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01-06-2011, 09:21 PM   #31
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QuoteOriginally posted by patriotap Quote
Take a look at this

HSS Test
Wow, that was a great read! I finally understand how HSS works

01-07-2011, 05:37 AM   #32
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and this

DIY - High Speed Photography at Home | DIYPhotography.net
01-07-2011, 12:30 PM   #33
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Though I posted one of the initial responses in this thread, I don't exactly know what I'm talking about. So after thinking about the topic for a while:

Can water droplets really be that fast? I'm hoping to try out the 1/8000 shutter speed on my K-7 to see for myself. Then, lots of ambient light would work for me (allowing the high shutter speed), not against me.

There isn't a lot of consistent information on the length of a flash pulse, partly because it varies depending on power, mode and model. It seems like one solution for not enough flash power or a pulse that's too long is multiple flash units, maybe operating at half power. Then you'd have lots of light and a shorter duration. But there must be a limit on the speed of syncing them together. A delay in firing would eventually be like HSS, lots of short bursts of light. Does anyone know what the speed limit is on a PC cord or optical sync?
01-07-2011, 01:46 PM   #34
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QuoteOriginally posted by Just1MoreDave Quote
Can water droplets really be that fast? I'm hoping to try out the 1/8000 shutter speed on my K-7 to see for myself. Then, lots of ambient light would work for me (allowing the high shutter speed), not against me.
You have absolutely right. It will work as well if you have a constant light source, like shooting videos. This is another solution of the same problem.

Personally, I feel it's not the same grad of satisfy when you can tame the flash, especially with existing equipment or little add-on like nd/cpl filters.

01-07-2011, 02:15 PM   #35
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QuoteOriginally posted by hoanpham Quote
You have absolutely right. It will work as well if you have a constant light source, like shooting videos. This is another solution of the same problem.

Personally, I feel it's not the same grad of satisfy when you can tame the flash, especially with existing equipment or little add-on like nd/cpl filters.
I would have to agree with hoanpham. Sure you could probably do it with ambient light, but trying to do the capture using the flash does make it more challenging, plus if you wanted to get that fast of a shutter speed, you may have a razor thin DOF, unless you bump up the ISO. I think it's six of one, half a dozen of another.
01-08-2011, 08:06 PM - 1 Like   #36
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For something this small, you could just shade the subject from the sun with your hand, body, jacket, piece of cardboard, stolen stop sign etc., instead of breaking out the ND filters which reduce the light from the flash as well. It would also help if your background was lit solely by the flash or shaded as well. I'm an advocate of making the outdoors into a mini studio.

All praise nikon and their flash manuals for publishing flash durations! Example, the SB-28 has:

Power level....duration
1/1....1/840s
1/2....1/1100s
1/4....1/2300s
1/8....1/4800s
1/16...1/9100s
1/32...1/19000s
1/64...1/28000s

I'd expect similar kind of results for other hotshoe flashes. At 1/4 power it (and my various sunpak 433's) will freeze pretty much anything I run into (no speeding bullet photography for me though).
01-08-2011, 11:31 PM   #37
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QuoteOriginally posted by BrianR Quote
For something this small, you could just shade the subject from the sun with your hand, body, jacket, piece of cardboard, stolen stop sign etc., instead of breaking out the ND filters which reduce the light from the flash as well. It would also help if your background was lit solely by the flash or shaded as well. I'm an advocate of making the outdoors into a mini studio.

All praise nikon and their flash manuals for publishing flash durations! Example, the SB-28 has:

Power level....duration
1/1....1/840s
1/2....1/1100s
1/4....1/2300s
1/8....1/4800s
1/16...1/9100s
1/32...1/19000s
1/64...1/28000s

I'd expect similar kind of results for other hotshoe flashes. At 1/4 power it (and my various sunpak 433's) will freeze pretty much anything I run into (no speeding bullet photography for me though).
Brian, congrats, nothing like the facts to get to the heart of a subject :-)

Looks like no shutter out there could keep up with 1/32 or 1/64 power level. My Metz 48 manual has no such detail even though it provides that kind of power breakdown in manual setting.
01-09-2011, 12:47 AM   #38
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QuoteOriginally posted by Just1MoreDave Quote
Can water droplets really be that fast?
A droplet that has travelled 20cm from detachment would have a speed of about 2 m/s and it would advance by 0.25 mm during 1/8,000s. The physics is straight forward:

Distance (m), Speed (m/s), Distance (mm) travelled during 1/8,000 s
0.1 m, 1.4 m/s, 0.18 mm
0.2 m, 2 m/s, 0.25 mm
0.5 m, 3.1 m/s, 0.39 mm
1 m, 4.4 m/s, 0.55 mm
2 m, 6.3 m/s, 0.78 mm

Simply, even with a shutter speed of 1/8,000 s, the droplet will travel a 'fair' distance and it may appear blurry. (You would like the droplet to travel by less than 0.1 mm (even better less than 0.05 mm) during the exposuire time.)

I have done similar photographs in the past in a dark room. I use a fast flash and the exposure time is about the half-life period of the flash, that can be typically much shorter than 125 ms (1/8,000 s). BrianR provided very a very useful example with the Nikon flashes.

Hope that the info will assist.


Last edited by hcc; 01-09-2011 at 02:09 AM.
01-09-2011, 11:21 AM   #39
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Estimating what aperture you'd need for 1/8000 based on the Sunny 16 rule would be f2 at 100 ISO. And if you'd want, say, f11 at 1/8000 you'd need to bump your ISO to 3200.
01-18-2011, 01:13 PM   #40
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QuoteOriginally posted by BrianR Quote
For something this small, you could just shade the subject from the sun with your hand, body, jacket, piece of cardboard, stolen stop sign etc., instead of breaking out the ND filters which reduce the light from the flash as well. It would also help if your background was lit solely by the flash or shaded as well. I'm an advocate of making the outdoors into a mini studio.

All praise nikon and their flash manuals for publishing flash durations! Example, the SB-28 has:

Power level....duration
1/1....1/840s
1/2....1/1100s
1/4....1/2300s
1/8....1/4800s
1/16...1/9100s
1/32...1/19000s
1/64...1/28000s

I'd expect similar kind of results for other hotshoe flashes. At 1/4 power it (and my various sunpak 433's) will freeze pretty much anything I run into (no speeding bullet photography for me though).
Note too that power and flash duration is a function of its circuit design. Typical on camera flashes like given here most likely use
use a semiconductor that interrupts the power to control its level and you get those really short durations at low power and no RC decay characteristic.

But on some bigger "semi-pro" studio monolight strobe type flashes around, say, 400ws, which may have shorter full-power duration, you can actually have longer flash durations with less power because they often just reduce the voltage on the capacitor for lower power and you are getting the tail end of the flash RC decay. But higher end pro units will have even shorter flash durations at full power and depending on what they do with the circuit if it has a shorter duration at lower power.

So for the shortest flash duration, use the low power on those speedlight design of the portable camera flashes.

Last edited by tuco; 01-18-2011 at 01:42 PM.
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