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Yongnuo RF 602's - my prediction .

Discussion in 'General flash photography, lighting, and technique' started by Desmond, Feb 2, 2010.

  1. I've ordered a set after reading all the good reviews about them .
    I'm guessing they are going to give us something that Nikon wireless doesn't give ..... the ability to harness the distance info of direct flash with TTL/BL mode .
    Since they come with the same number of pin contacts as the flash and hotshoe it seems reasonable to assume that perhaps the camera will not know the flash is working wirelessly and will use the distance info when the flash head is facing forward when it is in TTL/BL mode .
    This is something we would have to be aware of with these units in TTL/BL mode and off camera flash so we would have to either watch our working distance to make sure the flash is the same distance as the camera from the subject or give the flash head one 'click' off direct flash or swivel it backwards to cancel this distance info .
    Either way if it does still work this will give us greater accuracy and consistency with wireless flash .
    When it arrives I'll do some tests and see how well they work :smile:
  2. the 602's don't do ttl (of any flavour) it's basically just wireless flash sync with a wake up signal thrown in (the 'wake up' doesn't work on all flash combinations from what I understand)

    there's a newer version Yongnuo provide that do some kind of wireless ttl but last I read no one was quite sure exactly how it worked :smile:
  3. That sounds boring ! There go my hopes :( 
  4. O2zi3

    O2zi3 Guest

    lol...i wondered what you were going on about.......you completely threw me, i thought you going through the motions of a DIY iTTL conversion on them......come on, you know you can't resist taking them apart
  5. Hey , there was some wireless gizmo advertised a while ago with wireless TTL capabilities .... wasn't it the radio poppers or something ?
  6. Yep , that's the one I was thinking of - thanks !

    There may still be a cheaper way to gain some level of automation , even if it is just having the SB800 on "A" mode and somehow letting the flash know what aperture you are in .
    I just put a meter on my D40 hotshoe contacts and found out that when you turn the camera on the front pin gets a voltage ..... then a half press gives the right rear pin the same voltage . Now with my SB24 the front pin wakes the flash from standby mode when the camera is switched on though I have the rear pins disconnected .
    After finding around 4.8 volts at the pins I changed my meter to "AC" voltage and found that I actually had 9.6 volts "AC" at the pins .
    Now either it's my $12 meter that is out or perhaps we have a frequency there .
    I've brought my hand-held oscilloscope home so I think this weekend is going to involve some 'interrogation' of my camera and flash systems .

    I somehow have a feeling that the rear pin sends the vital information to the flash .. aperture , iso etc .
    Time will tell :rolleyes: 

  7. O2zi3

    O2zi3 Guest

    Yay....we should all club together and get Desmond some iTTL triggers (if they ever ship??) so he can reverse engineer them
  8. The feeds we have on the flash and hotshoe should give us all the information we need . But I have a feeling we will be dealing with frequencies and perhaps binary codes here .
    I was thinking about how the camera and flash could communicate 'if I had to build one ' :rolleyes: 
    The camera doesn't need to tell the flash iso and aperture [ though the Nikons probably do ] , it just has to give a variable output , probably different frequency for stability , to tell the flash how strong to fire .

    If we assume a base iso of 200 and the camera sends a signal to the flash that it wants 1/2 power for a situation , and then you change the iso to 400 [ from 200 ] , the camera doesn't need to tell the flash " iso just changed to 400!" , it just has to halve its request for flash power and ask for 1/4 power flash instead of half power .

    Now my brain is starting to go crazy and suggest we modify the camera remote triggering option of these systems and have your second camera body with a flash on it at the aperture and iso you are using , and make it fire when you press the button on your 'commander' camera and use the TTL reading of the other camera ............... :rolleyes:  :confused:  :biggrin:
    ok , time for my injection .

  9. I just put my [seldom used ] oscilloscope on the contacts . The front pin doesn't seem to do much but that back pin does crazy things - and very fast of course .
    I need to play with the settings but with a half press it sends a very fast pulse out and with my dinky little scope I may never be able to 'capture' it .
  10. Mike66


    Aug 21, 2009
    Darmstadt, Germany
    I brought an O-scope home last night and took some readings from my D90 and the RF-602 receiver. It was late and I didn't spend a lot of time with it, but can confirm Desmond's observations.

    There is a pulse stream on one of the rear contacts (I can't remember which) that is a steady low-voltage square wave with a fixed duration when the shutter release is not pressed, but is a higher voltage waveform when the shutter release is pressed.

