Nikon Nikkor-O 35mm f/2 pre-Ai ~ Lens Turbo II APS-C vs Full Frame

Continuing to work through the question of which lenses when used in conjunction with a Lens Turbo II focal length reducer exhibit unacceptable field curvature, here is an old and still rather pretty Nikon Nikkor-O 35mm f/2 pre-Ai lens.

 

 

I recently confirmed that this 50 year old Nikkor-O can, on the surface of things at least, keep up with newer current Wowy-Zowy optics.  If you think about it long enough, there is really no reason why old lenses can't produce images indistinguishable from the modern stuff.  As a bonus, old lenses can be purchased many times inexpensively.  If memory serves, I paid less than 50Euro for this 35mm f/2.

Setup - 

• Sony A7 with straight-thru adapter - ISO100, 2 second timer, in-camera levels used to square the whole plot up
• Sony A6000 with Lens Turbo II focal reducer - ISO100, 2 second timer
  
• Manfrotto tripod - it's capable of securing an 8x10inch view camera, so it's sturdy enough for this
  
• Nikon Nikkor-O 35mm f/2 pre-Ai - shot at two f-stops - f/2 and f/8
• Rawtherapee RAW to jpg conversion - Auto-Match function (no "Capture Sharpen")
  

 

Comparison - 

Here is the scene setup.  As you can see, I moved away from using the apartment scrims (curtains) to shooting a copy of le Canard Enchaine' tapped to a flat wall.  I'm looking more carefully at field flatness, right?  Even given the all-too-often shoddy work standards around Paris, this wall is sufficiently flat for my purposes.

 

 

[As always, click on the image and look at it to 100percent file size to see whatever there is to be seen.]

 

Comments - 

The Nikon Nikkor-O 35mm f/2 pre-Ai looks sharp in the center wide open and at f/8 on both the A6000 APS-C with Lens Turbo II and the Sony A7 full frame cameras.

Checking the extreme lower left corner of the scene at f/2 we see they are out of focus.  I believe this is minor field curvature in both the straight-thru and Lens Turbo II adapters.  If I focus the edges, they are sharper than they appear here.  

The A6000 with Lens Turbo II corners at f/8 don't fully "clean up".  There is still a small amount of field curvature.   On the other hand, Sony A7 with straight-thru adapter f/8 images at the very corners are quite sharp.

The Lens Turbo II induced field curvature "feels" relatively mild in this setup.  It certainly is nothing nearly as bad as the field curvature seen when the Nikon Nikkor 24mm f/2.8 Ai is used with the Lens Turbo II focal length reducer.