New vs Old ~ a little experience

Readers likely by now know how much of a nut I am about optics and minutia and details and things that really don't seem to matter to normal people.  

Certainly I've learned a lot over the years by poking and prodding at the subject, including that well designed optics are a result of balancing trade-offs. However, explanations of these trade-offs are all too often are missing from the marketing literature.  It seems as if there is a distinct disconnect between engineering and marketing.  

Helpful descriptions like what makes a good portrait lens are very rare.  In fact, I only know of one document that a manufacturer produced that guided users.  That was with the specialized Kodak Portrait lenses.

More normally interested parties are left to sort things out for themselves.  

A good example of this is Nikon's famous 105mm f/2.5 Nikkor-P.  It was commonly accepted that it is a wonderful optic, but no one could tell you _why_.  The marketing literature of the day is woefully lacking in explaining the unique property of that lens.  

It is only relatively recently with Nikon's 1000 and 1 Nights lens history series that we learn the designers controlled the under-corrected spherical aberrations behind the point of focus.  Here is how Nikon now explains it.

"... The lens also has characteristics of spherical aberration and coma. Basically close-range aberration variation is small, but at portrait distances the correction for aberration seems to be slightly insufficient. The insufficiency as far as spherical aberration in particular is what makes defocus background appeared beautiful. The aberration balance has been calculated carefully for use in portraits. When the aperture is open contrast is good, and delineation is soft..."

That, right there, is why that 105mm lens is so gorgeous. 

Being left to sort things out for myself, with years, experience, and patience, I think I've hit upon the things that make a lens interesting to me.  Resolution is a given.  As it turns out that is probably the easiest quality to design into a lens.  Even sub-$100 kit lenses are "sharp."

Field flatness is not all that important to me, unless, as in the case of the Nikon Nikkor 35-105mm f/3.5-4.5 zoom, the field curvature is extreme.  There is also the case of the Zhongyi LensTurbo II focal reducer with, with certain lenses, such as the Nikon Nikkor 24mm f/2.8 Ai, introduces an obvious amount of curvature to the field.  Other than that, field curvature is just one of those things to think about in specialized applications, such a document photography where a flat field might be helpful.

Other lens "faults" such as chromatic aberration can now be corrected in image processing software.

Which leaves me with the aforementioned spherical aberration.  When a designer deliberately uses this form of aberration in a lens, it can help lead to "creamy" smooth out of focus rendition.  This, I've come to learn, is what Nikon carefully considered in their manual focus lens designs.  I'm thinking of the fabulous 85mm f/1.8 H/H.C./K and famous 105mm f/2.5 P lenses, as well as, perhaps surprisingly, Nikon's 75-150mm f/3.5 and Nikkor 100-300mm f/5.6 AiS optics.

As I said, it can take time to sort out which properties might matter to you.  This is why I'm pretty sure why Leica once advised that photographers use a lens for a year before deciding if they liked it or not.   

Et voila! this is how I settled on Nikon lenses.  I've been using them consistently for many years after having used Canon lenses for even longer.

I recently picked up an attractively priced very low "mileage" (less than 800 clicks on the shutter) Sony A7 to use with a rather too big a stack of Nikkor manual focus lenses that I have.  Since I'd convinced myself that I'd find no better out of focus rendition than with these lenses, wouldn't it be nice to be able to use them without a focal reducer to get in the way of things?

 

~ Stack of Nikkors ~
Too many choices?
Worse, I've added two lenses
to this stack since the photo
was made.

Shortly afterward, in search of a lens that I could take on our travels and that was demonstrably better than the Sony APS-C mirrorless kit lenses, I bought off that auction site an inexpensively priced Zeiss 16-70mm f/4 OSS ZA.

The Zeiss has a very very small mark on the front glass.  It's really difficult to see the defect and it might only be a rub on the coating as the glass looks to be OK.  The lens has proved to be a good choice, being well constructed and pleasingly sharp and all that.  

However, I hadn't taken it as "seriously" as I do the Nikkors. The new to me Zeiss lens remained "just another lens." 

In fact, just the other day I enthused over a beat-up Micro-Nikkor 105mm f/4 Ai and its out of focus rendition.  So many project possibilities came to mind and I was excited to haul this thing into the wild to make a few images with it.

An opportunity to photograph a music group plopped into my lap and I wanted to confirm which lens(es) I would use.  Wanting the most flexible solution for this studio photoshoot I thought perhaps I should use the 16-70mm ZA.  And I'd better check things out beforehand.  As "beautiful out of focus" references I used my 85mm and 105mm Nikkors to compare them with the new to me Zeiss ZA.

I didn't expect much out of the Zeiss for out of focus rendition.  I'd read, for instance, that Zeiss' 24-70mm f/4 lens for full frame Sony cameras had "busy" out of focus rendition.  Could the little ZA lens really be any different?

... er... yes... I was in for a little surprise... and I like good surprises... so yipee!!!  Looking at the results at 70mm f/4 with the smaller APS-C 16-70mm Zeiss forced me to evolve my thoughts on the subject.  

Take a look at the following images, and as always, click on and enlarge them to 100percent.  Pay particular attention to the lettering/numbering around the inside front ring as well as the out of focus qualities of the rear cap.

 

Nikon Nikkor (Xenotar version) 105mm f/2.5
photographed with
Sony A6000 - ISO100
Zeiss 16-70mm f/4 ZA OSS

 

Nikon Nikkor (Xenotar version) 105mm f/2.5
photographed with
Sony A7 - ISO50
Micro-Nikkor 105mm f/4 Ai

The differences are rather subtle between the images.  Yet to my eyes the Zeiss is "smoother" in the out of focus regions than the Micro-Nikkor 105mm f/4.  The "edges" rendered with the ZA lens are "rounder."  

Don't get me wrong.  The Micro-Nikkor is quite wonderful and I'm certainly not in any hurry to kick it to the curb. It's just that the Zeiss does something that I find "special."

To continue my little exploration I took a look at the out of focus rendition with subject matter a couple meters from the lens and at other focal lengths across the Zeiss' zoom range.  What I found with the closeups at 70mm holds true when photographing at greater distance.  This Zeiss' out of focus rendition is "smooth" nearly everywhere and at nearly all focal lengths.

It turns out the 16-70mm f/4 ZA OSS is actually a very nice lens.  Whoever designed it really put effort into it to get so many details "right."

What a find, eh?

 

 Sony NEX-7
Zeiss 16-70mm f/4 ZA OSS
~
Which is not much bigger
than the same camera with
Sony's 18-55mm kit lens.