Res on 5K iMac for C4K

Hi everyone,
about to start playing around with FCP again after a long while, I wanted to ask what resolution are you people with 5K iMacs using when working with 4K or C4K material. If you use full 5K, how do you deal with the tiny text? If you use the lower presets, do you compromise quality control of 4K material? In my case, I've been recording GH4 C4K H264 for a while, and this is the first opportunity I have to check it at full res, besides in camera...

Leave it at the default "Retina" resolution.

That is the magic of retina: your video will be shown pixel per pixel, while the user interface elements are drawn at the size corresponding to half retina (hence not tiny), but extra smooth.

Thanks Lichinho, this is very good news. I didn't manage to find this clearly anywhere, and was a bit confused.