Nikon D40x Optics

Kit Lens

The Nikon D40x ships in kit form with the same updated version of the Nikkor 18-55mm f/3.5-5.6G lens that comes in D40 kits. We haven't tested a sample of the 18-55mm f/3.5-5.6G ED AF-S DX II on yet, but don't expect it to be radically different from the earlier model that shipped with the D50. The 18-55mm on the D50 was a fairly typical kit lens, with so-so optical performance wide open, but capable of very good sharpness if you stopped it down one or two f-stops. Kit lenses work well enough for most consumers, and serve their purpose, getting you started without breaking the bank; but a big part of the attraction with SLRs is that you can easily trade up to a better lens when your finances improve, and extend your reach to wider angle, telephoto, or macro photography just by adding to your lens collection.

As noted in the User Report, we did find that bright objects in sunlight still show a little more lens flare than we're accustomed to seeing, especially toward the telephoto setting, but it won't be very noticeable unless you routinely enlarge above 8x10.

Lens Compatibility

Like the Nikon D40, the D40x drops support for the older autofocus lenses whose focus mechanisms were driven from the camera. These lenses have what looks like a little screwdriver slot on their mounting flange that couples with a protruding, screwdriver-looking shaft on the camera body. A motor in the camera body thus drives the lens mechanics to adjust focus.

More recent Nikkor lenses have motors built into the lens body, which tend to be both faster and quieter than the old-style drive system. These newer lenses carry an AF-S or AF-I designation in their name, and are the only types of lenses the D40x can autofocus with. CPU-equipped lenses lacking built-in focus motors can be used in manual focus mode, and type G or D lens types will also support full 3D color matrix metering for more accurate exposures, particularly when flash is being used. (You can tell CPU-equipped lenses by the set of five electrical contacts arrayed on the side of the lens flange.) The table below (courtesy Nikon Inc.) tells the full story of lens compatibility for the D40x.

The lack of an onboard focus motor is a key feature distinguishing the D40 and D40x from the D80. If you need to use older lenses (or a lot of Nikon's current line of prime (non-zoom)) lenses with your DSLR, you need the D80 or D200. This is a factor that could turn away current Nikon shooters, but it makes sense for an entry-level camera like the D40x. Dropping the AF motor greatly helps with size and weight issues, and probably battery drain as well. Newcomers to the SLR world are likely to be perfectly content sticking with AF-S lenses, and all of Nikon's digital-specific DX lenses are AF-S models, providing a pretty wide range of options.

Autofocus System

While the D40 and D40x carried over a lot of the capabilities of the D80, their autofocus system is one area where cost-cutting has had a noticeable impact. The previous D50 had a 5-area AF system, and the D80 has 11 active AF points, but the D40x has only three, arranged horizontally across the frame. With the more limited AF array, the D40x's ability to track moving subjects will be less than that of the D50 or D80, but the 3-point AF array isn't unreasonable to find in its price bracket.

This is one area where the interests of novice and more experienced shooters may actually converge. Both would benefit from the D80's more sophisticated AF system, and the argument could be made that novices actually need a better AF system than advanced amateurs, as they'll be less accustomed to paying attention to what the camera is focusing on. That said, it's not too difficult to check that one of the 3 AF areas is covering your subject, and it's a relatively small step up to learn to aim the camera and lock focus.

Focus Options

The Nikon D40x offers pretty well all the focus options of the D50, the main difference being that options for setting the focus mode are presented on the LCD screen, as opposed to a little single/continuous/manual focus switch on the camera body itself. Many Nikkor lenses also have an Auto/Manual focusing switch on their barrels. If the switch on the lens barrel is set to "M," focusing will be under manual control, regardless of the setting of the switch on the camera body. Most AF-S lenses with the built-in Silent Wave focus motor let you manually focus the lens at any time, regardless of the camera's focus setting, so there's less need for a body-mounted focus-mode switch: The menu selection should do fine for most users.

To select between the three types of AF, you just navigate to the Focus Mode option on the camera's shooting display (or to the identical Focus Mode option in the Custom Settings Menu system) and choose between AF-A (Auto Servo), AF-S (Single Servo), and AF-C (Continuous Servo). Manual focus is the fourth option. Single Servo simply means that the camera sets focus only once, when the Shutter button is first pressed halfway, and is best for still objects. Continuous Servo means that the camera continuously adjusts the focus, as long as the Shutter button is halfway pressed, and is best for moving subjects. The Auto setting (added to Nikon's D-series SLR line with the earlier D50) lets the camera select the servo mode, depending on the movement of the subject.

