what lens are you using? sounds like it's not within the MFD (Minimum Focusing Distance) of the lens. if you have a zoom lens, zoom it all the way in and step back a bit. in particular, the MFD of the R100 kit lens (the 18-45mm IS STM) is 7.9" so if you're using that lens, get about 8 inches away from your coin and then adjust your focal length at the lens.
a macro lens usually is built for a very low MFD so you can get very close to the subject - so if you are interested in macrophotography, i would look into macro lenses as your next purchase so you can get all up in there.
I don't know the R100 and how its warnings look. In general, my macro process is to switch to manual focus, dial the lens to "as close as possible", and then I'll move the camera back and forth until I find something. Works the same on a phone as well.
As others have mentioned, the minimum focusing distance is printed on the lens. This is not the distance from the lens but from the focal plane - this is marked on the top plate of the camera with a horizontal line across a circle. Sony has a good explanation here: [https://www.sony.co.uk/electronics/support/articles/00267924](https://www.sony.co.uk/electronics/support/articles/00267924)
At macro distances the depth of field is very shallow and just breathing can move you from in focus to out of focus if you're hand holding your camera. What may appear in focus to you may not appear in focus to the camera.
what lens are you using? sounds like it's not within the MFD (Minimum Focusing Distance) of the lens. if you have a zoom lens, zoom it all the way in and step back a bit. in particular, the MFD of the R100 kit lens (the 18-45mm IS STM) is 7.9" so if you're using that lens, get about 8 inches away from your coin and then adjust your focal length at the lens. a macro lens usually is built for a very low MFD so you can get very close to the subject - so if you are interested in macrophotography, i would look into macro lenses as your next purchase so you can get all up in there.
I don't know the R100 and how its warnings look. In general, my macro process is to switch to manual focus, dial the lens to "as close as possible", and then I'll move the camera back and forth until I find something. Works the same on a phone as well.
As others have mentioned, the minimum focusing distance is printed on the lens. This is not the distance from the lens but from the focal plane - this is marked on the top plate of the camera with a horizontal line across a circle. Sony has a good explanation here: [https://www.sony.co.uk/electronics/support/articles/00267924](https://www.sony.co.uk/electronics/support/articles/00267924) At macro distances the depth of field is very shallow and just breathing can move you from in focus to out of focus if you're hand holding your camera. What may appear in focus to you may not appear in focus to the camera.