A Second Look at a Classic Lens on a New Camera

Does that older lens deserve a second look with a newer camera? Eight years ago, I did a review of my Nikkor AF-S 85mm f/1.4 G lens. Back then, my newest camera was the 16 megapixel Nikon D7000 DX camera, so I tested the lens on that model.

It’s well known that a high-megapixel camera should give you better resolution with a given lens, compared to a low-megapixel camera. Since my D7000 camera days, I have obtained better gear and thought it would be interesting to re-evaluate that old 85mm f/1.4 Nikkor on my Nikon Z9 mirrorless camera. I’m using the FTZ-II adapter on the Z9, of course.

Nikkor 85mm f/1.4 G mounted on Nikon Z9

As camera technology improves, you can get better results from a lens in more ways than just better resolution. Especially with the switch from DSLR to mirrorless, you get better focus accuracy without having to even bother with focus calibration. With fast lenses like this 85mm, focus shift problems with aperture changes are finally cured, since the mirrorless Nikons focus at the shooting aperture. Mirrorless cameras also focus better in dim light than DSLRs, since they don’t have focus sensors hidden behind partially-silvered mirrors. Another huge advantage is having in-body image stabilization (IBIS) on the mirrorless camera, since this lens doesn’t have VR.

The Nikkor 85mm f/1.4 AF-S has been the highest-ranked F-mount Nikkor lens at the DXO web site since they first measured it about 13 years ago. It finally got beaten by some of the Z-mount Nikkors; the highest-ranked lens from any manufacturer is currently the Nikkor 85mm f/1.2 S, which costs about $2,600. My 85mm f/1.4 still sells for $1,600 (it cost $2,200 at introduction). As of this writing, this F-mount 85mm is most likely doomed: Nikon is probably done making any more F lenses.

My primary interest in re-testing this lens is resolution. Since my original testing was done using a DX sensor, I’m particularly interested in how bad the edges look with a high-resolution FX sensor. Even though the Nikon Z9 has 45.7 megapixels, this lens isn’t quite good enough to reflect all of that additional sensor resolution. Nonetheless, the resolution measurements had better increase using this camera!

I found that focus repeatability was indeed much better using the Nikon Z9 (and the Z8) compared to the old D7000, but it wasn’t infallible. I have found that single-point focus is the least reliable way to focus this lens, which seems opposite of what you’d expect.

Focus speed is a little bit better on the Z9 and Z8 cameras than the D7000, but not by too much. The 85mm is fairly slow to focus, since it’s optimized for focus accuracy. There are better lens choices to evaluate focus speed than this one.

If you want to try manual focusing, the focus-peaking feature on the Z9 and Z8 cameras is really nice. The ability to magnify the image while looking through the viewfinder to really nail focus is also worlds better than using Live View on the old D7000.

Resolution Testing

I re-ran my old Nikon D7000 raw-format resolution test chart photos, using the newest version of my MTFMapper software. These D7000 test shots were created using an older version of a resolution test chart, but that chart is the same physical size and created using the same printer, paper, and ink as my new resolution test chart. The chart dimensions are 40” X 56”, which provides a very useful focus distance of about 13 feet, or 4 meters using an FX sensor.

I used my new-design resolution test chart for evaluating the 85mm on the Z9 camera. The MTFMapper program is happy using both the old and new chart formats, and the results are equal in precision.

85mm at f/1.4 MTF50 resolution on D7000

85mm at f/1.4 MTF50 resolution on Nikon Z9

As shown above, the lens resolution increased using the Nikon Z9 camera by about 14%. This is a lot less improvement than you might expect. What it shows is that the lens itself doesn’t have enough resolution to make a major impact on better resolution results with high-megapixel sensors.

What’s interesting to note, however, is that the edges of this lens don’t suffer much from a loss of resolution when increasing from DX coverage to FX. The corners have the very slightest dip in resolution.

I think that my copy of this lens has a slight lens tilt; the right-hand side always seems to have slightly better results than the left-hand side, at least when shot wide-open.

