iTTL and the SB800

I am currently experimenting with trying to set up my D70 to use iTTL by using a SB800 in a Subal housing.

On land and in the pool it works very well. My probem is coming from trying a find a second strobe to slave. I have failed with 1) DS125 and optical sensor 2) YSDX90 using pre flash sensor and 3) YS90 in slave TTL (that one was expected). I have now reverted to white slate and a bendy arm to reflect light back.

The sensors seem not to be able to distinguish the iTTL preflashes - I had read somewhere that the iTTL preflashes are much faster than eTTL or DTTL so this may be the problem. I am very interested to hear other comments on this if they have any?

Could anyone slave a strobe with the SUbal SB80 (DTTL)?

What setting(s) did you use for the DS125 w/ Optical sensor? Was it the Manual sensor or the TTL sensor?

Cheers

James

In some respects this does not surprise me. My understanding of the way the TTL works with the DS125 and DS50 is that they are meant to respond to a single preflash. I don't know about iTTL, but I seem to recall reading somewhere that eTTL uses a stream of 14 (???) or more preflashes to communicate with other strobes, and iTTL is similarly complex, perhaps a bit less...

I think that the only way you're going to be able to slave an additional strobe using iTTL will be to house another SB800, or the SB600 when it becomes available. There goes some more of those hard-earned scubabucks

Craig,

I'm not sure if I agree with you - the only way to find out is to try it. Therefore, I'll test D-TTL tonight w/ the Ike Manual Slave Sensor/DS125 slaved to the SB28DX.

D-TTL fires 18 preflashes.

If the Ike slave sensor is set to ignore the low power preflashes, then it might work, if the preflashes are in a pretty tight group (and they are according to Thom) and relatively low power.

So - we'll see. I'll point the SB28DX up towards the ceiling and the DS125 straight ahead at a subject.

Of course, tTTL may be significantly different when it comes to the preflashes, but I don't think it is.

Cheers

James

ETTL fires a couple of preflashes which will make your Ikelite slave sensor going crazy but only if the wireless slave TTL is on. In normal mode there is only one preflash and you can trigger another strobe, like the YS90 DX or Ike50DS with manual controller, on the mainflash only. I guess iTTL has such slave mode, too and it can be disabled in someway.