Why so dark in Tv?

I've been trying to figure out why I"ve been seeing inconsistancies in exposure while shooting in shutter priority (Tv). Below is an example of an image that came out much darker than anticipated and how to prevent it in the future (without changing out of Tv mode). I'm thinking it might be due to using spot metering in this case with a good bit of white within the spot being read by the camera, but not certain how to read it.

It was a bright sunny day most of the time. Camera was set to, Tv, spot metered, ISO 400 (manual), and 1/3rd exp comp to push histogram to the right. Center-point focus right on the scaup's head, maybe slightly over the top. The camera selected f/10, so it had plenty of aperture remaining to open. A great number of the 600 shots that I took, the camera selected f/5.6, and wanted more. A number of photos were as anticipated, slightly overexposed. Thanks.

Inconsistency is a consequence of letting the camera make exposure decisions. I know you said you're set on Tv mode, but I'm still amazed as to why you'd put yourself through all this. All the exposure compensation you're dialing in is practically the same as adjusting the aperture/shutter speed in Manual mode, only with less control and predictability of results.

On that particular photo you present, I think Evaluative or Centre Weighed Average woulda netted you better results. If you spot metered off the white patch on the bird, the camera decided such area was middle grey and proceeded to render it so, with the subsequent underexposure (your +1/3 compensation is practically irrelevant, since you needed to apply at least 1 stop of compensation for that white area to be rendered white –probably harping again, sorry, but such compensation is easier to make by your brain and hand dialing in the right values.

I see nothing about his exposure which is unusual, the mode (Tv) has nothing to do with nothing...

1. the metering (spot) falling on the center of the frame (the reflection on the water, the somewhat light back of the duck) tells the meter that there is 'more light' falling on what the meter assumes to be a midtone area (which it is not),
   
2. so it suggests an exposure combination to render that area to be mid-scale in the histogram (which is where the peaks are occuring!)
   

Try this: Need an exposure crutch?

"Why?": Post #47

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Larry,

You are using spot metering, and the subject has a white area near the center of the frame and also a black area near the center of the frame.
This type of inconsistency is exactly what you can expect 100% of the time with spot metering and this degree of subject contrast.
It has nothing to do with being in Tv mode.

If you want more consistent exposure and don't want to use manual exposure, then get out of spot metering and set Exposure Compensation accordingly.

It probably wouldn't be a bad idea to get out of Tv mode for this kind of situation, anyway, simply due to the fact that maintaining a consistent shutter speed isn't really doing you any good when there is this much light and you are not panning for background blur and you are not shooting a subject that is creating its own motion. Of all the viable reasons people have for using Tv, none of them seem to be present in this scenario.

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Alveric wrote in post #17916765
Inconsistency is a consequence of letting the camera make exposure decisions. I know you said you're set on Tv mode, but I'm still amazed as to why you'd put yourself through all this. All the exposure compensation you're dialing in is practically the same as adjusting the aperture/shutter speed in Manual mode, only with less control and predictability of results.

On that particular photo you present, I think Evaluative or Centre Weighed Average woulda netted you better results. If you spot metered off the white patch on the bird, the camera decided such area was middle grey and proceeded to render it so, with the subsequent underexposure (your +1/3 compensation is practically irrelevant, since you needed to apply at least 1 stop of compensation for that white area to be rendered white –probably harping again, sorry, but such compensation is easier to make by your brain and hand dialing in the right values.

Wilt wrote in post #17916770
I see nothing about his exposure which is unusual, the mode (Tv) has nothing to do with nothing...

1. the metering (spot) falling on the center of the frame (the reflection on the water, the somewhat light back of the duck) tells the meter that there is 'more light' falling on what the meter assumes to be a midtone area (which it is not),
   
2. so it suggests an exposure combination to render that area to be mid-scale in the histogram (which is where the peaks are occuring!)
   

It seems to be doing precisely what it should be doing. Had the spotmetering been targeted on a reflective target at midtone, it would have placed THAT area at mid-histogram.

