Command dial & Manual lens function help?

[pluton]

Further guidance on a 20mm will be greatly appreciated.

I take this as a license to blab on a little more.
My experience:
Nikon 20/3.5 AiS: nice and small, sharpness nice close up, sharpness problems at infinity.
Nikon 20/2.8 AiS: Sharpness good at all distances, after being stopped down a bit...1 or 2 stops always seemed safe. Pretty small and lightweight.  Pronounced wave distortion.
Zeiss ZF 21/2.8:  Nice sharpness across the frame at any stop and any distance.  Not small, not lightweight. Using the hood, which is very efficient, makes it even larger. Visible wave distortion.  Faint cyan shading occasionally visible in the outer zones on some scenes and some sensors.  Saw it sometimes on the D3, more rarely on the D800.
Just for fun: Nikkor-O 2.1cm f/4:  The best 20/21mm that we can't use. Mirror lock-up only.  No distortion. Zone focus.http://www.destoutz.ch/lens_2.1cm_f4_221921.html

[Derek of Venango]

Great Keith. Now we're cooking. 

[Birna Rørslett]

Drop any idea of the 2.1 cm f/4 Nikkor. It is dangerous to any modern camera, and a lot of older ones as well. 'Dangerous' as in being able to destroy the camera reflex mirror. Trust me on this as I have personal experience

If you really want a petite 21mm lens, try a Voigtländer SC 21mm f/4 -- however, you cannot use it on an F mount system, but it works wonderful on the Z6/7.

I'm quite fond of the 20/2.8 AIS which is tolerably small given one rejects the factory satellite dish disguised as a lens hood. In its place I use the HK-16. A little on the soft side wide open but quickly gets into its stride stopped down 1-2 clicks.

The short-lived 20/4 of Galen Rowell fame is smaller and may have more bite in the central parts of the frame, but corners tend to be mushy unless you stop down a number of stops. The lens is awkward to operate with gloved hands unless you combine it with the HK-3 hood as this gains you a wider focusing collar.

[Derek of Venango]

Thanks Birna. As always, salient points mixed with a healthy dose of humor.

If the VC SC 21/f4 was anywhere near the 40mm Ultron as a whole, I'd snap one up. I presume one would consider it a lovely cousin to the Zeiss 21mm.

[Birna Rørslett]

The 21mm f/4 Skopar is in the front row in the picture below ... compare it to the Z6 camera to appreciate how small it is.

[chris dees]

Drop any idea of the 2.1 cm f/4 Nikkor. It is dangerous to any modern camera, and a lot of older ones as well. 'Dangerous' as in being able to destroy the camera reflex mirror. Trust me on this as I have personal experience
.........

How about the Z6/7?
Is the distance with the FTZ enough so there will be no damage to the sensor unit?

[Birna Rørslett]

The 2.1 cm will *not* fit the FTZ.

However, it is possible to attach the 2.1 cm lens by combining the Voigtländer F-S adapter with the Roxsen N(RF)-Z. I much prefer using the 21mm Skopar though as it is far easier to handle and in most aspects, image quality is better.

[Erik Lund]

Obviously the  name should have been D_sp

What a wonderful classic set! Very cool 
 

The 21mm f/4 Skopar is in the front row in the picture below ... compare it to the Z6 camera to appreciate how small it is.

[Derek of Venango]

Hey Birna, did you make that focus ring adapter on the VC 21mm? Very cool.

[Birna Rørslett]

Have to disappoint you there, it was delivered with the lens. I just fixed the ring when it broke and attached it permanently.

However, I'm the 'creator'  of the focusing adapter for the 50mm f/1.4 (and similar 'normal' lenses without their own helicoid).