[Dark_Mist]

The pixel density of the K1 and your current Sony are approximately the same so if you're happy now you'll have no problems.

If you make a significant jump in resolution you could find it exposes any lens weaknesses.

[PixL8]

My experience is that my old 1986 full framed 50 mm lens is fabulous on my Ki MarkII and that goes for other older FF lenses I have or have purchased at a good price as they are used. The Ki seems to work very well with them and I have had no problems, You can even have it set to beep when you manually focus if you like.

The only think is that it takes K mounts only (obvioulsy) but you have full access to all the new and some very old K mount lenses.

I also use a few of the newer lenses that are not FF and there you run into cropping issues in the corners... however there is a mode in the K1 to accomodate for this and it uses only the inner part of the sensor so no cropping happens.

I love this camera and I think you will find it can capture the old lens softness and bocas as well as take advantage of the sharper new lenses. its beautiful.