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FORUMS General Gear Talk Flash and Studio Lighting 
Thread started 04 Dec 2009 (Friday) 21:44
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Force master to NOT fire

 
Steave
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Location: Chesapeake, va
     
Dec 04, 2009 21:44 |  #1

Using a Sigma 530 DG Super, how would one get the master flash to NOT fire? The manual said to press the select button until the flash symbol is lined out, and I did that, but no matter what I'm doing on my 50D it still fires.

I'm lost :confused:


EOS 1D Mark II, 70-200 f/2.8L, Sigma 24-70 f/2.8, Tamron 19-35, 50 f/1.8, 3x Sigma 530 DG Super
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snakekid
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Dec 04, 2009 21:47 |  #2

it fires to send out a command flash it doesn't contribute to the exposure.


-Will
40d, tamron 17-50mm, 85mm 1.8. a ton of flashes and cybersyncs.

  
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Steave
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Dec 04, 2009 21:52 |  #3

snakekid wrote in post #9137679 (external link)
it fires to send out a command flash it doesn't contribute to the exposure.

Ah, then I should change my question to how would I tell the master flash to switch to infrared command mode? (I'm pretty certain these do have radio or infrared, I managed to make the slave fire without the master firing but cant figure it out now!)


EOS 1D Mark II, 70-200 f/2.8L, Sigma 24-70 f/2.8, Tamron 19-35, 50 f/1.8, 3x Sigma 530 DG Super
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snakekid
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Dec 04, 2009 22:03 as a reply to  @ Steave's post |  #4

... your already doing it, the preflash determines what to set the power at. that is what your seeing from your master. Canon and Nikon both dont use IR anymore they use near visible light systems which is close to IR.


-Will
40d, tamron 17-50mm, 85mm 1.8. a ton of flashes and cybersyncs.

  
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Steave
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Dec 04, 2009 22:08 |  #5

That sounds plausible, but I'm still not sure. I've tried telling the master to fire and the shot comes out exactly the same as when I tell it not to fire, wouldn't it be underexposed when I tell it to not fire? I'm not saying you aren't correct, I just think I'm still missing something. I autofocus using the rear button, hit the FEL button, then meter with the shutter button and then fire.


EOS 1D Mark II, 70-200 f/2.8L, Sigma 24-70 f/2.8, Tamron 19-35, 50 f/1.8, 3x Sigma 530 DG Super
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Steave
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Dec 04, 2009 22:09 |  #6

Oh, and please excuse my lack of knowledge. This is my first time using any kind of wireless flash system.


EOS 1D Mark II, 70-200 f/2.8L, Sigma 24-70 f/2.8, Tamron 19-35, 50 f/1.8, 3x Sigma 530 DG Super
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snakekid
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Dec 04, 2009 22:16 |  #7

as for radio triggering ETTL is going to cost you quite a penny, but it has quite a few benefits. I would recommend manual using yongnuo triggers, if your stressed on cash. If you have money to spare get some radio poppers. Radio poopers allows for ETTL or manual, if you using manual mode im not sure if you keep hss. Strobist's blogspot is a great place to learn about off camera flash. I heard hot shoe diaries is a good book too. Im thinking about buying the book.


-Will
40d, tamron 17-50mm, 85mm 1.8. a ton of flashes and cybersyncs.

  
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PacAce
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Dec 04, 2009 22:24 |  #8

Steave wrote in post #9137835 (external link)
That sounds plausible, but I'm still not sure. I've tried telling the master to fire and the shot comes out exactly the same as when I tell it not to fire, wouldn't it be underexposed when I tell it to not fire? I'm not saying you aren't correct, I just think I'm still missing something. I autofocus using the rear button, hit the FEL button, then meter with the shutter button and then fire.

Where is the slave flash located? If you move it to one side away from the camera, then you should be able to see a difference between the master firing and the master not firing, assuming you're not so close to the subject that the command signal is contributing significantly to the exposure. Also, make sure you're not using a very high ISO (above 1600)


...Leo

  
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Steave
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Dec 04, 2009 22:25 |  #9

Thanks for the info, I've looked at strobist a few times.

In regards to my previous post though, I can guarantee you the master flash does fire at full power regardless of it's menu settings. I tested it by doing everything as normal, then firing the flash with my hand over the master flash leaving enough space so that the slave can pick up the flash to fire optically. Then I tried it without my hand. Comparing the two results I can tell that the first shot had only one light source from the shadows, and the second had two of equal power.

