[texandrews]

A1 is the size that I think discriminating viewers could be able to see the differences between medium format and FF somewhat routinely. I think this is also the native image size for the Z. Below A2 I don't think the differences are apparent 90% of the time, unless tonality is the main draw of the image---but it usually isn't in smaller prints. It used to be that A3 was a big print and A2 was quite large. But that was decades ago.

It still is a subject matter thing---in some cases the differences would remain so slight it may not be a difference that's worth it. But I can sure see it in my work, so I'm convinced.

Like you affordability is a fluid thing. There are lots of things that at my age I find affordable that i wouldn't have 30 years ago---because I'm well onto the "back nine", so I'm going to enjoy the life that remains for me to live.

[clackers]

I'm one of the rare photographers who take pictures with the goal of making prints, showing and viewing their image as poster sized prints (A1 size or larger).

Yes, a 645Z is right in your ballpark!

[biz-engineer]

Yes, a 645Z is right in your ballpark!

Yes, you are right, I can easily afford a 645z kit used, but I wouldn't buy one new because I think that the price displayed on Ricoh's webshop is not competitive compared to other brands offering the same format. And the 51Mpixels from the 645z barely match my standard print size, I would need ~75Mpixels 4:3. ratio. 7000 px on the short side.

---------- Post added 30-08-22 at 09:34 ----------

A1 is the size that I think discriminating viewers could be able to see the differences between medium format and FF somewhat routinely.

It still is a subject matter thing---in some cases the differences would remain so slight it may not be a difference that's worth it. But I can sure see it in my work, so I'm convinced.

Exactly my experience as well. The perception of image "crispiness" (not sure I can say that) also greatly depends on subject matter. David Yarrow shows very large prints of his wildlife closeup, from his D810 and D850 and fast prime lenses. You could easily see lot of the skin details of an elephant filling the entire image frame, even printed 60" on the long side. Landscape is a different "beast" because the foreground may not be the subject, and the subject may contain lots of relatively small details from the middle ground and background, depending on composition. I have A1 prints of ancient Japanese carved stone figures from a single K1 exposures, sharpened with AI, we can see all the details of the stone grain and traces of the tools used for carving the stone, and I don't think I would see any difference if the same photo was captured with a higher resolution camera. I have other seascape sunset shots with old traditional fishermen huts in the middle and background, moving water waves and stones in the foreground, even with AI sharpening, we can clearly see distant fishing huts lack details we'd like to see, because the fishing huts are a key elements in the images.