Banding with the E-M5 and the 20/1.7: A potential work-around

Started Oct 19, 2012 | Discussions thread
RCicala Regular Member • Posts: 384
Re: Banding with the E-M5 and the 20/1.7: A potential work-around

Anders W wrote:

RCicala wrote:

Anders, we did look closely at the boards, which were simply circuits with nothing that looked like a power supply or voltage regulator (I suspect those are inside the motors which we didn't disassemble). There were a couple of very small devices that I thought were probably fuses, but could possibly have been capacitors, although they were quite small and on the underside.

In looking at one of the earlier photos, I did wonder if all of the flex cables being right under the light baffle, perhaps there's some current leak from one of those? I don't know much about the electronics, though.

Thanks Roger! I am afraid my knowledge of electronic engineering is only skin deep as well. Hopefully, others will chime in here.

One further question that came to mind: You said the 20 wouldn't AF when deprived of its "Jack-in-the-box" mechanism. But exactly what happened and not when you tried to AF without the spring inserted? I suppose the motor would still run. So what exactly didn't work until the spring was back in place?

I am just as mystified by this spring as you are. And since it is in all likelihood unique to the 20 it is least worth considering whether, in some indirect way, it may have something to do with the banding, however unlikely that seems to be at first glance. So I am trying my best to figure out why it is there.

Obviously, it won't push the inner barrel forward quite on its own. The motor must at the very least be involved in controlling the movement. But what on earth would be the point of a construction where it takes very little or no power to move things forward but twice the power to move it back again. To reverse the rotation of an electric motor is no problem (just reverse the current) and a construction like the one outlined would require twice as strong a motor for no good reason. So there should be another and better explanation.

Honestly, for a couple of the points made, I may need to take another quick look at a 20. One thing that happens is we'll start doing these dissections and repairs start piling up so we end up putting the lenses back together without taking all the time we might otherwise.

I think (and my memory may be off) focus didn't work at all without the spring, but the lens was fully retracted and I made the assumption the spring moved it forward - since the entire optical assembly moves forward with focusing, it seemed possible.

The Olympus 45 f/1.8 has two small springs that seem to do the opposite thing (pull the lens back toward the mount), but those are, well, less dramatic. We've never seen anything like this spring and we were both mostly in WTF? mode. Totally shocked.

I've seen that 3 pin solder under a flex on a number of lenses, and also a similar looking 5 pin thing. It's mostly been in Sony alpha, Nikon, and some third-party lenses and to be honest I just assumed it was an old-fashioned solder.

A couple of the older design Canons have it too, but none of the Canons made in the last few years. Because the inside of Canon lenses generally looks more 'custom made' I assumed that just represented an older design (A lot of third party, alpha, and nikon lenses still use lots of soldered wires instead of flexes, for example). But I've certainly seen it in several lenses, mostly larger and older design glass.

Sorry I'm not more help. I know a bit about optics, but I'm electronically challenged.

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