10 out of 10 points and recommendedLarge Aperture, Fast/Quiet AF, Great Image Quality, Nikon Version is "G-Type" Lens; Outstanding 50mm-Equivalent Prime Lens for Nikon DXNone
After researching the various offerings from Nikon and others, I purchased this lens to serve as a Portrait and general-purpose low-light lens. The published reviews have been very positive, which ultimately made my purchasing decision easier. [For those interested, I am utilizing this lens with Nikon's D2X top-of-the-line digital SLR.]reviewed November 13th, 2006 (purchased for $400)
First off, bear in mind that this lens is intended to be a 50mm-equivalent, and is designed exclusively for Nikon DX digital SLRs. (All Nikon digital SLRs have a 1.5x "lens factor," due to the fact that the sensor is smaller than 35mm film.) Sigma states the following in the product specifications, but let me repeat it here: it is NOT designed for full-frame (e.g. 35mm) use!
In terms of comparable offerings from Nikon, they are: Nikon 28mm f/2.8D AF, Nikon 35mm f/2D AF, Nikon 50mm f/1.4D AF and 50mm f/1.8D AF. The two latter lenses are not really in the same category, as they are 75mm-equivalent on Nikon digital SLRs. The two former lenses are close in terms of focal length, so they are reasonable alternatives.
There are several key differences between Sigma's 30mm lens and Nikon's aforementioned 28mm and 35mm lenses. First up, Sigma's lens is equivalent to a Nikon "G-type" lens. Specifically, this means that Sigma's lens does not have a dial to set the aperture; instead, the aperture is set on the camera body. This is incredibly convenient, and allows one to quickly change the aperture while framing the picture in the viewfinder. Nikon's 28mm and 35mm lenses, in contrast, are the older "D-type" lens. Meaning, they both utilize an aperture dial.
The other key difference between Sigma's lens and Nikon's 28mm and 35mm, is that Sigma's utilizes a "Hyper Sonic Motor" for autofocusing. As a result, autofocus action is extremely fast and quiet. Nikon's 28mm and 35mm do not utilize a comparable technology, and instead make do with an older -- and slower/louder -- mechanism.
And finally, a word on optical quality. Because Sigma's lens is so super-fast optics-wise (i.e., the fast f/1.4 maximum aperture), depth-of-field can be extremely shallow. So shallow that, when taking a portrait at, say, 3 feet away, one can focus on the tip of the subject's nose -- with the rest of the subject's face slightly soft! (One might want to generally focus on the subject's eyes, but that is neither here nor there.) The point being, that when fully opened up at f/1.4 or f/1.7, it is easy to confuse the optical quality of the lens (which I have found to be outstanding!) with soft focus due to shallow depth-of-field. [For any newbies: this is a "feature" of fast aperture optics.]
Bottom line, the Sigma 30mm lens provides superb low-light performance (thanks to the fast f/1.4 maximum aperture), along with outstanding optical performance. It is highly recommended for any Nikon digital SLR owner who is looking for a 50mm-equivalent portrait/general-purpose lens. You will not be disappointed!
10 out of 10 points and recommendedGreat Optical Quality, Fast/Quiet Autofocus, Well Built, Autofocuses with ALL Nikon DSLRsNot Weather-Sealed
First off, bear in mind that I purchased this Sigma fisheye to replace Nikon's 10.5mm f/2.8 fisheye. While I was happy with the Nikon's optical performance, I was disappointed with the AF design. Nikon's lens relies on the AF motor in the camera, which makes for noisy AF. In addition, this design precludes full-time manual focus touch-up. And finally, the lack of an in-lens focus motor precludes AF on the existing D40/D40x and new D60, as well as future Nikon DSLRs lacking an in-camera focus motor.reviewed February 16th, 2008 (purchased for $650)
In any event, when Sigma announced their fisheye lens a few months ago, I decided that I would purchase one. And I am very happy with it! The HSM provides autofocus performance as fast as the Nikon (at least on my Nikon D300 DSLR), while being eerily quiet.
As for the optical quality, it appears to be virtually identical to Nikon's, which is to say excellent. Both lenses are slightly soft wide-open (i.e. at f/2.8), but sharpen considerably when close down one f-stop. Indeed, both lenses are almost as sharp at f/4 as they are at f/5.6.
Besides the built-in autofocus motor, another difference between Nikon and Sigma's fisheye lenses is the field-of-view (FOV). Sigma's lens is 0.5mm wider, and provides a small -- but definitely noticeable -- increase in the angle of view.
So, it all comes down to this:
* Do you currently own a D40/D40x/D60, or plan to purchase one?
* Do you prefer super-quiet AF to the noisy mechanical variety?
* Do you prefer a better-built lens?
The one advantage that Nikon's lens has is size/weight. While arguably not as durable and well-built as the Sigma, it is lighter and more compact. If this is important to you, then you may prefer the Nikon.
As for Cons, there is one. Sigma's lens is, unfortunately, not weather-sealed. I was hoping that Sigma would at least utilize a gasket around the lens mount, but that is not the case. As such, I recommend against using this lens in rain/drizzle -- or in a super-humid environment. (It is important to note that Nikon's fisheye lens is not weather-sealed either, and also lacks a lens mount gasket.)
Apart from the one aforementioned complaint, I highly recommend the Sigma 10mm fisheye lens. It provides all of the performance/quality of Nikon's fisheye lens, while providing fast and quiet autofocus to owners of ALL Nikon DSLR's, including the D40/D40x/D60. You will not be disappointed!