gdanmitchell wrote:
Oh, boy. Turns out there are three ways to figure that out. The complexity is that the miniMF format uses a 4:3 aspect ration (width:height) while 35mm (full frame) uses a 3:2 aspect ratio.
The simplest answer is that a full frame camera is essentially a 1.27x cropped factor by comparison to miniMF if you use the full frame of each. That would make the 250mm lens on Fujifilm GFX roughly the angle-of-view equivalent of a 197mm lens on full frame — so 200mm in round numbers. (For those who will certainly post a response otherwise, there is a DOF issue, too, that I won't go into here since I'm assuming that you either already know about it OR you are just interested in the angle-of-view question.)
As to the other ways to calculate comparable angle-of-view focal lengths, I'll spare you the details except to say that if you do either of the following you would want to look into the issue a bit:
1. You prefer the 3:2 aspect ratio of full frame and you would crop your miniMF 4:3 frames to 3:2.
2. You already crop your full-frame 3:2 aspect ratio images to 4:3 and you would use the full 4:3 frame on miniMF.
The answer is very simple. If you shoot a 4 X 3 or squarer aspect ratio, this lens is like a 180 f/2.8 on FF 35mm. If you shoot a 3 X 2 or skinnier rectangle aspect ratio, it is like a 200 f/3.4 lens on FF 35mm. There are calculators that provide this information. An FM member Lee Saxon has a good one.
