In this post, I’m going to compare performance in the image centre between these three telephoto lenses at 400mm:

• Nikkor Z 100-400 (e.g. from Amazon).
• AF-S Nikkor 80-400G (e.g. from Amazon).
• Sigma 150-600 Contemporary (e.g. from Amazon).

Unlike in the first post, where the focus was solely on the 100-400, I won’t provide exhaustive sample images of all apertures for all lenses – that would just be overwhelming. Instead, I’ll just provide the noteworthy cases.

30ft @ 400

The 150-600 is basically the same from wide open (f/6) through to f/8. It might be a tiny bit sharper at f/6 than narrower apertures.

The perceived sharpness of the 80-400 increases slightly when stopping down from wide open, and starts to soften again at f/7.1 and narrower. Its optimal aperture is f/6.3, vs f/5.6 for the 100-400.

Note that in practice I’ve tended to favour f/7.1 on the 80-400, including on 24 MP DX cameras which have higher pixel densities than the Z7 (and therefore should be more sensitive to diffraction, not less). That’s based on a large amount of real-world experience. There’s several possible explanations for the discrepancy, but my guess is that the increased depth of field, of f/7.1 over f/6.3, helps in practice because it:

• Increases the depth of field (sometimes important at close distances or with deep subjects).
• Provides a little more tolerance for focus errors.

Prev 1of3 Next

The 150-600 is clearly the sharpest, followed by the 80-400. The 100-400 is much softer than even the 80-400. The 80-400 is sharper at any aperture than the 100-400 is at any aperture (and the 150-600 exceeds both, similarly).

This was such a surprise that I went back and took many more photos with the 100-400, in a variety of modes (various autofocus modes, manual focus, VR on & off, silent shutter on & off), but the results were consistent – the 100-400 is much softer at 400 than its eight year old predecessor, let-alone the 150-600.

Note: the difference in sharpness is partially obscured by the JPEG compression used for the images in this post, even though I used the maximum possible JPEG quality. All my written statements throughout these tests are based on comparing the NEFs in Lightroom.

12ft @ 400

The 150-600 behaves the same as at 30ft – basically the same from f/6 (wide open) through f/8. Maybe a tiny bit sharper wide open.

The 80-400 gives its best performance at f/6.3 again. As at 30ft, the difference with f/5.6 (wide open) or f/7.1 is slight. f/8 is very slightly softer again, as diffraction more clearly kicks in.

Prev 1of3 Next

Unfortunately the comparison between the three is complicated by the fact that the 80-400 back-focused slightly while the 100-400 looks like it again front-focused a tad. After accounting for that it’s clear that the 80-400 is sharper than the 100-400. But the 150-600 is much sharper than either of them.

6ft @ 400

The 150-600 is out for this particular subject distance because it can’t focus this close.

The 80-400 is slightly sharper at f/7.1 than other apertures. Similar to the 100-400 (which still saw tiny improvement up to f/8, over f/7.1).

Prev 1of2 Next

At this point the comparison is getting tricky, because:

• The 80-400 back-focused again.
• The 100-400 is maintaining its nominal focal length much better than the 80-400. This change in focal length over different focus distances is typical behaviour for lenses – the stated focal length is usually only achieved at infinity; as you focus closer, their effective focal length drops.

It’s pretty close, between the two. There seems to be similar resolution on the image sensor, so the difference in subject detail is solely because of the difference in effective focal length. If you allow for that, then there’s a notable advantage to the 100-400.

MFD @ 400

Note here that the 100-400 can get down to about 3ft, while the 80-400 is not much shorter than the 6ft looked at above, and the 150-600 is way out at 10ft or so.

So unsurprisingly the 80-400 behaves the same as at 6ft – sharpest at f/7.1. Just like the 100-400. And the 150-600 is very similar from wide open (f/6) to f/8, with maybe a very slight improvement from stopping down just a tad, to f/6.3.

Note that I’ve also included the 150-600 at 600, in case you’re interested in comparing the maximum possible magnification across the three lenses.

Note: I don’t know why there’s such significant discrepancies in exposure, particularly with the 80-400. This was reproducible. The same exposure settings were used for all lenses. Possibly the differing fields of view impacted the camera’s metering?

Prev 1of4 Next

Here there’s no contest – the 100-400 is sharpest on the sensor (albeit by only a small margin over the 80-400), but also offers much higher magnification – almost twice what either of the other lenses are capable of. This matches the spec sheets – a maximum reproduction ratio of 0.38x for the 100-400 vs 0.2 for the 80-400 & 150-600.

