Canon Speedlite 550EX and 20D flash help

Hi, is anyone using this combination? I'm having problems getting the camera in Manual mode and the flash in ettl mode to compensate on the light meter. Does that make sense? Like in full auto mode the camera recognises the flash is on, and adjusts the shutter/aperture accordingly. Am I missing something?

In manual mode, the light meter only measures ambient light. If you're not relying on ambient light, ignore it. Let the flash and the E-TTL system take care of the flash metering.

Thanks curtis, i appreciate your reply.

In manual mode on the camera, how do i just let it use ettl on the flash? I mean, the shutter or aperture does not change regardless of if the flash is on.

I'm sorry if this is a really dumb question...

You're missing something ETTL-II doesn't use the cameras light meter except for situations where the light is quite bright (outdoors for example). For typical indoor flash photography ETTL-II and the cameras light meter are totally separate things that do separate jobs.

You use the cameras light meter to get the background (or ambient exposure) the way you want. Ettl-II looks after getting the subject exposure correct. So, you can have black backgrounds with a properly exposed subject or brighter backgrounds with a properly exposed subject ... it's all in your control by adjusting aperture, shutterspeed and ISO.

An example of a typical situation might be that you can set your camera for indoor flash to f/16, 1/200s, ISO 100 and the background may fade to black ... but the subject exposed by ETTL-II will be fine. For the same scene, setting your camera to f/2.8, 1/100s and ISO 400 and the background may be close to being properly exposed with no change to the subject exposure.

Also, if your subject is a bit too dark it still doesn't have anything to do with the way you've set aperture, shutterspeed or ISO as long as you haven't run out of flash power. In this case it's only because ETTL-II tends to underexposed just a wee bit (a feature from Canon) so you may have to dial in some Flash Exposure Compensation (FEC). I start with about +2/3 stops FEC, but it's also a taste thing so your mileage may vary

There is a flash sticky on this forum, sorry I don't have a direct link to it, but it's really worth reading.

bowman01 wrote in post #2043783
Thanks curtis, i appreciate your reply.

In manual mode on the camera, how do i just let it use ettl on the flash? I mean, the shutter or aperture does not change regardless of if the flash is on.

I'm sorry if this is a really dumb question...

ETTL is a function of the camera, not the flash. The flash just needs to be ETTL compatible to use it, like all Canon EX flashes. When you're using your 550EX, ETTL is being used.

Thank heaps bob, i'm just trying to get my head around this. I'm reading as much as I can on the sticky guides...

When in manual mode on the camera, how do i know what the right exposure is, eg when i don't use the flash, i can shift either the shutter or aperture to get the dial to move to the middle of the ambient light meter. But when i use the flash, what is my guide... ?

bowman01 wrote in post #2043876
When in manual mode on the camera, how do i know what the right exposure is?

If you're using it indoors, set the shutter at 1/250 (flash sync speed on the 20D) and whatever aperture necessary to get the depth-of-field you want. Start at ISO 100.

Pay attention to the distance scale on the back of the unit. If your subject is further away than the scale indicates, increase the ISO or open the aperture. You will see the distance reading change. At f/8 and ISO 100 you'll have a range of over 20 feet with direct flash.

If you're bouncing it gets a little more complicated. The distance scale disappears and some trial and error might be required. Chapter 3 of Flash Photography 101 will guide you through the process.

bowman01 wrote in post #2043876
When in manual mode on the camera, how do i know what the right exposure is, eg when i don't use the flash, i can shift either the shutter or aperture to get the dial to move to the middle of the ambient light meter. But when i use the flash, what is my guide... ?

ETTL (flash metering) takes care of the exposure. The 'dial' is only for the ambient light metering. (So when at 1/200s f/11, the dial will be off the low end of the scale probabely). It doesn't matter, since flash is your main light source. The ambient light (metering) only matters if you want to balance it to the flash light....
So, ETTL is your guide, basically

Thanks for you replies everyone, I really appreciate it!

Christian

Using flash is like taking two photos, one with ambient light (by the meter in the camera) and the other with the flash. Both are adjustable with the 20D and 550EX combination, the ambient light with f-stop and shutter speed, the flash with FEC.

I checked your web site and I'm amazed at these questions. Your site would indicate you really know what you are doing with light IMO. Perhaps the ETTL stuff is just new?

Hi Dave, thanks for the comments, much appreciated. I'm really into making sure i understand something fully before charging a premium for my services.

All of the stuff you see on my website is freeby work, looking to get into fashion photography it's definately a "who" you know industry. So i'm getting my stinky foot in as many doors as possible.

If you look at the "moda italia" shoots in my gallery, you will see my lack of flash photography experience.

Thanks again, I think it sort of dawned on me this morning that in ettl, my flash will shoot a preflash, then flash properly, capture the image. If the flash thinks that it didn't get it right it will tell me by NOT confirming with the flash exposure confirmation lamp. I think this is what i was trying to ask all this time...

In manual mode on the camera, if i set the shutter to 1/250th and pick an appropriate aperture, I'll assume that it will work unless i don't get confirmation from the flash. Obviously with digital i have the added benefit of changing ISO and aperture if the image doesn't look right on the lcd. I can then use FEC to get the results i need. Same with ISO, if the flash can't get the result from say 1/250th at f22 or something tiny then i can bump up the iso.

One thing i have to get my head around is the theory field of view and flash range. Eg, I'm using a 28-135mm lens on a canon 20D so does that mean on my flash that the flash range indicated should be read differently? eg. divide or times by 1.6 or something?

Everyone has been so good on these forums, i look forward to helping others down the track as i learn myself.

bowman01 wrote in post #2047776
One thing i have to get my head around is the theory field of view and flash range. Eg, I'm using a 28-135mm lens on a canon 20D so does that mean on my flash that the flash range indicated should be read differently? eg. divide or times by 1.6 or something?

Since your 550EX doesn't automatically account for the camera's crop factor when zooming (like the newer models do), you can zoom the flash manually if you want (e.g. with a 50mm lens you can zoom the flash to 80mm or thereabouts). But unless you're pushing the limits of your range, I wouldn't worry about it. The flash will waste some light but it will still meter itself properly.

If you're using a camera flip type bracket with direct flash then you need some extra coverage in the vertical position anyway. If you're bouncing, you can zoom it however you want to hit whatever you want.

wow this post has been very helpful
thanks guys

Thanks again Curtis, your help is much appreciated! Cheers!

Here is an update over 2 years later of my progress, thank you all so much in playing an important part of my learning:

www.christianbowman.co​m/photostore