Exposure Lock, I don´t get it

[Karmaschinken]

Hello girls and guys, I am trying to grasp the "Expo Lock"-feature. I unterstand how the whole thing works, but I cannot find out how to dial an exposure compensation.

How do you use that? Switch it off, put all parameters to a desired exposure, then switch it on, so the exposure is locked? Okay, even though this seems quite complicated to me, what if the lighting situation changes? How do I compensate on the fly then?

Thanks alot for your help!

[Audionut]

Exposure lock only works in full manual mode.  Canon does not have exposure compensation in manual mode.  I think the 1D series does, but whatever!

Expo lock does what it's says it does.  It locks in the exposure and allows you to adjust Av/Tv/ISO with a net result of the same exposure.

How do you use that? Switch it off, put all parameters to a desired exposure, then switch it on, so the exposure is locked?

Correct.

what if the lighting situation changes? How do I compensate on the fly then?

Disable Expo lock and adjust settings.

If your lighting is constantly changing, I would advise against locking the exposure.

[Karmaschinken]

Thanks a lot for your answer. So it is meant to be like that. I think it would be nice to enable and disable expo lock on the fly then, it would make it more flexible. By the way, is there a way to overcome the ISO limits too? When doing stage photography I would like to make my 5D2 to go up to 12800, too.

Thanks! Martin

[a1ex]

You should never want to go above ISO 1600 on a 5D2.

Here's why: http://www.guillermoluijk.com/article/isos5dmkii/index.htm

[Karmaschinken]

I don´t really understand the article, probably because the Google-translation from Spanish is not very good. However, I can´t believe that ISO 12800 is a pushed ISO 1600 only, is this is what is said there? Pushing a ISO1600 RAW won´t result in the same quality as a RAW shot at 12800, no?

[Audionut]

Take 2 shots, 1 at ISO 1600 and another at ISO 12800.
Boost the ISO 1600 shot +3EV in PP and compare.

According to the read noise figures from DxO, there should be a very marginal improvement in ISO 3200 vs ISO 1600 boosted +1EV.
http://www.sensorgen.info/CanonEOS_5D_MkII.html