We all know that the MFT "crop factor" is 2 don't we? Well, take a look at this post by Ned: https://www.mu-43.com/f40/alternative-m-zuiko-75mm-f1-8-a-43995/index3.html#post441259 I think this shows pretty well that whilst MFT may be notably narrower than APS-C, it's actually quite close in height (actually 13mm compared to 14.8mm) Inspired (!) by this, I did a quick bit of maths on what the crop factor would be if we kept the height of the MFT sensor but extended the width to match APS-C. The answer is 1.68 Now, I don't know about you, but one of the things I like about MFT is the 4:3 aspect ratio. I find the 3:2 of FF a bit 'oblong' and in any case I often crop my images to square. Given this, the extra width of APS-C (or FF) is somewhat irrelevant and I can get a closer approximation to an FF focal length if I use something closer to 1.7 than 2. Anyhow - hardly a profound conclusion, but interesting anyhow. Of course, as Ned points out, it's better to forget about crop factors entirely and just learn the FL/view relationship on MFT - but for old 35mm film users, it's still a helpful crutch.