# Canon Speedlite 600EX-RT



## tazdog (Jun 10, 2015)

How do you turn off the preflash?

Thanks


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## neuroanatomist (Jun 10, 2015)

Use manual exposure, not E-TTL.


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## privatebydesign (Jun 10, 2015)

If you want "Auto" exposure and no pre flash you can use 'Ext A' mode too. It is an auto thyristor system so it doesn't use a preflash.


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## tazdog (Jun 10, 2015)

I was shooting in manual and my light meter was giving me a lower reading than it should have. I spoke to Sekonic and they said it was the pre flash. Are you sure that when you switch to manual that it also turns off the pre flash. It should like that would be correct but are you sure there is not switch?

Thanks


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## privatebydesign (Jun 10, 2015)

tazdog said:


> I was shooting in manual and my light meter was giving me a lower reading than it should have. I spoke to Sekonic and they said it was the pre flash. Are you sure that when you switch to manual that it also turns off the pre flash. It should like that would be correct but are you sure there is not switch?
> 
> Thanks



Flash manual is different to camera manual. You can be in camera manual and flash ETTL.


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## tazdog (Jun 10, 2015)

Sorry about my earlier reply. My flash was in manual mode and my camera was also.


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## neuroanatomist (Jun 10, 2015)

tazdog said:


> I was shooting in manual and my light meter was giving me a lower reading than it should have. I spoke to Sekonic and they said it was the pre flash. Are you sure that when you switch to manual that it also turns off the pre flash. It should like that would be correct but are you sure there is not switch?



In manual flash exposure there's no preflash. There's no switch for preflash. 

If you'd like to test for yourself, enable mirror lockup. In that mode, the first shutter press locks up the mirror, and sets the flash exposure with a preflash. The flash for the image occurs when the image is captured with the second shutter press. With E-TTL, the flash fires at both shutter presses, with manual flash exposure it only fires with the second press.


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## tazdog (Jun 11, 2015)

Thank you


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