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Nikon DSLR Cameras
D7100
D7100 ocf issues. a little help?
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<blockquote data-quote="yauman" data-source="post: 266553" data-attributes="member: 15418"><p>You cannot - that how Nikon implements their modeling feature. Other speed light manufacturers may implement it differently. And actually it's worse - the "long" flash you see is actually many many pulses of short bursts, so close together that you see it as a long continuous light. If I remember right, i think the way SB700 implement it is to pulse at 1/16 (1/32?) power at maximum recycle speed, ie fire and quench as soon as 1/16 of max light power is reached, recharge and fire again. Since the charge capacitor bank is big enough to fire at 100% power and recharge in 2sec, at 1/16th power it will recharge fast enough to put out another light pulse without you seeing a "blank" so it looks like a long continuous flash. </p><p></p><p>FYI, these strobes are not capable of lighting up continuously. The light bulb (tube) is filled with Xenon which requires 5,000-10,000 volts to sustain a discharge to produce light - but no one wants to carry a 10KV power supply with them. So they build a charging circuit inside which steps up your 4x1.2volt battery to about 5KV-10KV to charge up a bank of tiny high voltage capacitors. When triggered, the capacitor makes connection to the xenon tube and the flash occurs. Another circuit then "quench" the capacitor when enough light power is put out for the particular setting. At full power the SB700 can sustain a light output of 1/1000 sec (full dump of a fully charged capacitor bank) and at lowest power 1/128th power, it puts out a light pulse of 1/40,000 sec's long. At 1/16th power the light pulse is 1/10000 sec long. The camera sensors can deal with that short time but our eyes cannot and our optic nerves and brain "stretch" out that 1/10000 sec pulse and when repeated, we think it's a continuous light! Now you can appreciate where the battery drain comes from when you use the modeling light feature and why the on-board flash's "modeling" light only give you just one full-power flash (the flash draws from the same battery your camera uses for other functions!)</p></blockquote><p></p>
[QUOTE="yauman, post: 266553, member: 15418"] You cannot - that how Nikon implements their modeling feature. Other speed light manufacturers may implement it differently. And actually it's worse - the "long" flash you see is actually many many pulses of short bursts, so close together that you see it as a long continuous light. If I remember right, i think the way SB700 implement it is to pulse at 1/16 (1/32?) power at maximum recycle speed, ie fire and quench as soon as 1/16 of max light power is reached, recharge and fire again. Since the charge capacitor bank is big enough to fire at 100% power and recharge in 2sec, at 1/16th power it will recharge fast enough to put out another light pulse without you seeing a "blank" so it looks like a long continuous flash. FYI, these strobes are not capable of lighting up continuously. The light bulb (tube) is filled with Xenon which requires 5,000-10,000 volts to sustain a discharge to produce light - but no one wants to carry a 10KV power supply with them. So they build a charging circuit inside which steps up your 4x1.2volt battery to about 5KV-10KV to charge up a bank of tiny high voltage capacitors. When triggered, the capacitor makes connection to the xenon tube and the flash occurs. Another circuit then "quench" the capacitor when enough light power is put out for the particular setting. At full power the SB700 can sustain a light output of 1/1000 sec (full dump of a fully charged capacitor bank) and at lowest power 1/128th power, it puts out a light pulse of 1/40,000 sec's long. At 1/16th power the light pulse is 1/10000 sec long. The camera sensors can deal with that short time but our eyes cannot and our optic nerves and brain "stretch" out that 1/10000 sec pulse and when repeated, we think it's a continuous light! Now you can appreciate where the battery drain comes from when you use the modeling light feature and why the on-board flash's "modeling" light only give you just one full-power flash (the flash draws from the same battery your camera uses for other functions!) [/QUOTE]
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D7100
D7100 ocf issues. a little help?
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