Originally Posted by ted_smith
sorry for being a bit late in the game with my answer, but I think I can give some helpful information.
I am a multi-format shooter as well, and in 35mm Nikon is my main used system for more than 30 years.
You have asked about the 1,8/50 Nikon versus 50mm Zeiss ZF glass for Nikon.
I am using the Nikkor 1,8/50 AI-S (the better long barrel version with 0,45 min. focus distance), the 1,8/50 AF-D, and for four years now also the Zeiss Makro-Planar 2/50 ZF.
Besides using the Zeiss in my daily photography, it is also our standard test lens in our optical lab for film and sensor tests.
What are the differences between these three lenses?
Advantages of the Zeiss are
- much better performance at f2 (much better resolution and contrast) compared to the Nikkors
- a bit better performance at f2,8 (resolution, contrast)
- more even sharpness across the whole frame at from f2 - f8, the Zeiss is better at the borders compared to the Nikkors
- no chromatic abberation
- nicer bokeh
- better build quality
- a bit less distortion (compared to the AI-S, my AF-D sample has less distortion than the AI-S)
Advantages of the Nikkors
- less vignetting at f2
- lower price
In our resolution test at f5,6 both the Zeiss and the Nikkors achieved the diffraction limit of white light with 240 - 260 lp/mm on Spur Orthopan UR / Adox CMS 20 film (object contrast of 1:4).
That are outstanding values. You would need a 200 MP FF sensor to get the same resolution in digital under the same test conditions.
Each lens manufacturer has some "jewels" in his lens programme, and some lenses which are not so good.
That is also the case with Zeiss.
The 2/50 Makro is excellent, and the 2/100 has an even better reputation. Also the 2,8/21 belongs to the best 35mm SLR lenses available.
On the other side the 2,8/25 for example is one of the weaker lenses in the current Zeiss programme.
Here you may have a look at tests of most of the Zeiss lenses:
Just as an important additional information: The photozone tests are based on 50% MTF tests with digital sensors. If you test the lenses with higher resolving films (like slide films, T-Grain BW films, BW microfilms) you get higher resolution values if you use object contrast above 1:3.