ΔE 7.7, close: similar, with a visible difference side by side. Mid Feldgrau is a little darker, cooler than Field Grey FS-34159.
Usually, if you are not matching paint already on the model. Close match (ΔE 8). Mid Feldgrau is a little darker, cooler than Field Grey FS-34159.
The same difference applies the other way round: Field Grey FS-34159 is a little lighter, warmer.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Field Grey FS-34159 on the colour wheel See Mid Feldgrau on the colour wheel
All matches: Field Grey FS-34159 equivalents · Mid Feldgrau equivalents