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Nikon 24-120 f/4 VR Revisited

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My view of lenses is often colored by measurements, numbers, taking them apart, and other geeky things. I also take photographs with them. One of the things I’m always interested in is comparing my measurements with actual photographs.

When Uwe Steinmueller from The Digital Outback suggested we compare the same lens from both perspectives it sounded like a great idea to me. Uwe would write his assessment of the lens from a photography standpoint, I would write a bit about its testing and measurements.

He suggested we start with the Nikon 24-120 f/4 VR. It’s a lens he really likes for obvious reasons: it’s relatively small, covers a very useful range, and has superb vibration reduction. For him it provides a superb one-lens solution.

I’ve considered it an “OK” lens. I understand the attractions but was less than excited about its distortion, chromatic aberration, and borderline corner resolution. It’s not a bad lens by any means, but not one that made me ‘ooh’ and ‘ah’.

 

Resolution Numbers

When I first evaluated the 24-120 for use with the D800, I tested it only at it’s extremes (24mm and 120mm) so I went back with a couple of copies and repeated Imatest at several different focal lengths.

First we’ll look at the 24-120′s Imatest MTF 50 at 5 focal lengths. The table below shows MTF50, measured in line pairs/image height for raw files at the center, averaged over the entire lens, and the average of the 4 corners.

Center Avg. Avg corner
24mm1080880460
35mm1100885460
50mm1040900490
85mm990845450
120mm970820420

It’s apparent the lens is quite good in the center, although it’s not quite as sharp at the long end. The corners are OK, but on a D800e I’d really like to see resolution of 500 line pairs / image height and these aren’t quite there.

We’ve repeated them at f/5.6 to see how much benefit the lens gets from closing the aperture a bit.

Center Avg. Avg corner
24mm1100920560
35mm1100930560
50mm1075940575
85mm1050920545
120mm1020880500

The center, which was already quite excellent, doesn’t really improve with stopping down much except a bit at the long end. The corners do sharpen up nicely at f/5.6 and from a pure MTF 50 standpoint I’d call them acceptable at this aperture.

Other Numbers

Like most 5X zooms, there is a fair amount of distortion. The lens has 3.5% barrel distortion at 24mm which zeros out by 35mm. Almost immediately, though, pincushion distortion sets in, reaching 2% at 50mm and staying right there through the end of the zoom range.

There is a fair bit of vignetting at both ends of the zoom range, but it’s not awful by any means. Vignetting isn’t nearly as strong in the central part of the zoom range (30mm-80mm or so). There’s also a good bit of chromatic aberration in the corners throughout the zoom range and even when stopped down.

My Summary

The usefulness of a 24-120mm lens, with excellent vibration reduction and excellent center sharpness, can’t be argued. That makes it the perfect lens for a lot of people.

However, the corners are rather soft at f/4, becoming acceptable at f/5.6. Distortion and chromatic aberration are easy to remove in post processing, obviously, but doing so reduces resolution a bit. So looking at the numbers I wouldn’t recommend this lens for people who need sharp corners and edges, like landscape or architectural photographers.

However, Uwe’s article clearly demonstrates that with careful postprocessing the images shooting the 24-120mm on the D800 are really quite good. I think to some degree this is because the D800 allows such great resolution. Even average corner sharpness can look good dressed up in a D800 outfit. I also think good postprocessing is wringing every bit of resolution out that is there. I suspect out-of-camera jpgs are not quite as good as Uwe’s postprocessed images.

And again, for many people using this lens, the corners aren’t critical for their photographs anyway. They would, I think, they’d be very happy with images right out of the camera.

 

 

Roger Cicala

Lensrentals.com

February, 2013

11 Responses to “Nikon 24-120 f/4 VR Revisited”

Digital_analog said:

Roger, thanks again for the nice work, and looking forward this series. I was very curious in know more about this lens in particular, so I am glad that you started with the 24-120.

