Multi-spot metering for AV-mode

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Please, describe the enhancement of feature requested below:

Useful when there are big different (> 2 stops) in brightness among some areas 
of the image.

Do multi-spot metering for 3 areas as below:
1. Enable multi-spot metering option and choose 3 metering spots (3 areas)
2. Set camera in AV-Mode and spot metering
3. Choose f8 to take photo in AV mode
4. Point the camera at the first area for light metering and then press AE-Lock 
(*) to start multi-spot metering and the camera remembers this value (f8, 1/250)
5. Light metering for the second and the third areas and also press AE-Lock (*) 
for the camera to remember these values (f8, 1/60 and f8, 1/15)
6. Use the Jump button to delete the light metering values if wrong and light 
meter another area to get new value
7. After getting these all 3 values, the camera will calculate automatically to 
give out the average value of shutter speed (f8, 1/60)
8. Change to Manual mode and use calculated value above to take photo

Need to add to camera:
- Multi-spot metering enable / disable
- number of light metering spots
- ability to remember light metered values
- ability to calculate average light metered values (shutter speed)

Regards,

Original issue reported on code.google.com by phathth1...@gmail.com on 22 Jun 2011 at 5:30

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interesting, though i'm not sure we can easily implement it in current hack.
and doesn't it a bit like the calculator proposed by Edu ? could those two be 
merged in one feature ?

the easier way to implement it perhaps would be:
use some button to reset the calculator, then AE-Lock at first point, then 
second, etc...
so whatever number of spots you AE-Lock, it will show you the average of all 
spots ? when you want to start again, you will use the reset button again. 
would it do what you need ?

Original comment by fired...@gmail.com on 22 Jun 2011 at 12:05

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Did you mean DOF calculator by Edu? In that case, I think it's different.

Your suggestions sound good :D. We should also have an option to enable / 
disable this feature in case we want to go back for AE lock normal use.

Regards,

Original comment by phathth1...@gmail.com on 23 Jun 2011 at 4:18

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Sorry, but I do not see how this could be useful...

Original comment by eduardo....@gmail.com on 18 Jul 2011 at 6:32

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Usefulness: Read a nice web article below about multi-spot metering using Canon 
1DMIII.

http://www.learn.usa.canon.com/resources/articles/2011/multispot_metering_markii
i_cameras_article.htmlp

Don't know how you would attempt to code such a thing in 400plus though.  It's 
possible I guess.  Would certainly be a cool feature.

Original comment by mike.guf...@gmail.com on 18 Jul 2011 at 4:29

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More info from a Fred Miranda forum:

http://www.fredmiranda.com/forum/topic/130059

Original comment by mike.guf...@gmail.com on 18 Jul 2011 at 4:46

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Ok, now I see it; thanks!

Original comment by eduardo....@gmail.com on 19 Jul 2011 at 5:34

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Most of the work we did for AutoISO can be used for this feature, too; so we 
are now one step closer.

I am thinking we could try to expand it to do thinks like ETTR (pick the 
brightest measure and and +2EV) or AEB (pick the darkest and brightest measure 
and calculate the exposures needed to capture the full dynamic range).

Original comment by eduardo....@gmail.com on 31 Aug 2011 at 9:01

• Changed state: Accepted

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I was actually thinking about ETTR recently, but couldn't imagine how that 
could be programmed. You would have to know the exposure value that just clips 
the highlights. If this feature were at all possible, then the camera should be 
forced into using RAW mode.

Original comment by colinban...@gmail.com on 1 Sep 2011 at 11:27

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Wow, if you were able to pull off multi-spot metering, I think it would take 
the rank of my most favorite feature of 400plus, whereas the 'presets' are at 
the top of my list right now. This would be an awesome addition to an already 
outstanding list of camera features!

Original comment by mike.guf...@gmail.com on 2 Sep 2011 at 12:35

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I really wonder how useful this feature would be. Multi-spot metering was first 
introduced on the Canon T90 (I think) - the last great non-autofocus camera. 
Back then, evaluative metering on Canons was non-existent. The feature was 
carried forward on higher-end EOS cameras, even after evaluative metering was 
introduced. In the film era, multi-spot metering was very important for a few 
reasons:
1) Compared to a memory card, film was expensive, and came in 24 and 36-shot 
rolls.
2) Slide film had small exposure latitude, so you had to nail the exposure.
3) You couldn't see whether you screwed up until the film was processed 
sometime later.

I used multi-spot metering a fair bit on my EOS 3, especially when using slide 
film. Much less so with print film.

Now we're in the digital era, we can check exposure immediately after the shot. 
For a digital sensor, the histogram is the best way to check exposure. If the 
exposure is off, we adjust appropriately with some compensation.

I'm certainly not against the feature...just wanted to add some perspective. On 
the other hand, if we could pull off exposure-to-the-right (ETTR), that would 
be something else.

Original comment by colinban...@gmail.com on 2 Sep 2011 at 11:14

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Original comment by eduardo....@gmail.com on 22 Mar 2012 at 10:40

• Added labels: Milestone-M2

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* Activation:

Storing the different measures seems easy; but I do not see a method to modify, 
on-the-fly, the exposure time (or the shutter speed) decided by the camera. So 
we must have an explicit activation method for the "shooting phase", that will 
invariably set the camera to M mode; on the other hand, this also means that we 
can have the "measuring phase" always active, without further interferences.

* Store a point:

We can probably store as many points as we need (I guess it's safe to say that 
sixteen million points are enough for anybody). We will probably not be able to 
use the AE_LOCK button for this task, however; but fortunately we have SET and 
DOWN available while looking at the viewfinder. 

* Delete last point:

Deleting the last measurement (but only the last one, just after a point has 
been stored) seems easy, too; and the TRASH button looks like a good candidate 
for this: we can just add it to the list of options for the TRASH / JUMP 
buttons and let the user decide.

* User interface

So far, we have the "measuring phase" cleared:
- Set the camera to P / Tv / Av mode.
- Look through the viewfinder, take a measurement, and press the SET button.
- Camera records current point, makes a beep, and displays the number of stored 
points using the burst counter (or "9" if there are more than nine values 
stored).
- If last point was wrong, the user can press the TRASH / JUMP button 
(configurable) to delete it.

And now comes the tricky part, for the "shooting phase":
- Option 1: Look through the viewfinder, and hold the DOWN button pressed down; 
camera enters M mode (with the proper exposure time and aperture) while the 
button is kept down, and will go back to P / Tv / Av when it is released. So 
the user has to press the shutter release button while holding the DOWN button 
down. This option has to be experimented, because I do not know whether is 
technically possible.
- Option 1b: Instead of holding down the DOWN button, perhaps we could release 
the shutter directly from this button; has to be investigated, too.
- Option 2: The DOWN button just sets the camera to M mode with the proper 
parameters; and after the first shot, the camera goes back to the previous mode 
on its own. In this case, using DOWN to "write down" a measure and SET to "set" 
camera to M mode seems more reasonable.
- Option 3: ???

Original comment by eduardo....@gmail.com on 31 Jan 2013 at 11:53

• Changed state: Started

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This issue was closed by revision r1690.

Original comment by eduardo....@gmail.com on 2 Feb 2013 at 9:46

• Changed state: Fixed

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Good Job !

Original comment by fired...@gmail.com on 4 Feb 2013 at 9:25

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I agree... Great job on this!  Very cool feature.

Original comment by mike.guf...@gmail.com on 6 Feb 2013 at 3:12