Use of the flash with a telephoto lens

[Ouessant]

Hi all,

I want to take bird photos with a 400 f/5.6 + 580 EX II + better beamer in the forest.

I'm not so familiar with the use of a flash in those conditions, and I'm concerned about the maximum sync speed of my camera (7D, so that would be 1/250s) being way too slow to avoid motion blur when taking handheld shots.

Of course, I could use the HSS mode of my 580 EX II to work at higher shutter speeds, but then the power of the flash is dramatically reduced, and it might not be sufficient for fill flash.

What technique do you use in such conditions ? Is it more efficient to stay at 1/250s to benefit from maximum power of the flash, or switch to HSS to avoid motion blur ?

[CDMOOSE]

I'm sure you'll get several opinions here and I'm certainly no expert, but exactly with your equipment I prefer HSS.
Al

[Ouessant]

Thanks for your input, Al.
Do you have typical settings ? You usually shoot in Tv and set the flash in E-TTL with HSS ?
Does it sometimes turn out that the flash was not powerful enough to light the bird correctly ?

[CDMOOSE]

I do usually shoot in Tv mode. The flash is set to HSS but in manual mode, then I simply dial the power setting required accordingly. 1/4 power is a good place to start and adjusting as conditions dictate. You'll soon develop a feel for darkness and distance. I rarely shoot at full power as the results are often not pleasing. I get the best results at 1/8 to 1/4 power, which is often enough to illuminate without creating harsh and artificial shadows.

[jhayesvw]

agreed HSS is the way to go.
Ive used ETTL mostly and had good results but manual would be more precise I bet.

[Kevin Hall]

Have you tried shooting at 1/250th or slower? Set your flash to 1/4 power or less and give it a shot, see what happens...... In fact, see what 1/100th will do.

Exercise your intellectual curiosity, explore photography.

[Ouessant]

Originally Posted by CDMOOSE

I do usually shoot in Tv mode. The flash is set to HSS but in manual mode, then I simply dial the power setting required accordingly. 1/4 power is a good place to start and adjusting as conditions dictate. You'll soon develop a feel for darkness and distance. I rarely shoot at full power as the results are often not pleasing. I get the best results at 1/8 to 1/4 power, which is often enough to illuminate without creating harsh and artificial shadows.

Thanks for the tip, I'll try that in various situations and see what I get.

Originally Posted by jhayesvw

agreed HSS is the way to go.
Ive used ETTL mostly and had good results but manual would be more precise I bet.

Another vote for HSS, thanks for your input Jeremy !

Originally Posted by Kevin Hall

Have you tried shooting at 1/250th or slower? Set your flash to 1/4 power or less and give it a shot, see what happens...... In fact, see what 1/100th will do.

Exercise your intellectual curiosity, explore photography.

Hi Kevin, You're right, there's no such thing as trying.
In fact, the best technique might be different depending on the time of the day.

I will be doing both night hikes and day hikes in the virgin forest of Madagascar, and I suppose I can use a slower shutter speed during the night because the movement will be frozen by the flash, no matter what shutter speed I use.

But in broad daylight, I fear the bright sky above the canopy may induce motion blur if I use slow speeds such as 1/100s, plus I'll have to balance ambient light with the flash.
I suppose it will be a lot more delicate during the day.

[Kevin Hall]

François, if you are not in Madagascar yet then you have homework to do. It will not be the same but get yourself to a dark woods with your gear and play, have fun trying things out. Then you will know how you are going to make your images in Madagascar, you will have more confidence in what you are about which will be much more enjoyable.

Many people worry about keeping to a faster shutter speed to prevent blurred images, it is a legitimate concern. But flash can be very forgiving of lower shutter speeds which is something that is often misunderstood. I have made hundreds of bird images with flash where my shutter speed is 1/250th or slower, a large percentage at 1/100th even. I can count on two hands times when I've even gone as slow as 1/50th and made sharp images - like this Wood Thrush:



1/50th @ f11, ISO 400 on my old 1D mk II

Wood Thrush are deep forest birds, they have a beautiful song but are very shy and will not often come out into the open. To shoot a thrush is to deal with the dark conditions that they prefer. I needed lots of light and a way to stop motion for sharpness. The easy part is stopping the action, birds on a stick are easier than birds in flight but it is still a consideration to be taken.

To do this I forget about the shutter speed and stop it with the flash. Why? Because at 1/4 power I'm getting a flash duration of around 1/4000th of a second. This is fast enough to stop any action of a perched bird, even the most active ones.

It is also going to illuminate the bird but it is also going to kill the background - your photos will look like they were taken at night. This happens because of the fast flash duration time and the low level of ambient light. So instead of faster shutter speeds you need to go longer to allow time for collecting as much ambient as possible. 1/100th to 1/250th can often get you there, sometimes you may need slower.

You are going to get some images with ghosting, where flash has stopped the action but because of the longer shutter speed you have collected additional motion in the image. You will also get sharp images that have better ambient exposure and good subject exposure which is the reason you are taking your camera to Madagascar.

There will be a limit as to how slow you can go, it is different for everyone so you will have to discover your own ability. I've made images as slow as 1/100th hand held but I can go slower with a tripod like in the photo above.

What is there to lose, go forth and discover your equipment and yourself - it should be lots of fun.



1/100th @ f11, ISO 100 - wild juvenile Sharp-shinned Hawk that came in to my perch set up - a very nice surprise.

[Ouessant]

Thanks for this very useful information Kevin, your shots are really neat and very sharp indeed !

I'm not yet in Madagascar, and will be there for 5 weeks "only", that's why I'd like to be ready to shoot when I'm over there and not waste my time experimenting in the field.

So I have to make a quick training before mid september. I'll try to find some cheap fake plastic bird that I'll put onto a branch in my garden, and shoot it in various light conditions and with different flash settings to see what I get.
I'd be really upset if I missed a rare species because my lack of skills with a flash.
And I'm not just talking birds, but also lemurs, cameleons, frogs, and so on.

Btw does someone have any idea how I could get the lens to focus on an animal in the night ? Do I have to light it first with a flashlight to help the lens make the focus, or will the 580 emit a pre-flash that will help get the job done ?