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04-24-2011, 02:35 AM   #1
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Metering in Av or Tv mode

I am now comfortable in metering in Manual mode as I started with that mode and getting the hang of it. Can somebody suggest me, for example, how I can meter a grey tone in my frame (while in Av for example) to zero or a highlight to +2.0 as all that I understand is that now the shutter speed is able to change automatically while the aperture is fixed by me and another element I see is Ev compensation that can be adjusted.
Probably the metering happens automatically and it is just that I am unable to understand. Please help me understand (or point me to a resource) the metering in this semi-manual modes as to how they work and how we can control it.

04-24-2011, 03:55 AM   #2
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So what do you do in M? So set aperture and next you set shutter speed to a avalue that gives you the result you want; or vice versa (set shutter speed and adjust aperture).

Av and Tv are the same from that perspective. But instead of you deciding on the second parameter the camera does it for you. In M it's easy to deviate, you just adjust one of the two. In Av or Tv, you need the ev compensation to deviate from what the computer calculated.

Hope this makes it a bit clearer.

PS
Can you please use a normal sized font in your next post. My eyesight is not the best so I have to enlarge to be able to easily read your post. Thanks.
04-24-2011, 05:30 AM   #3
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Thanks for your reply, I think my newbie question is still not clear.
I want to bring more clarity into my question. So let me first list below how I would meter in the manual mode.
1. I will point my spot meter to a neutral tonal area (at this time the exposure meter would either be in zone 4(-2) or zone 6 (+2))and play with the aperture or shutter speed numbers and bring the meter to a neutral zone ie., 0.0. Then I may check for the highlight to see that it is not blown out or overexposed by making sure the meter is below +3.0 and that it is not blinking.
2. But with Av or Tv mode since the meter always reads 0.0 I am presuming that the camera automatically tries to bring everything in the neutral tone area. Does this mean, there is a job for AE lock here? Then I can lock the setting on a gray tone. Or should I point the meter to a highlight in my frame and bump up the EV compensation accordingly? This was my question. All springs out from the fact that the EV always reads 0.0
I am not whether I have attempted to bring more clarity in my question, anyone please join here to help express my question further to simplify.
04-24-2011, 06:58 AM   #4
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I think Sterretji means use the normal font and size (just like what I do here). With regard to the metering options, first, metering from the camera can be set in 3 modes... spot, center-weigh and matrix. With spot metering it is a bit tricky since the camera will metering based on the spot where the focus point is at - it also is based on the EV setting you have set. If you set the EV at +0.7 in Av mode, then the camera will metering off the spot and give the appropriate Shutter speed. With M mode, I don't think EV setting comes into play since it is manual.

04-24-2011, 09:40 AM   #5
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QuoteOriginally posted by sany Quote
Thanks for your reply, I think my newbie question is still not clear. I want to bring more clarity into my question. So let me first list below how I would meter in the manual mode.
1. I will point my spot meter to a neutral tonal area (at this time the exposure meter would either be in zone 4(-2) or zone 6 (+2))and play with the aperture or shutter speed numbers and bring the meter to a neutral zone ie., 0.0. Then I may check for the highlight to see that it is not blown out or overexposed by making sure the meter is below +3.0 and that it is not blinking.
2. But with Av or Tv mode since the meter always reads 0.0 I am presuming that the camera automatically tries to bring everything in the neutral tone area. Does this mean, there is a job for AE lock here? Then I can lock the setting on a gray tone. Or should I point the meter to a highlight in my frame and bump up the EV compensation accordingly? This was my question. All springs out from the fact that the EV always reads 0.0
I am not whether I have attempted to bring more clarity in my question, anyone please join here to help express my question further to simplify.
If you are using the spot meter in Av mode, the meter will give you the neutral tone reading for whatever is in the bracketed area. The reason to use Av in this case is to choose the aperture and have the camera suggest a shutter speed for a neutral exposure at that spot.

If you want to check a highlight in the frame, when you point the spot meter at another part of the frame, the meter just suggests a new shutter speed. So I think your question is, how can I find out the difference in stops between these two points in Av mode? In M mode, the information is right there in the viewfinder.

