Saturday, October 24, 2015

Yet another lens comparison... 50 to 85 millimeters...

I can't help myself.  Really.  I can't.  I should probably seek help.

I found a very very nice Nikon Nikkor 85mm f/1.8 K multi-coated c.1977 optic.  Legion are the comments by people who claim this is the most amazing 85mm Nikkor ever made.  The claim is that the sharpness is incredible.  It's supposed to be superior to modern glass, according to some pundits.

When we returned to the US to clear out our storage unit I picked up an earlier single coated "H" version of the lens.  The one I picked up is much sharper then the first copy I owned some years ago., and it's resolution is very similar to the Nikon 85mm f/2 Ai and Pentax 85mm f/1.9 Takumar (which I sadly sold).

I was, therefore, interested in seeing how the God of Gods (the "K" version of the Nikkor) behaved.  If the talking heads were right, the "K" lens would demonstrate optical qualities "to die for".

And while I was at it, why not take Yet Another Comparative Look at a few 50mm lenses, too?

Using a Sony A6000 mounted to a very stout tripod with the shutter released on a 2 second timer, here is a list of the lenses I compared ->

  • Sigma 60mm f/2.8 Art DN - this acted as my "control", since it's perfect from wide open
  • Nikon 85mm f/1.8 "K" - the new multi-coated c.1977 toy
  • Nikon 85mm f/1.8 "H" - the old single coated c. 1971 toy
  • Nikon 50mm f/1.8 E - a 25Euro lens I picked up at the Bievre photoswap this year
  • Nikon 50mm f/1.4 pre-Ai - I've had this forever and wish I'd sold it and kept the 50mm f/1.2
  • Helios 58mm f/2 44M-4 - a 24Euro lens I picked up a couple years ago
  • Sony 55-210 SEL OSS - a cheap compact zoom I picked up at Bievre this year, too

Take a look at the comparison at 100% resolution to more clearly see subtle and not so subtle differences between all this glass.

50 to 85mm Lens Comparison

Findings -

  • With old manual focus glass, stopping down one stop brilliantly clears up the center of a scene.  Even the cheapest lenses perform very well stopped down one click from wide open.
  • Modern AF glass (Sigma, Sony) can be wonderously glorious from wide open.
  • The focal reducer I own (Zonghyi Lens Turbo II) introduces rather obvious focus shift as I stop lenses down from wide open.  The lesson is to focus at the aperture setting I shoot at when using the Lens Turbo II.
  • The biggest differences between the various lenses is how quickly, or not, the edges of a scene clean up as I stopped the lenses down.
  • Optical performance neither degrades nor improves with the use of a focal reducer.
I like debunking myth and legend by direct comparisons.  This leaves little room for interpretation.  Either something is clear superior to something else, or it's not.  So what do I feel I've debunk?  Two things, actually.

First, I was led to believe the "K" lens was a Gift from the Gods.  I read this on many sites after doing a little research using the Force (Google).  Reviewing my results here the Nikon Nikkor 85mm f/1.8 K Ai is not demonstrably "better" than other not so legendary lenses.  Yes, it's good, but it's not that good.  Just look at the Sigma and Sony cheap zoom performance and you may see what I mean.

Second, claims are often made that focal reducers can improve resolution by shrinking the area of coverage (in this case going from full frame coverage to APS-C).  People think it's logical that when you shrink optical coverage that resolution would increase (in this case by 1.5x), but that is not how optical physics work.  Look at the 85mm "K" lens comparison between the Zonghyi Lens Turbo II and the lens mounted on an adapter that comes without focal reducing optics.

Yes, I need another project to take my mind off such silliness.  Lenses are lenses.  It's hard to find a bad one in the bunch.

Don't believe everything you read on the 'net, no matter how "right" nor how "good" something might feel.  Do your own comparisons and you might see that reality is a bit different than all that.

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