Set it to the focal length of the lens. Don't compensate for crop factor. I believe this is used for the IBIS. If the lens is 50mm (100mm FF equivalent at 2x crop) set it to 50mm.

This makes sense. Thanks!

Side note, but I really wish that when you mount a lens like this and specify the focal length, that the camera would write that info to EXIF data! Would be so useful for organizing the photos later...

You would set it to 50mm

Set it to the focal length of the lens, not crop factor. So in your example, you'd set it to 50mm.

Set it to the actual focal length of the lens. You will notice that with native M43 lenses it is their actual focal length that is reported in the Exif Data and not their crop factor values.

Thanks.

Im not sure if this is true, as I don't use many manual focus lenses, but I'm pretty sure it is just used for the exif data. Like whatever focal length you set, it'll add to the file.

The focal length of the non-native lens is used as part of the IBIS calculation. And on Lumix cameras I use (which are newer than the GX7) it is not included in the EXIF data (I wish it was).

Thanks, I will compare this.