[Larne]

I'm guessing that there must be a thread about this but I couldn't find it so here goes...

Whenever I shoot with flash (whether the on-board one or my 430EX) I always end up with an image that is heavily under-exposed. Put it through Adobe RAW and it comes up okay but at a trade-off of massive amounts of noise. Going from the settings when I click 'Auto' on Adobe RAW the image is under-exposed by 1.5 stops.

If I switch everything to manual (camera and flash) then I can get pictures that are well exposed (with a bit of trial and error) but TTL more just doesn't seem to work for me.

What am I doing wrong? Any suggestions?

Camera is generally set to evaluative metering - perhaps I should be using a different option there?

[brian wright22]

Larne,I had a problem getting my head around the Canon flash exposure modes with my 350D.

I have copied a post I sent in January about the same problem I think you are having.
Regards Brian


Hi Ray ,I had a bit of a problem recently with my Canon 350D & 430ex flash.

I had under exposed portrait shots when taking some shots with either the 430ex attached or using the on board flash.


With some help from Pixalo members and finding a faulty switch on the camera body this led me to fully check how the Canon E-TTL11 works.
Whatever the mode switch is selected to, ie Av,Tv,P or Manual (forget the fully auto) at this stage,the flash system is controlled fully automatically. This is with the external 430ex attached or the internal flash popped up, and is something I did not realise, when in the Manual Mode!! you still get auto flash control.
Whatever you set the other parameters to, when the camera is set to any of its priorities settings the camera exposure tries to expose the background correctly and the flash power is automatically adjusted to correctly expose the foreground. In the case of a portrait you will get a nice exposure and the background will be exposed resonably. On an indoor shot this will give ,probably an under exposed background but at least it won't be pitch black. It depends what shutter speed you choose.
If you look on the lcd of the external flash gun there should be an range of distance shown that the flash will cover when you partly depress the shutter release button prior to taking the picture.
I hope this helps.
Brian.

[Tofufah]

Hi Larne, I had the same experience. I compensate by increasing the EV value on the flash unit instead of changing my camera settings. Maybe its not the proper way but it works for me most of the time.

[silkstone]

Unless you want fill-in flash with ambient light as the main source, set the camera to Manual, the shutter speed to anything up to the Xsync speed, the aperture to a suitable value for DoF etc, and the gun to ETTL. The flash exposure will be automatic. If the shots are still dark, the gun may not have enough power, so either use a larger aperture or a higher ISO. (That's quite common with bounce flash.)

If there's a bright or reflective object in the frame, that can confuse the ETTL metering, so best experiment on something matt to see if it all works as expected.

Let's know how you get on.

[Larne]

Originally Posted by silkstone

If there's a bright or reflective object in the frame, that can confuse the ETTL metering, so best experiment on something matt to see if it all works as expected.

Looking at the pictures I think this must be the issue. Mostly these are pictures at events, in crowded rooms, and there always seems to be someone wearing a white top close to me!

I have been experimenting with using both camera and flash on manual (on the recommendation of my brother who is a wedding photographer) and that works very well but it is a pain having to remember to change the flash each time the range changes (especially as the buttons are very fiddly).

What I was hoping for was a magic "oh you just need to set this option" but I guess I'll just keep practising

[Larne]

I found the following as part of a discussion thread on the web yesterday. I haven't tried most of it out yet but it ties in 100% with my experience and clearly shows that it is not just me having problems with Canon and flash! The full thread can be found here. I realise that I am providing more ammunition to the Nikon boys but it's better to admit there is a 'feature' and know how to work with it than to just suffer.

OK....here is the basic 5 minute guide to Canon Flash. I am a wedding photographer and use these settings every weekend with excellent results on a 5D and a 1DII.

If you simply remember that at zero flash compensation the camera tries to match flash exposure with ambient exposure you may remember these rules.

FILL FLASH

Outdoors in daylight for fill - with no adjustment the flash will be too bright, causing unnaturally bright fill as it tries to match the ambient. Hence here are the daytime rules:

Set Camera to AV with your preferred aperture.
For fill with a shaded subject: -1.5 to -2.0 stops
For fill with a bright sun subject: 0 to +1 stop (you need to overpower that full sun and its shadows.

PRIMARY FLASH

Use M mode for flash in low light, otherwise in AV your shutter speed will be much too long. I use say 1/60 and then adjust my aperture for the requirements of the subject.

Indoors with good levels of ambient light I use zero compensation. Once light levels fall I add one stop of compensation as the flash becomes the primary light.

Important - these rules for primary flash are all for an average subject. If you are shooting someone in a black suit against a dark background then naturally you override and dial in minus 1 stop from your selected stop. If you are shooting someone in a white dress etc you add in one stop. This is just like normal metering - your camera is dumb and assumes everything is grey - you need to tell it to change using your flash compensation.

Finally, shoot everything in RAW for best results. That way you can rescue a poor shot if you need to.

Best regards,

Antony