Monday, September 29, 2014

Nikon 20mm f/1.8G lens -- a hands-on review

This lens has been a long awaited -- by me at least -- update of the original Nikkor 20mm f/2.8D lens design that is 30 years old. In the film era this lens had always been my favorite super-wide, but on a digital camera it showed its age and was, to my mind, totally unusable. Although updated several times with mechanical changes, the optical system of the f/2.8 lens has remained the same as that of the original 1984 model. The new version not only refreshes the optical layout with a new design containing ED glass and aspherical elements, but adds over one stop to the maximum aperture.

Even with its extra f/stop, and 77mm as opposed to 62mm filter size, the new lens weighs in slightly more that 3oz than the older f/2.8 version (9.52oz) and does not exhibit the bulkiness of zoom lenses in a similar focal range. In other words, its a perfect super-wide option for when you want to travel light.

The real problem for resolution with a super-wide is usually found in the corners. This lens does not disappoint. Although at its most extreme aperture you can detect some corner softness, I did not find it objectionable, and once the lens is stopped down even to f/2.8 it is acceptable, and really good at f/5.6 as you would expect, and is probably the range where most of us would normally use a lens like this. If this lens had come out with an f/2.8 aperture this review would be even better and I would have been content simply for an updated replacement of the older model. As it is, the f/1.8 aperture is an added bonus that will undoubtedly come in handy for many applications.

Below are some sample images where you can download high res files to judge the performance for yourself. All were shot as original jpgs.

In my brick wall test you can see the obvious vignetting occurring in the f/1.8 image on the left, but gone from the f/5.6 image on the right. Of course, vignetting is one of the easiest things to control in post-processing and typical at very wide open apertures on most lenses. The gray triangular shape at the bottom is a perpendicular fence I use to be certain the camera back is parallel to the wall during these tests. I included a few of the tests below for downloading so you can see the results. 

A 20mm focal length is very well suited to capturing subjects like night time starry skies and the fast f/1.8 aperture allows working at a lower ISO for better noise control, while also keeping the exposure time down so as not to blur the stars.

Despite its appearance in one extreme example below of the interior of Grand Central Station, the correction for chromatic aberration in this lens is really excellent. The green tree image below is a test I do for chromatic aberration.

This is a lens test I do for chromatic aberration by shooting an open image of leaves over-exposed against a bright sky. I know from experience that chromatic aberration is almost always present in a shot like this. With the Nikon 20mm lens it is almost non-existent except in subtle traces towards the top of the frame.  Click here to download the high res version of this file.

This image of the Brooklyn Bridge and World Trade Center is typical of the way I would normally use a 20mm lens for a travel shot. Taken at f/5.6 on a D750 the focus is sharp everywhere, even in the corners. Click here to download a high res version of this file. 

Note the chromatic aberration occurring in the bright window area at the bottom of the frame. To be fair, this is exactly the set of circumstances where I would expect this type of fringing to occur with almost any lens. Fortunately, it is very easy to correct. Click here to download a full res version of this file.

The scene below (taken with a 16mm focal length) is typical of how I shoot a landscape with a super-wide lens. I put the focus in the foreground and stop down enough to obtain enough detail in the background. The foreground is usually filled with detail that I want to preserve. If a lens cannot hold detail in its corners, it becomes glaringly obvious in a shot like this. The test I do to determine how a lens will perform in this situation is shown in the photo below this one of a cobble-stone street.

For this test I place the lens close to the ground and focus on the foreground. I want to see if the lens can hold focus across the focus plane into the edges of the photo. The Nikon 20mm lens proved itself a real winner in this test. Below are some links to full res files taken at different f/stops.  Even at f/1.8 this lens is looking good.
The close-up range of 7.9" makes it easy to get right on top of your subject, closer than the super-wide zooms.

Situations like this is why 20mm is my preferred super-wide lens. It delivers just the right amount of sweeping perspective and depth with minimal distortion. This image was taken late in the day with a Nikon D750 and the 20mm lens set to f/7.1.


Stopped down, which is where a lens like this is typically used for landscape photography, the results are impressive with edge-to-edge sharpness. It's fast f/1.8 aperture is an added bonus useful for dimly lit interiors and night photography.  It comes in a light-weight package and can easily replace in weight and performance any of the heavier zoom lenses that hover around this focal length. 

The resolution for this 20mm lens is no match for the Nikkor 24mm f/1.4, but it is much wider and, at $796.95, less than half the price. For me it has already become a welcome addition to my camera bag and I will probably sell off one of my shorter zooms -- like the much slower 18-35mm, which it out-performs -- to make room for it.

If you are planning on buying this lens, you can help support this site at no extra cost to you by clicking the link and purchasing from one of our affiliate sellers listed below -- and thanks for your support.
The Nikon 20mm f/1.8G lens can be ordered from:  BH-Photo   Amazon   


  1. Thanks for the review, Tom.
    This looks like a useful new addition.

  2. Can you compare the 20mm to the 24mm 1,4? Do you have examples?

  3. Thank you very much for this review/test

    " The resolution for this 20mm lens is no match for the Nikkor 24mm f/1.4"

    Very interested in more about this = I have the 24mm f/1.4, and it is OK, (but not fantastic), and it is more heavy


  4. Great review with real-life examples--and very nice ones at that!
    This pretty much clinches it for me--I want this lens!
    Thank you!
    (P.S.: The character recognition requested of anonymous posters is exceedingly difficult--I had to try many many times before I got it right...)

  5. Hi Tom,

    I have the 24 1.4G and am thinking of selling it and getting the 20 1.8G for a lighter, wider lens, but I have heard web reports of the 20 1.8G having back focus issues and is too lightly (plasticky) build. Care to share your comment on the 20 as well as the 24 (in comparison with the 20)?

  6. Thanks a lot for that great articale.
    I have a small problem or maybe its just something normal I am not sure.
    Nikon D750 is my first camera.
    And in my viewfinder I can't see the actual view with the changes I made in ISO, Is that normal or I should change something in the setting ?
    I can see the numbers below the image but I don't see the changes in the photo itself. While when I use the live-view I can see the photo with the changes before shooting.
    can anyone help please :/

  7. The reason for this is that, unlike a mirrorless camera, with a DSLR like your D750, you are looking at a real scene by means of a mirror. You are not looking at an electronic interpretation of the scene. When you use live view you are seeing an electronic interpretation of the scene on a video screen.

  8. every camera with viewfinder will act like that

  9. So we can consider Nikon D750 is a Mirrorless Camera?

  10. No, the D750 is not a mirrorless camera. It is a DSLR, which means it has a mirror.