Anyone shoots burst with SB-700 and SB-600?

[TheCROW]

Hey All,
I had to shoot a rally at night this evening; I used the shutter mode on my cams and used high iso to get a shutter of 1/500 which was good. But as I was shooting in Continuous High (burst) mode, I noticed the flashes shoot 3 times in a row with decreasing light power and then they recycle as I'm still shooting so the 4th and 5th shots are dark and as I continue shooting the flash fires again and then stops....
Is that normal? How should I go about this? Any recommended settings for cam and flash?
Thanks

 

[WayneF]

Yes, that is very normal.

If you use the flash full power, it depletes itself, and takes 2 or 3 seconds to recycle to be Ready again (Ready LED shows this). It ain't gonna work again until it recycles.

Assuming you are not using a D40, D50, D70 camera, then your 1/500 second is Auto FP mode, and is NOT regular flash mode. However, I am speaking of regular flash mode.

If you use lower flash power, like maybe 1/16 power, then it can recycle much faster, and it might keep up for a short while with a burst rate. The lower the power, the faster it recycles, and the longer it takes to get behind. If you can use wider aperture and/or shorter distance and/or higher ISO, for less power requirement, it could work. Speaking of regular flash.

The shutter speed of 1/500 second however, is a different world. This exceeds maximum shutter sync speed, so it is no longer flash (no longer a speedlight). The flash unit becomes a continuous light (for maybe 1/250 second, even at faster shutter speeds), and drops to no more than 1/4 power to be able to do that. This is its new full power level.

I'm surprised it worked three times for you, but you will have to drop the power level requirement to do more. Rules are different for this mode. It is continuous light, so shutter speed or aperture will make no difference to power if compensated to still be equivalent continuous exposure. Higher ISO or closer distance could help the flash.
See http://www.scantips.com/lights/flashbasics2b.html


I dont know your camera, nor what a rally is, but if you can make do with 1/200 second shutter speed (1/250 second on some), you will be way ahead at an (assumed) indoors event. Your speedlight is called a speedlight because it is much faster that the shutter speed. Take advantage of it. :smile:

 

[TheCROW]

looool Wayne!!! Always to the rescue!!! I knew you would be to pitch in :smile: and I am so gratefull!
Sorry I should have specified, it was a car rally and I opted for 1/500 shutter speed in order not to have blurry shots of the cars speeding by. Now the cars are usuall a few meters away from me, and I shoot burst as they get closer and drive by. I Use D90 and D7000. the first has a maximum Sync of 1/250 and the latter 1/320 Auto FP.
I have to say that I do not know what these mean, so I use TTL and Shutter mode and set the speed I want.

Any tips on how to benefit from maximum flash burst duration? Settings on both Flash and Camera? Is there a basic tutorial I can read that explains these things?
Thanks for the link btw I'm checking it now.

 

[WayneF]

There are three large subjects here... all involving flash basics.

Speedlights are very fast duration (called speedlights), used to stop motion in High Speed Flash Photography. Low power conditions are significantly faster than any possible shutter speed. But using flash to stop motion in a brightly lighted area (where the ambient light can blur the motion too) is another issue - the ambient.

And the issue of Auto FP flash mode being so drastically different than regular flash mode (probably not remotely what we imagined it to be). The flash is no longer a speedlight in this FP mode, and cannot help AT ALL to stop motion.

And trying to help the flash recycle speed keep up with shutter burst rate.

For this last one, if the flash recycle speed cannot keep up with the shutter rate, then the only answer is to reduce flash power requirements more (so it can recycle faster).

Move closer (if possible).
Use higher ISO
Could use multiple flashes to increase total flash power at lower individual levels.
Open aperture, without increasing shutter speed to compensate the continuous light (this works with regular flash mode).

My own notion is the best single try for all three issues to keep the dad-gummed flash OUT OF FP mode. Stay at maximum shutter sync speed. The speedlight is fast - use it. (it is NOT a speedlight in FP mode).

See the regular speedlight durations in the spec section in rear of the flash manuals - SB-700 is page H-17. SB-600 is page 88. SB-900 is page F-15. SB-800 is page 122.

Yes, bright continuous ambient light at 1/200 second can still blur the motion that the fast speedlight already stopped.
This depends.. if the proper ambient exposure is say 1/30 second, then the 1/200 second sync speed can keep it out (ambient light is three stops down). But if the ambient exposure is also 1/200, then the ambient also causes blur.

To minimize this, the flash power has to relatively overpower the ambient in some degree. Normally easy indoors. Regular flash mode has more than 4 times more power than FP mode to attempt this. Or with respect to recycle speed, regular flash mode uses less than 1/4 the power at the same light level. And FP flash has zero motion stopping capability.

So again, staying OUT OF FP mode is likely the best try (however out in bright sunlight is a tough opponent).

 

[TheCROW]

Coool!! Thanks for the detailed info Wayne!!! You're the man!!!