This off camera flash business really is quite fun, but trust me, it isn't as complicated as you'd think or some websites would have you believe.
In fact if you're shooting inside you don't really need to take your flash off the camera to get different lighting effects. Just use a strobe with a swivel head and you can bounce the light of the walls, ceilings, behind you and even recreate bare-bulb effects with certain pieces of tupperware...
But, back to this review of the Yongnuo YN560 Mk.1 Flash, which yes, I picked up from our Sunday morning car-boot for the bargain price of £20. Apart from the price, what makes the YN560 special is it's feature set. In this bargain speedlite you're getting a flash with a motor-zoom head to zoom in and out, the head can also swivel all the way round and aim all the way up. With a variable power output you can go from full power to 1/128th, and this can all be controlled manually or with two very useful slave functions, which I'll talk about in a minute, but trust me when I say that this flash will be powerful enough for most situations.
Let's look at these triggering modes. In m mode you can mount the flash on your camera (in manual mode) and it will fire when you press the trigger. Start off with an informed guess for the required ISO / aperture / power setting then chimp and consult your histogram to adjust the exposure to taste. Whip the flash off the camera and onto a wireless flash trigger and it'll work the same way. Remember that there's no TTL - the camera cannot adjust the power of the flash, so it's up to you to get it right, but with a little practice it's not that difficult.
The other two flash modes, S1 and S2 turn the YN560 into a remote flash without the need for a wireless trigger system. In S1 mode the flash will trigger itself when other manual non-ttl flashes go off, like those on older cameras or other YN560's. With S2 turned on the YN560 will work with TTL flashes, just like the on-camera strobe on your DSLR or compact. That's right, with this cheap little Yongnuo your can do off-camera flash simply using the flash on your camera as the trigger.
The downside to all this is build quality. Check the net for reviews and you'll read stories of broken zoom-heads, dead units and a lack of consistency in the finished product. All I can say is that so far my YN560 has been fine. I rarely use it at full power and I treat all my Yongnuo flashes with kid-gloves and they've all given me excellent results. You get what you pay for, and if you're a skint photographer like myself then the YN560 MK.1 could be a cheap way for you to get into off-camera flash, with most of the bells and whistles of the much more expensive models.