For your viewing pleasure..... a comparison of the Century Optics tele-extender options. A 1.6X and 2X are available. Both of these adapters are large pieces of glass, the 1.6X at 26 ounces (1.6 lbs) and the 2X at a whopping 47 ounces (just under 3 lbs). Rails are included with the 2X, and it is recommended that they be used to help support the adapter because of this weight. It should be noted here for ALL users of EX cameras that any additional weight placed on the lens mount (whether this is from an adapter on the stock lens, or a larger lens mounted on an EX3) that care must be taken to lift the camera as much as possible by the top handle and NOT the lens grip. I have been told by a very experienced lens technician (Ron Cotty, of ENG Optical Services for those of you who ever need a top-notch lens repair source) that the EX lens mounts are not designed for a lot of stress from increased weight. If you have one of these larger adapters (the 2X or Extreme Fisheye), or a 2/3" broadcast lens or large 35mm telephoto on an EX3, that if care is not taken supporting extra weight the lens mount can be damaged. So always use the top handle when carrying the camera or hoisting it up on your shoulder when hand-holding in these situations.

Here are the frame grabs. As before with the WA adapters, these grabs are direct from Clipbrowser and no alteration or adjustments have been made whatsoever.

With the tele-extenders, there is a very obvious 'porthole' effect when the lens is at wide angle. With the 1.6X, the widest angle without seeing this vignette is approximately 25mm, with the 2X it is approximately 43mm.

For EX1 and EX1r users, these adapters provide a great ability to get some extra throw out of your lens. For most EX3 users, I think the alternative to mount a longer 1/2". 2/3" (with adapter) or 35mm (with adapter) lenses is probably a better choice unless you don't want to deal with removing the lens and resetting backfocus each time. (maybe not always needed, but something I do every time I remove a lens)

And a second batch.... along with a couple of images of the adapters mounted. (I did not attach the rails for these photos because, well, I'm lazy, but primarily because they were only on for a few moments. If I was doing any serious shooting with the 2X, I would most certainly have included the rails)

It was kind of a hazy day, so disregard the softness on the mountain top shots, but there is some CA noticeable along the high-contrast edge where the mountain meets the sky. This is noticeable in the stock lens, so I don't think it's coming from the adapters, but it is magnified with the adapters on. I did include some shots without so much contrast and it is not noticeable there. Maybe someone knows what causes this?

I'll have to include the mounted shots in another reply, I'm out of attachments already-

Finally a couple shots of what the adapters look like. I have lots more shots of the various adapters mounted on the camera if anyone wants to see them:
.6X, .75X, Fisheye, Extreme Fisheye (already posted that one)

Looks like the 2x almost perfectly picks up where full telephoto on the stock lens ends. Helpful, thanks.

Thanks Derek, great examples!