How to blade blur?

Yesterday a little brush fire, well, about thirty trucks were involved as a precaution, and it was my first experience trying to catch drop helicopters in motion. I caught them all right but I kept stopping the blades. How in the world do you shoot slow enough to get some blade blur and still hand hold a 70-200 at 200? I went as show as 125 and was still pretty much stopping the blade, and at that speed the images are going to be pretty soft.

I see images here at 1/160th with good propeller bur on airplanes but the helicopter blades must be much slower moving. Advice appreciated.

Shoot at a slower shutter. say 1/60th or so. You might want to bump the ISO though depending on your light.

FWIW...

Some folks feel that if you can't see the entire rotor disk (or prop disk for fixed wing aircraft) it isn't enough blur. IMO, a couple of widths of the rotor blade-worth shows motion.

Like any type of photography, it takes practice. Can you post a couple of your shots at 1/125? That ought to have yielded enough rotor blur.

It really depends on the speed of the rotors. Since you're shooting 'copters at a hover, the speed of the rotors is liable to be pretty slow.

This here is a hover. The shutter speed is 1/125. Any slower than that, then I might have had unsharpness due to camera shake.

Pete wrote in post #5962388
It really depends on the speed of the rotors. Since you're shooting 'copters at a hover, the speed of the rotors is liable to be pretty slow.

This here is a hover. The shutter speed is 1/125. Any slower than that, then I might have had unsharpness due to camera shake.

Thank you for the responses.

They weren't hovering they were dumping on the move, so my camera was moving all the time. On top of that I had to shoot directly into the sun. My 1/125s looked pretty bad camera-shake wise. 'll try to dig one or two out. I tried mode 1 and 2 IS. The shooting conditions were so difficult, for me in my inexperience, that I don't think I can tell any difference.

I'm sure practice is the key, but not sure I want any more under these fire conditions in California.

Here's one thing to remember. As the tip of the blade or propeller approaches supersonic speed, that is the limit. Therefore small diameter propellers will spin about 2700 rpm, larger props about 2400 - 2500 rpm. Helicopter blades are much bigger, and so spin around 1200 rpm or so. Larger helicopter blades will be slightly slower, and the smaller choppers will be a bit faster. The key is to catch the blur, so with propellers you can be successful with a 1/200 or so, but with a helicopter you must use a much slower shutter speed to catch the same blur. Trial and error is best, but armed with the rpm knowledge, you will at least have a good idea where to start . . .

Gordie

Thanks for such a knowledgeable response Gordie.

To clear up a few points (I fly these for a living):

"Helicopter blades are much bigger, and so spin around 1200 rpm"

Er, no they don't. At that speed they would come off!
About 400rpm for a Squirrel (Astar in the US) similar speeds for most others.

"It really depends on the speed of the rotors. Since you're shooting 'copters at a hover, the speed of the rotors is liable to be pretty slow"

No sorry, that is wrong too. The Main rotor blades spin at a constant rpm, as does the tail-rotor, which is linked to it through a series of drive shafts and gears.


I shoot at between 1/60 - 1/250 depending on the blur you want. Try 1/15 for an interesting effect.

Thank you for your response Mick. Looks like getting a nice blur while hand holding a longer lens on an erratically moving firefighter would almost be impossible. Well, at least for me.

so if the blades spin at a constant speed, how do they speed up and slow down? Just by the angle of the helicopter?

I am no pilot, but I would think if the speed stays the same, then the pitch would have to change in order to give it lift and direction.

adblink wrote in post #6108971
so if the blades spin at a constant speed, how do they speed up and slow down? Just by the angle of the helicopter?

You balance Blade Pitch Changes (Collective) with Mast Angle Changes (Cyclical) along with Tail Rotor Pitch Changes.

In other words, you balance a well greased elephant on a bowling ball that's rolling accross a sheet of ice.

Remember: Helicoptors don't actually fly .. They just beat the air into submission...

Good guess Chris, you are right.

Look here for a good explanation:
http://science.howstuf​fworks.com/helicopter6​.htm

The above shot was taken from another helicopter with a:
Canon 30D
24-70L f2.8
Focal length - 70mm
F-stop - 3.5
Shutter speed - 1/200
ISO - 100

This shot I changed to:
F-stop - 7.1
Shutter speed - 1/80
ISO - 200

Mick Finn wrote in post #6110698
ISO - 800
F-stop - 5.6
Shutter speed - 4 seconds

Must be nice to have a job that supports your hobby.

Nice shot.