The 150-600 is the worst by far, for sharpness on the sensor as well as magnification – not only do you have to zoom in to “600” to get similar magnification as the 80-400 does at “400”, but both are basically at something more like 200 if not less.

In fact to my eyes it appears that there’s nothing but empty magnification in going from 400 to 600 on the 150-600.

Conclusion

😧A surprise upset! I had assumed the 100-400 would be at least as sharp as the 80-400, and of course hoped it’d be even sharper. The 80-400 has always had good sharpness at 400 in my experience, so there wasn’t a lot of room for it to be surpassed. Still, that the 100-400 is much softer (at all but the very closest subject distances) is very disappointing.

The only thing the 100-400 has going for it (so far) is with very close subjects – there, the 100-400 is vastly superior, in large part because it can simply focus much closer while simultaneously retaining more of its nominal 400mm focal length. If you expect your subjects to always be less than ~10ft away, the 100-400 is clearly the better lens.

The 150-600 results surprised me, and may be tending unrepresentative, as they don’t match my real-world experience. I do think the 150-600 is a good lens – and excellent value at a quarter the price of either of the other two – but I’ve found it just doesn’t deliver results quite as good – nor as reliably – as the 80-400, except when you utilise its 50% extra reach. I strongly suspect this is mostly due to differences in image stabilisation – the 80-400 has the best image stabilisation of any lens I’ve ever used, while the 150-600’s image stabilisation is average at best.

Granted, this is only in the centre of the frame. Maybe the 100-400 has redeeming image qualities elsewhere in the frame? A subject for a subsequent post, perhaps.

Of course, it’d be nice to see how those two lenses actually compare – I suppose I could keep using the 80-400 and return the 100-400, if the older lens turns out to be better.

Unfortunately California has decided this “weather” thing it’s never had before is the new hotness, and it’s basically rained non-stop for weeks now. So I haven’t been able to use of the 100-400 for real yet. Luckily, I was able to conscript a wild Stitch to help me do some rudimentary tests, in the interim. That’ll be the subject of this and a couple of subsequent posts.

The most important thing I want to know about any new lens is how it performs in the centre across various apertures and subject distances. That way I know what it’s capable of in the best case (the centre) and which aperture(s) to favour. So that’s what this first post is about.

Equipment

• Nikkor Z 100-400 (e.g. from Amazon).
• Nikon Z 7 (e.g. from Amazon).
• Neewer 660-LED constant light panels (e.g. from Amazon).
• Induro AT-313 (discontinued).
• Movo GH800 gimbal tripod head (e.g. from Amazon).
• Stitch (from outer space, via Hawaii).

Methodology

I tested five different subject distances:

• MFD (minimum focus distance) at 100
• MFD at 400
• 6ft at 400
• 12ft at 400
• 30ft at 400

I didn’t measure the actual MFD – all distances above are only approximate anyway, give or take a few inches – but it was something in the vicinity of 3ft, like the specs say. MFD is a bit closer at 100 than 400.

400 is basically the focal length that counts – that’s where this lens will spend the vast majority of its time – thus the inclusion of only one subject distance for 100, nor any intermediary focal lengths.

Stitch was lit (as shown in the photo above) by two Neewer 660-LED panels, set to maximum brightness & running off mains power. Diffusers were not used.

I chose to focus on Stitch’s nose because it has a nice fine-detailed fabric texture, that looked better as a test subject than the low-contrast threading of e.g. his eyes. I also deliberately focused only about a third down on his nose – not in the very centre – so that the centre of the nose, being the closest part to the camera, would be slightly out of focus. That way I could visually confirm that the plane of focus was where I expected and not short of the subject (in the cases where depth of field was so narrow as to matter).

I focused wide open using AF-C single-point (centred). I used a five second delayed shutter release, with pure electronic shutter (“Silent” mode). I did have to touch the camera between exposures, in order to adjust the aperture and press the shutter button, and this is why in some cases images are misaligned by a few pixels.

I used a fixed ISO of 64 in aperture-priority mode, letting the camera maintain constant exposure by varying the shutter speed (which ranged from 1/25 – 1/100). I did not normalise exposure in post – any variation you see in the images could be due to:

• Differences in metering based on differing fields of view.
• Error / inaccuracy in exposure by the camera.

