# What is master and slave flash?



## danman281 (Nov 28, 2008)

What is master and slave flash? I have a speedlite 430ex and I know that is a "slave" but what is the difference? My cactus v2 is coming in but I don't see what the master is for if I don't really need it? Thanks


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## Warren_G (Nov 28, 2008)

With the 430ex, the master must be another Canon Flash with IR master capabilities. The 580ex, or the 580exII, or Canon makes a dedicated slave: [ame]http://www.amazon.com/exec/obidos/tg/detail/-/B00004WCFY/ref=ord_cart_shr?%5Fencoding=UTF8&v=glance[/ame]

The Canon system has advantages in that it retains the ETTL info, and can use the "brains" of the flash as if it was attached to the camera. The disadvantage is that it uses IR and must have line of sight between the master and slave.

The cactus triggers use RF so they will be more reliable in larger space, or outdoors, but the flash must be adjusted manually if you want to change the flash power.


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## danman281 (Nov 28, 2008)

Warren_G said:


> With the 430ex, the master must be another Canon Flash with IR master capabilities. The 580ex, or the 580exII, or Canon makes a dedicated slave: http://www.amazon.com/exec/obidos/tg/detail/-/B00004WCFY/ref=ord_cart_shr?%5Fencoding=UTF8&v=glance
> 
> The Canon system has advantages in that it retains the ETTL info, and can use the "brains" of the flash as if it was attached to the camera. The disadvantage is that it uses IR and must have line of sight between the master and slave.
> 
> The cactus triggers use RF so they will be more reliable in larger space, or outdoors, but the flash must be adjusted manually if you want to change the flash power.



So basically, having master/slave only affects the IR? 

I was thinking of purchasing another flash but don't know if I should save money and go with a budget vivitar. I think I'll be using RF mostly


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## Big Mike (Nov 28, 2008)

Yes, the 'Master' & 'Slave' are when used with another Canon unit.  The Master is usually on-camera and can control one or more 'slave' units.  When the system works, you get to use E-TTL flash metering and the other features of the units, just like they were on-camera.  The 580 doens't use IR by the way...it uses pulses of light from the flash head.  There is a unit, the ST-E2 that is a master but doesn't have a flash...it uses IR.

As mentioned, when using radio triggers, you don't have the same communication, so it's all manual...but the signal is better in many situation.  

If you are strictly going to use RF, then it might be cheaper to go with a budget flash...but it's also a great benefit to have one or more Canon flashes on hand, so you at least have the option of wireless E-TTL, not to mention you can use them on camera with full functionality.


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## danman281 (Nov 28, 2008)

Thanks a lot guys. It seems pretty clear now.

My cactus V2 just now came in the mail!! w00
I just found out how hard it is to shoot without TTL


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## Big Mike (Nov 28, 2008)

> I just found out how hard it is to shoot without TTL


Don't worry, it's one of those things that gets a lot easier with practice and experience.


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