It's been a long while since I posted anything here (I seem to post in 'waves'), so thought today I had a good enough reason to blather about something.
Today's topic is why photo's taken with and without using AE Lock, vary so widely.
This morning, I quickly shot a photo of a fruit flan. I just needed a quick 'snap' or two to send to relatives to show our culinary experiment. However, I decided to take one photo using the AE Lock button and another without (just let the camera use its own pre-flash to meter). There were no other differences between the two shots (same position, lens, flash & settings - all done in manual mode, except for the flash, which was using ETTL II).
As you can see in the attached picture, there is a very large difference between the two shots (the lighter one uses the AE Lock). Why is this? I'll admit that both photo's used my 'Beauty Dish' as a light-modifier, but can't see how that should cause this effect. I've even seen this difference without any light modifiers - even without using flash - but still using the AE Lock and then shooting the same scene again without it.
A fellow Canon user and I have discussed this before and both leave the conversation scratching our heads (and he does a LOT of professional shooting, so you'd think he'd have an answer for us). It seems to just be one of those 'things that make you go "hmmm"...'
Equipment used: Canon 6D (hand-held), Canon 580EX II (on a stand, with 12" Beauty Dish with 'shower cap' over it). Flash and camera tied together by dedicated cable, using ETTL II.
If you have any ideas, please reply to this post - enquiring minds are dying to learn!