The old saying goes that pros don't use normal zooms. Yes, the lenses that pros supposedly don't use because they are too busy trying to make their pictures not look like they were taken by normal people with normal zooms. Concession to rationality... real people using stand zoom lenses is a thing.Also: pros are real people.
There is some truth to the saying, though... but it's a subtle truth. Professionals most certainly do use stand-zooms; it's almost unthinkable to work a wedding with a D810 without a 24-70mm f/2.8 in the kit. What the saying should mean is that professionals don't use normal-zooms in the way that amateurs do. The actual truth is that if you are using a standard zoom and are contentiously thinking about quality photography, you will be gravitating towards either the towards the longer or wider ends of the lens, and using the middle portion of the zoom less. Conversely, if used thoughtlessly, normal zooms can encourage a certain amount of sloppiness in controlling subject perspective
Note that this is primarily concerned with DX-specific lenses. It goes without saying, pairing the Nikon D7100 or D7200 with an AF-S 24-70mm f/2.8 ED will be awesome, but not having a real wide angle option with that combination will get tiresome eventually. With Nikon's tepid love for DX many people might be thinking off accumulating full frame lenses for an eventual jump to FX, possibly a DD750, maybe a D810 if they are really ambitious. This is not an inherently bad idea, but you tend to get more joy out of the equipment by matching DX specific focal lengths to DX equipment rather than trying to make FX focal lengths work. You may, in fact, never make the switch to FX, but you will always be using whatever equipment that you have in the here and now.
(Updated April 2015.)
For lack of a better term these are the "kit-zooms", though the 16-85mm isn't a kit lens. These aren't true standard zoom lenses because they are either not sharp enough or don't offer enough depth of field control that more experienced users expect. The variable aperture nature should say it all; so does the extended focal range, as the target audience prioritizes zoom-flexibility over aperture-flexibility. Because of their convenience, these lenses and make good travel and vacation lenses and for situations where size and weight are considerations.
Nikkor AF-S DX 18-105mm f/3.5-5.6 G ED VR
This lens was originally bundled with the D90 and the D7000, and for the most part is only available used. Pass on this one if you haven't already got it. Unless you are upgrading into the DSLR realm and have no lenses to start with, there are better choices. That said, there is nothing egregiously wrong with this lens as it covers a useful zoom range and offers decent resolving power for the price. However, it has visible weaknesses, such as vignetting at both wide and long ends of the focal length range, visible pin-cushion distortion through the longer focal lengths, and high levels of chromatic aberration.
That said, I think this lens is an interesting alternative if you are looking for a vacation lens like the Nikon 18-200mm f/3.5-5.6G IF-ED AF-S VR DX. The still are a number of these lenses on the used market, and because it is an inexpensive lens when purchased used it makes for an interesting "disposable" option for trips where equipment damage may be a possibility. Unlike it's successor, the 18-140mm, the 18-105mm uses a plastic bayonet mount. This is only an issue if the lens has sustained impact damage; otherwise the lens mounts are surprisingly durable over regular use. If anything, the only problem with normal wear and tear is that there's a piece of trim behind the hood bayonet mount on the front of the lens that tends to come un-glued with repeated time; even if this happens it is immaterial to the operation of the lens.
Nikon AF-S DX 18–140mm f/3.5-5.6G ED VR
If you want a vacation lens and are deciding between either a body-only or kit version of the D7100 or D7200, then go for the kit. This lens is better than the 18-105VR; the optics are better and it uses a proper metal lens mount. For D7100 and D7200 shoppers who have a budget in mind, buying this lens in kit form with a camera body gives the best bang for the buck. If you already have the 18-105mm, are using it on a camera like the D7000 or the D5200 and are looking for an upgrade, it's best to go to another lens other than the 18-140mm. The newer lens is better in every way but the cost of buying this lens at full retail price separate from a kit bundle makes the difference in image quality tough to justify.
The focal range of this lens is useful, but it does make for a long-ish camera for casual walk-about use. However, it's not a lens that more serious photographers are interested in as the variable-aperture design restricts some of the creative possibilities that better lenses offer. On the whole, its nice to have the extra reach, but if you were truly shooting seriously, you would need longer reach than what this lens offers, or a wider aperture and the shorter focal lengths. As with the 18-105mm lens, the 18-140mm is a better practical alternative to the 18-200mm as it is less expensive, does not have as much pronounced focus-breathing and is generally sharper all-around.
