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Thread: PT-04 Wireless flash trigger questions

  1. #1

    Default PT-04 Wireless flash trigger questions

    Hi CSers,

    would like to ask. i just bought the trigger from artworkfoto. but just now i tried in on my 420EX. whe photos are taken under slow shutter speed, the photos were over exposed totally.
    but as i change my settings like increasing my shutter speed, half of the photo is totally black, and other half is normal. i tried this with both of my 500D and my friends D90, both showed the same thing. so the point is?is it a faulty unit or my method to use it is wrong?or is there any other reason?

    1/400s, iso 200, f4.0
    Last edited by RoyZilla92; 2nd June 2010 at 10:03 PM.

  2. #2
    Senior Member +evenstar's Avatar
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    Default Re: PT-04 Wireless flash trigger questions

    ETTL does not work with this trigger if i'm not wrong. u have to manually set the flash output, which u can't do so with the 420EX, so it'll always fire at maximum output
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  3. #3
    Member blaz7's Avatar
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    Default Re: PT-04 Wireless flash trigger questions

    There is no metering information passed on to the flashgun using this flash trigger, so the flash will always be flashing at the power you set it at. With slower shutter speed, its brighter, high shutter speed, its darker, you need to manually adjust the flash power vs the shutter speed to get the result that you want.
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  4. #4

    Default Re: PT-04 Wireless flash trigger questions

    Evenstar already explained why the ETTL won't work through the PT-04. As to why half your photo is black, you might try googling 'flash sync speed' to find out why.
    Essentially, changing the shutter speed won't affect your flash exposure, but changing your aperture will

  5. #5

    Default Re: PT-04 Wireless flash trigger questions

    owh yeah.. 1/200 is the most fastest speed that can be used in flash sync. the conclusion is that the half exposed photos are captured, because of my cam is faster than my flash?!
    quick response from CSers thanks a lot!

  6. #6

    Default Re: PT-04 Wireless flash trigger questions

    No, your cam isn't faster than your flash

    There should be some good explanations out in the Web, with diagrams, but here goes:
    Focal plane shutters (the kind in DSLRs) use two curtains. First curtain 'covers' the sensor. When you press shutter release, first curtain moves aside, letting light fall on sensor. After the predetermined exposure time, the second curtain closes. As shutter speeds get faster, the 2nd curtain starts closing before the 1st curtain's travel is complete.
    Max sync speed is the fastest speed when the sensor is completely exposed at any point in time -- this is when your flash fires, when the 1st curtain is out of the way, but before the 2nd curtain starts to move. The black area you see in your pix (1/400s, about double your max sync speed) is actually the 2nd curtain covering part of your sensor.

    Hope you understand -- like I said, diagrams would help!

  7. #7

    Default Re: PT-04 Wireless flash trigger questions

    Quote Originally Posted by Edwin Francis View Post
    No, your cam isn't faster than your flash

    There should be some good explanations out in the Web, with diagrams, but here goes:
    Focal plane shutters (the kind in DSLRs) use two curtains. First curtain 'covers' the sensor. When you press shutter release, first curtain moves aside, letting light fall on sensor. After the predetermined exposure time, the second curtain closes. As shutter speeds get faster, the 2nd curtain starts closing before the 1st curtain's travel is complete.
    Max sync speed is the fastest speed when the sensor is completely exposed at any point in time -- this is when your flash fires, when the 1st curtain is out of the way, but before the 2nd curtain starts to move. The black area you see in your pix (1/400s, about double your max sync speed) is actually the 2nd curtain covering part of your sensor.

    Hope you understand -- like I said, diagrams would help!
    YEah i can understand it very well. Thanks a million!!!

  8. #8
    Moderator ed9119's Avatar
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    Default Re: PT-04 Wireless flash trigger questions

    i believe u are firing the shutter at a faster speed than max sync speed stated in the cam's spec sheet

    both the 500D and D90 Flash Sync Speed are 1/200 sec

    shoot at 1/200 or slower if you want to avoid the problem you have in your uploaded image above
    Last edited by ed9119; 3rd June 2010 at 12:40 AM.
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  9. #9

    Default Re: PT-04 Wireless flash trigger questions

    Black part of photo is because you care shooting above max sync speed (you shot at 1/400). I think the max sync speed on your cam is probably between 1/180 to 1/250.

