I like the 85mm focal length very much. On a Nikon crop-size DSLR, the 85mm focal length is a very useful short-to-medium telephoto length, giving a nice field of view with just enough distance compression to get a pleasant telephoto perspective. This lens' wide aperture gives plenty of control of depth of field, allowing you to isolate your subject and get just the right amount of defocus elsewhere in the frame. I tend to prefer to use it at f/2.8 or so, although having the ability to go to f/1.8 is certainly useful at times.
A few notes on specific performance issues, some of which seem to be in disagreement with others here:
- I would not characterize the lens as very sharp wide open. I've sampled three of these lenses, two "AF" models and one "AF-D" model. The AF-D was the best. Like any lens I've used, it loses sharpness at wider apertures, and I would characterize it as soft at f/1.8, still moderately soft at f/2.8, good at f/4, sharp at f/5.6 and very sharp at f/8. There is a definite difference in sharpness at each aperture up through f/8. This is not necessarily bad. A bit of softness at f/1.8-f/2.8 might be desirable for portraits and some other types of photos, and the lens is very sharp where you would usually use it for landscapes and general photography - f/5.6-f/8 or so. At wider apertures, the contrast between a blurred background and relatively sharp subject remains striking and is a very pleasant effect that will allow you to get exceptional images.
- This is not a high-contrast lens, due at least partly to a lack of ED glass. This is appropriate and probably contributes to its reputation as a good portrait lens - skin tones are pleasantly rendered and the overall effect is slightly subtler and gentler compared to Nikon's most contrasty lenses. I can shoot the same scene with this lens and then with my 16-85mm (consumer DX zoom), and colors that leap off the screen with the 16-85 are significantly mellowed with the 85/1.8.
- I don't see any loss of contrast at wider apertures. This is good. The 50mm f/1.8 loses a lot of contrast wide open, for example (and mine is considerably softer than the 85mm at wide apertures).
- I would not say the quality of bokeh is particularly pleasing. It can be distracting at times, and I see color effects in the blurred areas (chromatic aberration), which occurs because different wavelengths of light are blurred differently by the lens (some very expensive lenses are "apochromatic," meaning that they correct for this). This does not in my opinion detract significantly from my images, since the whole idea of defocus is to attract the viewer's eye to the subject rather than away from it and so consequently one does not tend to study an out-of-focus background unless actually evaluating it specifically; but this might be one of the reasons the f/1.4 lens is a more popular choice among those willing to spend three times the money. This is speculation on my part as I have not tried the f/1.4.
- Focus is very quick and as far as I can tell completely accurate. I do use a simple test chart to test focus with all my lenses and this lens focuses well within its depth of field even wide open.
This lens is very good for tight indoor shots as well as outdoor photography. At near-wide-open it can be used indoors with fairly low available light and make very pleasing shots of tight groupings of people from a reasonable distance. A slower lens will tend to bring the background into the photo more than is desirable, which can be distracting in the final image.
It is not a good only lens and perhaps not even the first prime lens one should buy. It is a very good lens to have after all the basic focal ranges are covered, and perhaps after a "normal" prime, and it is a very good lens for taking pictures of people. In addition to this lens I highly recommend Nikon's very affordable 35mm f/2 (2/25/09 note: Nikon has recently announced an even more affordable 35mm f/1.8 lens for DX which will probably prove to be an even better choice for DX users), which is very sharp indeed and in my opinion a far better lens than the 50mm f/1.8. I do however prefer the 85mm as a matter of pure personal taste: it is my personal favorite fixed-length lens.
I wish I could give it 4-1/2 stars as it is a good, good lens, but can not justify giving a full five. I don't think anybody would regret buying it, however. With a bit of help from the user it is capable of making some truly fine images.
Other Lenses:
I've had the opportunity to own and use many different Nikon lenses and have posted my impressions of some of them here on Amazon. For those interested, here are short summaries. I have used all these lenses on Nikon DX-sized DSLRs, most recently my current D90. Refer to the full reviews for further detail.
Nikon 28mm f/2.8 AF-D: *** Competent, sharp lens is a good fit as a bargain DX "normal" prime. Slow f/2.8 max aperture poor. Very inexpensive in used market.
Sigma 30mm f/1.4 HSM: *** Poor focusing consistency and below average large-aperture acuity combine for disappointing real-world performance. Fast max aperture, very capable if used with appropriate care.
Nikon 35mm f/1.8 AF-G: ****1/2 Terrific lens at a bargain price. Not without flaws, but excellent in all important respects. A pleasure to use.
Nikon 35mm f/2 AF-D: **** Sharp, especially at large apertures, moderate contrast. Classic "normal" lens for DX but consider new 35mm f/1.8 AF-S instead.
Nikon 50mm f/1.8 AF-D: *** My sample was unacceptably poor at large apertures. Perhaps a below-average sample. Focal length not ideally suited to DX.
Nikon 16-85mm VR ***** Very sharp at all settings, excellent contrast, very useful zoom range including true wide-angle at 16mm. Excellent VR. Best-kept secret for DX users.
Nikon 28-200mm AF-G *** Of two samples, one was excellent and one poor, so watch for sample variations. Very good contrast. Not ideal hand-held due to lack of VR. Not ideal for tripod use due to design.
Nikon 55-200mm VR **** Very good lens, very good sharpness and contrast, no fatal flaws. Cheap feel and feature-challenged, but has effective VR. A bargain.
Nikon 70-300mm VR *** My sample had very poor performance above 200mm, good to very good elsewhere. Good contrast, generally very good focus performance. Good sports/action lens. Not good where critical sharpness is desired. Possibly a below-average sample.