This TC is weather sealed, optically good, built strong and maintains the AF and useful for that extra reach - when you need it....It’s so so steep though. I bought it as a tax write-off but have only used it sparingly. I have not yet come across times when I did need it that often. Only a couple lenses will accept this TC, the 250mm and I think the 120mm only.Gfx 100 users would probably benefit more from the TC as that camera has much better AF and tracking performance than the 50s or 50r. I’m thinking track and field using a MF camera and a TC with the 250mm lens. Possibly Tele landscapes and you really need to get up close like tight sun/moon set/rise shots or wildlife pics.It’s a big big setup though, I found it a bit silly looking when I attached my 250 ... MoreThis TC is weather sealed, optically good, built strong and maintains the AF and useful for that extra reach - when you need it....It’s so so steep though. I bought it as a tax write-off but have only used it sparingly. I have not yet come across times when I did need it that often. Only a couple lenses will accept this TC, the 250mm and I think the 120mm only.Gfx 100 users would probably benefit more from the TC as that camera has much better AF and tracking performance than the 50s or 50r. I’m thinking track and field using a MF camera and a TC with the 250mm lens. Possibly Tele landscapes and you really need to get up close like tight sun/moon set/rise shots or wildlife pics.It’s a big big setup though, I found it a bit silly looking when I attached my 250 to a TC & MY 50s with the attached battery grip and the hood on.I think I would be arrested by the police if I pulled that setup out in a public place, it looks like a serious weapon at first glance.Out in the open space of nature or the athletics track the setup would shrink down a bit and look more proportionate to its surroundings.All in all, it works well and will do the job; when it’s finally called upon to do so.....

This teleconverter is very solidly build. It is a hunk of glass and the weight is quite substantial. I have never owned a teleconverter before, but I wanted the extra reach. I use this with the 100-200 and there is no loss of image quality. If there is, it is so minimal it is not noticeable. There is a loss of 1 stop of light; f5.6 is now f8.0. Metering reading, autofocus, and all communication with the camera is there. I'm pleased.

This is a great addition for turning the Fujifilm GF 250 into a 350mm lens. Easy to use, only 1 stop of light loss and images are still very sharp.