TTL has been explained above. iTTL is Nikon's latest iteration. Features on their SB800 flash includes being able to remotely control another SB600/800. From my understanding this only works if you have an SB800 controlling a 600 or 800 but not if you have an SB600 controlling another 600.

As far as it being expensive is concerned, compared to Olympus, your SB800 is less than have the price of their equivalent top of the line flash which is roughly $500 and doesn't have the remote control capabilities.

There are a number of iTTL compatible flashes including units from Metz an Promaster. About the only missing feature on these 3rd party flashes is the aforementioned remote control feature.

I should point out that the promaster is about the same price as the 800 and the Metz is nearly $500. Both Promaster & Metz are usable for multiple brands and types of cameras through the use of specific modules which is a nice feature if you own different brands of camera's like me.

HTH.

thirdlife wrote:
> Can someone explain TTL/iTTL to me?
>
> I am just getting back into photography and trying to get up to
> date on technology.
>
> Also, why are flashes and flash accessories so expensive? The
> SB600 and SB800 specifically.
>
> Thanks!

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Primary Camera: Nikon D70 w/ Tamron 28-300 lens
Backup Camera: Olympus C-8080WZ