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peter38a wrote:
Thank you all for your posts. As a guest here, and with limited photo experience, I want to take care not to trod on any toes or seem unappreciative.
To reiterate I wanted my SB 700 to work in SU-4, controlled by my camera popup. No camera shop here in Phoenix could help, nor Nikon USA and I posted to this site as my last hope for help. Shortly after my original post I noticed that when the SB was switched to Remote the screen presented an M and an output number. Duh, I never noticed it before but when I clicked SEL and changed the power output to anything other than 1/1 it does give an output as set, perfectly!
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It gives some output, but probably not the full effect you imagine.
The usual plan is for optical slaves (SU-4) to be triggered by the other manual flashes. It does not need the popup unless there are no other flashes. But usually, one manual flash is triggered some other way (either PC sync cord or a radio trigger), and it triggers the optical slaves on all the other flashes in sync.
When it flashes at a power lower than 1/1, then less than full power means there is some capacitor energy left, not totally expended. You might assume that it could do two half power flashes (1/2 + 1/2 = 1), but not quite. It will flash twice quickly, but the second won't have full 1/2 power output, because it was not recycled fully to full capacitor voltage again. Flash energy is C * (V squared). V squared is pretty important to full output. Full power output requires full recycle to be Ready again. That takes a little time at higher power levels.
Speedlights always fire at full voltage and full power intensity, and then a timer cuts them off, at say the 1/2 or 1/128 designated power point. At low power, they get short and fast, is why they are called speedlights. But a quick second flash before it can fully recycle will not then be at full voltage, and thus not full power, and then it provides less than expected output (since it was not fully recycled)
It possibly might do two proper flashes at maybe 1/8 power or less. Guessing about the available recycle time, but some flashes (SB-910, SB-800) have a Repeating flash mode, and at 100 ms recycle time (ten per second), they can do 1/8 power. I am not making it up, there are charts in the manuals about this property, about what it can do. It cannot do two proper 1/2 flashes that fast.
But do you really want to run your flash session that way, always double firing the SU-4 unit?
In Commander Mode I changed the pop-up to "--" from 128 and everything works consistently as above. The link to the article on flash is wonderful and I will be pouring over it for the next few days but when it says that Commander and SU will not work together it is mistaken because it works here for me, the day before yesterday, yesterday and today.
Here's something a camera store guy passed on to me. I carry a chrome knob and when I don't have direct line of sight I use it as a reflector and so it far has triggered any flash out of direct line of sight.
Please allow me to say thank you again for your interest and input. May I respectfully suggest that you try what I've described and see for yourself?
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The flash sensor is more sensitive in SU-4 mode than it is in Commander Remote mode.
Same sensor, but the commander signal is 1) a complex binary encoded signal that must be properly decoded, and 2) is at very low power (probably a bit less than 1/128 power), so that the flash will have some power left for the final contributing flash (see concept above).
It can recycle fast at very low power.
But the SU-4 trigger signal is 1) a very simple detection of any flash at all, and 2) from the strong full working power of the other other flashes. SU-4 is quite sensitive, and the trigger is very powerful, and line of sight should NOT be any concern at all (for SU-4). I put them anywhere in the room without any concern, and they always trigger (not true of Commander).
Did you not determine yet that it was in fact flashing twice (as outlined above)?
So OK, you are not yet a believer, but as you get more experience, you will realize this mixing is the very hard way to do it. Simply not designed to be used that way. Real Genuine Actual Manual Flash Mode (the mode called M in the flash menu, with the commander turned off) works really great, and is simply unbeatable. Might as well do it right, the way things are designed.
Buy a $28 Yongnuo RF-603 radio trigger (transmitter and receiver units), Amazon. Trigger one remote flash that way, with all the other flashes in optical slave mode (SU-4 on Nikon flashes). That should work great, and consistently.
Or if you want to use the commander, then use the Commanders system, which does NOT include any real manual flashes, and certainly no SU-4.
Make your choice, and go with that system. Trying to be helpful.
Good luck.
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