I have an older 550EX that I used to use with my 600mm. I have a Really Right Stuff flash arm and a camera body plate that I used, along with a Canon Off-camera shoe cord.
I have since moved toward using my 80D body with the 100-400 IS ii lens. Do most people simply use the flash on the camera body flash mount, or is there any way to get the flash higher off the camera, which is what most people recommend?
I have looked at all of my pieces mentioned above, and cannot see how they can be used with the 80D and 100-400...
If people have success shooting birds with the flash mounted on the camera body, then I will give it a try.
Any and all comments welcome!
I did first start with an off-camera shoe cord. But personally found it too limiting for what I wanted to do.
Now, I only ever use off-camera flash without any cables. I have numerous light-stands. Both lightweight stacking-style Manfrotto stands and heavier-duty C-stands. Then, modifiers to shape/direct the light.
Having said that, all my subjects are fairly close. And when outdoor (and attempting to "compete with the sun"), you really need to either have the light source very close to your subject, or gang-up your speedlites. I have a Lightware Direct Foursquare bracket so I can mount four 600-series speedlites to a single modifier. Even when all of them are all full power, that light source still needs to be fairly close to my subject.
Example (using sunny 16). I want to overpower the sun by say 1 full stop. So, I need light output of f/22. Say my aperture is f/2.8. (Side note: I'm going to ignore the power loss in using high-speed-sync for the purposes of this paragraph). With a single bare 600 EX speedlite, to get f/22, I'd need to run that at full power and be around 8 feet from my subject. Problem is that if want a softer/larger light source, I'll use a modifier that will eat up say arround 2 stops of light. Hence my using four speedlites together (which gives me now that 2 stops back).
Since your subjects are birds, I don't think flash is going to do you much good at all due to the distance they'd be at from your light source.
Wanting the flash on your camera though means the light source is now the same distance from your subject as the camera itself. I just don't think the math will support want you want to do.
If I did the math correctly, for a fill flash say 2 stops under the ambient (sun), you'd need to be 32 feet away from your subject and run the flash at full power. This is with f/5.6.
How far away are you from the birds?