[Brightcolours]

In practical terms, probably nobody.

You can't put a Âµ4/3 lens on any other format, so if you're using that, you only have this sensor size for reference. Putting a full frame lens on a Âµ4/3 body is, most of the time, not very optimal either (unless it's a long tele you want to make even longer).

I can admit to never own a full-frame camera (and not going to change that any time soon) so why does that format have to be a benchmark for me, I don't know. Most Âµ4/3 users are probably the same.

 

Anyhoo, the G9 and 200mm lens. Somehow I doubt they're going to sell a lot of units. And no, the Canon 200mm f/2.8 lens is not entirely comparable as that is a 20+ year old design with no IS. The internal construction is probably very different even if you disregard that fact.

What a lot of misconceptions. 

You can't put an Nikkor APS-C lens on a Pentax medium format camera either. Yet it is quite handy to know what a certain lens for that Pentax actually "means" in respect to what one is used to (Nikon APS-C format, in this case). Does that have ANYTHING to do with putting an APS-C Nikkor on that Pentax, or that Pentax lens on the APS-C Nikon camera? No, of course it does not.

 

Example.

One sees an advertorial about a Pentax 645D with a Pentax 55mm f2.8, and really likes the FOV look. Question one gets... What would I need to do something similar with the camera I have (which happens to be a Nikon D500)? Easy, use the crop factor to calculate which equivalent focal length and aperture will be needed. The crop factor of the Pentax sensor compared to the D500 sensor is 0.51x. Easy peasy, that means that lens is equivalent to a 28mm f1.4 lens on APS-C.

 

Does that have to do with FF? No. Does that mean any format is "the benchmark"? No. It just means that you figured out how two formats relate to eachother.

 

So, you never have used FF, you are used to APS-H Canon format. Handy to know that when you look at whether that Canon PowerShot 1G-X mark III is or is not offering what you are after for a compact travel solution, for instance. How to know? By looking what it is equivalent to in APS-H Canon format terms, the terms that are YOUR benchmark. That PowerShot has a 15-45mm f2.8-5.6 lens with IS. Simple to figure out what that is equivalent to in APS-H Canon format terms, just look at what the crop factor is: 1.23x. Now you know that the equivalent APS-H Canon format lens of that Powershot 15-45mm f2.8-5.6 would be a 18-55mm f3.5-6.9. 

 

Does that have to do with FF? No. Does that mean any format is "the benchmark"? No. It just means that you figured out how two formats relate to eachother. You can make an informed decision about whether this camera will offer what you need (lens wise), without having to have used it to get an idea about what would be "da wide" for that PowerShot's sensor size or what would be "tha long". You know what "da wide" for your APS-H Canon format camera is in numbers, and now you know what it would be for that Powershot.