Superzoom Lenses

As discussed in my previous blog entry, my first experience in photography was with fixed focal length lenses. With my Nikon F3, I used an 80 - 200 mm zoom lens because of the specific needs of color slide photography, but I still used fixed focal length lenses for the normal and wide angle ranges (24 - 50 mm). This philosophy was turned upside down when I switched to my first digital camera, the Nikon Coolpix 5700: this featured an 8x super zoom lens covering the equivalent of "normal" focal lengths of 35 - 280 mm. This had the huge advantage that lens changes were no longer necessary, and the optical quality of that lens was actually quite good, though I did notice some barrel type distortion at the wide angle end. Typically, this distortion was not too bad, though: more often than not, the most obvious "defect" in such photos was not the barrel distortion, but the perspective distortion that is observed when the camera is not held exactly horizontally when taking pictures of architecture or other objects with vertical lines.

My Nikon D200 and Nikon D300 cameras were/are supposed to be cameras for semi-professionals, and so I had higher expectations into the lens, too; but as I was coming from the Coolpix 5700 with its 8x superzoom, and I was scared of getting dust on the sensor, I again wanted to avoid lens changes, and so I opted for the AF-S DX VR Zoom-Nikkor 18 - 200 mm super zoom lens (11x), giving me the amazing focal length equivalent of 27 - 300 mm in full frame format all in one single lens.

Yes, that is a convenient lens — but there's no free lunch: there had to be disadvantages, even though it is an elaborate construct with 16 lens elements in 12 groups! I used that lens for the four years between January 2006 and spring 2010, when I finally decided to get rid of it. Here are the reasons why in the end I decided for better "pro" style lenses:

At the wide angle end, the lens distortions were stronger than those of the Coolpix 5700 — worse than that: the Coolpix mostly suffered from barrel type distortions that can be corrected by post-processing. What turned me off with the 18 - 200 mm lens was the following picture (a shot from the Lugano train station towards the Monte Brè):

Lugano TI/Switzerland: Cathedral and Monte Brè
Nikon D300,  AF-S DX VR Zoom-Nikkor 18 - 200 mm
ISO 200, f/11, 1/320, 18mm (27mm equiv.)

Some people call this "moustache-type distortion" — it is hard to correct, if at all — plus, I think it looks pretty awful!

Another, sometimes neglected aspect of lens quality is the bokeh, i.e., the looks of objects that are not within the depth of field, i.e., way out of focus. The 18 - 200 mm super zoom often showed a rather strange-looking bokeh, e.g.:

Mountain flowers near Muottas Muragl, GR/Switzerland
Nikon D200,  AF-S DX VR Zoom-Nikkor 18 - 200 mm
ISO 100, f/6.3, 1/160, 150mm (225mm equiv.)

or in the background to the left of this colored woodpecker:

Colored woodpecker (Buntspecht)
Nikon D300,  AF-S DX VR Zoom-Nikkor 18 - 200 mm
ISO 200, f/5.6, 1/125, 200mm (300mm equiv.)

 or, similarly, the grass in the background of this picture of a green woodpecker:

Green woodpecker (Grünspecht)
Nikon D300,  AF-S DX VR Zoom-Nikkor 18 - 200 mm
ISO 200, f/5.6, 1/80, 200mm (300mm equiv.)

Now, compare this to background of this auction photo, taken with my new 70 - 200 mm zoom lens:

Water-driven laundry centrifuge
Nikon D300,  Zoom-Nikkor 70 - 200 mm f/2.8
ISO 200, f/2.8, 1/125, 70mm (105mm equiv.)

The contrast in pictures from the 18 - 200 mm lens is probably OK:

Valle di Bregaglia / GR, ascent to Soglio, view into Sciora valley & mountains, unprocessed
Nikon D200,  AF-S DX VR Zoom-Nikkor 18 - 200 mm
ISO 100, f/9, 1/320, 95mm (142mm equiv.)

especially once it has been enhanced by post-processing ... :)

Valle di Bregaglia / GR, ascent to Soglio, view into Sciora valley & mountains, enhanced
Nikon D200,  AF-S DX VR Zoom-Nikkor 18 - 200 mm
ISO 100, f/9, 1/320, 95mm (142mm equiv.)

Sharpness is OK in the center, but clearly has its limitations close to the edges; take this shot from a hill near our place, towards the northern part of Zurich:

Wermatswil ZH/Switzerland, view onto the north of Zurich
Nikon D300,  AF-S DX VR Zoom-Nikkor 18 - 200 mm
ISO 200, f/6.3, 1/160, 135mm (202mm equiv.)

 When you zoom into the right edge of that picture, the limitations are obvious:

Lens creep is a well-known disease of Nikon's 18 - 200 super zoom lens: if you carry the camera on its neck strap, the lens points downwards — and slowly, but surely it will zoom to the maximum focal length of 200 mm. This is most pronounced when the lens is left at an intermediate focal length, slightly less if the lens is "parked" at the 18 mm wide angle end. This is a minor nuisance, but still! My impression was that this was getting worse when I used a Skylight filter to protect the front lens; there is a newer version of the lens where Nikon added a focus lock — but as far as I'm informed, this lock only works at 18 mm (i.e., minimum) focal length (where the lens creep is minimal anyway): that's not really worth much at all, as often one would like to keep the lens at an intermediate focal length, requiring less zooming for a quick shot.