Something that usually bothers me a lot is astigimatism on the corners. Is there some standardized value to measure it besides using s/m lines? Is it possible to know this characteristic from your mtf numbers?

derek said:

yeah, it is a terrible lens for landscapes and buildings. but as you said , it is extremely useful for snaps and casual walk-around at dusk kind of things.
I think all zooms especially in this range are some kind of compromise anyway, the 24-70f2.8 is not much better than the 24-120f4VR.
I guess if you are serious about fully optimizing your D800 or E sensor , then you need a set of Zeiss or Samyong , most of Nikon AF primes are optically compromised (there are a few exceptions such as the 85f1.4G , 85f1.8G , 50f1.4G and 28f1.8g).

pieter kers said:

I think if it is about the corners you have to test at d8 or even d11
Not many lenses are good in the corners at d5,6 even some primes…
If i look at my 24mm 1,4 g nikkor i have to uses d8 to get the whole picture right

tedtedsen said:

this is a kit lens and dos not belong on d800e whyput an diesel engine on Your ferrari

Ben Wilkes said:

It would be interesting to compare this on a D600 with the 16-85 DX on a D7100 or D5200. Which has fewer compromises/better trade-offs?

JR said:

Perhaps I’m more cynical than the rest, but I find that there’s some sort of conspiracy against the Nikkor 24-120mm F4. Instead of folks trying to find the virtues of the lens, they spend more time dogging it.

I completely agree that a more useful gauge for landscape and architectural photography would have been to test this lens at f8 or f11. Why stop at f5.6?

With all due respect, Roger, but your conclusions needed to be backed by more testing:

You said that “the corners are rather soft at f/4, becoming acceptable at f/5.6″, then conclude by saying that “I wouldn’t recommend this lens for people who need sharp corners and edges, like landscape or architectural photographers.”

How many landscape or architectural photographers shoot at f5.6? Unless the subject is no more than 50 feet away and completely flat, with nothing meaningful in the foreground, “landscape” images usually include near and far(infinity) objects that mandate f8-f16. Same for architectural work.

Use any DOF calculator and you will see that f8 is typically your lowest f-stop that will allow for a reasonable hyperfocal-near limit distance. When you move to f5.6, or lower, the near limit starts to get very far from the camera and anything interesting in the foreground can be blurry in the final image.

Most published tests of the 24-120mm F4 have shown that the corners become *MUCH* sharper at f8 and f11. Here’s one well-known test that shows just that:

http://www.photozone.de/nikon_ff/574-nikkorafs24120f4vrff?start=1

Look at the results at f8 and f11 for 35mm and 50mm. Those indicate that the 24-120mm F4 is ‘respectfully’ close to the Nikkor 35mm f1.4G @f8 and the Nikkor 50mm f1.4G at f8. And, at f11 the zoom is actually AS SHARP, if not sharper than the primes!

If so, why isn’t anyone testing this zoom -vs- primes at f11? I suspect because most people don’t shoot at that aperture very often. But for landscape shooters who will be printing large and shooting at f11, this test is VERY important.

Sure, there’s diffraction to be concerned about when stopping the lens down to f11-f16, but this lens on a D800 shouldn’t have any meaningful/visible diffraction at those settings. The following calculator shows that’s the case:

http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm

I’ve found that the “sweet spot” of the 24-120mm F4 is between 35-70mm. Inside those parameters at F11 it’s *SHARP*. It’s as sharp as my 50mm f1.4D, in every respect, when used on a D600.

On the other hand, from beyond 70mm up to its limit of 120mm, the 24-120mm F4 is trounced by my 80-200mm f2.8D ED-AF. I ran some tests a few weeks back and the 80-200mm is *MUCH* sharper, showing higher contrast, at 85mm and 120mm at f11. Not even close. But, not only is the 80-200mm sharper, it’s able to resolve details in the shadows that were nothing but black blotches with the 24-120mm.

What did that test tell me? That the 24-120mm has limitations, but it also has a nice sweet spot, right in the middle.

A *VERY* meaningful test, and one that will put to rest a lot of the guessing would be to test the 24-120mm F4 side-by-side, from f8-f16, against the Nikkor 24-70mm f2.8G. A true “landscape” test that will answer a lot of MY questions. My guess is that at f11 and f16, we won’t be able to see much difference.