Your compensation told the meter, "The target you see is 1/3EV brighter than your 12% target, so give it 1/3EV more exposure to get it to mid-scale" but it was pointed at the reflective water and the somewhat bright back of the duck.

Here my target in the center is truly a mid-tone, and the meter suggested an exposure to render the histogram peaks in this screenshot...


...with the peaks for the midtone area at the middle of the histogram, as expected.

PhotosGuy wrote in post #17916792
Try this: Need an exposure crutch?

"Why?": Post #47

Tom Reichner wrote in post #17918227
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Larry,

You are using spot metering, and the subject has a white area near the center of the frame and also a black area near the center of the frame.
This type of inconsistency is exactly what you can expect 100% of the time with spot metering and this degree of subject contrast.
It has nothing to do with being in Tv mode.

If you want more consistent exposure and don't want to use manual exposure, then get out of spot metering and set Exposure Compensation accordingly.

It probably wouldn't be a bad idea to get out of Tv mode for this kind of situation, anyway, simply due to the fact that maintaining a consistent shutter speed isn't really doing you any good when there is this much light and you are not panning for background blur and you are not shooting a subject that is creating its own motion. Of all the viable reasons people have for using Tv, none of them seem to be present in this scenario.

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Thanks for the replies and detailed explainations. It confirms what I suspected after seeing the "underexposed" photo in post processing; poor choice of metering mode. I completely understand the prodding to use manual mode, and will explain why I no longer use it at this location or at some others. There's lots of waterfowl and lots of potential for action (i.e. wing flapping behavior, an occassional fight, or birds flying in) to be initiated at the blink of an eye. I want a fast shutter to capture that action as crisp as possible (though I don't mind some wing blur). Durring the lull, I'll shoot some portraits. Tv mode gives me the flexability to roll back the speed on portraits to get more depth when there's other ducks in the frame. Often I don't, or forget. Sometimes I do and forget to roll it back up when the action starts, and I blur the action shot. Worst case. I like the rapid flexibility it gives me. At any rate, when I shoot in Tv, I'll select a more appropriate metering mode. Thanks.

As long as you know what the camera is doing, you should be fine in any mode, methinks.

You can use a cheatsheet to anticipate how the camera will see a particular tone or hue and adjust accordingly, either via EC or shutter speed/aperture/ISO in manual mode.

Looks like you had +2/3 exposure compensation. Put it back to 0 and see what happens.

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Hannya wrote in post #17921986
Looks like you had +2/3 exposure compensation. Put it back to 0 and see what happens.

I think we all know exactly what would have happened - it would have been even worse (darker) by 2/3 of a stop.
In these situations, it is usually advisable to add even more exposure compensation, not less.

If you were using sarcasm in your post, then please forgive me for my literal response. I often do not understand sarcasm, nor realize when it is being used.
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Tom Reichner wrote in post #17921993
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I think we all know exactly what would have happened - it would have been even worse (darker) by 2/3 of a stop.
In these situations, it is usually advisable to add even more exposure compensation, not less.

If you were using sarcasm in your post, then please forgive me for my literal response. I often do not understand sarcasm, nor realize when it is being used.
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I agree with everything Tom says. Allow me to expand on his ...more EC... comment.

OP, you are correct to shoot this in TV. Auto-ISO would have served you better. Dial in enough shutter speed to keep the aperture wide open and the ISO near 200. Too slow on the shutter will force the lens to stop down. Too fast and you're shooting ISO 1600 in broad daylight. It is easy to manage all of that with one dial: the shutter speed.

I very rarely use spot metering. I believe it is easier to stick to one metering method, learn how to use it well, and apply its vagaries per situation. I don't know how 'spot' behaves, primarily because I don't want to learn 4 different metering methods, and how to use them. Evaluative works well for me, in most any situation.

