Nikon 85mm f/1.8G on Nikon 1

By using the Nikon FT-1 mount adapter, you can connect Nikkor F mount lenses to a Nikon 1 camera. Most newer lenses work well on Nikon 1 cameras, in the sense that you can operate the aperture as usual, and you can also use the autofocus. When using an adapted lens, you can only use the centre focus point, and you cannot use the AF-A mode. Otherwise, it is mostly like using a native Nikon 1 lens.

It still doesn't make sense to use any Nikon F lens on a Nikon 1 camera. I would only bother if the Nikon F lens is one of:

1. Fast (large aperture)
   
2. Very long (tele, large magnification)
   
3. Macro (close focus distance)
   

A lens in the first category is the entry level fast portrait lens, the Nikon 85mm f/1.8G. To understand why an 85mm lens is called a portrait lens, you can read this article.

On a Nikon 1 camera, this lens becomes equivalent to 230mm f/1.8, due to the 2.7x crop factor. Such a lens can be interesting for various purposes, for example low light photography in concerts or theatres. Here you see the Nikon 85mm f/1.8G mounted to the Nikon FT-1 (to the left), compared with the native CX 70-300mm f/4.5-5.6 to the right, mounted to the Nikon 1 V3.

When mounted to the camera, the lens becomes somewhat unbalanced. I would recommend holding the lens with the left hand, to avoid stress on the camera lens mount:

Image quality

But how does it work then? To compare the image quality, I have taken the same photo using both lenses above. I used the camera at base ISO, on a tripod.

Nikon 85mm f/1.8G @ f/1.8	CX 70-300mm f/4.5-5.6 @ 85mm f/4.8

To better compare the image quality, here are 100% crops from the centre of the image, at various apertures:

And from the top of the image:

From these example images, we see that the lens exhibits severe chromatic aberration (CA) artefacts. As you close down the aperture, these become less pronounced, but it is a problem until you reach around f/5.6. Hence, if you have a strong contrast subject, e.g. backlight, you need to stop down to at least f/4 to avoid CAs. This makes the lens hard to use in practice.

However, the good news is that this can be corrected in post processing. Scroll down in this article to see how these effects can be removed, and what the resulting images look like afterwards.

Here is another example, at a closer focus distance:

Nikon 85mm f/1.8G @ f/1.8	CX 70-300mm f/4.5-5.6 @ 85mm f/4.8

Here are 100% crops from the top of the image:

In this case, we see that chromatic aberration (CA) is not a problem here, as there are no hard contrasts. And the Nikon 85mm f/1.8G sharpness is in fact rather good even wide open.

Autofocus

As mentioned already, when adapting the Nikon 85mm f/1.8G using the Nikon FT-1, one can only use the centre autofocus point. This makes it somewhat less useful, but most of the time this is just fine.

Focus is generally very quick on the Nikon 1 V3 camera.Using AF-C, it is even easy to focus on birds in flight (BIF). Here is an example image illustrating this:

The picture was taken at f/1.8, ISO 400, 1/2000s. This 100% crop shows that the bird is in focus, and the sharpness is good, even if there are some CA effects:

The picture was taken in AF-C continuous autofocus mode, and a whole series of images, at 20 FPS, were all in focus. So the camera and lens combination is certainly well suited for birds in flight, as long as you can keep the bird centered in the frame to be picked up by the central focus point.

Here is another example image taken at f/1.8:

The 100% crop shows just how much CA you get:

These CA effects can be mostly removed in a good image processing program, like Photoshop. So it is not the end of the world, but it can be annoying. It seems like the lens gives more CA effects when you focus closer to infinity.

Removing CA in post processing

The heavy Chromatic Aberration (CA) artefacts surprised me. I have just tested the lens on a Nikon DX camera (click to read my test), where I found that the lens is a bit dull, but there were no adverse CA effects at all.

It turns out that the CAs are removed by in-camera processing when using the lens on an FX or DX camera, but not on a CX camera (Nikon 1). However, you can remove these effects yourself with, e.g., Lightroom. Here is how I did it.

I opened the .NEF RAW file in Lightroom 6, and in the Developer mode, I used the "Remove Chromatic Aberration" option, in the "Lens Correction" section. Move the top slider as far to the right as needed for the effect to go away:

Here is a typical outcome:

Applying this correction to the tests above, we find this comparison:

As you see, the images are still not super sharp at f/1.8, but without the adverse CA effect, they are way more usable.

Perhaps future Nikon 1 cameras will also apply in-camera CA removal with adapted Nikon F lenses.

Conclusion

Using the Nikon 85mm f/1.8G on the Nikon FT-1 mount adapter works fine. But if you have strong contrasts in the image, you can expect severe chromatic aberration (CA) artefacts if you use an aperture larger than around f/5.6. In lower contrast situation, the sharpness is quite good.

With the CA issues, you may be limited to using the lens stopped down to f/2.8-f/5.6, depending on the situation. Hence, the lens is not that fast anymore. However, by using post processing software like Lightroom, you can remove the CA effect, with a minimum of effort.

The autofocus is very quick and accurate, even with moving subjects.

If you also use a Nikon DSLR systen, I can see the benefit of using the lens on both systems. But getting the Nikon 85mm f/1.8G solely for use on Nikon 1 does not make as much sense. Even if it becomes equivalent to 230mm f/1.8, you cannot expect to be able to use it wide open in all situations. If you take the time to remove the CAs, though, the lens has some interesting uses.