The Nikon D40x is similar to the D50 in how it behaves in out-of-focus conditions. Some SLRs will let you fire the shutter in Continuous Servo mode if the lens hasn't achieved focus, but not in Single Servo mode. The D40x never fires the shutter if the lens isn't focused. (Unless of course, you have the camera or lens set to manual focus operation.) This more restrictive shooting could be an inconvenience to more experienced shooters, but will almost certainly be a benefit to novices, as the camera itself will guard against capturing out-of-focus images.

Focus can be confined to one of the three specific focus points in both Single Area mode, and in Dynamic Area which offers focus tracking. Single Area AF simply means that the camera sets focus based on the specific area you've designated. Dynamic AF employs all three of the autofocus areas. When Dynamic Area focusing is enabled, the camera first focuses on the subject in the chosen focus area. After the camera has initially "locked on" to the subject, if it moves to a different AF area, the camera will shift its focus to "follow" the subject. This is great for irregularly moving subjects. (Sports and kids come to mind.) In both Dynamic and Single Area AF modes, you can change the primary focus area using the right or left directions on the Multi-Selector pad. Closest Subject Priority is a third option, selected via either the AF-Area mode option on the shooting screen or by a custom settings menu item. Closest Subject Priority means that the camera will focus on the closest object that falls under one of the three focus points.

There are two methods by which you can lock focus with the Nikon D40x. The first is via the Shutter button, placing your subject in the selected focus area, halfway pressing and holding the Shutter button, then realigning the composition and firing the shutter. Alternatively, when using Single Servo AF, you can press the AF-L/AE-L button to lock focus (and exposure, unless the button is set for focus-only in the Custom Settings menu) after having initially established it by half-pressing the shutter button. Keeping this button pressed will maintain the focus and/or exposure lock, even if the Shutter button is released. This lets you recompose the photograph without having to keep your finger on the Shutter button, but rather on the AE-L/AF-L button instead. (Reducing the chance that you'll accidentally trip the shutter when you don't intend to.)

There are several options available for the AE-L/AF-L button, which can be set via the Custom Settings Menu. You can program it to lock either focus or exposure separately, or both together (the default). You can also change its operation so a single press locks and holds the exposure setting. (No need to keep the button held down.) Finally, you can set the AE/AF lock button so it alone controls the autofocus system, meaning the autofocus won't actuate when the Shutter button is half-pressed, only when the AE/AF lock button is pressed instead.

If you're a novice user considering purchasing a Nikon D40x, and all this focus/exposure lock mumbo-jumbo sounds confusing, don't let it worry you; the camera's default operation is very straightforward, but the availability of features like these is really liberating for more advanced users.

AF Assist

Like past Nikon SLRs, the D40x's AF-assist light is a bright incandescent bulb that emits from the body near the handgrip. We thought to call particular attention to it, because some competing cameras (notably the Canon Digital Rebel series) use the flash as an AF-assist light. This would be fine, but they also require that the flash be used in the exposure, so there's no way to have AF assist for available-light shots. The D40x doesn't have this limitation.

Sensor Cleaning!

Everyone understands that lenses sometimes get dust on them and need to be cleaned, and there are a lot of lens-cleaning cloths, solutions and other accessories on the market that work well. BUT, what do you do when your sensor gets dusty? Dust specks on the sensor tend to show up when shooting at very small apertures, appearing as dark blobs on your images. They're distracting at best, a terrible nuisance at worst, if you end up having to retouch every image to rid of them.

Most of us are naturally leery about the idea of poking around inside the delicate innards of our DSLRs to wrestle with recalcitrant dust specks. Gently blowing the sensor surface (actually, the surface of the anti-aliasing filter) with compressed air gets rid of some dust, but there's invariably a lot that just stays stuck, no matter what. So what do you do?

If you've got dust specks on your sensor (and sooner or later you will), you're going to need to clean it. There are a lot of products out there intended to address this need, but a distressing number of them work poorly (if at all), and many are grossly overpriced. Advertising hype is rampant, with bogus pseudo-scientific jargon and absurd product claims run rampant. And prices - Did I mention prices? How about $100 for a simple synthetic-bristle brush?

