As a multi-format shooter (MF Hasselblad, 35mm Nikon F5) this question is aimed at the 35mm range, not medium format.

I own two Carl Zeiss lenses for my Hasselblad - really pleased with them etc. However, my Nikon body has Nikon lenses only. I've read on the web and watched on YouTube lots about Carl Zeiss lenses that fit Nikon bodies. An extreme and expensive example is the 55mm Distagon with 12 lens elements that costs about 3K I gather. https://www.youtube.com/watch?v=8mEj...fuveOA&index=2

Anyway, my question is whether the more 'normal' Carl Zeiss lenses are really as good as they claim to be (I can't afford that 55mm one so not even interested in that!)? It's obvious that they must be better than your standard Nikon lenses, but are they so much better to justify the cost? I've never used one and never seen a non-biased side-by-side comparison of a shot taken with, for example, the 50mm 1.8 Nikon or even the 1.4 pitted against a comparable CZ lens? Curious to know if it's worth spending about twice as much?

(and, out of interest, are those side-by-side comparisons in the video linked above accurate, or exaggerated marketting tricks?)