The obvious difference is that it is one stop slower at 400mm which is the part of the zoom range most important to bird photographers. So what else do you lose to save approximately 40% of the price of a 100-400mm.

First and probably most important is there a sharpness compromise? Being a non-S series lens the expectation is that the 28-400 will be less sharp, less weather sealed and less rugged – all properties of importance to bird and wildlife photographers. On the plus side the expectation is that it will be lighter – also important to travelling photographers who struggle with airline weight limitations.

At 725g as opposed to 1435g the weight saving is almost 50% for the 28-400 which is a clean win for the wider range lens. What is the point though if the image quality is lacking. To check this I did some real world test shooting on birds using the Nikon Z8 with the Nikkor Z 28-400mm f4-8 VR and the Nikon Z9 with the Nikkor Z 100-400 f4.5-5.6 VR S. This gave me a range of images to compare and in summary the 100-400mm is definitely sharper but I was surprised by how little advantage it showed.

When it was released I was impressed by how much the Z 100-400mm was an improvement over the previous F mount 80-400 and I would probably have to say the 28-400mm is probably as sharp as the 80-400mm. I no longer have one to compare back to back but that is my feeling looking at the images. The difference in sharpness between the 100-400 and 28-400 is something that is unlikely to be visible once a RAW image has been processed and resized for presentation in any way other than as a large print.

The following images show quite clearly to my eye the differences between the 28-400mm and 100-400mm. The latter is sharper with better contrast but the difference is not as large as I would have anticipated

This post is simply about image quality in decent light. In a subsequent post I will explore whether the 28-400mm is a viable replacement for the 100-400mm in a travelling bird photographers kit.