Nikon Nikkor-P 105mm f/2.5 Xenotar-type ~ Lens Turbo II APS-C vs Full Frame

Today I look at an old Nikon Nikkor-P 105mm f/2.5 Xenotar-type pre-Ai lens.  This is the last in this series of field flatness comparisons.  

The original question came up when I realized the Lens Turbo II focal length reducer was introducing field flatness issues.  The matter has come down to determining which lenses are most effected so I can avoid using them focal reduced on APS-C Sony mirrorless.

 

 

I've owned several of 105mm Nikkors over the years.  Currently I own two.  One was sent to me by a friend back in the States.  The lens is the earlier Sonnar design and it is very sharp from wide open.  It suffers from just a hint of field curvature wide open.

A couple years ago there was a newer design pre-Ai Xenotar version that came up on That Auction Site.  No one bid on it.  The opening bid was low enough I could ask "why not?"  For not much money I scored another pretty little lens.

Wide open the Xenotar version is not as razor sharp as the early Sonnar version, though the field is in my case flatter than the older design.  Stopped down (from f/4, on) I can't tell anything between them.

A different friend says that owning lenses can be like owning shoes.  Who wants to own just one pair?  It's a form of madness, I'm convinced.  I can't help myself.

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-P 105mm f/1.8 pre-Ai - shot at two f-stops - f/2.5 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-P 105mm f/2.5 pre-Ai is 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.

The extreme lower left corner of the scene at f/2.5 the Lens Turbo II APS-C image looks a tiny bit soft, but unlike other lenses, this combo looks very good at f/8.  

The Sony A7 with straight-thru adapter at the very corners are quite sharp wide open and stopped down.

Finishing up this sequence of comparisons with a bang! the 105mm Nikkor looks pretty darned good on both Lens Turbo II focal reduced APS-C and Full Frame.