So how do you know what product to use?

We don't pretend to have used everything currently on the market, but can tell you about one solution that worked very well for us. The "Copper Hill" cleaning method is straightforward and safe, and in our routine usage here at Imaging Resource, highly effective. Better yet, the products sold by Copper Hill Imaging are very reasonably priced. Best of all, Nicholas R (proprietor of Copper Hill) has put together an amazingly detailed tutorial on sensor cleaning, free for all.

Sensor cleaning is one of the last things people think about when buying a d-SLR, but it's vital to capturing the best possible images. Take our advice and order a cleaning kit from Copper Hill right along with your d-SLR, so you'll have it close at hand when you need it: You'll be glad you did!

(While they've advertised on our sister site from time to time, we receive no promotional consideration from Copper Hill for this note. We just think their sensor cleaning products are among the best on the market, and like their way of doing business. - We think you will too. Check them out.)



Good performance from the Nikon D40x's 18-55mm kit lens.

18mm 55mm

The Nikon D40x is available bundled with the Nikon AF-S 18-55mm f/3.5-5.6 DX II kit lens. which covers the basic zoom range most commonly used. Results were quite good in these shots, where the programmed exposure stopped the lens down to f/8.0, in the sweet-spot of most SLR lenses. Corner-to-corner sharpness is quite good, although some chromatic aberration is visible. Wide open, some softness appears in the corners, but the lens performs well when stopped down one or two f-stops. If you look in the trees on the far right side in the 55mm shot, you can also see evidence of the lens flare mentioned in the User Report.

A small macro area with good detail. Flash performs well up close.

Standard Macro Macro with Flash

As with zoom performance, the Nikon D40x's macro performance will depend entirely on the lens in use. However, with the 18-55mm kit lens set to 55mm, the D40x captured a small (for a non-macro lens) minimum area measuring 2.73 x 1.83 inches (69 x 46 millimeters). Detail and resolution were both quite good, though there was a fair amount of softening in the corners, most likely the result of spherical aberration in the lens. (Most cameras have some softening in the corners in macro mode.) The flash produced fairly even results, with only minimal falloff in the corners of the frame.

Average barrel distortion at wide angle, but almost none at telephoto.

Barrel distortion at 18mm is 0.8%
Barrel at 55mm is less than 0.1%

This is the tendency for the lens to bend straight lines outward (like a barrel -- usually at wide angle) or inward (like a pincushion -- usually at telephoto). The Nikon D40x's 18-55mm kit lens produced about 0.8% barrel distortion at wide angle, which is about average among the cameras we've tested, and is noticeable in some images. At the telephoto end, the lens produced less than 0.1% barrel distortion, which is much less than average and imperceptible in images.

Chromatic aberration
Noticeable to very low distortion with the 18-55mm kit lens.

Wide: moderate and bright,
top left @ 200%
Wide: moderate and bright,
top right @ 200%
Tele: very low,
top left @200%
Tele: very low,
top right @200%

Chromatic aberration in the corners with the Nikon D40x's kit lens is pretty evident (we'd call it on the high side of "moderate," or "noticeable") at the 18mm setting. It's less distinguished by its width and more by its brightness, showing about 7-8 pixels of fringing in the extreme corners. At 55mm, the distortion is very low, but the flare is more evident, especially in the top right corner. (This distortion is visible as a very slight colored fringe around the objects at the edges of the field of view on the resolution target.)

Corner Sharpness
Some softening in the corners with the 18-55mm kit lens.

Wide: soft in the
corners (upper left).
Wide: sharp at center.
Tele: slightly soft in the
corners (upper left).
Tele: fairly sharp at center.

The Nikon D40x's 18-55mm kit lens produced soft corners in a few shots. At wide angle, corners were a bit soft, compared to the center of the frame. Sharpness improves fairly rapidly as you look toward the center of the frame, the worst of it going away by the time you're 10% of the way to the center, and essentially all of it at 20% toward the center. At telephoto, corners showed less blurring, and the center was still fairly sharp. Not a bad performance for a kit lens.


The images above were taken from our standardized test shots. For a collection of more pictorial photos, see our Nikon D40X Photo Gallery .

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