BetterPhoto Q&A
Category: Digital Cameras and Accessories

Need Lens Advice (Purchasing a Nikon D80)

I am buying a Nikon D80 and need advice as to the lens I should get with it. I most often do portrait work (not much scenic or wildlife). I do however have a 4 yr old son that is constantly moving and therefore always a blur in many pics! Just wondering what lens would be best... I'm stuck between 2 choices and they are...

1) Nikon 18-55mm AF-S DX & 55-200mm f/4-5.6G AF-S DX Zoom-Nikkor Autofocus Lens

or the

2) Nikon 18-70mm f/3.5-4.5 G-AFS ED-IF DX Zoom- Nikkor Autofocus Lens

** Image quality is my number one priority, not necessarily zoom capability. If you have any other recommendations (within that same price range) I'd love to hear them! Thanks so much for your time.

~ Deb T.

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November 20, 2008

Other than the two you mention' why not throw into the mix Nikon's best kept secret?

The 50mm 1.4 or 1.8 is an amazing piece of glass in the $100 to $150 range. You don't have zoom capability, but for those fast moving toddlers, it's a fast lens.

Pete

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November 20, 2008

The Nikon D80 sports an image sensor that measures 15.8mm by 23.6mm. We can calculate the diagonal of this rectangle, = 28.4mm. The diagonal measure is significant because it is the measurement lens makers use to determine what lens focal lengths to mount.

A normal lens has approximately the same focal length as the diagonal. Thus normal for this camera is a lens about 30mm. Note the kit zooms sold for this model center up on 30mm.

A wide angle is any lens shorter than normal however it is customary to start this category at 70% of normal. Using this criteria, a wide-angle would be 20mm or shorter.

For telephoto, convention is 270% of normal. Using these criteria the telephoto of range for this model is 80mm or longer.

Now for portraiture the lens of choice is one that presents a view that replicates the human experience equivalent to the self-image view as seen by the subject in the make-up mirror or shaving mirror. Familiarity with this concept makes for successful portraits. Hollywood uses a rule of thumb that the focal length for close-ups should be 3x of normal. Still photographers gravitate to 2.5 times normal or longer. That works out to 75mm for the D80. This rule of thumb has a real foundation based on science. It is predicated on viewing an 8x10 print at normal viewing distance. Shorter focal lengths tend to deliver an image whereby the nose is rendered too big and the ears too small. The differences are miniscule however given the subject’s pre-conserved mental self-image, any infringement leads to the phrase “I don’t photograph well”. Also, photography is both art and science, you are free to follow your heart and choose other focal lengths.

Magnification or crop factor: We tend to judge lenses based on their performance when mounted on a 35mm film camera. That’s because the 35mm has been around for 85 years and teachers and photographers have lots of experience with this format which is 24mm by 36mm and the diagonal is 43mm. Now we can say that the D80 sports a smaller format. In fact it is 65% of that size. Another way to present this information is to say the 35mm camera’s format is 1.5 times bigger. Thus the D80 is said to have a magnification factor or crop factor of 1.5. Stated another way, if lenses designed for the 35mm camera are mounded on the D80 the image produced by lenses intended for the 35mm camera will be cropped top and bottom and both sides. In other works some of the edges will be lopped off. Suppose you are showing slides in a classroom. The projector and screen are matched; the images just fit the screen. Now the history department comes and takes the screen. You find a screen in the closet, it’s smaller. Your slides are cropped top – bottom and both sides. You will find the prospective of the images have changed. Your images now appear to have great magnification, an illusion they were taken with a telephoto.

The 18mm ~ 55mm zoom centers on 30mm normal. At 18mm it functions at the beginning of the wide-angle range. At 55mm it fails to enter into the telephoto or portrait range. The 55mm ~ 200 envelopes the portrait and telephoto range, it leaves out wide-angle and normal. The 18 ~ 70mm functions as a moderate wide-angle extending into the realm of portraiture but fails as a telephoto.

Alan Marcus (marginal technical gobbledygook)
alanmaxinemarcus@att.net

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November 20, 2008

I'll echo that, as it will be a better all-around lens than the two cheaper lenses, and the image quality will be better also.

You might also want to consider the Sigma 17-70/2.8-4.5 lens. It is a great performer, and would be perfectly suited for your purposes.

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November 21, 2008