Nikon's new "DX" Lenses for Digital SLR's
Nikon this week issues a "Development Announcement" of the AF-S DX Zoom-Nikkor 12-24mm f/4G IF-ED, due out in the spring of 2003. This lens is slated to be the first of a new series of "DX" lenses specifically designed for the D1-series and D100 digital SLR cameras.
The first thing one notices about such a lens is that it is a 12-24mm zoom, something absolutely unheard in the realm of ultra-wide angle lenses. Given that the image sensor (CCD) in Nikon digital cameras is smaller than the standard 35mm frame size, the sensor only "sees" the central portion of what the lens produces, causing the effect that digital images are cropped by a factor of 1.5x from those produced on 35mm film with the same lens. As such, a 12-24mm zoom on a D100 will produce the same angle of view as an 18-36mm zoom on a film SLR (multiplying by 1.5x). But still, a 12-24mm zoom? How did Nikon make such a thing?
The image produced by any lens is a circle, known, simply enough, as the "image circle." With a 35mm SLR, that circle is then cropped to the 24x36mm frame size, regardless of how big it was to begin with. With a D100 digital SLR, the image circle is cropped even smaller, to the CCD size of the 15.6 x 23.7mm, with everything that hangs of those edges not being recorded. What Nikon has done with the new DX lenses is to design them to produce a smaller image circle that more closely matches the CCD size of digital cameras. As such, if you use one on a film SLR, even though the F-mount is the same and it will work, what you will end up with will be a black frame with a circular image in the middle. With the new lenses though, digital shooters will soon have the equivalent of an 18-36mm ultra-wide zoom, something that has been sorely missing until now, and the lack of which has caused some people to be hesitant about switching to digital. Of course, at the telephoto end, this same "problem" becomes an advantage since a 400mm lens on a DSLR has an equivalent focal length of a 600mm lens on a film SLR.
While the announcement of this new lens has been greeted with praise by many, others have given it a cooler reception. How come? For some time now, there has existed an almost quixotic quest for a "full frame" sensor (one whose size matches that of a 35mm frame) so that they can finally have a wide angle lens and with the idea that larger sensors could produce images with more pixels and thus greater resolution. This might be nice in theory, but manufacturing difficulties have delayed its introduction while the resolution of smaller sensors continues to increase. The bottom line is that there's no longer a need to have larger sensors solely to get greater resolution. What Nikon has done then is to solve the wide angle lens problem by coming up with the DX lenses rather than continuing with the pursuit of larger sensors. Personally, I think they've gone the right route. Lenses that produce a smaller image circle can be designed to be smaller and lighter than current lenses, for one thing. Only time will tell, of course, and in the realm of digital, the future is a moving target.
Update 05/18/2003 - Nikon recently announced pricing for the 12-24mm DX lens on their Japanese website as 162,000 Yen which works out to roughly $1392 US list price. They also show the release date as being June 28 which will be newsworthy for at least the next month or so. Thank goodness there are websites that can translate Japanese for me since I can't even pretend to read the language myself. Don't you just love the internet?
Update 12/28/2007 - Nikon has now joined Canon in producing a DSLR with a "full-frame" sensor. By all reports, the new Nikon D3 is outstanding, but it is not cheap by any means. The market for Nikon DX bodies and lenses will remain strong for a long time to come. Oh, and the new DX-sensor Nikon D300 is also outstanding.