Since you are using the latest firmware updates and the problem occurs even when the lens is externally stabilized, I suspect you may have a defective or damaged copy of the lens. It's especially suspicious that the doubling you see occurs exactly horizontally by such a large amount when used with a tripod. It seems the lens is attempting to compensate for non-existent movement. I have no idea why it would behave differently with MS vs ES.

It is also possible there is an issue with your camera. This seems unlikely since you have used other lenses with your camera without problems. You can rule out issues with the camera body as a cause if you see the same effect when using the lens with a different body, preferably a different model.

A normally working copy of the lens should function as described below, which was written before you posted the tripod images showing the severity of the problem you are experiencing. Consider contacting FujiFilm to see if they are willing to repair or replace it.

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The double images you describe appear to be caused by movement beyond the ability of OIS to stabilize. OIS is attempting to compensate for the movement by resetting itself. When the camera is externally stabilized, image doubling should not occur.

You can see the image "jump" in the EVF by half-pressing the shutter and observing the image as you move the camera. It's easier to see if you zoom in all the way and very slowly move the camera.

• By performing this exercise, you should be able to see that the amount of movement necessary to cause the jump is greater than what the shutter alone can produce.

• The jumping seen in the EVF is not as apparent in the XF 18-55 and XF 18-135 as it is in the XF 50-230. It may be that the XF 50-230 tries to "hold" its position more strongly, or it may be that the greater zoom makes it easier to see.

Sample Images

I am able to recreate the double image effect with shutter times of 1 second, with and without electronic shutter, with multiple different lens models on an X-T20. Lenses tested were XF 18-55, XF 18-135, and XF 50-230.

• XF 18-55mm F2.8-4 R LM OIS and XF 18-135mm F3.5-5.6 R LM OIS WR

  

• XF 50-230mm F4.5-6.7 OIS II, mechanical shutter / electronic shutter

  

  The doubling does not occur when the camera is externally stabilized (such as with a tripod) with mechanical shutter. There is no OIS "hunting".

  

• This effect is not unique to FujiFilm. It may also be seen with several EF-mount lenses. Here is a 1s exposure with a Canon EF-S 18-135mm F3.5-5.6 IS USM on a Canon 550D.