brian_caldwell

The 50/1.8 is a sharp lens, but if you ever intend to use it stopped down to f/16 or f/22 for landscape work I would strongly recommend the older AIS version over the newer AIS or AF versions. The reason is that the newer versions suffer from a central flare spot even when there are no bright light sources in or near the image frame.

Hi Mike:

I publish a database of lens designs (LensVIEW) from the patent literature, but unfortunately I have never encountered a prescription for the Noct-Nikkor. In general, fast double-Gauss designs use high-index Lanthanum crowns and moderately dense flints, but without actually doing some extensive measurements on the acutual elements my best guess for the refractive indices would likely be off by as much as 0.06 or so. Another difficulty is that Nikon makes alot of their own glass, and in particular many of their Lanthanum crowns don't precisely match off-the-shelf glass that you can buy from Schott, Hoya or Ohara.

 

Using patent data, glasses (listed as index/Abbe number) for the 50mm f/1.2 and 50mm f/1.4 are as follows:

 

50mm f/1.2:

Element 1: 1.79668/45.5

Element 2: 1.79631/41.0

Element 3: 1.71736/29.5

Element 4: 1.7552/27.6

Element 5: 1.77279/49.4

Element 6: 1.77279/49.4

Element 7: 1.7443/49.4

 

50mm f/1.4:

Element 1: 1.79668/45.5

Element 2: 1.79631/41.0

Element 3: 1.69895/30.1

Element 4: 1.72825/28.3

Element 5: 1.79668/45.5

Element 6: 1.71300/54.0

Element 7: 1.77279/49.4

 

As you can see, some of the elements use identical or very similar glasses, but others may be sufficiently different to throw your coating design out of whack. The Noct-Nikkor almost certainly glasses that are similar to these two designs. Some multi-layer coatings aren't that sensitive to substrate index,

 

There are several ways to directly measure the refractive index of each element in the Noct, at least one of which is non-destructive. However, it is not a trivial business. Also, stripping off lens coatings involves re-grinding, then re-polishing, and finally coating. You might be better off designing and building a completely new lens. I'm a lens designer by profession, and can help you do just that if your interested.

 

Brian

www.caldwellphotographic.com

Hi Alex:

I've tested a number of Nikkors for distortion and color fringing on a D1x and have published the results: http://www.caldwellphotographic.com/ccmain.html

 

It turns out that very few lenses have truly zero distortion, even on the reduced format of the D1x. Some examples are the 85mm f/1.4 AIS, 105mm f/2.8 AIS micro, and 105mm f/2.5. Of these three, only the 105 f/2.8 AIS micro is fully corrected simultaneously for both distortion and color fringing. The55 f/2.8 micro is an extremely good lens that I use more than any other for mosaic work, and it only has a tiny trace of distortion. The 50mm f/1.8 and 45mm f/2.8 GN both have a very small (but still detectable) amount of distortion. I assume the new 45/2.8 is similar to the old 45/2.8 GN.

 

In the wide-angle area the closest thing to a truly distortion-free lens is the 17-35 AFS zoom when used at about 24-25mm. Interestingly, this zoom has far less distortion than any corresponding wide angle prime that I've tested.

 

I rarely use wide angle lenses for stitching because this would limit the resolution too much. Most often I use the 55/2.8 micro or 105/2.5. Although the 55 has a trace of distortion and the 105 has a trace of color fringing, in both cases the amount of aberration is small enough to ignore for the purposes of high quality stitching.

 

The quality you can achieve by stitching is definitely in the large format range, and it is ideal for architecture.

 

Good Luck!

Brian

www.caldwellphotographic.com