Flash exposure on manual modes

[ben_cops]

All

Apologies in advance as this may be a stupid question.

I have a 20d and a 430ex. When I have the camera in one of the auto modes (eg

portrait) and the flash fires, the shutter speed is fast and the entire scene

is exposed for the flash. If I take the same shot in one of the manual modes

(eg AP) the shutter is open long enough to expose the background normally, then

the flash fires to expose the foreground. Whilst this sounds good on paper I

think the results are usually terrible (indoors portraits with the white

balance of the background all over the place, blurred backgrounds, etc).

 

My question is how do I make the flash fire in a similar way to auto mode in a

manual mode. Usually I just want to set the aperture, ISO and shoot in RAW.

 

Thanks in advance!

 

Ben

[colinsouthern]

Hi Ben,

 

We discussed this in some depth just recently - point your browser at http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=00Mig9

 

You'll also find references to the EOS Flash Bible (basically a free web book on the topic) on the photonotes.org site.

 

Hope this helps,

 

Cheers,

 

Colin

[robin_sibson1]

Ben, I think you are talking about Basic Modes and Creative Modes. Manual Mode (M) is just one of the creative modes. It's easy to use flash in Program (P) Mode, where it will give main illumination with a sensible shutter speed in dark conditions and fill-in flash in light conditions. In M mode you are in control of the background exposure and the flash will expose correctly (we hope) for the foreground, and this is also quite easy to use. It's in Av and Tv modes that unexpected behaviour can happen - it shouldn't be unexpected because the system does what it claims to do, it's just that what it claims to do is not necessarily what you want.

[picturesque]

Robin is right--use Program. Or true Manual mode, where you set both the shutter speed and aperture for the effect you want.

[KenPapai]

Listed for the 350th time this year:

 

http://www.photonotes.org/articles/eos-flash/

 

The EOS Flash Bible.

 

"The invention and subsequent automation and miniaturization of electronic flash revolutionized photography. If you?re a photographer you?re no longer tied to available light. A reliable and portable light source is immediately at your disposal if you choose.

 

"But flash photography has always been a very difficult technique to master on any camera system. It?s easy to take a snapshot of your friends in a restaurant and get that hideously blown-out rabbit-in-the-headlights look from built-in automatic flash. But using electronic flash well - achieving natural-looking images - is quite tricky..."

[ben_cops]

"Listed for the 350th time this year:" - that just goes to show how poor the experience is with speedlites on non-auto. Personally I simply didn't know how to search for the answer on google!

 

Anyway thanks all for your responses. In my travels on this forum I came across the CF "flash sync speed in Av" - doesn't setting this to 250 (fixed) do what I want? Having shot a couple of photos in the dark... it appears to?

 

Maybe I should spend some time trying to get to grips with full manual (which I had previously discounted as just for the most special of edge cases - I use bulb mode more than manual).

[picturesque]

You can set that custom function so the shutter in AV is always set to the flash sync speed--if you don't care about the background rendition. In some indoor, flash situations, you will end up with correctly exposed flashed subjects but black backgrounds (with the medium to medium-high ISOs). Program will at least set an aperture (wide-ish) and shutter speed (1/60th or 1/125th in most cases) that will allow some ambient light into the picture, thereby allowing more background to show without it being rendered completely or almost black. It seems you don't mind the black/dark backgrounds. Most people do.

 

Most people think Canon's decisions regarding how AV and TV work with flash are faulty (along with ETTL in general, actually), and some even get emotional about it. Unfortunately, whether you think they are or not--that is the way they work. In my opinion, Canon decided that Program mode is the mode to use if you want a one-setting, all purpose camera mode. Even with the flash on, you can still shift aperture somewhat.

 

By the way, wouldn't it be easier to just use manual camera mode and set the aperture to whatever you desire and the shutter speed to 1/250th, if you don't care about background rendition?

[KenPapai]

I admit I still suck using my 580EX with my EOS cameras. I am fairly good shooting in Manual mode on the EOS dial, but my fill flash is extreemly wanting. I need to practice much more. My fill images are either blown in the subject area or contrast is way minimal.

 

I stick to M when shootnig indoors.

[ben_cops]

Nadine - good point about setting M with shutter speed at 250.

 

To be brutally honest I didn't pay any attention to P mode when reading the manual. Trying it out with the flash it seems it pins the aperture at 2.8. My MO at the moment is to stick it on Av and pick the aperture and ISO I want - clearly this aint gonna work with flash.

 

"It seems you don't mind the black/dark backgrounds. Most people do.

"; what I want is whatever the hell its doing in the auto modes - apparently its evaluating whats the conditions are like and picking a foreground and background exposure that will be hand holdable.

 

I just think... canon did such a good job with the flash in the auto modes - with that bouncing the photos look like they were shot in full daylight. I just wish I could have that AND pick the aperture AND have it expose the photo correctly without me frantically spinning a wheel whilst I miss a shot trying to make some green numerals stop flashing in the viewfinder!

[picturesque]

So what is wrong with continuing to use Portrait mode for whatever you want to photograph? Those modes are optimized for the activity named--so Portrait probably picks a wide-ish aperture and handholdable shutter speeds. Sports mode picks a fast shutter speed, etc.

[dave_holland]

"what is wrong with portrait mode?"

 

Well, nothing, if you are happy to have your camera do your thinking for you. But it's a lot easier than you may think, and if you make that jump you will expand your horizon of understanding.

 

Dave

[ben_cops]

My main problem with portrait mode is lack of control over ISO and not being able to use RAW. Other than that its perfect for flash photography of people indoors - the results are really good.

 

Somebody who shoots with flash on full manual - what's your "workflow"? What do you think when you're about to take a shot, what do you adjust when you've got your eye to the viewfinder and you're lining up the shot?

[ben_cops]

Anyway thanks all for your detailed responses and opinions.

[picturesque]

I assume you mean full manual camera mode, not full manual flash. I shoot weddings, and I'm always looking to balance flash with ambient, and when flash is dominant, in making my flash pictures look nicer than just direct flash (by bouncing and modifying the flash). I use camera manual mode most of the time, with a small percentage of shots in AV or TV outside. When inside, I am always using manual camera mode unless it is during a ceremony with no flash. When using the automated modes like AV or TV with flash, I usually minus compensate the ambient and use evaluative flash metering (custom function 14). I also use center weighted ambient metering, not evaluative. I minus compensate the ambient to preserve highlights and to underexpose the background (slightly or a lot) to accommodate the added light from the flash. Try testing these combinations--you might find an easily manageable method that will get you what you want. The flash is separately compensated according to subject value and whether there is backlighting, etc.

[picturesque]

Also, spend some time reading the article at planetneil.com, under techniques, about using on-camera flash. It is easy to read and understand and gives a lot of good information re using flash.

[ben_cops]

Thanks Nadine, will do.