The trick is to look at the whole scene, not just your subject. This scene is 90% highly reflective water. It is almost like shooting a polar bear in the snow. Knowing that, and how EVAL works, I would have started with +5/3 or even +2 EC, checked the histogram and blinkies, make a correction (if needed, you'll get better at this), and take another shot. If you shoot raw, you've got just over 1 stop of recoverable headroom, so you don't need to hit the EC on the head.

I think SPOT, CWA, and Partial are a waste of time and effort. To use them effectively, you have to know the vagaries of all 3. Stick to EVAL. Learn it well. You can't do anything with those other three you can't do with EVAL. And EVAL offers one significant advantage: it keys on the selected AF point. The others are designed NOT to do that. Sometimes this feature is helpful. It is not available in the other 3 modes.

I come from the film cameras of 40 years ago. CWA was the only option. We've come a long way, baby! Eval and EC you can reach with your thumb while using two hands on the camera is a modern marvel. Use it.

Bassat wrote in post #17922093
I think SPOT, CWA, and Partial are a waste of time and effort. To use them effectively, you have to know the vagaries of all 3. Stick to EVAL. Learn it well. You can't do anything with those other three you can't do with EVAL. And EVAL offers one significant advantage: it keys on the selected AF point. The others are designed NOT to do that. Sometimes this feature is helpful. It is not available in the other 3 modes..

Ironic that you state that Spot and Partial have vaguaries but that Eval does not... In reality, the inverse is what is true!

Here is a photo with Spot reading taken on the grey card (exposure made in M, tp permit reframing shot without the meter reading an unwanted part of the frame), resulting in perfect recording of the grey card as a midtone:

Yeah, I never use Evaluative. It's like auto modes: trusting a camera database to make exposure decisions. My camera is permanently set on Spot (I use a handheld meter anyway); for when I don't have a lightmeter I meter off a patch whose tone is about the same value as neutral grey, dial the exposure manually and fire away. Consistent exposures 99% of the time. Heck, I'll even use Sunny 16 before I turn to Evaluative.

Alveric wrote in post #17922138
Yeah, I never use Evaluative. It's like auto modes: trusting a camera database to make exposure decisions. My camera is permanently set on Spot (I use a handheld meter anyway); for when I don't have a lightmeter I meter off a patch whose tone is about the same value as neutral grey, dial the exposure manually and fire away. Consistent exposures 99% of the time. Heck, I'll even use Sunny 16 before I turn to Evaluative.

While Nikon supposedly uses a database of photos and how the brightnesses fall into different patterns, the Canon Evaluative metering does not employ similar methods. It simply places...

• highest priority to the AF zone
  
• lower priority to all the surrounding zones
  

Wilt wrote in post #17922159
While Nikon supposedly uses a database of photos and how the brightnesses fall into different patterns, the Canon Evaluative metering does not employ similar methods. It simply places...

• highest priority to the AF zone
  
• lower priority to all the surrounding zones
  

What does it do if you focus manually?

I use CWA most often and would much rather have the weight on my focus point, whether it's at the center or not.

Allow me clarify. By 'vagaries' I mean 'how it reads the scene'. Any and all exposure modes have vagaries. I mean only that they function in a particular manner. SPOT certainly prioritizes the central X% of the VF, but it does not completely ignore the remainder. Same for CWA and Partial. There is no point to learning how all three of them work. If you understand one of them, and apply that knowledge judiciously, you will get - for the most part - proper exposures.

I grew up on CWA, but just happen to prefer EVALUATIVE. Which method deployed is irrelevant. I could just have easily used Canon's CWA and been just as successful once I mastered its function. I did OK with film cameras 40+ years ago. Remember, no chimping back then!

OhLook, I am trying to make sense of your statement. You primarily use CWA, and would rather have the exposure weighted toward the focus point? CWA is not capable of that. It is by definition, CENTER weighted average. Can you help me see what I am missing, please? If I remember correctly, you shoot a 5D3. That is a load of AF points that basically get ignored if you are using CWA. I think.