bem

View from the starting point when I'm finished with the boatride late in the evening.

Hi,
New lens XF 50mm F1.0 R WR, "launch" late September 2020.
When it is possible to buy I have not a clue.
It has a rather hefty recommended price tag (that I have read info about from a Photo Magazine in my country).
- Large diameter mid telephoto prime lens.
- World's first Autofocus capable F1.0 interchangeable lens for mirrorless digital cameras.
Etc.
Source and more info:
https://www.fujifilm.com/news/n200903_01.html

/Bo

Update 2: So far (I'm writing this Nov. 2, 2020) my new Haoge LH-X18 square metal lens hood has not deattached while out in the terrain. I doubt it will ever deattach by itself from the lens.
/Bo

Read in the X-T4 user manual what HDR is and then You will understand the multiple exposure shots.
I recommend to spend some time reading the user manual. This camera is a "beast" as far as the amount of settings it has that can be changed in the menu and via dials, buttons. I'm new to this camera also and it has a steep learning curve for me, new to Fujifilm cameras and this type of more advanced cameras. One has to have patience I think and experiment some what the settings really do to get good photos in varoius situations. This camera is not a point and shoot camera for sure (in my opinion), maybe it will be easier later on when I know my X-T4 better.
/Bo

Great it was solved. It seems X-T4 is little "tricky" about SD cards, I have a common problem - I almost always need to insert the SD card(s) twice before Card Read error is is gone (yes I use Fujifilm recommened SD Cards, Sony UHS-II V90).
Anyway this is what is said in X-T4 user manual, Troubleshooting section about the error You had (same suggestion for all 3 errors):

FOCUS ERROR, 
LENS CONTROL ERROR or
TURN OFF THE CAMERA AND TURN ON AGAIN
Explanation:
Camera malfunction. Turn the camera off and then on again. If the message persists, contact a Fujifilm dealer.

I would have contacted Fujifilm support if the problem had persisted.

Have a nice day and I hope Your X-T4 will work fine for You now and in future.
I have X-T4 also (I had a lot of trouble with it first and it was a "lemon" and I got a new and it has worked fine).
/Bo 

Fix the autofocus in video.  Thomas Heaton (landscape photographer/blogger) commented when he reviewed the camera that they ought to sell it with a Bow and Arrow because it likes to Hunt (he likes the camera otherwise).  For stills it's pretty good but for video it keeps doing this thing where it loses faith in its own ability and suddenly rechecks focus by tuning out and back.  On some lenses (Viltrox 33mm) it makes it virtually unusable

Fujinon XF 16-80 mm F4 R OIS WR is in use here.
/Bo

Same factory September 1 2020 in daylight. The breadfactory front facade is huge, as You can se in below photo. I have been up on the roof once when I had summer job during high school period, I think it was in 1977 I was up on the factory roof. It was magnificent  view to watch my hometown here in Sweden from about 50 meter (160-170 ft) above the ground. It is a viewpoint on the roof up to the left where it is a flagpole. In the photo I took with my X-T4 camera they had just cleaned (almost finished) the facade with help of the crane You can see in the photo below.
/Bo

Very old stone bridge, several hundred years old, in my hometown here in Sweden.
I took the photo late in the evening Aug 2 2020 with my Fujifilm X-T4 camera and lens XF16-80mm F4 R OIS WR.

Wasa crispbread factory in my hometown here in Sweden.
Largest crispbread factory in the world.
(homepage for US, for anyone that want to know some facts: www.wasa-usa.com)
I took the photo late in the evening Aug 2 2020 with my Fujifilm X-T4 camera and lens XF16-80mm F4 R OIS WR.
/Bo

Yes, Ken Wheelers books I have started to read a while back. Glad I found them and You confirmed it is worth reading, and I think I understand most what he write also

/Bo

A short distance from the starting point and I turn and there is beautiful sky and lake is like a mirror.

Out on the lake on my way back to starting point where I had my boatrailer. Speed is almost 40 knots in this photo.

Just happened to see late in evening yesterday, July 31 2020, that it was "interesting" sky and absolutely calm on the surface of this lake, and I had the camera with me, so... I'm just learning to use my Fujifilm X-T4... Not easy task to take photos that is reasonably sharp in the evening but this one is OK for me...
/Bo