Edu-ma-cate me on flash

SmellyTofu

To put it bluntly.. so far, ETTL II on my 580EX suck like the proverbial... the biggest problem is using the 17-40 with the 5D and there's hot spots and what not (talking bouncing the light only)... I've got a "fake" Gary Fong lightsphere and it doesn't seem to help all that much except soften it. I tried it on manual mode (1:1) and it seems to really put on the charge and make a really big flash... comes out alright but haven't drive it in a high ceiling situation to really trust it... annnnyway....

What am I doing wrong? What can I do to make it look so nice like the Nikon SB800's that seem to be so deadly great every single time??

shutterbug

I don't understand what your problem is....so you're bouncing and you get hotspots?  That's pretty impossible unless your ceiling is very low and shiny....

Most of the time ETTL will underexpose not over...

And if you use manual flash, you should be able to do whatever SB800 can do.  Have you read a website that explained how ETTL works?  If not, I might be able to dig it up for you...

SmellyTofu

Yeah, I was working on the weekend... inside a chapel and it had relative high ceiling in flat white paint.. maybe 3.5-4 m high... but on 17mm (coz I had no room), the flash pointing up, all I see is a really bright spot on the ceiling where I've pointed the flash and the rest fairly dark.. I'll post a pic here tonight when I get home... I read a bit about ETTL but it just seems like it's the best setting to have but from my results, it doesn't appear that way.

lerico

Is there any high reflection object in the scene? mirror or chrome object usually throw off ETTL.

Since you are at 17mm full frame, is the ceiling in the photo too? and your flash is pointed up to the ceiling? Maybe that's why. ETTL sees the ceiling in the photo, and it thinks that that part is properly exposed, so it turns down the output.

ETTL always avoid ANY blown out highlights. That's why many people say it underexpose.

You should try using center average or spot metering, zoom-in to your subject, press the * button for flash exposure lock, then take your picture. In that case, under the same setup, you should see proper exposure for your subject (or whatever in your spot circle when you zoomed in and pressed FEL), and a blown out ceiling.

However, you should try to avoid blown out ceiling anyway. So in that case, I might avoid using lightsphere and use a home-made softbox/reflector that doesn't require a ceiling bounce.

Anyway... to conclude, from my experience, ANY highly reflective object will thrown off ETTL. Becuase ETTL always avoid highlight blown out. When that is the case, one must use either spot metering -> zoom in -> FEL method or set manual flash exposure.

SmellyTofu

Yeah, the ceiling was in part of the shot... maybe that's what I need to avoid.... but quite hard with 17mm...  my fd suggested I use spot and then FEL.. never really used that one b4.. but I'll see how I go with it.

shutterbug

if you're in a rush...shoot a frame then dial in flash compensation...

it's better to overexpose a bit than underexpose

SmellyTofu

OK.. here's the shots.. pls don't worry about the actual composition of it as these are off-shots.

shutterbug

The pics seem normal to the settings you have, the bright spot is normal because that's where your flash is aiming, and the dark area is normal too because the flash falls off and the place seems to be pretty dark.

There are many way to fix this situation though.

lerico

Definitely it is the white ceiling, light brown wall WITH dark dressed people and dark carpet that thrown off ETTL.

echo

你第二張相既主體曝光都係正確. 至於第一張就 UNDER 左,  ETTL 想準最好就用 FEL LOCK, 問題係FEL LOCK 又要PRE FLASH 又要構圖, 好多野都係一閃即逝. 對於移動物體作用不大.

兩張相就算用 FEL lock 都係冇得救. 加大閃燈 OUTPUT, 背景係會光左, 但主體 OVER, 你點揀?

而且 17MM + 5D, 根本580 唔可以 COVER 到 !! 直打都未得, 更何況 BOUNCE???

想要背景光D? 用機頂燈係呢D 場合打  bounce? 唔係唔得, 不過好難打得靚. 長方形場地, 後面夠光前面爆!

SB800 係好野架, 你用咩 MODE??

由550 時代已經投訴 CANON D FLASH 唔得, 580 話配合原廠鏡會自動配合距離去計算OUTPUT. 不過 " BOUNCE" 除外.