Some SB-20 Sync Problems

I set up a little studio in my garage (details forthcoming) and in doing so I learned a few more things about the SB-20 that I'd like to share. Namely, it is a little quirky when it comes to syncing, and I think I've finally figured out some of the problems.


The Multiple Trigger Problem:

First, I've known for a while that if an SB-20 gets triggered twice in a row (rapidly) it seems to dump all the capacitor charge into the tube on the second trigger. In other words, if you have it set to 1/4 power and hit the button twice very quickly, the first flash will be 1/4 power and the second will be whatever is left (3/4 power).

In practice, this is less of a problem than it sounds, because even when my 20D is at full speed (5 fps) it isn't fast enough to cause a problem. But I noticed the effect a lot when I had a crappy connection between the SB-20 and my eBay wireless trigger. To solve the problem I rewired the connection (clipping the end of the trigger and attaching a separate 1/8" plug) and it has been very reliable ever since.

In other words, don't worry about it, but understand that a poor connection or rapid cycle time can cause the SB-20 to become inconsistent.


The Chinese Optical Slave Problem:

This second problem is a bit more serious and I had to find alternate hardware to get around it.

Apparently, the cheap Chinese optical slave triggers (seen in the picture above) lock the SB-20 up after each fire. The slave will fire the SB-20 the first time, but then it won't respond. Removing the slave from the flash will reset it as will pushing the test button on the back of the SB-20. Actually, the first time you push the test button on the SB-20 there isn't a flash, but then afterward, since it has reset, it will flash each time you push it.

Once I figured this out, using all three lights (I only have two radio triggers) meant firing a single shot, manually pushing the test button on the SB-20, shooting again, etc. In other words, it very much interrupted my flow.

FYI, I verified the problem on both SB-20s yet my eBay trigger works fine with both of them. So it is definitely some sort of incompatibility between the SB-20 and this specific model of optical slave. Sadly, this unit (a boxy little guy with a hemispherical clear window and a PC connection) is the primary optical slave available at the low end of the market.

But, there's another slave out there made by Sonia, an Indian company. So I ordered one of them (including a hot-shoe mount with two extra PC connections) and I really hope it won't cause the same problems on my SB-20s. If it works, I'll probably get one or two more to have the option.

If you are interested, the current eBay listings for optical slaves are below. The sonia slaves have a clear epoxy package with some sort of color to them (from the circuit board inside). The Chinese slaves are the boxy ones. I'll review the Sonia slave once I receive it!