Wednesday, October 11, 2017

Out of Focus Rendition ~ a quick look at a few Nikkors and one Sony

Before the Strange Beasty Pentax 85mm f/2.2 Soft landed on my doorstep, I took a look at the out of focus rendition (OFFR) of various lenses that I have on hand.

Here is the incredibly boring but sufficient to the task scene.  It was taken with a Nikon Nikkor 85mm f/1.8 K pre-Ai shot wide open.

Nikon Nikkor 85mm f/1.8 K

Here is the comparison (follow the link and head to the files to select the largest, and then view it at 100 percent to clearly see what I will describe in just a moment).  All lenses were shot wide open.

Bokeh Studies

Organizing my comments by ranking these lenses from doughnut shaped OOFR to the smoothest -

  • Nikon Nikkor 50mm f/2 H pre-Ai
    [huge gap in OOFR]
  • Nikon Nikkor 50mm f/1.8 AiS
  • Nikon E-series 75-150mm f/3.5 AiS
  • Nikon Micro-Nikkor 55mm f/3.5 pre-Ai
  • Nikon Nikkor 135mm f/3.5 AiS
  • Nikon Nikkor 135mm f/2.8 pre-Ai
  • Sony 50mm f/1.8 SEL OSS
  • Nikon Nikkor 85mm f/1.8 K pre-Ai
  • Nikon Nikkor 105mm f/2.5 AiS
Looking at the old double gauss 50mm f/2 H OOFR I see what a Zeiss whitepaper on optical design described as over-corrected rendition.  Before I say the OOFR is "horrible" I would like to note that some people love the soap-bubble rendition.  Recently a manufacturer started selling lenses that deliberately give this effect, so who am I to judge?

What's interesting to me is that the more current implementation Nikon Nikkor 50mm f/1.8 AiS gives a much smoother OOFR (hence the previous note about a "huge gap in OOFR").  Looking at cross section diagrams of the two lenses (the f/2 vs the f/1.8) I see the classic double gauss implementation.  They look to be identical and I would've thought their performance to be more comparable, yet it's clearly not.

Further, if I'm correct in thinking about the cross section diagrams of the other lenses I compared here, all but one (the 75-150 E-series zoom) are in one form or another derivative double gauss designs.

If the goal is to find lenses that give smooth OOFR (that is to say, lenses that melt the OOFRs into creamy smoothness), then all but one (the Nikkor 50mm f/2 H) meet the criteria of "goodness".  The standout of the short, "standard" focal length lenses is the 50mm f/1.8 AiS.  It's OOFR is the best of any 50mm lens I've ever owned.  This one is a "keeper."

One surprise is the performance of the Micro-Nikkor 55mm f/3.5.  Yes, the aperture is somewhat small at f/3.5 so the depth of field is not razor thin when shot wide open.  Yet the OOFR is creamy smooth.  It's really quite interesting to see and might be very usable for shooting portraits where the nose and eyes are in focus.

Another surprise is the 75-150mm f/3.5 E-series zoom.  I read somewhere that this lens used to be a favorite of fashion photographers back in the day.  It was considered a "sleeper" lens, and I can see why.  This is a great lens for OOFR at _all_ apertures.  I don't understand it.  The aperture blades do not form a circle, yet the OOFR remains creamy and smooth all the way down thru f/11.  I'm not convinced Nikon designed the lens this way (it's cheap and not otherwise widely regarded), but the effect is clear.

The sharpest lens in the group when shot wide open is the 135mm f/3.5 Nikon Nikkor AiS.  Period.  There are not enough superlatives to explain just how brilliant the lens is.  The OOFR, however, is not quite as buttery-smooth as it's sister the f/2.8 135mm Q.

Stuck in the middle of all these Nikkors is a little Sony 50mm f/1.8 SEL OSS.  The link has disappeared, but there was a page out on the 'net that showed the Sony to be the equal of new Leica lenses.  Well, it's true (in my experience, at least).  The OFFR, too, is really quite outstanding.  For portraiture on APS-C Sony mirrorless this lens is a "keeper."

The 85mm f/1.8 K gives very nice OOFR and lightly "swirls" the background (ala Petzval).  I would've claimed it the winner in my OOFR comparison except for one lens.  And that lens is the 105mm f/2.5 AiS.  It is the smoothest-butteriest (how's that for making up  new words?) OOFR lens I currently own.  It's reputation appears to be well founded.

Prices on old manual focus lenses seem to be dropping.  Perhaps the market is finally saturated with lenses, new and old?  In any event, to stock up on optics to perform this comparison cost me very little.  The 50mm f/2 and f/1.8 lenses are commonly found for between 25Euro and 50Euro.  The 75-150mm E-Series, the 135mm f/3.5, and the 80-200mm f/4.5 lens (not compared here) were _all_ picked up in mint condition off eBay for around 40Euro each.  The 105mm f/2.5 AiS came as a trade for an 85mm f/1.8 H I had and cost me nothing.  The 135mm f/2.8 was very kindly given to me by a friend who picked up a Zeiss 135mm f/2.

In the end, this comparison is about finding many great lenses with wonderful OOFR, while, at the same time, costing next to nothing.

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