Just don’t. Really. I have no idea why anyone ever does. I so wish I wasn’t tied into the damn things. They’re probably fine and dandy if you’ve got shed-loads of cash. If you haven’t, they absolutely stink.
Take, for example, the subject of a ring flash for macro photography.
If you are fortunate (or sensible) enough to have a Canon or Nikon DSLR not only will you already have a high quality, reasonably priced macro lens (unlike the pathetic misguided – and I use the word advisedly – Olympus owner) but you will also be able to acquire a perfectly adequate ring flash for a mere £128 or so, no doubt considerably cheaper in dollar terms if you live in the US.
If you own an Olympus then dream on. There’s no third-party ring flash for you. Should you want a set-up like your happy Canon or Nikon owning friends you have to shell out for the notoriously over-priced Olympus branded accessories. So a mere £470 (lowest price I could find) is all that’s required. Unless of course you actually want to – gasp – use it with your macro lens. In which case you also have to shell out for the “optional Flash Adapter Ring FS-FR1” (in what sense “optional”, I ask myself, when the fucking thing won’t actually fit on the lens without it) which is a no doubt highly engineered piece of kit looking suspiciously like a plastic tube which costs the absolutely trifling sum of £85.
To summarise. Nikon or Canon? £128. Olympus? £555.
And don’t get me started on lenses. Just don’t. I might have an embolism or something.