Nikon 16-85mm f/3.5-5.6G AF-S DX ED VR
This is probably the best variable aperture normal zoom lens on the market. That's not saying much; it's like being the best rock band in the the local small town... outclassed by the big names, but not without its charms. The optical quality of this lens is such that even pros like using it, despite the variable aperture. If you are choosing this lens, you are making a conscious choice to forgo the faster maximum aperture offered by the third-party lens makers; in exchange you get generally better flare and ghosting resistance and a bit more constant contrast consistency through the focal range. However, the 16-85mm is pricey when new, and still expensive on the used market. If you like the convenience of the 18-140mm, want to do better optically but are hesitant to give up too much reach, this is your lens. To make up for the slow variable-aperture, many people pair this with the inexpensive Nikon AF-S 35mm f/1.8G DX or a 50mm prime.
The "C" version of the Sigma 17-70mm f/2.8-4 offers a lot of value for the photographer looking for something better than the kit lens options from the mainline manufacturers. This is the type of shooter who is looking for more quality but also doesn't need the depth of field control of a constant f/2.8 lens. This Sigma only gives up one stop of loss when zoomed out, but maintains consistent sharpness across the zoom range; the exception being weak corners at 17mm. Optically, there isn't much to separate the 2nd generation lens from the "C" version, though the newer lens is better. However, the "C" version is physically more attractive (if that matters to you) and is compatible with Sigma's USB dock. This is often an overlooked lens because it isn't a constant aperture f/2.8 lens like it's older sibling, the 17-50mm, nor does it belong to the higher-grade "ART" series. If you compromise on both, you end up with a compact lens, versatile lens with decent image quality.
Faster(er) Aperture Constant Zooms
These are the more serious lenses, the ones that experienced shooters tend to gravitate to. With some caveats, they replicate the field of view that you would get with the standard 24-70mm zoom on a full frame camera.
The first version of the Tamron 17-50mm was a venerable favourite. That lens, the older AF-D screw-drive version is quite dated, but is still relevant in today's world. The optics of this lens are superb, and give you 90-95% of the performance of the much more expensive Nikon 17-55 f/2.8 for a fraction of the price. There are four weaknesses; fairly noticeable vignetting when used wide open, chromatic aberration, a high amount of field of curvature at 17mm, and fairly harsh bokeh rendition. On the upside, this lens is consistently sharp throughout its zoom range. If you take your pick of any 17-50 f/2.8 zoom by Tamron, Sigma and Tokina, the Tamron is the most consistently sharp across all focal lengths, and is the most usable wide open at f/2.8. In terms of sharpness, this was a lens that was ahead of it's time.
The older AF-D version is more desirable than the newer built-in-motor (BIM) version, as the first version has focus faster and are generally trouble free from a mechanical perspective. There is also a newer VC version that has a different optical formula in exchange for image stabilization. The stabilization is excellent, but in terms of optics the VC version behaves more like a consumer lens... even with the constant f/2.8 aperture.. whereas the older versions are more like pro lenses. The difference is that the older version of this lens is sharp at f/2.8, whereas the VC version requires stopping down to get the most out of it.
You might find a good bargain for the VC version on Craigslist, but they don't seem to enjoy as much demand and tend to trade at a slower pace. Speaking of Craigslist, that's the only place where you will find the AF-D version now as it is out of production.
A note about this lens and AF fine-tuning compatibility on Nikon bodies. Because of the way that Tamron and Tokina have reversed engineered the Nikon mount, the information for all such lens is stored at one single location in a Nikon body's AF fine-tune memory bank. For example, if you have the Tamron 17-50 and a Tokina 11-16, the camera will properly detect the correct aperture and focal lengths for both lenses, but will address them both to the same AF fine-tune value. If you need separate AF adjustment factors, this will become a royal pain in the backside.
|Nikon D7200 and Sigma 17-50mm|
Probably the best all-around option of the f/2.8 standard-zooms, even if it isn't the sharpest or doesn't have the fastest aperture. Like the Tamron, it is sharp throughout its zoom-range, but it is not as sharp when used at f/2.8. However, the Sigma has bokeh that is not as harsh and fringey as the Tamron. However, the more obvious advantage is that it is a stabilized lens. Images don't have the immediate sharpness bunch of the older Tamron, but the Sigma is a generally better choice than the VC version.