You can create a similar display to what you see in M mode by remembering the initial shutter speed number of your neutral area. Then aim at the highlight and use the Ev compensation dial to get the same shutter speed. Now the Ev compensation reading in the viewfinder tells you the difference in stops, just like in M mode.

A one-dial camera might make this technique more annoying than it's worth.
04-24-2011, 09:43 AM   #6
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QuoteOriginally posted by sany Quote
2. But with Av or Tv mode since the meter always reads ‘0.0’ I am presuming that the camera automatically tries to bring everything in the neutral tone area. Does this mean, there is a job for AE lock here? Then I can lock the setting on a gray tone. Or should I point the meter to a highlight in my frame and bump up the EV compensation accordingly? This was my question. All springs out from the fact that the EV always reads ‘0.0’
I believe that you are correct. You can meter and use AE lock if you are satisfied the highlights are blown. Then you can recompose and shoot. I sometimes change the white balance and meter again, and manually adjust EV steps up or down as needed. If I am being picky or having trouble I usually switch to M mode as Av and TAv can be somewhat inconsistent in my experience. I think sometimes it is because the scene changes or I don't re-frame the scene exactly.
04-24-2011, 09:56 AM   #7
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QuoteOriginally posted by aleonx3 Quote
I think Sterretji means use the normal font and size (just like what I do here).
sterretje thinks you're right
04-24-2011, 10:03 AM   #8
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Use Exposure compensation (EV Comp) in the semi auto modes to correct for your zones. Though, if you are using Zone, I don't know why you would want to use any of the Auto Exposure modes.



04-24-2011, 11:00 AM   #9
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Thanks all for the input. Since I am new to this world, I am just making sure what I am thinking is right from all of you experts. I am lucky I found this forum full of invaluable experts.

Font size was not deliberate, I originally typed my questions in MS Word and kept them all ready when I copy pasted it in, the fonts took its own decision. Apologies for that.

cheers
04-26-2011, 03:13 AM   #10
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QuoteOriginally posted by JeffJS Quote
.....Though, if you are using Zone, I don't know why you would want to use any of the Auto Exposure modes.

Hi Jeff, your statement once again leaves me in a confused state. If that is the case, what is the normal practice?
What will pro in the profession do - do they just take a metering coming out of the camera (even if it was a matrix metering or is it that a default metering which we can't set while in an auto mode)?
Just for me to learn - how do you approach a scene in auto mode - will you just bump up or down the EV comp after you take a first trial shot and look at it in the monitor, maybe with histogram?
04-26-2011, 03:42 AM   #11
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The Ev compensation button simply biases the in camera meter one way or the other. In any mode.

If you don't agree with the in camera meter, or for whatever purposes, you want the exposure to be less exposed or more exposed than the computer thinks, then use the EV button to effectively change the centre point of the meter.

for example, to manually bracket a series of shots, one could set up an exposure (say F/4 1/50th @ ISO 100) then take shots usine the EV button to bias the meter above and below that exposure without changing the other settings.

hope this example helps.
04-26-2011, 04:13 AM   #12
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Sany,
If you are really talking zones and spot metering and checking for zone placement, you are talking old time Zone System use as in Ansel Adams (and many others). This world requires different thought patterns and the use of Manual controls (including ISO, Shutter and Aperture). Once you start tpo talk about AV, TV, TAV, P, Green modes, you are letting the camera make the final decision for you (under your thoughtful control). In camera spot metering can be used for Zone System thought, but you'd be better served with a seperate spot meter rather than the built in one. Center Weighted metering averages several spots in one scene with a bias towards the central area. Matrix Metering uses a wider array of spots and tries to balance the exposure over the entire frame. All metering methods try to measure to create a "neutral grey" area. The only concession that the "advanced" metering methods make towards the thought process involved in the Zone System is through the exposure compensation adjustments. That adjustment effectively allows you to move your measured zone 5 (neutral grey) up (+) or down (-).
04-26-2011, 06:42 AM   #13
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QuoteOriginally posted by sany Quote
how do you approach a scene in auto mode - will you just bump up or down the EV comp after you take a first trial shot and look at it in the monitor, maybe with histogram?
Yes.

