Flash issues, Help !

So I was shooting a friend today at the beach, nothing that I haven't done before and I can't figure out for the life of me why I was having issues, I tried using my flash to eliminate shadows and it was NOT cooperating. No matter what I seemed to do it only got worse.

I'm hoping to get some general direction of what could have gone wrong.

I was using my 50D, 24-70 lens, 580EXii flash with a diffuser angled at 45 degrees.

I was shooting at 70mm, AV at f/2.8, ISO 100. With my flash turned off the camera was setting the shutter at 1/3200. The sun was pretty high in the sky off to the subjects right. The ocean was the background. The shot / exposure looked good except for shadows from the sun.

The second I turned on the flash (on ETTL mode) the camera set the shutter at 1/250 (sync speed?) and as you would imagine the photo was severely blown out.

What did I miss here ?

First thing you missed was turning High Speed Sync, HSS, on the flash to on so your camera would allow shutter speeds above the max sync speed of 1/250th.
The second thing that makes no sense is what exactly did you thing the flash was going to bounce off of in the outside with the head tilted up? When you say DIFFUSER are you talking about a Stofen? If so take that thing off and shoot direct.

dedsen wrote in post #13592129
First thing you missed was turning High Speed Sync, HSS, on the flash to on so your camera would allow shutter speeds above the max sync speed of 1/250th.
The second thing that makes no sense is what exactly did you thing the flash was going to bounce off of in the outside with the head tilted up? When you say DIFFUSER are you talking about a Stofen? If so take that thing off and shoot direct.

Ahh...good point about the HSS it must have gotten turned off by accident somehow because I didn't turn it off and I've used this setup before in the past with good results.

Yes I am using a Stofen, I was tilting it to minimize the light, was that wrong ?

So you are saying direct the flash head on with no Stofen ?

Personally I think a stofen is just a waste of flash power. Especially outside. They are made to scatter light in all directions and when outside there is nothing to bounce off of and you are just wasting the light and your batteries. Turn the flash power down if you want to minimize the light. To soften light you have to increase the apparent size of the light source. A stofen does not do that.

dedsen wrote in post #13592159
Personally I think a stofen is just a waste of flash power. Especially outside. They are made to scatter light in all directions and when outside there is nothing to bounce off of and you are just wasting the light and your batteries. Turn the flash power down if you want to minimize the light. To soften light you have to increase the apparent size of the light source. A stofen does not do that.

I just checked my flash and low and behold HSS was off

I will try shooting head on from now on.

Such a simple thing ruined my day......

HSS is not necessarily a fix! While it is true that enabling HSS would permit your shutter speed to be faster than 1/250, enabling HSS also severely reduces the amount of power and the maximum effective distance that the flash can reach!

1/3200 is about 3.5EV faster than 1/250. So your HSS flash will have about a -5.5EV reduction in Guide Number. For example, what started as ISO 400 and GN320 --> GN160 simply by going to HSS, and then you lose 3.5EV more light due to the incremental change in shutter speed above 1/250.
1/250 -> 1/500 -> 1/1000 -> 1/2000 -> 1/4000

If at ISO 400 you could shoot 80' at f/4 it suddenly drops to 40' at f/4 simply by going to 1/320. Then when you switch to 1/3200, the max range at f/4 drops to less than 5' at ISO 400.
BTW these figures are for illustrative purposes. POTN members have discovered that certain Canon 580 flash units drop -3EV, while others drop -2EV simply in going into an HSS shutter speed when HSS is enabled. The problem is that you lose power initially when you simply go 1/3EV faster than X-synch speed (and this happens *at* x-sync speed with some camera models). In testing which a number of us have done, when you are faster than X-synch speed, one nominally has lost -2EV to -3EV in total flash power!

Wilt wrote in post #13592955
HSS is not necessarily a fix! While it is true that enabling HSS would permit your shutter speed to be faster than 1/250, enabling HSS also severely reduces the amount of power and the maximum effective distance that the flash can reach!

1/3200 is about 3.5EV faster than 1/250. So your HSS flash will have about a -5.5EV reduction in Guide Number. For example, what started as ISO 400 and GN320 --> GN160 simply by going to HSS, and then you lose 3.5EV more light due to the incremental change in shutter speed above 1/250.
1/250 -> 1/500 -> 1/1000 -> 1/2000 -> 1/4000

If at ISO 400 you could shoot 80' at f/4 it suddenly drops to 40' at f/4 simply by going to 1/320. Then when you switch to 1/3200, the max range at f/4 drops to less than 5' at ISO 400.
BTW these figures are for illustrative purposes. POTN members have discovered that certain Canon 580 flash units drop -3EV, while others drop -2EV simply in going into an HSS shutter speed when HSS is enabled. The problem is that you lose power initially when you simply go 1/3EV faster than X-synch speed (and this happens *at* x-sync speed with some camera models). In testing which a number of us have done, when you are faster than X-synch speed, one nominally has lost -2EV to -3EV in total flash power!

OK.....

Is this necessarily a detriment / issue when trying to use the flash for fill on a Sunny day from @ 10 feet away ?

What are my other options ? (no assistant to hold a reflector, etc)

alexxn, the short answer is no. While it is true that you do loose power with HSS enabled, in your situation it will still work for you. Where you really notice all this techno discussion that Wilt is throwing out is when your flash is more of the main light. All this theory is good to know, and then it helps to know what the limits and practical applications are for the real world. I am not discounting Wilt's facts, just telling you to keep them in mind when setting up and then try what you need to do to get the shot.

Thank you all for the suggestions, that's why I love this site !!

I just took some test shots and the HSS made a WORLD of difference.

You guys rock !

alexxn wrote in post #13592018
I was shooting at 70mm, AV at f/2.8, ISO 100.

If you want to avoid the reduced power of HSS, set your shutter at 1/250 and stop down the aperture to properly expose the background. This may give you more DOF than you want, but that's the trade-off.

Nothing wrong with HSS if you understand its limitations. Dial in your settings, including zooming the lens to where you need to be (so the flash will autozoom to match), half-press the shutter button and look at the distance scale on the back of the flash. If it won't reach your subject then you need to go to plan B.

alexxn wrote in post #13593611
OK.....

Is this necessarily a detriment / issue when trying to use the flash for fill on a Sunny day from @ 10 feet away ?

What are my other options ? (no assistant to hold a reflector, etc)

To paraphrase dedson's answer, "It depends!"

Let's analyze the sunny day example of fill from 10' away, shooting a backlit subject with 105mm lens on a FF camera...

• Sunny 16 says 1/ISO f/16 for typical bright sunlight, so 1/400 f/16 today
  
• You want to use flash fill and reduce the DOF down by using f/4, so 1/6400 f/4 results
  
• 1/6400 is 5EV faster than 1/200 (FF camera X-sync speed is 1/200)

Leave the darn flash at HSS all of the time. When your shutter speed is at or below 1/250 second the flash reverts back to normal sync automatically.

When you are shooting with higher sync speed, you are also opening up your aperture so the power loss is pretty much moot.