Two MF 28mm F/2.0 AIS Nikkors - and one visibly inferior!

[Per Inge Oestmoen]

Hello my friends!

I have in my possession two copies of the MF 28mm F/2.0 AIS Nikkors. Yes, the rather less common 2.0 version.

Both are mechanically supreme, no blemishes of any kind, nothing indicates that either copy has been subject to any kind of abuse.

Naturally I then was curious to find out whether there was a difference in optical performance.

What was my consternation upon seeing with my own eyes that one of these copies was brilliant, whereas the other was so-so particularly in the corners but also in the center there is a visible difference albeit not strikingly visible. To me it looks like the left side of the lens is the absolute worst, and to ascertain this I believe a professional technician or a very experienced Nikon user should examine the lens.

Can this be remedied at a professional repair workshop? Is there a serious misalignment here? Pictures follow below.

THE INFERIOR COPY

The inferior copy, aperture 2.8 - infinity focus:

http://www.coldsiberia.net/lens_investigations/_DSC1792_cut_srgb.jpg

The inferior copy, aperture 2.0 - this is the center of the lens and around 1.2 meters from the subject:

http://www.coldsiberia.net/lens_investigations/_DSC1783_cut_srgb.jpg

THE SUPERIOR COPY

The superior copy, aperture 2.8 - infinity focus:

http://www.coldsiberia.net/lens_investigations/_DSC1796_cut_srgb.jpg

The superior copy, aperture 2.0 - this is the center of the lens and around 1.2 meters from the subject:

http://www.coldsiberia.net/lens_investigations/_DSC1791_cut_srgb.jpg

Do the symptoms seem familiar? Is this indicative of a decentering issue?

Sincerely,
Per Inge

[Bjørn Rørslett]

These 28 class lenses do have frontal CRC. Thus they are quite susceptible to knocks and bumps in hat region. Harm can be inflicted even through the lens appears to be perfect on the outside.

[Per Inge Oestmoen]

These 28 class lenses do have frontal CRC. Thus they are quite susceptible to knocks and bumps in hat region. Harm can be inflicted even through the lens appears to be perfect on the outside.

Yes, so it is not at all unlikely that the lens in question has some misalignment of the lens elements if the symptoms indicate that - which I infer that you believe.

I take it that it will be rather expensive to repair the lens, but given its proven inherent quality it is still worth it. I take for granted that it is necessary to let a repair shop remedy this.