I’ll be renting the Nikkor 24-70mm f2.8G in two weeks and will know more after I run some tests.

JR said:

Oh…one more thing…

I know about Nasim’s test, at photographylife.com, where he paired the 24-120mm f4 and the 24-70mm f2.8G in a head-to-head test. He lauds the F4 zoom and claims it’s the equal of the other, and in some respects surpasses the much more expensive lens.

But, he concludes with this gem of a cliff-hanger:

“Looking back at the images I shot outside compared to lab results, the Nikon 24-70mm seems to produce slightly sharper images in the corners when shot at infinity between f/4.0 and f/8.0. This could be a sample variation issue though, since most of the images I shot outside were done with a single lens (I only had the second sample for two days). I will wait for others to provide some feedback on this.”

After touting the 24-120mm lens as a possible replacement for the 24-70mm f2.8, as a result of some “lab tests”, he concludes that in the field the 24-70mm f2.8G is superior.

Can that test be trusted in its entirety?

Why I need to do my own testing!

LensRentals Employee

Roger Cicala said:

JR, I don’t make conclusions about lenses, nor do in-depth testing. I do optical screening and do it from the point of view of the gear-head. I celebrate superb efforts by lens designers, look for weaknesses in the engineering, sample variation, etc. I leave it to others with more patience than myself to do in-depth long-term reviews of lenses.

I would never make a lens decision based on a simple optical test (well, I might rule some lenses out).

But I’m a bit puzzled – we discuss a very good general walk-around lens, the 24-120 VR. Everything I’ve read and my own findings are just that. Is it the best landscape lens? No, not close, but it’s very good. And the best landscape lenses (tilt-shift primes, usually) aren’t very good at many other things. Is it the best portrait lens? No, not close but very good. And the best portrait lenses (standard to short telephoto wide primes) aren’t very good at a lot of other things. Best walkaround lens? Well, probably so, because it’s quite good at very many things even though it’s not the very best lens at anything. I’ve really never heard anyone trash the lens. Rather I hear people say things like “it’s just about as good as the 24-70 f/2.8″ which is good praise in my mind.

I agree that f/11 tests are very useful for landscapers and some need to be done here. But diffraction softening isn’t an on-off switch, it’s a combination of optical improvement at smaller apertures with diffraction softening at smaller apertures. In reality, every lens I know of tested on Nikon D800s has shown center softening between f/8 and f/11. Many, but not all or even most, will slightly improve corners between f/8 and f/11. Nothing gets better past that, and more than a few lenses peak at f/5.6 in the center. But these are all relative, pixel-peeping numbers things.

I don’t hesitate to take an f/16 shot when it’s indicated, realizing I’ll have to use a different post-processing workflow than my usual shots, but more than happy to give up a bit of resolution and increase my post processing to get the shot I want. The main reason I don’t generally test at f/11 or f/16 is those apertures are the Great Equalizer – lenses that are hugely different at f/4 are only slightly different at f/16.

If I was using Nikon full-frame as my walk-around right now, I’d almost certainly have a 24-120 as my walk-around lens on it. It would handle the vast majority of my needs. The 24-120 is a great all-around tool, good at almost everything. But I wouldn’t claim there weren’t better lenses for many specific purposes: landscape, action, portrait, low light, telephoto, wide angle.

Roger

JR said:

Thanks for the reply, Roger!

At times I’m concerned about diffraction at or above f11, and can see it slowly creeping into some of my images. But, like you, I’m “willing to give up a bit of resolution and increase my post processing to get the shot I want”; and sometimes the shot I want has an object of interest in the near foreground with a killer background at, or near, infinity. There’s no getting around using f8-f16 under such circumstances.

“The main reason I don’t generally test at f/11 or f/16 is those apertures are the Great Equalizer – lenses that are hugely different at f/4 are only slightly different at f/16.”

That’s right! And isn’t it great that such an Equalizer exists, specially for landscape work? Precisely the reason why I don’t see the value of replacing my 24-120mm f4 with the *MUCH* bulkier, heavier and much more expensive 24-70mm f2.8G.

Cheers!
JR

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