need help - Underexposure with ceiling bounce?

[sgogula]

I was following Curtis N steps here to bounce the flash for the ceiling but all my pictures are coming out underexposed.

here are my settings:

ISO 400, 1/60 , f4
Zoom: around 20-30mm
distance to the subject: 6 ft
subject to background distance: around 3 ft
ceiling ht: 9ft
Flash: 430 EX II
The only step i missed from his tutorial is : >Zooming the flash head to its widest setting will illuminate a larger area of the ceiling.

Is this the reason for underexposed pictures?. I shall post the pictures when i get back home in the evening.

I had to up the FEC to + 1 1/3 to get the properly exposed picture, Is this common?

[tjongkristian]

It is actually quite common. When you bounced flash and got an underexposed picture, you compensate it with the FEC. "If the FCL lights, take a look at your histogram to determine if the shot is properly exposed. If the image is too dark, dial in some +FEC (flash exposure compensation). The need for +FEC is normal with bounced flash and E-TTL flash metering. After adjusting the FEC, test, chimp, and adjust again as needed. More info on how to read a histogram here". Quotation from Curtis tutorial.

[Wilt]

Originally Posted by sgogula

I was following Curtis N steps here to bounce the flash for the ceiling but all my pictures are coming out underexposed.

here are my settings:

ISO 400, 1/60 , f4
Zoom: around 20-30mm
distance to the subject: 6 ft
subject to background distance: around 3 ft
ceiling ht: 9ft
Flash: 430 EX II
The only step i missed from his tutorial is : >Zooming the flash head to its widest setting will illuminate a larger area of the ceiling.

Is this the reason for underexposed pictures?. I shall post the pictures when i get back home in the evening.

I had to up the FEC to + 1 1/3 to get the properly exposed picture, Is this common?

In fact, with Canon ETTL, over many years it has been a chronic complaint that the flashmetering underexposes, and many of us dial in FEC +1EV even for direct flash, not merely for bounce flash!

[40Dude6aedyk]

Doesn't it depend on what the camera sees when it does eTTL?

I see that the zoom is set to 20-30 mm. My understanding is that the flash head may automatically zoom to 50 mm whenever the head angle is not 0 degrees. Also for that zoom range, doesn't one have to flip out the wide-angle diffuser? So there could be a problem with reading the flash manual and using it. [And you unzoom to the widest setting; you don't zoom to the widest setting ]

Secondly, the metering mode of camera can have an affect. If the metering is only in the center spot, then there could be less light around the outside of the image. This would be exacerbated by the wide angle of the lens. So there could be a problem with reading the camera manual and using it.

[Curtis N]

OP:

Don't worry about that "zoom to the widest setting" thing, at least for now. It's not the cause of your problems.

Underexposed flash photos are generally related to two causes:
Possible cause #1: Your flash didn't have enough power, given the circumstances. With the settings and conditions you described, I would guess that the 430EX should have enough power. But the way to find out is to look for the flash confirmation light on your flash unit immediately after taking a shot. If it lights up, that means the flash had enough power to do what it was trying to do.

Possible cause #2: Metering issues. Usually E-TTL requires some +FEC when flash is the only significant light source. That's just how it's calibrated. Also, white or highly reflective areas (white clothing, glass, shiny metal, etc.) can cause it to underexpose, requiring more +FEC to compensate.

I suggest giving things another try. Check the flash confirmation light, and check for reflections that may be messing up the E-TTL metering.

[sgogula]

Thanks Curtis for your advise.

I shall look for flash confirmation light today. I would also make sure there wont be any metal or glass within the frame.

[Benji]

One thing the "bounce the flash off the ceiling for great results" guys forget to tell you (or don't know) is first of all most of the time the light bounced off the ceiling will give the subject the dreaded "raccoon eyes" and you lose A BUNCH of light doing it.

You stated you are six feet away from the subject, and the ceiling is nine feet up. Assuming you are about six feet tall and you aim the flash at the ceiling it will travel three feet up, bounce and spread out (thereby losing some of it power) then it must travel back down three feet from the ceiling AND go out six feet to where the subject is standing. So in other words the light is traveling a total of 12 feet in order to illuminate a subject that is six feet away, PLUS it has been bounced off of a (hopefully) white ceiling. Pure white will reflect about 85% of the light striking it. So by the time you factor in losing 15% of the light due to the white ceiling, an additional 15 to 20% (or more) due to light spread, then add in an additional six feet of travel, it is no wonder you must shoot at ISO 3200 to get a properly exposed image.

I suggest using the little pop up card that Canon supplies inside the flash unit.

Benji

[SDavis Photo]

Originally Posted by Wilt

In fact, with Canon ETTL, over many years it has been a chronic complaint that the flashmetering underexposes, and many of us dial in FEC +1EV even for direct flash, not merely for bounce flash!

I always start with +1E when using my flash. Seems it is always off that much both in direct or bounce flash.

[sgogula]

Originally Posted by Benji

One thing the "bounce the flash off the ceiling for great results" guys forget to tell you (or don't know) is first of all most of the time the light bounced off the ceiling will give the subject the dreaded "raccoon eyes" and you lose A BUNCH of light doing it.

You stated you are six feet away from the subject, and the ceiling is nine feet up. Assuming you are about six feet tall and you aim the flash at the ceiling it will travel three feet up, bounce and spread out (thereby losing some of it power) then it must travel back down three feet from the ceiling AND go out six feet to where the subject is standing. So in other words the light is traveling a total of 12 feet in order to illuminate a subject that is six feet away, PLUS it has been bounced off of a (hopefully) white ceiling. Pure white will reflect about 85% of the light striking it. So by the time you factor in losing 15% of the light due to the white ceiling, an additional 15 to 20% (or more) due to light spread, then add in an additional six feet of travel, it is no wonder you must shoot at ISO 3200 to get a properly exposed image.

I suggest using the little pop up card that Canon supplies inside the flash unit.

Benji

Thanks Benji. Very good technical information. i will try with pop up card also tonight and see which one will give pleasing results to my eyes.