    When using a wireless system like a PT-04, it does not have a communication between camera and flash. You have to set the flash and camera exposure on manual. You'd need to google and read up on using manual flash.

  10. #10
    Moderator daredevil123's Avatar
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    Default Re: PT-04 Wireless flash trigger questions

    Quote Originally Posted by Edwin Francis View Post
    No, your cam isn't faster than your flash

    There should be some good explanations out in the Web, with diagrams, but here goes:
    Focal plane shutters (the kind in DSLRs) use two curtains. First curtain 'covers' the sensor. When you press shutter release, first curtain moves aside, letting light fall on sensor. After the predetermined exposure time, the second curtain closes. As shutter speeds get faster, the 2nd curtain starts closing before the 1st curtain's travel is complete.
    Max sync speed is the fastest speed when the sensor is completely exposed at any point in time -- this is when your flash fires, when the 1st curtain is out of the way, but before the 2nd curtain starts to move. The black area you see in your pix (1/400s, about double your max sync speed) is actually the 2nd curtain covering part of your sensor.

    Hope you understand -- like I said, diagrams would help!
    Best answer

  11. #11

    Default Re: PT-04 Wireless flash trigger questions

    yeap, i can really understand it now. thanks for all of the response and points are noted!newbie afterall..will try using my friends 550ex today..

  12. #12

    Default Re: PT-04 Wireless flash trigger questions

    Quote Originally Posted by RoyZilla92 View Post
    Hi CSers,

    would like to ask. i just bought the trigger from artworkfoto. but just now i tried in on my 420EX. whe photos are taken under slow shutter speed, the photos were over exposed totally.
    but as i change my settings like increasing my shutter speed, half of the photo is totally black, and other half is normal. i tried this with both of my 500D and my friends D90, both showed the same thing. so the point is?is it a faulty unit or my method to use it is wrong?or is there any other reason?

    1/400s, iso 200, f4.0
    I also got this problem! Now I know wat's going wrong !
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  13. #13
    Senior Member Numnumball's Avatar
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    Default Re: PT-04 Wireless flash trigger questions

    TS/Zahne:-

    Thats why you can’t set your camera’s shutter speed over a certain value when you have your speedlight switched on (and when u have High speed sync disabled)

    Just to add, the light from your flash is dissipated as an instantaneous burst of light. Its somewhat like 1/2000th of a second (read frm somewhere). So its extremely important to realise that the light from your speedlight isn’t continuous light, but instantaneous.

    To explain in another way Edwin Francis did (which is already quite detailed ): -

    Basically, your shutter consists of two curtains that travel across your sensor/film gate. So for flash to be exposed over the entire frame, your shutter speed needs to be low enough that the first curtain has completely cleared the sensor area (ie, the sensor is fully open), BEFORE the second curtain starts moving. In that moment, the flash is discharged, and the entire frame is exposed.

    If we will to shoot in a dark environment (e.g studio with no lightings which is near dark) then we can get correct flash exposure at slower shutter speeds like 1/15th to 1/60th etc…no problem.. the shutter speed has no effect on flash exposure … as we remain below maximum sync speed.

    So maximum sync speed, is the highest shutter speed at which the entire frame is still open for flash to expose for the entire frame (whether a digital sensor or piece of film).
    If we go over maximum sync speed, we’ll get one of the shutter curtains blocking the flash exposure!

    In your underexposed pic above, that dark area on the right is the shadow of the one shutter curtain obscuring the light from the flash!

    hope this clearer explanation (on top of Edwin Francis) will help those still in doubt

    Cheers

    Bryan
    Last edited by Numnumball; 3rd June 2010 at 06:48 PM.
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  14. #14
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    Default Re: PT-04 Wireless flash trigger questions

    http://www.youtube.com/watch?v=hvZ6VujbhjM

    this video gives details description.

  15. #15

    Default Re: PT-04 Wireless flash trigger questions

    ps to dig this thread.
    What can affect a strobe sync speed?

