Regardless titles

you may want to give a Fujinon GF 500/5.6 lens - it is PERFECT to work with ! You don't have to be a hunk to manage it. It just feels right in your hand without being "too much" in any kind of way. (Assuming that you already know or have dealt with larger lenses, I mean.) The camera seem to handle the weight of the lens, just fine !

Honeymoon - I know, I know...

As you may hear or not, i am a dude who is in love. So, I am on a honeymoon now. Again. Don't put my words on a weight scale. You need to understand, that this is anything but neutral and objective written.

Yes, the focus is...

both fast and slow. (It depends) If the focus is already closer to the object you wish to focus on - it is rather fast for mediumformat AF standards. However if the lens needs to search, for example because it couldn't find the focus point at the first attempt - then it suddenly slows down considerably. Or it goes into the opposite direction, away form your motive, because it already was far away from it in the first place. Then it is slow. (So is the Pentax FA lenses, too). Only that the Fujinon GF 500 sounds far more elegant slowing down AF while searching *LOL*

Use the focus limiter

Here I feel that the focus limiter switch (5m to infinity) is a great help, to speed things up, because it limits the range - and with that, the focus speed. (The minimum focus distance is 2.8 meter - not much different from the 3 meter in the Pentax 645 FA 400/5.6 ED lens.

Booster AF setting (GFX camera)

Enable the booster focus AF setting in your GFX camera. I (assume) this does speed things up a little bit. I already had it enabled when i bought the Fujifilm GFX 100s II camera.

I have no idea how the Fujifilm GF 500/5.6 OIS acts and works focus-wise on the older Fujifilm GFX 50s II camera (which is only has contrast based focus).

Another "funny" impression

is that using the Fujifilm GF 500/5.6 OIS - almost doesn't feel like using a super telephoto lens. I don't know how to put finger on the feeling. It feels as if i am using a shorter lens - but not the 400 mm focal length it gives in effect (due to the larger sensor, the lens appears to be 400mm and not 500 mm).

Normally - when using 400mm or 500 mm lenses - it really feels... well heavy, bulky and "really long". But with this lens, it feels as if i am using a moderate telephoto lens.

Perhaps because everything feels so smooth ? The size and weight also being less than what you would expect from a 500 mm lens, could give you a psychological feeling of using a shorter lens ?

Now since I barely have taken any photos with this lens - I will see how it feels like when I am really out and about with it - for example in the city of Stockholm again. In order to get a deeper feeling behind every characteristic.