Does anyone know of a real review of these devices? There are a number of comments around on the net saying "I like," but nothing else.

I'm leaning towards the Sony, since I can find it for under $300. But I don't know if that is smart move or not.

The Sony Ring Light is a complete waste of time and doesn't even fit your camera without an adaptor. it's also not a flash, just a light so it will not freeze motion. The Sigma is at least a flash and works pretty well. it has a lot of features. If your not using one of the SLT cameras there is a Marumi/Delta/Bower branded (they all look the same) flash that is compatable and will give you TTL support as well. it's cheap but not as full featured as the Sigma.

I had the Sony Ring Light and found it all but useless for anything but product and still-life shots. It went through batteries pretty quickly also. Sold it and bought the Sigma ring flash when Amazon put it on sale for about $196 awhile back. Haven't used it much yet, but it's definitely much better for outdoor macro shots and portraits.

Ring lights are just that, not much good for other than lighting.
As the others have said the Sigma is far better, or you could try one of the flash gun conversions made by Flaghead, I have not used one myself,a friend of mine has with Nikon and he says it works well, you won't be able to switch sides (right or left) If you want to use this sort of thing lots of times go for the Sigma flash it may cost more but it willdo all you ask.
regards
Richard

You might find the following article helpful:

http://shutterbug.com/equipmentreviews/lighting_equipment/1110macro/

I picked up the ring light (again, mistakenly thinking it was a flash unit) but am reasonably happy with it for what it is. However, I was lucky to pick it up as an 'end of line' bargain in PC world for 149 GBP - at 280 or 300 plus it goes for at Jessops, I might have returned it.

Scott

I would not pay the Sony price either. But I found one on ebay for $200 and its about what I expected. Not great, but not bad for what it is. After playing a bit, I figure its a going to a great tool for copying documents that are in archives and can't be taken to a copier.

I'm going to ask the US National Archives if they will allow its use on documents. They allow a few LED scanners to be used. Maybe this device will pass their concerns too.

Someday soon I'll try it on spring flowers too. If winter ever leaves.