Partial metering problem for 10D

[liuhao]

just now i shot some head shoulders type of portrait today, in outdoor, backlight situation. only use centre focus point.

i first tried to shoot some in partial metering mode. it was just that simple: let the face of subject fill the center circle of viewfinder. half press to lock the exposure and focus. re-compose or not re-compose at all then shoot. however the result turned to be very dissapointing: the face is very dark, as if the metering is not based on face of subject at all. why?

2nd i switched to evaluative metering. shot in exactly same way as above. the results are slightly better. why slightly better? theorically it should be slightly worse than above right? although overall face is still a bit dark.

finally i tried centre weighted metering. results are same as partial metering: not acceptable. but this has no surprise.

the frontlight situation does not have problem btw. only for backlighting.

does my tandy have problem in partial metering mode? i just can not figure out why. anyone tried shooting in partial metering on 10D?


this two were using partial metering. the face filled centre circle when half pressing shutter button.





this was using evaluative metering. slightly better but still dark in face:

[liuhao]

upz

[mushroom]

For backlit situations, you might want to use a fill flash. Dial in -1 stop flash exposure compensation, aperture priority, and shoot. Otherwise, you either get only the background right or the person with blown out background.

[liuhao]

Quote: Originally posted by mushroom For backlit situations, you might want to use a fill flash. Dial in -1 stop flash exposure compensation, aperture priority, and shoot. Otherwise, you either get only the background right or the person with blown out background.

yea i know a fill flash will work. but why partial metering does not? it should work right?

[mushroom]

Quote: Originally posted by liuhao yea i know a fill flash will work. but why partial metering does not? it should work right?

It does, but you must be careful in how it's used. Although Canon says the partial metering is the 9.5% in the circle, my experience is that it is somewhat larger than this circle. Also, it is a reflective metering vs best results if you can use incidental light meters, I think it can be fooled if there is a lot of ambient light (eg strong backlight shining on the camera itself).

What I normally do is to zoom is as much as possible (full frame if possible), use the AE lock (the button behind) to "sample" a few regions of the subject. Think about colours, ie if you sample a whitish colour area, the EV reading will be higher. Find a grayish area (18% grey) and use that as the exposure lock. Zoom out, then recompose before AF then taking the picture (all the way keeping AE locked).

An example (sorry couldn't find a "live" subject :



See how overexposed the backlighting is. For this shot, I partial metered the blue face of the Totoro rather than the white belly.

[liuhao]

thank you very much for ur info. it helps a lot. will try again for the same subject at the same location soon.

[Bluestrike]

Hmm...

Custom setting?

What the setting of Custom Function 4?

[mylau]

did u recompose after half-press?

[liuhao]

Quote: Originally posted by Bluestrike Hmm... Custom setting? What the setting of Custom Function 4?

by default. what is default btw?

[liuhao]

Quote: Originally posted by mylau did u recompose after half-press?

oh i didnt lock the exposure by half-pressing? will go back and check CF4. if the exposure was not locked....oops what a shame.

[Bluestrike]

Quote: Originally posted by liuhao by default. what is default btw?

by defalut, I THINK that shld be 0.

Shutter button/AE lock button

0. AF/AE lock
1. AE lock/ AF
2. AF/AE lock, no AE lock
3. AE/AF, no AE lock

I think you shld check it out lor....

[liuhao]

i just heard from someone that if CF4 is 0 (by default), half pressing will lock exposure but ONLY under evaluative metering.

for partial metering and centre weighted average metering, need to press the * explicitly to lock the exposure, regardless what CF4 settings is...

will go back test and see.

[liuhao]

did some test yesterday. i think i know the reason.

my CF4 is set to default. means halfway pressing locks the AF and AE. however, this is only designed to work in evaluative metering. under partial metering and centre weighted metering, halfway pressing will NOT lock the AE. i need to press the * to lock AE. this design is not very obvious to me.

[Shadus]

hi,

Your pic actually looks fine for partial metering. meaning, its working.

Do remember that strong background lights can overwhelm the picture *even* if it forms *only* partially of the metering system.

[Bluestrike]

Quote: Originally posted by liuhao did some test yesterday. i think i know the reason. my CF4 is set to default. means halfway pressing locks the AF and AE. however, this is only designed to work in evaluative metering. under partial metering and centre weighted metering, halfway pressing will NOT lock the AE. i need to press the * to lock AE. this design is not very obvious to me.

hehheahhaa.. so now we know what the book in the box is for right?

hehhehhee

[RCheah]

Not sure if this helps (this article for D30) ==> http://www.dlcphotography.net/ChuckT...m#anchor221746

AE lock upon focus completion? - Evaluative Metering
One-Shot AF: Yes
AI Servo AF: No

AE lock upon focus completion? - CW Avg. and Partial
One-Shot AF:No
AI Servo AF: No

[Wai]

Quote: Originally posted by liuhao did some test yesterday. i think i know the reason. my CF4 is set to default. means halfway pressing locks the AF and AE. however, this is only designed to work in evaluative metering. under partial metering and centre weighted metering, halfway pressing will NOT lock the AE. i need to press the * to lock AE. this design is not very obvious to me.

now then i know

luckily i use evaluative most of the time....