Canon vs Nikon flash tests

[DesmondD]

This is not an argument but rather an invitation for submissions to my blog for some tests I would like Canon users to perform . I reverse engineered Nikon's TTL-BL and would like to attempt the same with Canon flash and share my results with those who may be interested in learning the 'nuts and bolts' of canon's ETTLii flash system .
The tests I've done are all on my TTL-BL blog but if anyone is interested please let me know and I'll suggest some tests to do so we can try to work out the basics of ETTLii .

[MarkChap]

yep, I would be up for this Desmond,

Have actually been thinking that Sunday was going to be a good for just running heaps of tests that I have in my mind

[DesmondD]

yep, I would be up for this Desmond,

Have actually been thinking that Sunday was going to be a good for just running heaps of tests that I have in my mind

Sounds good - I'm not sure what other input I'll be getting so won't mention any specific tests until you are ready . In the meantime I'll update my blog with the new tests and mention any changes .

If anyone wants to see what we've got so far and confirm the results ...... it seems strange that the flash exposure decreases when focus is moved to infinity .

[DesmondD]

For the first test I asked someone to repeat the focus distance test that I did with TTL-BL .








This was the result .







What I've concluded from this so far is that Canon ETTLii almost totally drops any distance information from the lens and resorts to plain 'average gray' metering when it doesn't detect anything actually in focus .

The next test[s] we need to do is like this :

]


TTL-BL ignored the white in the foreground when it detected the subject in the background in focus .
We need some tests from the Canon flash system with a reflector in the foreground , one picture with the subject next to the reflector , one with it far behind the reflector and another one in manual focus on infinity in the second scenario to show the effect of the flash system losing the distance info ... please

[DesmondD]

Just submitted on a NZ forum :


These two interest me [ ETTLii ]




That's a little crazy ! When you focused on the white object toward the front it exposed pretty well considering the subject was highly reflective .
But when you focused on the object behind it , a black object at a greater distance it under-exposed in comparison ?
The way I see it , one option is that for the background focus the camera did not register focus confirmation or it exposes any out of focus objects as average grey regardless of where they are and in this case the white object fooled the meter - strange ?

Update : I was just informed that the second shot was done with manual focus and the camera could not detect a focus-lock , this explains how things went darker - it dropped the distance info and resorted to average metering . We'll need to see the results with the background automatically focused and confirmed by the camera .[ can a Canon do that ]

[DesmondD]

Am I asking too much ? A canon photo on focus

[DesmondD]

Ok , now we have focus lock and almost identical histograms !
that looks more like it ! Suddenly the histograms are in the same place since focus-lock was confirmed and the distance info gave a more accurate output ....





I don't see any sense in Canon dropping the distance info when there is no focus-lock . I mean if a subject

is so badly out of focus why bother with changing the equation anyway ? If it is only out by a small percentage and could be a keeper when why not use the distance info anyway for a more accurate exposure ?

[DesmondD]

ok , the first two are interesting . I see you were in spot metering mode . I don't know how that affects ETTLii , but I do know that Nikon TTL-BL can't work in spot metering mode because the rest of the pattern gets switched off .
I'm wondering why the whites got so much brighter in spot metering and whether you can actually spot meter flash with canon systems ?

If we were using a lens with distance info I could imagine the image getting brighter when you focused on the black background because of the increased distance but why is it getting so bright with spot metering unless it is actually spot metering flash off the black object ?





So why are the two pictures that have distance info under-exposing in comparison ?





The other two are more accurately showing the whites as they are .
I think perhaps spot metering may be interfering with ETTLii ?