For the last three years I have been happily using my Pentax 645Z, with a collection of used lenses (other than buying the 25 mm.) and have largely been happy with the arrangement. The corners of the 25 weren't perfect but for what it is, pretty decent, and very wide. I tended use the 35 more often, and I have the 75, 120 (my favourite lens) 200 and 300.
I did have two issues. Shutter shake from faster than 1 second to slower than 1/250 made use of the 300 very problematic, solved on the fast end by raising the ISO, and at the low end by shooting in dark places. A neutral density filter was an option but outdoors and with any wind and this long lens, I feared camera movement anyway.
Then I heard about the upcoming Fuji GFX - it had electronic first curtain (the Pentax doesn't) and the tilt and swing LCD would be very nice (why do manufacturers think we don't take vertical pictures?) and that lifting and swinging viewfinder extension, well that would be the cream on the cake.
I put my name down, and have had the camera for a week now. I ordered the just announced Pentax 645 to Fuji G adapter from Fotodiox and it arrived on Tuesday this week, so I can take pictures for the last two days.
My observations so far:
The 300 is a very sharp lens and works perfectly with the Fuji
The 120 is great and will remain my most used lens
The 75 seems to be fine but awaits more serious testing
The 35 isn't great with significant softening in the corners even though excellent over more than half the image.
The camera feels very nice and use is fairly intuitive. There's a my menu but so far I don't see that i can add card formatting to it - the single biggest use - on every shoot - damn.
The LCD screen is very nice, and tilts and swings, even better it's a good touch screen with good response and easy tapping to enlarge for focusing. One of the frustrations I had with the pentax was enlarging to focus, then very very slowly scrolling over to the corner where the thing I needed to focus on happened to be, especially when doing focus blending. With the Fuji I scoot around the image at will. If I want to enlarge the centre, I just press in on the rear dial - awesome.
I'm not wild about the small exposure scale on the far left of the viewfinder. It isn't always visible with my glasses and is quite small.
One thing I quickly came up against is that the refresh rate on the viewfinder and LCD slows dramatically in low light, making magnified focusing hand held impractical, and even tripod focusing less than ideal. This could turn out to be a deal breaker.
With the entirely mechanical Fotodiox adapter, you lose lens information and f stop. The latter isn't an issue if you happen to be looking down on the camera so can set the f stop by eye, but if the camera is at eye level, you can't see the f stops and will have to remember how many clicks to what f stop. I'll make a chart and learn - on the 35 it was five clicks to f11. For the kind of work I do, it doesn't seem to be a big issue to open the lens to focus, close to shoot.
Looks like if I keep the camera, I will need to get the 32-64 lens. Testing the Fuji lenses for use with focus bracketing will need to be ok, and I'd be surprised if it wasn't a lot sharper in the corners than the Pentax 35. I should say though that checking sharpness at 100% on screen isn't really fair. I made a corner print from what would be a 50 inch wide print and it's very respectable. So maybe I'm being a bit harsh on the 35 - I'd never had any issues with it in real photography.
The importance of sharpness is inversely proportional to how interesting the image is. Test images are the most boring so need to be near perfect, boring landscapes in poor light, not well composed and not that interesting in the first place need to be bloody marvelous and I've been happy with images made on micro 4/3 because it was an interesting photograph.
So, do I need something like the Fuj GFX 50s - hell no, do I really like most of it, sure do, can I justify it - probably not - but it's cheaper than a sports car, or a mistress, or going to Iceland. Now, if I could take this camera to Iceland...