    Say using D90, I have a SB600 + SB900, using pt04 triggers, which says it max at 1/200 - 1/250, shooting indoor with 2-3m from subject.
    But @ F4.5, with ISO100, i had only managed to max out @ 1/125 else 1/160 with F2.8-F4.

    What affect the sync speed? I do not seems to find any possible reason. What am i missing here?
    I understand the cam sync speed and speed light operate like what numnumball said, light burst instantaneously not continuously.

  16. #16
    Moderator catchlights's Avatar
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    Default Re: PT-04 Wireless flash trigger questions

    Quote Originally Posted by akagi07 View Post
    ps to dig this thread.
    What can affect a strobe sync speed?

    Say using D90, I have a SB600 + SB900, using pt04 triggers, which says it max at 1/200 - 1/250, shooting indoor with 2-3m from subject.
    But @ F4.5, with ISO100, i had only managed to max out @ 1/125 else 1/160 with F2.8-F4.

    What affect the sync speed? I do not seems to find any possible reason. What am i missing here?
    I understand the cam sync speed and speed light operate like what numnumball said, light burst instantaneously not continuously.
    sync speed, as in the shutter speed where the front and rear curtain of the shutter are fully opened when flash fired.
    here is the when how the shutter able to fully open at 1/60s



    here is how the shutter become a slit when the speed is 1/1000.



    the higher the shutter speed, the narrower the slit, this is the is how the black strip come from when you using higher the than sync speed.
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  17. #17

    Default Re: PT-04 Wireless flash trigger questions

    yes, but what can affect the sync speed.. since D90 can perform up to 1/200.. and my flash output set at 1/4, I just dun get it.. unless kana cheated by the poor quality trigger

  18. #18
    Moderator ed9119's Avatar
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    Default Re: PT-04 Wireless flash trigger questions

    Quote Originally Posted by akagi07 View Post
    ............ and my flash output set at 1/4, I just dun get it...... unless kana cheated by the poor quality trigger
    your camera's max flash sync speed is built in already into your camera ... there is nothing u can do about it

    1/4 output on your flash probably means it is giving out 1/4 power NOT 1/4sec

    stop pointing fingers at the trigger ..... its function is to trigger the receiver ... nothing else....

    when receiver cannot read signal from trigger leading to NO flash going off ......THEN point your finger at the trigger/receiver
    Last edited by ed9119; 12th July 2010 at 04:58 PM.
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  19. #19
    Moderator catchlights's Avatar
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    Default Re: PT-04 Wireless flash trigger questions

    Quote Originally Posted by akagi07 View Post
    yes, but what can affect the sync speed.. since D90 can perform up to 1/200.. and my flash output set at 1/4, I just dun get it.. unless kana cheated by the poor quality trigger
    some triggers may not sending the signal to the receiver accurately, hence causes the syncing issue, it is very easy to overcome by using a slower shutter speed.
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  20. #20

    Default Re: PT-04 Wireless flash trigger questions

    Quote Originally Posted by ed9119 View Post
    your camera's max flash sync speed is built in already into your camera ... there is nothing u can do about it

    1/4 output on your flash probably means it is giving out 1/4 power NOT 1/4sec
    i know its 1/4 power not 1/4 secs like my cam shutter else my pic is OVerexposed.

    Quote Originally Posted by ed9119 View Post
    stop pointing fingers at the trigger ..... its function is to trigger the receiver ... nothing else....
    when receiver cannot read signal from trigger leading to NO flash going off ......THEN point your finger at the trigger/receiver

    Quote Originally Posted by catchlights View Post
    some triggers may not sending the signal to the receiver accurately, hence causes the syncing issue, it is very easy to overcome by using a slower shutter speed.
    perhaps what catchlights highlighted is what I suspected.. thanks dude..
    what ed9119 quoted is true for a faulty set, which I'm not idiot right.. to not know that

    even though a product made in china, so if they say its able to do high speed sync @ 1/250, so I dun think 1/200 is an issue, when I have checked everything mah.
    So if not the body, if not the light output, so it gotta be the trigger right..

    am i like asking stupid quest here.. i'm trying to clear my doubts..

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