Aircraft photography

Just wondering what shutter speed I need to be using to avoid the "helicopter with frozen rotors" problem? Also applicable to conventional prop-driven aircraft!

RIAT is still a long way off but I've struggled to find much advice about this. Obviously you don't want too low a speed as with a long lens tracking a moving subject hand held you'll run into shake problems.

Matt,

Rotorcraft are somewhat different, in that the main rotor rpm is generally in the mid hundreds - unlike a prop (be it piston or turboshaft, reduction or direct drive).

Freezing the rotor in an image thus becomes a distinct probability, and a whole lot earlier in terms of shutter speed than it would for a prop (assuming the prop is not idling of course).

Even at 1/60th shutter speed, a rotor at 600 rpm (thus only doing 10 rpm per second) will merely be completing roughly one sixth of a single revolution. Halving the shutter speed will double the arc travelled by a blade - say one third of one rev.

This does not bode well...

Well, so long as there is some blur I'd be happy. It just looks seriously odd to see a helicopter in mid air with the rotors apparently stationary.

I always try to shoot around 1/125

Nice shots Mike

Matt - there is a very brief discussion of this on flickr:
link
which (unsurprisingly) coincides with Mike's 1/125th shutter speed. There are also a LOT of helo pics on flickr with frozen blades

Regards

Mat W

Those look good - thanks for the advice chaps!

Did you need an ND to allow you to use a low enough shutter speed? I don't currently own any NDs to fit my big zoom but I've been considering buying a set.

Nope, just went over to TV mode, dialled in 1/125, spot metering and let the camera take care of the rest. The inbody SR of Pentax works very well for stuff like that.

With British weather, I don't think so
Simply use a higher f-number.

The 125th of a second shutter speed seems about right in Mike's pictures, enough blur to show movement but not enough to make the rotor almost vanish. But that raises another question, what length lens are you using? Aircraft photography generally requires a quite long lens so at 125th of a second camera shake becomes a problem.
david

David, Mike using 500mm for his shots so with some practice it can be done

Thanks to shake reduction I presume. I would find a tripod too restrictive for any sort of action shot.
david

Last year was my first attempt at aircraft photography, so lacking confidence to use slower shutter speeds, I have lots of frozen rotors an propellers. I'm posting this picture to illustrate a point.

[IMG]http://i217.photobucket.com/albums/cc222/Oggy3323/BUG.jpg[/IMG]

Notice how the two blades to the port and starboard of the helicopter are frozen because they have very little movement relative to the camera, but the ones fore and aft are blurred as they have more relative movement.

Anyway, what blade blur? clicky.

Actually it is a little known fact that helicopters cannot fly but they are so ugly that the earth repels them

That seems to work well Oggy. There is obvious movement despite the rotors in the outboard position being frozen.
david

The Bournemouth air show last year was my first time .. I was rather disappoined on the firt day when I got home to see lots of decent aircraft shots with totally static blades.

Lucky for me it went on for four days so I had plenty of practice by the time it had finished.

I'll most likely be using a 100-300mm zoom, so I'll have to learn how to hold that steady. Unfortunately I don't think my 200mm prime is quite long enough!