Well, one previous poster said it best in my opinion. I don't know if these Sony's are "best" in their class or not, but I do know that Sony was very marketing savvy in coming up with deals for giant media organizations. Between volume discounts and exclusive contracts, they have gotten their products out into full public view. Hey, I might use Sony myself if they gave me sweetheart deals...

Yes, I asked this question when I was using only X-T4 cameras. But now I am using an X-T5 and new lens while before one lens was damaged and the other not new. So I am more confused than ever on what is happening and WHY.

I am on my third Fujinon 150-600mm lens. I really love the reach, lightweight and sharpness that's fine for my needs. But there is a reason I am on my third one. The first was purchased new and worked fine until I dropped it. Sent it to Fuji for fixing. Came back with unreliable IS - worked fine at times but other times rolled and/jerked. Sent back and waited. Problem not fixed but I know intermittent problems are hard to fix sometimes. So, purchased a nearly new one from Japanese dealer off Ebay. Within a few days, it was doing the same intermittent thing. Perfect sometimes; annoying other times. I have 2 Fuji X-T4s and the same lens issue when I switched the lens from one to another. Well, I finally opted for an X-T5 and got a brand new lens. Guess what... same intermittent problem. Rock solid sometimes but jumpy others. I can not figure out a pattern of when one way or the other. Flipping on/off several times does not resolve problem. Sometimes the problem does resolve after shooting a while. Most of my pictures fine but ...
My question, am I extremely unlucky or is there a design flaw in this lens or am I not understanding something.

Got a new X-T5 and decided to break-it in with a new XF-150-600 lens. [No I am not rich as I will be selling older gear to fund much of this purchase.] I meticulously set up the menu options and thought I was ready to go. So I found a nearby tug boat to start my photographic journey. But as I looked through the viewfinder, the autofocus did not appear to be working. When I pressed the shutter button, the image did not snap into sharp focus. So I started checking all the dials/buttons I could think of on the lens and camera. Tried again, and same result.

I was about to panic, but then I looked at the pictures on the LCD monitor and they seemed to be focused. When I enlarged the view, they still seemed focused. What the heck. Good pictures but bad viewfinder. It then clicked: DIOPTER needed adjusting! Whew. Panic averted.

Just wondering if anyone else has done something as silly as this and needlessly panicked themselves?

That would be an option if I am still unsure after reading replies here.

Can you explain what you mean by a different "look"? I am hoping that the pictures should look the same except in very large print size when shot in M rather than L. Would anything change except pixel density?

I understand I can do that. But I will be downsizing even at medium. I just have no use for larger files that I need to more drastically compress.

My question is basically can I get the same quality of picture from a L size in the X-T4 and a M in the X-T5? I need to buy one or the other and the price is essentially no factor. I can stick with the X-T4 which produces pictures nearer the size I want or buy the X-T5 because it has some improvements over the X-T4 if I can keep picture size down.

Now, those may not be the important factors for some of you. Bottom line: will I lose anything by shooting in M on X-T5 versus L on X-T4?

As I understand it, the Fujifilm X-T4 will no longer be produced. At this opoint the X-T5 and the remaining X-T4s in stock cost the same at $1699. I don't want or need the extra pixels in the X-T5 as I have to reduce jpeg size anyway. I am thinking of buying the X-T5 for its improvements and then just setting the jpeg capture size to medium rather than large. Any big downside to this? Again, new pricing seems to be the same so it is not a money issue.

Yes, the camera body was also damaged but as I explained, the problem persists when I switch either lens to a different XT-4 camera body that hasn't been damaged.

No, I was just explaining how I take pictures. I rarely use manual mode but it does seem to still be a problem in manual mode.

I have two XF 150-600mm lenses that I use on a Fuji XT-4 body. I bought one new and it worked wonderfully for a long time. But I damaged it on a fall to the ground. I sent it to Fuji for repair. It came back but it soon developed episodic image stabilization issues. Many times it was rock solid. But other times it would roll or even mildly jerk. It was sent back to Fuji who supposedly repaired it. But I soon experienced the same problems of good days and not so good days.

So I purchased a second almost new lens. It worked great for a week or two and then the same erratic behavior started again. It can be rock solid or it can roll/mildly jerk. Sometimes it can exhibit both in a long photo shoot. I can switch the lens from one XT-4 body to another and that does not fix the issue.

I am puzzled. Most of the time I shoot in auto mode and it does this jekyl & hyde thing. I don't know if I have two lemons or I am the lemon (i.e. the fault is with something I do or don't do).

Anyone else experience this issue and have solved it?

Thanks! Nice comparison and informative.

I appreciate all the advice but remember this was a curiosity question. I have not/am not really considering buying a 600mm prime. I am an amateur hobbyist with no photographic income to justify any such purchase. I was simply wondering what those people with deep pockets and/or professional needs were getting for their money over and above what my Fujifilm 150-600mm was giving me. I hear bokeh, aperture for low light and a small increment of detail/sharpness that might easily not be apparent to my 75 yr old eyes. And of course, the additional substantial weight of the lens (and comcomitant lightening weight of my wallet!)

Again, thanks to all.

Thanks to all for the responses and some wonderful pictures. I think the weight factor would be enough to discourage me from owning a 600mm prime just by itself. I really like the portability and hand-hold factor of my Fujifilm 150-600. When I tried the Sigma 60-600mm, I quickly nixed that option due to weight though I loved the range. I really hadn't thought about the primes being so heavy.

Again, thanks to all.

Nice pictures Wallen. I have the Fujifilm 150-600mm and I am very pleased with it. But it is $2000. My guess is that it is at least 90-95% as good as a 600mm prime, but I just wanted to see if my guess was accurate or wildly inaccurate.