Interview to the designers of AF-S 105/1.4E

[Roland Vink]

Yes, we know.  I was curious about the actual focal lengths of other Nikkor 105s.  Ais Micro 105/2.8 is known to be 82mm with the built-in teleconverter.  How about Ai/Ais Micro 105/4.0?

Other 105mm lenses including 105/2.5 (sonnar and gauss) and 105/4 micro are exactly 105mm - you can check the lens schemas on the mir site. I'm pretty sure the AIS 105/1.8 is also 105mm. These are all unit focusing lenses so the focal length does not change when focusing.

The other 105mm lenses - AIS 105/2.8 micro, AF 105/2.8 micro, AFS 105 VR micro, 105 DC - all have CRC, IF or RF, so have focal length shortening at close range. I assume all are 105mm (or very close) at infinity ...

[richardHaw]

it's nice to see that Nikon is recognising that people are using class lenses for a reason and they are doing something about it

[Roland Vink]

Sometimes the angle of view given in the lens specifications gives us a clue about the real focal length. For example the newer "35mm" lenses have a slightly wider angle of view than the older lenses, which suggests they have true 35mm focal length instead of 36mm as with most older models.

For the 105/1.4 Nikon gives the following:
  Nikon FX-format D-SLR cameras: 23°10'
  Nikon DX-format D-SLR cameras: 15°20'

This is almost identical to the angle of view for all other "105mm" lenses. Actually, other 105mm lenses give 23°20'  for FX format, which suggests the focal length is very slightly longer than 105mm 

[Akira]

Other 105mm lenses including 105/2.5 (sonnar and gauss) and 105/4 micro are exactly 105mm - you can check the lens schemas on the mir site. I'm pretty sure the AIS 105/1.8 is also 105mm. These are all unit focusing lenses so the focal length does not change when focusing.

The other 105mm lenses - AIS 105/2.8 micro, AF 105/2.8 micro, AFS 105 VR micro, 105 DC - all have CRC, IF or RF, so have focal length shortening at close range. I assume all are 105mm (or very close) at infinity ...

Ais Micro 105/2.8 goes up to 1/0.88 magnification with PN-11.  All AF Micro 105s are intended to be used without PN-11, so a little deviation from the nominal focal length could be tolerated.

[Akira]

it's nice to see that Nikon is recognising that people are using class lenses for a reason and they are doing something about it

According to LensRental review, the sample variation of 105E is a bit wider than that of 85/1.4G.  The variation may become smaller over time...

[Akira]

Sometimes the angle of view given in the lens specifications gives us a clue about the real focal length. For example the newer "35mm" lenses have a slightly wider angle of view than the older lenses, which suggests they have true 35mm focal length instead of 36mm as with most older models.

For the 105/1.4 Nikon gives the following:
  Nikon FX-format D-SLR cameras: 23°10'
  Nikon DX-format D-SLR cameras: 15°20'

This is almost identical to the angle of view for all other "105mm" lenses. Actually, other 105mm lenses give 23°20'  for FX format, which suggests the focal length is very slightly longer than 105mm 

Hmm...apparently things have become complicated.   

The 105E uses three ED glasses that are known to have larger expansion factor than the normal glasses.  I wonder if the difference of the tempertarure of the testing room should be counted in?  Although it is hard to believe that the expansion factor affects the focal length by the order of several millimeters...

[richardHaw]

Ais Micro 105/2.8 goes up to 1/0.88 magnification with PN-11.  All AF Micro 105s are intended to be used without PN-11, so a little deviation from the nominal focal length could be tolerated.

https://richardhaw.com/2016/10/30/repair-nikon-pn-11-extension-tube/
Here is my PN-11 teardown
i opened it up from the wrong side

longer lenses doesn't have as much difference when compared to wide lenses so a little bit of difference in FL should not be too noticeable.

[Akira]

Good job, Rick, as always!  Yes, the deviation of the focal length will be less influential on a longer lenses.

[Ilkka Nissilä]

Lensrentals did a teardown of the 105/1.4E:

https://www.lensrentals.com/blog/2016/12/taking-apart-the-new-nikon-105mm-f1-4e-ed-af-s/

No ring type SWM; early information seems to have been incorrect regarding this aspect. (Not that it matters to me; I don't care about the implementation when in fact the lens focuses well.)

[bobfriedman]

thank you Akira!

[Akira]

Thanks, Ilkka, for the link to the teardown article.  I wonder if they could have used a stepping motor, if it is a USM micro motor.

The reason for the second element group is sealed should be because of the nano-crystal coating.

thank you Akira!

You are welcome, Bob!