Image stabilisation was disabled.

All the images you see embedded in this post are JPEGs with the quality set to 100%, as rendered from the raws by Lightroom Classic.

The crops are all from the exact centre, and are 1024 square.

All images were recorded as 14-bit lossless NEFs, and imported into Lightroom Classic with no modifications other than:

• Reducing the exposure by 0.75 stops. I exposed-to-the-right to maximise image quality.
• Setting the white balance to 4,500 with no tint. I left the camera on auto white-balance; I could have specified it as some fixed value in-camera, but I knew I could standardise it in post.

This also means that any built-in lens corrections, whether by the camera or Lightroom Classic, were performed. I left all those at factory settings, and I see no purpose in mucking with them since I – like most people – don’t muck with them in real-world use.

Lightroom Classic nominally applied some sharpening & noise reduction, per its defaults, but the settings were the same for all images (40/1.0/25/0 sharpening, 0/-/-/25/50/50 noise reduction).

Finally, I’ve provided the images for every aperture in a carousel, but also an A | B comparison of wide open vs what I feel is the most interesting juxtaposition (usually the sharpest aperture, though not always).

30ft @ 400

Prev 1of4 Next

Almost no change across the apertures. This is either an excellent result or a terrible result, depending on whether it means it’s sharp from wide open or never gets sharp. That’s best judged by comparing it to other lenses – a task for a subsequent post.

There’s a very slight softening starting at f/7.1 (vs f/6.3 or wider), that’s slightly more pronounced – but still very minor – at f/8. This is most likely diffraction softening and as such is expected. On the 46 MP Z7 diffraction becomes the limiting factor in acuity beyond about f/6.3 (in theory).

12ft @ 400

Prev 1of4 Next

It’s very slightly softer wide open, at f/5.6, than at f/6.3 or narrower. It’s less clear if diffraction has kicked in (as the limiting factor) by f/8 – to my eyes there’s very little difference between f/6.3, f/7.1, and f/8.

6ft @ 400

Prev 1of4 Next

Perceived sharpness increases significantly from f/5.6 to f/6.3, and then only very slightly more up to f/8.

However, I don’t see any change in actual resolution – it’s entirely just about contrast. Careful post-processing re. micro-contrast might significantly reduce if not eliminate the difference in perceived sharpness.

MFD @ 400

Prev 1of4 Next

Perceived sharpness improves significantly, steadily, all the way up to f/8 (which is as far as I tested).

As at 6ft, I don’t see any change in actual resolution – it’s entirely just about contrast.

MFD @ 100

Prev 1of6 Next

Perceived sharpness increases significantly between f/4.5 (wide open) and about f/6.3. After that there’s no meaningful change.

Interestingly, unlike at 400 some portion of the perceived sharpness difference appears to be due to actual resolution differences, not just contrast. So this is the only case in any of the tests I’ve done here where stopping down might be strictly necessary for maximum possible sharpness.

Conclusion

I can’t really compare across focal lengths, because the subject changed size (in the frame). It seems to me that the achievable acuity is pretty good, and pretty similar, at all focal lengths.

There was a clear trend w.r.t. subject distance and wide-open performance, i.e. as the distance gets shorter, wide open becomes softer in comparison to narrower apertures. Thus the optimal aperture is (in my opinion):

• MFD:
  • 100: f/6.3 (-1 stop)
  • 400: f/7.1 (-⅔ stop)
• 6ft: f/6.3 (-⅓ stop)
• 12ft: f/5.6 (wide open)
• 30ft: f/5.6 (wide open)

In some cases you do technically get slight improvements in perceived sharpness by stopping down further, but if you have to do so by raising ISO then it is definitely not worth it – the additional noise will outweigh the benefits.

Keep in mind, also, that at 400mm even when there was a difference in perceived sharpness, it was basically only due to changes in contrast. As such, in theory it can be fully compensated for in post-processing with e.g. micro-contrast adjustments. So I definitely wouldn’t stress if I forgot to stop down when my subject came super close.

It’d be great if wide open wasn’t slightly softer-looking at close distances, but as just noted the difference is largely correctable in post. More importantly, at most distances wide open is basically as sharp as any narrower aperture.

In a nutshell, this is an excellent result overall. At most subject distances, at 400, the only reason to stop down is if you actually want increased depth of field.

That all said, the real test is how the 100-400 compares against some of its competitors…