My one-sentence review:
The Sonia slave syncs great with the SB-20, but it's still an inexpensive optical trigger and has limitations.
Hardware and Build Quality:
Most eBay Sonia slaves have a female PC-sync and are packaged as a pair with a hot shoe -- at least, that was what I purchased. Sonia slaves are available individually with other connection mechanisms (FlashZebra has a range with male PC, female PC, microphone jacks). While I'd love if they'd packaged the male PC-sync slave (so I could slap it directly on an SB-20 if I desired) I expect it was probably a safety-type issue to make sure the multiple-sync capability worked.
Yes, I said multiple sync. But more on that later.
I went with the hot shoe option because the price was about the same as the peanut alone and I need a 1/4" screw mount to fit my flashes to my tripod/light stand/monopod. For the record, I paid $12.95 + $2.01 shipping, which is relatively cheap for a slave + hot-shoe mount, but still the cost of half an SB20.
Actually, maybe I should refer to everything in terms of SB-20s now... I get paid about one SB-20 an hour at my job and my rent is a little under 100 SB-20s a month! Yes, I know my hourly rate is too low compared to my rent -- I live in the bay area after all! Anyway, back on topic...
First, the slave itself.
There really isn't much to it -- a few components soldered together and epoxied into one solid little package about the size of my thumbprint. By inspection, it looks like a few resisters, a cap, a transistor, and a phototransistor at the business end. My phototransistor isn't centered very well which may be influencing my sensitivity (or maybe that's by design). The female PC connection is solid and unlikely to break (good thing too -- I could never fix it if it did). I'd have no qualms about letting these little guys float around in a gear bag -- they'd never break. FYI, all pictures are clickable if you want to see the units larger.
The hot shoe is definitely a big step up from the Chinese optical triggers. Instead of plastic, the entire unit is made from metal. I suspect it is machined because I see no obvious mold marks, which is remarkable for such an inexpensive unit. It really is a tank and you'll break your hot shoe before you break the foot of this thing. The back is marked with "Sonia, multi-terminal slavettach solid state" in retro RCA fonts. Somebody in India likes their antique radios. And you gotta love the solid state to let us know they didn't cram any vacuum tubes inside!
The most important part of any hot shoe is the connections, and there's no disappointment here. The peanut attaches to the shoe very securely. All three PC connections (two female, one male) are a step above what you usually get in a cheap unit. I don't foresee anything breaking in the future. And the hotshoe on the top is simply a tank. Overall, the whole thing is the most solid accessory I've seen. As you'd expect, it has some mass to it, but it's small enough that it doesn't really matter.
Funny thing actually -- the other day I found that the back of my Chinese optical slave had fallen off. Apparently it had gotten hot enough in the garage to make the adhesive fail and the back just popped off on its own -- luckily it wasn't structural and I snapped it back on easily.
Functionality:
Of course, what really counts is how an optical slave trigger works. And in that respect, I can't tell it apart from my Chinese optical slave other than the fact it works with a Nikon SB20. That's not necessarily a good thing.
Indoors, it works pretty well as long as there is a direct line of sight from another flash to the eye, or at least a line of sight from a bright reflection (like white paper) to the eye. The only time I've had trouble getting sync was when the trigger was in shadow, as you'd expect. Once you get things set up, the triggers work as their supposed to near 100% of the time.
Outside, though, it is a whole different story. In deep shade with the source flash on high, close, and directly illuminating the trigger you may have a chance. In the sun, or near sunlight, the Sonia unit will just not trigger. When I was shooting the bees I tried a lot of different approaches (including shading the sensor) and nothing worked. So with cheap triggers, the verdict is still OUTDOORS = BAD, INDOORS = GOOD.
I should also mention that there are reports of the Sonia slaves not working with the Canon 580 EX II. I believe I read something somewhere about a mod to the Chinese slaves to make them work on the 580 EX, but it isn't really possible on a Sonia since everything is encased in epoxy. Anyway, you've been warned.
Multiple Sync:
If the solid build of the hot shoe unit wasn't enough to motivate you to pay the extra few bucks for it, they've also added a multiple-sync capability with 'built-in diodes'. What this means is, if you attach the peanut slave to the male sync socket, you can attach a flash to a hot shoe and two other flashes to the female PC sockets on the sides with PC cables. And yes, everything will trigger at the same time!
It turns out I have PC cables for my Sunpak 383 and another hot shoe around the house (I had totally forgotten about them), so I verified multi-sync capability with all three flashes. Of course, I couldn't get a picture because my 20D refused to omit the preflash.
So, the image at left only shows two flashes going off. But I was seeing all three go when I fired my 20D.
I love the idea of using this little baby to triple the power of the flash (or cut the recovery time). Sadly, the best place to use that feature would be outdoors, where the trigger refuses to even go. But, I may try adapting a radio trigger to female PC-sync to make a super-powerful three-flash rig.
While multi-flash capability isn't really a killer app inside, I'd rather have the capability than not. And if I had a longer PC-sync cable, it'd let me add even more to a studio rig.
Conclusions:
If you use SB-20s or might buys some in the future, you need to buy this optical trigger, period. Chinese triggers just don't cut it with those units.
If you don't use SB-20s, I still might recommend the Sonia triggers because of their superior build quality and multi-sync capability. I'm not sure I'd pay double for Sonia triggers, but a few bucks is definitely worth it.
If I get another flash, I'll likely pick up another Sonia trigger and/or another wireless trigger. Either way, I'm definitely not buying any more of the cheap Chinese triggers.
If you're curious, here are the current Sonia trigger listings on eBay. eBay seems to have the best prices for the triggers, but that could change -- make sure you look around!
Note: I recently posted an update about some problems I've been having with the trigger.