When compared to either of the Canon and Nikon counterparts, the Sigma is cheaper, smaller and offers better value for the money. As a normal zoom, its the everyday walk-around lens that many people are looking for for their 60D's, 70D's and D7000's or D7100's. The size and weight of this lens balances appropriately on these bodies, where as the Nikon and Canon versions tend to overwhelm their own camera bodies. Out of all these three lenses, only the Nikon is truly a professional-grade lens. Even though it lacks image stabilization, its build quality and optical performance are enough to distinguish it from the others. Conversely, for non-paid work, the difference between the Nikon and the other lenses isn't enough to justify the price.
In terms of size and weight, the Sigma is similar to the Tamron, meaning that it will balance well on the D7100, but has the downside of requiring larger diameter filters. This lens predates the ART-era, though it is probably one of the best of the classic-era of Sigma.
There is a bug to watch out for if you are using this lens on a Nikon D7100. The problem stems from the fact that the OS image stabilization system doesn't work as intended on the D7100. After taking a shot, it remains active for up to a minute. There are two consequences to this. The first is increased battery drain, and the second is that the multi-selector has to be tapped repeated to navigate during image reviewing, instead of the usual press-and-hold operation. See this DPReview thread for more details. The problem seems to be with Nikon, as this behaviour didn't manifest on the D7000 or older cameras; something in the D7100 firmware is new or different. All of the later releases of the Sigma 17-50mm are marked "D5300" compatible; even so, these units display the so called "scroll bug" on a D7100. Nikon ostensibly changed something in the EXPEED 3 generation, but never explicitly documented it. However, in an even more interesting twist, the D7200 (EXPEED 4) does not display this flaw and works perfectly.
Nikon 17-55mm f/2.8G ED-IF AF-S DX
Expensive, and having the size and weight of a mortar shell. Optically one of the best f/2.8 zooms, but if you get any of the ones that I listed above, you won't notice because of how much less money you will have to pay. This lens was originally designed for the metal body semi-pro cameras like the the D2x and the D200. It's an anachronism in 2013, as there is no longer a current full metal body professional DX camera left in the Nikon lineup. Yes, you can use it with the D7100, would the handling would be awkward. Upon consideration, nothing highlights the demise of serious DX in Nikon's line-up so much as this lens, which has become something of an orphan in the age of smaller and lighter bodies.
These lenses aren't traded in high volumes (maybe an estimated 200,000 units were produced in the first ten years of production), but there are copies that show up on the used market from time to time. However, the lack of a serious commitment to a true D300s successor makes this a hard lens to resell in a future where the lighter D7xxx body style is the highest level of Nikon DX. That could change if/when the mythical D300 successor arrives.
The Sigma 18-35mm is a unique lens with no direct competitors. For Nikon shooters, the closest comparable lens in build quality and price is possibly the Nikkor 17-55mm f/2.8G IF-ED. That particular lens is an older design but a known quantity; the Sigma is the flashy new kid in town. However, ignoring outright image and build quality, the closest market competitor to the Sigma 18-35mm is probably its little brother, the less expensive Sigma 17-50mm f/2.8 EX DC OS HSM. That is a cheaper lens built to a cheaper price point, but the image stabilization will give it a slight edge in safe hand-holding shutter speeds.
Much has been made of the fact that this is finally the crop sensor lens that gives the equivalent field of view of full frame on a crop frame camera. That may be true, but a portion of that equation is missing. The 18-35mm range is not so much a normal-zoom range as it is a wide-to-normal range. So the continuum of usage goes like this: landscapes -> street photography -> general people snaps. What's missing is the "head shot" part of the normal-range. In other words, to achieve the fast aperture, Sigma needed to pair down the lens from the typical 50mm down to 35mm.
This has some implications... and in other ways it doesn't. The first problem is that depth of field increases as you go to shorter focal lengths. Yes, you get f/1.8, but at the wider focal lengths that this lens dwells at, you won't get ultra creamy backgrounds unless you shoot at closer distances. A hidden downside to this short focal length is that you will get pin-cushion distortion at a focal length that you wouldn't ordinarily expect it. When this lens is at its long end, other normal-zooms would be in the middle of their range. The distortion isn't heavy and it is correctable, but it is uncommon to see this type of distortion at this focal length. At the commonly used crop focal length of 24mm, the lens is essentially distortion free.
The lack of 50mm is a downside on paper, but probably not a practical downside if you are conscientious shooter who will work for your image quality. With a constant f/2.8 18-50mm normal zoom, shooting wide open at the long end makes for a serviceable portrait shooting experience, but it's nowhere near as ambitious as shooting with a dedicated lens. Since old 50mm lenses are so cheap, many serious enthusiasts have them; shooting a portrait at 50mm and f/1.8 on a prime is "better" than 50mm of a f/2.8 zoom.