off camera flashes?

[Christi V]

ok i am trying to do the glowing tangerine.. i have a flash which also has a "slave' feature... the camera flash ( auto mode) also flashes, there for it wont really show a really black background.
I dont think the flash in slave mode will go off in any other mode on my cannon T1x so do any of you guys know if I will have to get a 'cord' to make this work?

[inkista]

What flash do you have? There are different kinds of slave modes. We need to know if you're talking about an optical slave, or an eTTL "slave" mode.

If you have an optical slave in the flash, like with an SB-26, you can use the pop-up flash on the T1i to command it, you just have to set it to 1/2 power or lower so that it can recycle between the pre-flash and the main flash burst. But most optical slaves will have a problem with the Canon pre-flash from eTTL, and you can't turn this off, like Nikons can.

If you are talking about an eTTL "slave", with a 430/580EX speedlight set to Slave mode, then yeah, you're going to need some kind of triggering scheme like a sync cord, or radio triggers, or you're going to need another Canon speedlite (550EX/580EX/580EXII/ST-E2) on the hotshoe to be the "master" unit.

[Christi V]

I bought a Vivitar 648 power zoom it has the option to switch to Slave Mode or eTTL.. i set it a 1/1 which makes the camera flash go off at the same time in AUTO. but they go off at the same time... do you think a cord would be better? the little book didnt give much instructions on how to set the flash anyways? I have returned one cord already... b & H says the cannon off shoe cord # 3 will work with the Vivitar 648Zoom.. i had to return one already as it didnt work..
fustrating....

[inkista]

I think your "Slave" mode is an optical slave, so the only issue is whether it's actually firing in synch with your pop-up flash. If it is, then you can use that. You can dial down the FEC of the onboard flash if you want to reduce its light in the image.

A sync cord would be better in some situations, but given that you're using a 3rd party flash, I'm not sure what to tell you in terms of compatible sync cords. Basically, you'd want to use a sync cord if a) you wanted to use eTTL to automatically set the power on the flash for you or b) you wanted to position the remote flash in a way that it might not see the pop-up flash or c) you didn't want the onboard flash to contribute any light to the scene at all. If the sync cords are to much of a pain, you might want to consider using cheap radio triggers, like Cactus V4s or the YongNuo RF-602s. You won't be able to use eTTL with them, but an Rx/Tx set can actually cost about the same as a sync cord.

You may want to search through the Strobist group discussions on Flickr to see if anybody else knows your Vivitar model well enough to advise you on what works for them.