And, when you shoot RAW pictures in Auto mode (either Av, Tv, Tav or P) you'll have some headroom to correct them in post processing.
If at all necessary.... after all, that's why they have put in all that electronics.

Modern DSLR's are pretty much PHD (Push Here Dummy!) camera's, however, still giving you some to all control if desired.
You seem to have approached the camera from the other side than usual: Manual to Automatic.
Most people on this forum who say they are learning go from: Auto to Manual.

It seems to me that you may want to try this: put all buttons and levers in Green mode and see what happens.

I guess you are an old school camera user and you can probably teach a few tricks to most of us once you have mastered this machine, rigth?

Bert

Last edited by bymy141; 04-26-2011 at 06:49 AM.
04-26-2011, 07:20 AM - 1 Like   #14
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QuoteOriginally posted by sany Quote
Hi Jeff, your statement once again leaves me in a confused state. If that is the case, what is the normal practice?
What will pro in the profession do - do they just take a metering coming out of the camera (even if it was a matrix metering or is it that a default metering which we can't set while in an auto mode)?
Just for me to learn - how do you approach a scene in auto mode - will you just bump up or down the EV comp after you take a first trial shot and look at it in the monitor, maybe with histogram?
Before I start let me state, this is My way. There are many ways of handling exposure, mine is only one of them.

I don't remember responding to any of your other posts so I'm unsure of where 'once again' comes from. Doesn't matter though. I couldn't begin to tell you what Pros do because I am not one. However, what I do, is use Spot metering in M mode.

I decide what about a particular scene is important to me. If I'm just going out for snap shots, I'll point the camera (in M mode) at the concrete sidewalk or something of a similar shade, and hit the green button. That will get me close. If I want to change something to favor shutter speed or aperture, then hit the AE-L to lock in the exposure value (EV). That will allow me to change one (aperture or shutter speed) while the camera adjusts the other accordingly.

If there is no concrete colored object to meter off of then I'll look for something else to meter from and make the necessary adjustments. That could even be a white cloud in which case, hit the green button and make adjustments to allow in 2 more stops of light. Do so by opening the aperture more, slowing the shutter, or boosting the ISO... or some combo of the 3. I hope you can see what I'm getting at here. If you do a quick run through the exercise I outline in the above link, you will.

Now, All the semi-Auto modes do is the same thing the Green button does (for metering). In a semi auto mode, that same exposure value (EV, Remember that?) will always be used unless you tell the camera to do otherwise. Enter EV Compensation. Set it to plus two (EV +2) and whatever I told the camera was white by metering off of it, will appear white in my photo. If I am in Av, the EV Comp will adjust the shutter speed to make the adjustment. If I am in Tv, the EV Comp will adjust the Aperture (if possible). Example just for the sake of the numbers.

ISO 80, Av, f4, meters at 1 second aiming at a white object (my front door inside). Setting EV Comp to +2 will take my shutter speed to 4 seconds (each full step doubles the shutter speed). Now, that white door will be white no matter how many times I look at it. If I take my aperture to f8, the camera will meter the shutter speed at 4 seconds (two stops difference). EV Comp will take that shutter speed to 16 seconds.

Using that method requires even a basic understanding of what you are looking at. You have to learn to take your Color glasses off and understand what you are looking at in a black and white world because that is all the Camera sees. More to the point, the camera Meter assumes Everything it is evaluating is 18% (nominal) grey. You mentioned the Histogram but may notice that until now, I have not. Regardless of metering method, the Histogram is useless unless you understand what you are looking at and have some understanding of how to expose for it. You can then use the histogram basically to check your work. It will give you better information than just looking at the photo on a tiny screen at that point.

Using the different metering modes also requires some basic understanding of what they are telling you. Spot metering takes a reading of a small portion of the center of the frame, ignoring the rest. Center Weighted, gives priority to the middle of the scene but also takes into account the rest. Matrix tries to look at everything and make a best guess based on the range of readings. For someone living in auto modes, matrix is probably the safest way to go.

Clear as mud. Right?

04-26-2011, 08:08 AM   #15
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QuoteOriginally posted by JeffJS Quote
Clear as mud. Right?
Then open up three stops.
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