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I'm quite an amateur in photography and have to take several photos from similar objects in the same place during the day. So, I use Canon utilities' software libraries to write a C# program, and do this with my computer.

I have a Canon EOS 1100D and know how to set the properties in camera manual mode with my computer, but I want to adjust all metering parameters that would change in different light situations in my program dynamically.

How can I get and set all the metering parameters? I can set ISO and focus in Auto mode, but I need all the camera metering parameters.

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  • \$\begingroup\$ Sorry, but you have to elaborate on what you want to accomplish here. Do you want to use auto or manual mode? In auto you have almost zero control of the settings, tethered or not. \$\endgroup\$
    – Hugo
    Commented Jan 23, 2014 at 8:11
  • \$\begingroup\$ I use tethering mode and control the camera with my program(computer); so, have to set the camera on manual mode. But I need to get meterig prarameters from the camera. \$\endgroup\$
    – Zhr Saghaie
    Commented Jan 23, 2014 at 8:14
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    \$\begingroup\$ It is still really unclear what you are asking. I'm both a photographer and a developer, but I have no idea what you are trying to accomplish here. You say you know how to adjust properties in manual mode but then say you want to know how to adjust parameters. Then you talk about what you can change in auto. What are you actually trying to accomplish and what specific parameters do you need to adjust? \$\endgroup\$
    – AJ Henderson ♦
    Commented Jan 23, 2014 at 15:26
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    \$\begingroup\$ Ahhh. So you don't want to adjust the metering, you want to read it, and then manually set the exposure parameters (shutter speed, aperture, ISO) once you know that. \$\endgroup\$
    – mattdm
    Commented Jan 23, 2014 at 17:22
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    \$\begingroup\$ That said, in my opinion, that puts this squarely off-topic as a programming question. \$\endgroup\$
    – mattdm
    Commented Jan 23, 2014 at 18:01

4 Answers 4

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I don't have access to Canon's SDK to know what's possible or not, but thought I'd point out you can also use libgphoto to interact with a tethered camera. It allows you to read and write a variety of camera settings. On the 1100D this includes ISO, aperture and shutter speed (and much more) so should be enough.

You can even script this using Gphoto2 (which obviously runs on libgphoto), a command-line utility that lets you get/set basic info like this, without having to call C code directly from the library.

Most likely this will not work at the same time as the EOS Utility or in parallel with Canon's software library, so it's one or the other.

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Your question is programming-related, so I can only provide one link for you if you cannot find out any other ways. (And this answer is photography related BTW, unlike my comment).

There is a hack called CHDK which allows much finer control over your camera, and most probably you can either tether out all the internal configuration and measurement values or you could ask those folks about this.

Have a look, maybe try that, and if you did so, please let us know if that worked out (I am an ex-Canon fan, currently on Nikons, but really miss CHDK :-) ).

EDIT: another way as a workaround: make a test photo, download it, and check out the EXIF data, there are many parameters saved there.

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API library does not give this info ? strange for an official API.

another way, if you cannot use a method from the API, is to take a picture and read the info from the EXIF. Picture could be take with the lower resolution/quality (for fast transfert/treatment )

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To add a little more details than the previous answers: on my Canon Rebel XSi, the photos I take have a MeasuredEV and MeasuredEV2 tag in the EXIF data. Unfortunately I haven't been able to find a way to get this information before taking a photo, but for my purposes (taking a time-lapse) using the measured value from the last photo taken is acceptable.

(I also don't know what the difference is between the two tags, other than one seems to give a more precise value while the other seems to be rounded off)

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