I have always maintained that an MTF50 resolution of roughly 30 lp/mm looks “sharp” and I’m sticking with that position. Using programs like Topaz DeNoise AI really helps enhance the sharpness, too. This means that the 85mm f/1.4 can be used wide-open, if desired. You should be more concerned with background bokeh and depth of focus decisions; in other words, concentrate on composition and art instead of sharpness.

MTF contrast plot (actual measurements) f/1.4

The plot above shows how much real astigmatism the lens has, starting from the lens center. Nikon doesn’t ever show you actual measurements, just ‘theory’.

85mm at f/2.0 MTF50 resolution on D7000

85mm at f/2.0 MTF50 resolution on Nikon Z9

At f/2.0, the Z9 managed to get about a 15% resolution improvement over the D7000 camera. You can see the corners take a resolution dip, since the FX sensor sees so much more of the lens fringes.

The lens takes a significant resolution jump going from f/1.4 to f/2.0 of about 38%. Now, it’s getting closer to ‘modern’ lenses for resolution.

85mm at f/2.8 MTF50 resolution on D7000

85mm at f/2.8 MTF50 resolution on Nikon Z9

At f/2.8, the Z9 saw about an 18% resolution increase overall, compared to the D7000 camera. The corners and edges of the FX sensor are excellent here. You may have started to notice a trend; the mid-frame resolution performance always seems to be a bit better than the center. I have read that the Nikon engineers made a design decision to sacrifice some center performance to enhance the mid and edge performance.

Nikon chose to use no exotic lens elements here; there aren’t any aspheric elements. The lack of aspheric elements means that there is a small sacrifice in what could have been done with smooth resolution, but that would also have probably meant worse bokeh.

85mm at f/4.0 MTF50 resolution on D7000

85mm at f/4.0 MTF50 resolution on Nikon Z9

The Z9 has an increase in resolution of about 22% overall, compared to the D7000 at f/4.0.  Resolution across the frame is really, really good. At this aperture, it’s now competitive with modern lenses.

85mm at f/5.6 MTF50 resolution on D7000

85mm at f/5.6 MTF50 resolution on Nikon Z9

This lens reaches peak performance at f/5.6, which is just a bit better than f/4.0.  Compared to the D7000, the Z9 is about 15% better.

85mm at f/8.0 MTF50 resolution on D7000

85mm at f/8.0 MTF50 resolution on Nikon Z9

The Z9 is roughly 14% better than the D7000 at f/8.0.  The resolution dip, due to diffraction, has begun.

Summary

Using this lens on a Nikon mirrorless, such as the Z9, does indeed improve the lens resolution results, although not as much as people probably expected. The biggest benefit is being able to nail focus far more often.

Even after all these years, the Nikkor 85mm f/1.4 AF-S is a great lens. It’s a favorite of many portrait photographers for good reason. It’s pretty sharp, has great bokeh, and can provide very thin focus depth when needed. This lens has aged better than most.

I feel that this lens’ biggest problem has always been focus shift when changing the aperture (spherical aberration). Now that the Nikon mirrorless cameras focus at the shooting aperture, that problem has been solved.

This lens’ biggest strength is the overall edge-to-edge resolution balance, combined with really good bokeh. My Sigma 70-200 f/2.8 Sport lens, for instance, smokes this lens for resolution, but the 85mm beats it for bokeh and of course being able to get to f/1.4.

I always missed having vibration reduction with this lens; with the Nikon mirrorless cameras having IBIS, that problem has disappeared.

The new Nikkor 85mm f/1.2 S lens is admittedly better in every category (except price), but the performance of my 85mm f/1.4 is so good that I personally don’t see the need for an upgrade.

Switching to mirrorless cameras has really been a delight. My D850 DSLR sensor is just as good as the Nikon Z9, but the advantages of mirrorless can’t be denied.

It’s really amazing to see the progress in cameras since the D7000. There’s virtually no aspect of that camera that hasn’t been usurped. My old lenses seem more like new ones when I mount them on my Z8 or Z9 cameras.