Question

Tell me if this is how you would use say the 580ex II flash outside on a sunny day while doing portraits.

1. Use a reflector to diffuse the light on the subject
2. Meter for the background
3. Focus on subject
4. Flash exposes for the subject
5. take the shot

Is that how it works? Would that give perfect exposer for the subject and the background?

Right now i'm using a diffuser without the flash and on sunny days the background gets totally blown out.

Was wondering if a flash would fix this problem?

that sounds pretty good
experiment and see what you get
the reflector should help fill any shadows
you might want to turn the flash down half - one stop or so depending on skin color for a more natural look

sounds good to me!

if its bright out and you have a fast lens and want to shoot with it wide open for minimal dpf, be prepared to set the flash on HS sync and shoot in manual with the flash on auto. meter for the overall scene and let the flash handle the exposure of the subject. You might have to mess with FEC to get it just right.

Thanks you guys. I'm trying to decide if i should spend 400 dollars on a flash rather than the 100's of other things that i need. But if a flash is the key to perfect exposure of both subject and background for portraits than a flash is exactly what i need.

Go with the decent flash and you'll not be sorry..

580exII on a MKIII will default to autoflash, which means it meters it's reflection instead of the ttl system

basroil wrote in post #4091131
580exII on a MKIII will default to autoflash, which means it meters it's reflection instead of the ttl system

Actually, it defaults to E-TTL II. C.Fn. 05-2 will set the camera to auto thyristor flash.

so with the 580ex II flash what is the maximum shutter speed i can use in HSS with the 40d? I'm usually shooting at f/4 or f/5.6 so on sunny days my shutter is usually in the 1-2 thousands range. Would the flash work at that shutter speed?

Scarter275 wrote in post #4103290
so with the 580ex II flash what is the maximum shutter speed i can use in HSS with the 40d? I'm usually shooting at f/4 or f/5.6 so on sunny days my shutter is usually in the 1-2 thousands range. Would the flash work at that shutter speed?

Yes, the flash will work, but the faster the shutter speed, the less effective distance the flash will work for. On bright days if you don't want to go up to f/13 or f/16 (why not? other than reasons of DoF...), then shoot very close to your subject...

so would i have issues with using my 70-200mm? Given the tele i might not be able to get far enough away?

Scarter275 wrote in post #4107408
so would i have issues with using my 70-200mm? Given the tele i might not be able to get far enough away?

I don't understand what you're saying. The effective distance of the flash is lower in HSS. So you want to be close to your subject. You "might not be able to get far enough away?"

sbressler wrote in post #4110114
I don't understand what you're saying. The effective distance of the flash is lower in HSS. So you want to be close to your subject. You "might not be able to get far enough away?"

His sig only mentions one lens: the 70-200. I think what he's trying to say is that he's concerned about the capabilities of the flash limiting him in terms of how far away he can move from the subject before it becomes ineffective. His lens forces him to move further away from his subject in order to get good framing and I guess he's concerned that his flash won't be effective at those distances...

That's just a guess, but it seems logical...

wow lol, yeah your guess is exactly what i meant thanks for clarifying. does anyone have any input on that?

Your game plan and the suggestions given are great.

'Getting closer' will help in getting good flash coverage when in HSS but really it will be through trial and error that you will figure out what lighting balance suits you. You may find standing 5 to 8 feet from your subject with your 70-200 won't give you the framing you want and you'll need to move back. This is where going HSS may not work to well due to weaker flash output.
Options...you can boost FEC, take off the diffuser, or get your shutter speed at or below your max sync speed (probably 1/250 for your 40D) which will put you back in normal sync mode and gain greater flash output range.

Just know that HSS will work but has some limitations. I use it a lot when I want to shoot wide open in bright back lit environments or if I need faster than 1/250 shutter speed.