you want a larger sample size.

If you are going to use spot metering, it can be hand to pick part of your scene/subject and meter off of that. Another example, if there is something white, you could meter off of that and set your exposure to roughly +2.

So yes, your meter reading will jump around while in spot mode...but it's meant to be small so that you can meter off of something specific...and that's only useful if you understand where you want your exposure to be, relative to that post. (or if you want to analyze your scene, as mentioned above).

Of course, you could use a grey card to meter off of and set your exposure. That's not usually as quick and easy as we would like...but once you set your exposure, you don't have to change it (unless the light changes etc.)

jwbryson1 · Dec 7, 2011

pgriz said:
Well, use the spot meter as a probe. Ideally, you should point it at the brightest spot where you want to see detail and get a reading. Say it is 1/1000sec at f/8 at ISO 200. Then you see what the darkest spot reads. Say it is 1/4 sec at f/8 at ISO 200. That means that the lightest and darkest parts of your image are about 8 stops apart. Now meter something in the scene that is at the midpoint of brightness. It might be 1/125sec at f/8 at ISO 200. Chances are, if you go to evaluative metering for this scene, you'll get something close to 1/125sec (f/8, ISO 200). Now you know that your highlight is about 3 stops above the midpoint, and your detailed shadows are 5 stops below the midpoint. For most DSLR cameras, the image will be within the dynamic range of the camera, and you will get detail in both the highlights and the shadows.

However, suppose the highlight read at 1/4000 sec, everything else being equal (ie, two stops brighter). Now, your camera may not be able to extract detail in the highlights as they risk being "blown". So as a photographer, you make the decision about what is more important to you - the highlight detail or the shadow detail, and bias your exposure accordingly. It should also be clear that the exposure will be set manually because you are overriding the reading that the camera makes and you set an intelligently-derived exposure that will give you the photo you want.

The exception to the above is when the point of interest is very small (relative to the size of the frame), and the exposure of that point of interest has to be right - then I will go with the camera's reading on that spot. An example of this would be shooting a performer on stage, lit by bright floodlights, but surrounded by black (or very dark) background. The spot reading on his/her face would give me a much better exposure reading than an "evaluative" or averaging reading. The same applies if you are shooting a person surrounded by very bright background (snow or sand), and the averaging exposure will usually drastically underexpose the person.

I truly understand all of this and find it to be a great post, but this is not the kind of thing that I can typically do quickly in my head and really utilize when I'm taking a shot. I find myself having to stop and really think about what I am doing and I don't always get there. What do I need to do to get to this frame of reference? I guess keep shooting...

Good post.

Derrel · Dec 7, 2011

jwbryson1 said:
>>SNIP>>I truly understand all of this and find it to be a great post, but this is not the kind of thing that I can typically do quickly in my head and really utilize when I'm taking a shot. I find myself having to stop and really think about what I am doing and I don't always get there. What do I need to do to get to this frame of reference? I guess keep shooting...

Good post.

"How do you get to Carnegie Hall?"

"Practice,practice,practice!"

To an accomplished musician, pages and pages of complex, varied musical notes are instantly translatable, on the fly... You will get there. If you set your camera to SPOT metering and an AUTO-exposure mode, it will very quickly show you the suggested readings as you use it "as a probe", as pgriz suggested. I would say set the camera to SPOT metering and Av mode, and then watch the shutter speed suggestions shift as you aim first at the brightest important object in the scene, and then at the darkest important object in the scene. This measuring the brightest and darkest important objects is a method of exposure metering that goes back to the 1940's, with the first widespread adoption of exposure meters. If you do this type of light metering in landscape type shooting for say, one season, you'll soon be able to guesstimate exposures, and you will also be able to pick out the mid-tone value subjects pretty fast as well.