I was surprised to find, after reading so many positive reviews of this lens, that the copy I received was so fuzzy at wide-open apertures that I could see it on UN-MAGNIFIED images right on my D90's 3" screen.
All lenses lose sharpness at wide apertures: this is a matter of basic physics and is the result of something called spherical aberration. Some are much better than others though, thanks to better optical designs that more effectively correct for this tendency. The 35mm f/2, for example, is very good wide open; the 85mm f/1.8 is decent (and very appropriate for portrait use). My copy of the 50mm f/1.8 lost both sharpness and significant contrast as f/1.8 was approached. I would quantify it as follows:
f/1.8: very fuzzy (well beyond "soft"), reduced contrast, almost un-useable
f/2.8: still quite soft, much improved contrast
f/4: slightly soft, good contrast
f/5.6: sharp, good contrast
f/8: very sharp, good contrast
These results were repeatable on my sample and held true regardless of shutter speed and technique.
Notes:
- The advantage of a lens like this is the ability to use wide apertures. A good portrait lens need not be particularly sharp, but wider than f/4 my copy of this lens was soft enough that I would use it for nothing other than casual people-photography. It would not suffice for critical night or low-light photography, or for general photography where sharpness might be desired. For photos of people it was fine at f/2.8, but below that it lost so much sharpness, and enough contrast, that photos of almost any subject looked dull.
- The lens seems like an obvious choice as a first prime due to its price and the many excellent reviews of it here on Amazon and elsewhere. Even besides the sharpness degradation wide open, I found it less useful than I'd hoped. On a crop-size DSLR, it is a short telephoto lens, and it just hasn't turned out to be a focal length I use all that much. I would urge potential buyers to consider the 35mm f/2 before this lens as it gives the traditional "normal" perspective on a Nikon crop-size DSLR.
- Some reviewers like this lens for portrait use, but again, I found it poorly suited for this. The 85mm f/1.8 is admittedly more expensive, but it has far more potential as a portrait lens.
- This is not a high-contrast lens. It does not use any ED glass elements, which seem to be quite magical at improving contrast, and color rendition is noticeably less vibrant than such lenses. For some types of photography this can actually be desirable, but for general or landscape photography I prefer the higher-contrast lenses.
- My sample of this lens may have been below average, considering that most reviews of the lens are very positive. However, if you read carefully, most thorough reviews do mention that it loses contrast and acuity at wide apertures. Ken Rockwell, for example, has reviewed the lens very positively, but when it came time to suggest lenses sharp enough to be used on the new D3x, with its ultra-high-resolution sensor, he gave the similar-performing (possibly better) f/1.4 "G" version only three stars. I would submit that it is really not quite as sharp a lens as its reputation would lead one to believe. My excellent 16-85mm DX zoom, for example (the only lens I've given a five-star review as of this time), is far sharper than this lens up to around f/8 and hold an edge even there and beyond.
- Nikon has recently announced a new 35mm f/1.8 DX lens. I've ordered one and will probably post a review once I've had a chance to use it. I would suggest that it is very likely to be a better choice than this lens for almost any DX user. Being designed for the smaller DX sensor, it will probably be optimized for high linear resolutions within the smaller DX image circle. It is also a fairly inexpensive lens, not much more than this lens now that the 50mm has crept up a bit in price.
- Even if my sample is significantly poorer than average, my experience indicates that it would be a good idea to thoroughly test a copy of this lens before committing to buy it. Be sure to compare images at wide apertures to those made at f/8, where sharpness should be very good, and determine for yourself whether the loss of sharpness and contrast is acceptable for your purposes.
- Focus is plenty quick and accurate, at least on my sample. No problems at all in this regard (and none expected).
Final note: This is an honest review of a lens I've actually owned and used, in comparison with other lenses that I've actually owned and used. Unfortunately there are always people who click negative reviews as unhelpful no matter how accurate the review, and that does a dis-service to other Amazon customers as those reviews wind up at the bottom where they are not seen. I wish more honestly critical reviews were available to help me make purchasing decisions, and I hope you think so as well.
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.