Camera Labs

Hey guys

I used to do a lot of dark flash photography, but I never used it for sports until tomorrow - I have to shoot a cross country - lots of sun but lots of trees so lots of shadows and I will be using my flash.

Since Im going to take pics of kids running through the bush, I am not 100% sure which sunc setting I need to use

I was thinking of using High Speed sync since Im sure the camera will be using shutter speeds of more than 1/125. BUT 2nd curtain sync I was told is better at capturing motion and freezing it.

Which is more appropriate for my needs if anyone has any suggestions?

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1) Olympus OM1 [Zuiko Auto-S 50mm f/1.8]
2) Pentax MZ-60 [Sigma 28-90 & 100-300]
3) Canon 7D [EF-S 15-85 & 70-200mm f/4 IS]

Leo's Flickr Page

HSS is useful if you need the faster shutter. One scenario might be using fill flash outdoors, where the background may already be very bright. Combined with a big aperture, you can run into limits. e.g. ISO100 f/1.4 1/250s is usually far too much exposure in sunlight. Your choices are then to use a ND to bring the exposure down, or use HSS on the flash to allow faster shutter speed. Consider carefully the exposure of the dark and light parts, and why you might need a faster shutter speed to use HSS.

As for rear curtain, normally the flash goes off as soon as the 1st curtain is fully open. The remainder of the exposure time passes and it closes again. When tracking a moving subject with stationary camera, you get a bright image when the flash goes off, but you also get a residual ghost from the exposure time. The trail then goes ahead of the subject and it can look wrong. If you use rear curtain, the trailing is behind the subject which looks more natural. The drawback of rear curtain is you have a longer delay between activating the shutter and the flash going off.

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Canon DSLRs: 7D, 5D2, 1D, 600D, 450D full spectrum, 300D IR mod
Lenses: EF 35/2, 50/1.8, 85/1.8, 135/2+SF, 28-80 V, 70-300L, 100-400L, TS-E 24/3.5L, MP-E 65, EF-S 15-85 IS
3rd party: Zeiss 2/50 makro, Samyang 8mm fisheye, Sigma 150 macro, 120-300 f/2.8 OS, Celestron 1325/13
Tinies: Sony HX9V.

I have not played around with hss, but have played around a bit with using the flash in av mode. The 7D by default, varies the shutter speed in av mode between 1/60-1/250. The is a setting in functions menu, number 3 I think, where you can fix the shutterspeed at 1/250. I have found that sufficient to freeze the kids in action. I play around with a bit of - + fel, that with iso at 400 seems to work well for me.

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Canon Powershot S95, Canon 7D, 15-85, Canon 85 1.8 USM, Sigma 30 1.4, 50mm 1.8, Canon 100 2.8L IS Macro, Canon 70-300L IS USM+Kenko 1.4 Pro 300DGX, Canon 430EX II and RS 4 Classic

High Speed Sync is your only option if shooting at high frame rates because Second Curtain Sync only works at shutter speeds of 1/30 or below - far too slow for sports - or rather slow enough that moving people will be blurred.

With a slow exposure you get a blur trail on moving objects. Firing a flash helps to freeze the object so you can see it clearly but it doesn't eliminate the blur trail. If you use normal (first curtain sync) flash the result is a frozen subject with a blur trail ahead of them. This is because the flash fires, freezing the subject, then the exposure continues and the subject moves, creating a blur trail in front of the subject - this looks rather odd.

With second curtain sync the exposure starts but the flash doesn't fire. You get the blur trail caused by the motion and then, just before the second curtain starts to close, the flash fires, freezing the subject. The result is the frozen subject with a blur trail behind them, which looks more natural.

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Dan Marchant
I am learning photo graphee - see the results at www.danmarchant.com