This system MUST (from what I can figure) use infrared/near visible light command and firing, how else would you be able to remotely controll power output on the slave from the master? I don't see my master shooting flashes in binary :p


[edit] I just think my main problem is that I'm not sure how to set my flash from optical trigger to infrared.


EOS 1D Mark II, 70-200 f/2.8L, Sigma 24-70 f/2.8, Tamron 19-35, 50 f/1.8, 3x Sigma 530 DG Super
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PacAce
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Dec 04, 2009 22:31 |  #10

Steave wrote in post #9137949 (external link)
Thanks for the info, I've looked at strobist a few times.

In regards to my previous post though, I can guarantee you the master flash does fire at full power regardless of it's menu settings. I tested it by doing everything as normal, then firing the flash with my hand over the master flash leaving enough space so that the slave can pick up the flash to fire optically. Then I tried it without my hand. Comparing the two results I can tell that the first shot had only one light source from the shadows, and the second had two of equal power.

This system MUST (from what I can figure) use infrared/near visible light command and firing, how else would you be able to remotely controll power output on the slave from the master? I don't see my master shooting flashes in binary :p


[edit] I just think my main problem is that I'm not sure how to set my flash from optical trigger to infrared.

You are correct, the visible light which is also made up of the invisible IR light is used to communicate the command to the slave. However, the intensity of the command flash is relatively low so it shouldn't contribute much lighting, if any, to the resulting image unless you are using a very high ISO. If you can see that the master is contributing significantly to the image, then you must not have the master flash turned off properly.

BTW, there is no way to just have the IR portion of the flash emitted unless you use an IR filter in front of the flash head.


...Leo

  
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Steave
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Dec 04, 2009 22:39 |  #11

PacAce wrote in post #9137985 (external link)
You are correct, the visible light which is also made up of the invisible IR light is used to communicate the command to the slave. However, the intensity of the command flash is relatively low so it shouldn't contribute much lighting, if any, to the resulting image unless you are using a very high ISO. If you can see that the master is contributing significantly to the image, then you must not have the master flash turned off properly.

BTW, there is no way to just have the IR portion of the flash emitted unless you use an IR filter in front of the flash head.

Hm, I always thought that with an IR system it uses infrared only to fire the slave, and an optical system used visible light. It just doesn't make sense to me why a system that can talk to one another via infrared would not use that to send the fire command, though I'll take your word for it :)

[edit] So I know why the flash was affecting my photos, and it's fixed now. I also realized that the optical flash command fires before the exposure is taken, so it does not affect the final image. I still just don't get why it isn't possible to send the fire command via infrared only.


EOS 1D Mark II, 70-200 f/2.8L, Sigma 24-70 f/2.8, Tamron 19-35, 50 f/1.8, 3x Sigma 530 DG Super
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PacAce
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Dec 04, 2009 22:54 |  #12

Steave wrote in post #9138038 (external link)
Hm, I always thought that with an IR system it uses infrared only to fire the slave, and an optical system used visible light. It just doesn't make sense to me why a system that can talk to one another via infrared would not use that to send the fire command, though I'll take your word for it :)

[edit] So I know why the flash was affecting my photos, and it's fixed now. I also realized that the optical flash command fires before the exposure is taken, so it does not affect the final image. I still just don't get why it isn't possible to send the fire command via infrared only.

The flash fires a light that's composed of both visible light and IR light. The only way to get the flash to fire the command pulse using only IR would be to place an IR filter in front of the flash head. But if you did that, then the flash would be useless for lighting up your images. The ST-E2 works exactly like that. It's basically a small flash with an IR filter covering the flash head. That's the reason it can only be used as a master but not a flash and can't contribute any light to the picture.


...Leo

  
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Steave
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Dec 04, 2009 23:01 |  #13

PacAce wrote in post #9138113 (external link)
The flash fires a light that's composed of both visible light and IR light. The only way to get the flash to fire the command pulse using only IR would be to place an IR filter in front of the flash head. But if you did that, then the flash would be useless for lighting up your images. The ST-E2 works exactly like that. It's basically a small flash with an IR filter covering the flash head. That's the reason it can only be used as a master but not a flash and can't contribute any light to the picture.

Ah, it all makes sense now. I thought for some reason that the infrared signal came from the devices in the red-tinted part of the flash. I never would have thought that the main strobe sent it!

Considering my 530 cost as much as the st-e2, I think i'll just make an IR filter (external link) and have at it. Thanks for the help all! :D


EOS 1D Mark II, 70-200 f/2.8L, Sigma 24-70 f/2.8, Tamron 19-35, 50 f/1.8, 3x Sigma 530 DG Super
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Force master to NOT fire
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