    The front pin on the D90 is 5V DC when the shutter release is pressed half way. On the RF-602, the same pin has a steady 2.8V for the same action, but since the RF-602 is powered by two 1.5V AAA batteries, this voltage will never be higher than the combined voltage of the batteries. I suspect the low voltage is the problem with waking up the SB-600 speedlights, but doesn't explain the SB-900 problem.

    I took one of the RF-602 receivers apart, and the two rear contacts on the hotshoe do not appear to be connected to anything on the circuit board.
  11. Sounds like the two rear contacts are fake to make them look more fancy !

    As I mentioned with my SB24 conversions - the flash only seems to need the feed from that front pin to wake it up . With my D40 I was getting the 5 v at the front pin as soon as the camera was switched on - perhaps it goes to sleep after a while as well and turns it off when the camera has been sitting for a while .
    Maybe we can use that rear pin on the receiver then to send a "power request" signal via other means for TTL wireless !?
  12. ok I looked at that other thread to see the problems you mention .... it won't wake the SB600s and it won't let the SB900s go into standby mode and it is ok with the SB800s !
    Cool , I only have 800s :D  .
    I think that a resistor from the front pin to ground may fix the SB900 problem while it sounds like the SB600 needs more voltage ?
  13. Mike66


    Aug 21, 2009
    Darmstadt, Germany
    I can't tell from the circuit board how the front pin is connected, but it might already be tied to ground with a terminating resistor or through the CMOS circuit. It has been bad design for decades to let terminals float as the results are usually unpredictable. With the old TTL digital chip design, pull-up and pull-down resistors were common as the output gates floated. With CMOS and later design, the circuits provided this feature internally. However, it's worth a try.

    I have not set up a voltage divider yet, but I suspect that the SB-600 requires more than 2.8V to wake it from its slumber. If that is the case, then there is no hope for the RF-602 in its current configuration. The acceptable (for me) work around is to disable the standby mode on the SB-600.
  14. Obsidian


    May 12, 2009
    Here's something no one has talked about yet which I feel debunks may Mike's voltage theory. I have two sets of RF-602s and while its true that a half press shutter on the camera does not wake the sb-600, a quick press of the transmitter will. Here's the kicker, the half press of the transmitter that is sitting in the hotshoe won't do it but if I half press a second transmitter it will. I've gotten into the habit of keeping the second transmitter in my pocket and if the SB-600s are asleep, I just press it quickly in my pocket and they wake up. Seems kinda silly but I don't see how that's any different than pressing test on the PWs to wake them up. Test it and see if it works for you.
  15. Mike66


    Aug 21, 2009
    Darmstadt, Germany
    I have never been able to wake up a sleeping SB-600 regardless of which transmitter I use. The first time I tried, the transmitter was not mounted to the camera. Maybe your SB-600s are more sensitive, but this problem with the RF-602 is well documented on the various photography sites. Yours are keepers! :biggrin:
  16. aesop


    Oct 2, 2008
    When my SB600 goes into sleep mode the first trigger gets lost/wakes it?.. and the 2nd ones fires it fine. Nothing fully tested.. just what I've noticed.
  17. TXAvi8tor


    Feb 6, 2009
    Or Yongnuo was thinking ahead. Not that the rear contacts will ever do anything in the 602's, but perhaps they have plans for the next generation, & it was simpler to mfr a single shoe design. They also could have found reverse engineering the AWS / CLS protocol more difficult than anticipated and released 602's without implementing it, even though their initial plans included it.
  18. That sounds very possible - hopefully the next step is wireless TTL .
  19. Mike66


    Aug 21, 2009
    Darmstadt, Germany
    Here is what I found on the left rear contact of the speedlights. When active, each contact had a DC component with a negative going square wave pulse. When in standby, the contact was zero Volts.

    3.75V DC with a negative pulse of 40mV. The pulse width is 8ms and the period is 130ms.

    4.00V DC with a negative pulse of 100mV. The pulse width is 8ms and the period is 250ms.

    4.00V DC with a negative pulse of 80mV. The pulse width is 60ms and the period is 260ms.

    The SB-800 had another interesting surprise on the front right contact, which neither of the other speedlights shared. When the speedlight was active, this contact had a positive going square wave pulse train of 2.5V. The pulse width is 2.5ms and the period is 250ms. When the SB-800 went into standby, the voltage on this contact was zero with no pulse train.
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