I have seen a few second hand strobes on the market and wonder whether I can configure them as a second slave, firing as a slave to my S&S YS110.
...
* Is this a good idea?
* Will the second flash balance the main flash or are they to weak anyway?
* Will it work with these strobes (or other)?
It should work. I added a second YS-90, triggered only by the flash of the first one. It worked VERY reliably (100% I think), but that is probably because I used it only with a macro lens, and kept the strobes angled in tightly on either side, so that one was almost firing directly at the other. If you face them both forward or outward, you will probably want a fiber optic cord to trigger the second one rather than depend on reflected light to trigger it.
You can get a secondhand late model YS90 for little money, and that would give you about the power of the 110, and the capability of fine-tuning with 12 levels to either match the other or just act as a fill light.
I think it's a good idea because you avoid shadows, and have to do less fiddling with the strobes to match fish position. With one strobe, if a critter is in 3/4 profile facing to your right, you're okay with a strobe on the left, but bad if it's on the right. With two strobes you're not bad either way it's facing, sorta. With your extra firepower you can turn both down a little and you have faster recycle time too.
