A 200mm lens at f/2.0 on a Nikon D-series camera has the same DOF and magnification characteristics as a film based 300mm f/2.8 lens when the subject size is the same. Look at this situation. A bird is full framed with a beautifully blurred background in your Nikon F5 and 300mm f/2.8. You elect to switch to the D2h with its 1.5x crop and use your 70-200mm f/2.8 VR AF-S at its longest setting and biggest opening. Suddenly the background isn't nearly as out of focus. Why is that? The effective focal length is the same--300mm's. Why isn't the DOF the same. Well, the 70-200mm at 200mm's is still a shorter focal length lens at the same aperture. Since it's shorter with the same aperture the DOF will be longer which causes the background to come into focus.
Now that we have the 1.5x crop factor of Nikon's digital cameras, to get the same optical characteristics of a film based 300mm f/2.8 combo you need a 200mm f/2.0. The 200mm lens is smaller and lighter than the 300mm. Essentially you're getting the same capability as your film based combo with a smaller outfit that allows more light in. You need less sensitive ISO settings with this setup that yields better pictures. Or, you can keep the ISO the same and use less flash power therefore extending that capability. The relationship between the 300mm f/2.8 and 200mm f/2.0 is exactly the same between the 600mm f/4 AF-S and 400mm f/2.8 AF-S. The bottom-line here is with the 1.5x crop using slightly smaller and faster lenses you're getting exactly the same optical characteristics as your film buddies but with twice the light coming in. This leads to a lot of possibilities.
Now add the D2x's 2x crop mode. Here your 400mm f/2.8 lens becomes a 800mm f/2.8 with regards to magnification and light gathering capability when compared to a film setup. For the same subject size your DOF is more like a 800mm f/5.6 which btw was a mainstay of bird photographers all over before the advent of excellent teleconverters and quick auto focus systems like the Nikon's Silent Wave system. But, let's say you want more pixels. All you have to do is not add the 2x crop mode, add the TC-14e which gives you a 560mm f/4 and approximates a 840mm f/4 in magnification/light gather terms for film cameras. Further, you get a similar optically performing 840mm f/5.6 for DOF but in a much larger file size.
What does all this indicate with regards to Nikon's camera strategy. I think it means better long lens capability over 35mm film photographers. It also seems to point out that you don't need as much of the new vibration technology as you might think. Why is that? First, let's look at why people need that capability. It's sole purpose is to improve sharpness when using long lenses. For the hand held scenario I've found I can get sharp images using about half the recommended shutter speed shooting with Nikon's D-series cameras and their 1.5x crop as needed when compared to film. While I would've needed 1/300sec or more for a 300mm lens when shooting film, I get away with needing only 1/200sec when using my 70-200mm f/2.8 AF-S without the VR turned on. This means you can keep shooting with the light about a third as what you needed before. Now imagine using the 200mm f/2.0 AF-S without VR turned when the aperture is wide open. You now can keep shooting in almost two stops less or 30% as much light as when shooting film with the 300mm f/2.8 scenario. And, we did this without even turning VR on. It obviously gets better when you have VR. To me this means the pressure to add VR to long lenses is diminished to keep up with competitors. I'm not saying you don't need to have it. It only means you don't have to have it right away and still sell lenses at equivalent prices to your competitors without adding the extra stuff. It means extra profits which really is the bottom-line.
What does this mean to the future? I expect we'll see some new and innovative lenses come out that take advantage of the 1.5x optical crop of Nikon's digital cameras.
- A 50 to 135mm f/2.0 AF-S VR to match the old 80-200mm f/2.8's. It'll be just smaller than the 70-200mm f/2.8 VR.
- A 18-50mm f/2.0 AF-S VR to match the older 28-70mm f/2.8 AF-S. It'll be big like it's older brother but it'll be awesome.
- A 12-20mm f/2.0 DX AF-S to complement the 17-35mm f/2.8 AF-S. It'll be big. It'll be DX but it'll be made of the stuff that make legends.
- The 400mm f/2.8 AF-S VR will be delivered to match the 600mm f/4 AF-S.
- I don't expect to see a 300mm f/2.0 AF-S VR to match the 400mm f/2.8.
- I would've expected to see a 135-270mm f/2.8 AF-S VR to directly match the old manual 200-400mm f/4 though it appears that's on hold with the direct duplication of that lens with the introduction 200-400mm f/4 AF-S VR.
This is an exciting time for Nikon users especially if you're into shooting with long lenses. You can get better lens capability as your film brothers without additional costs.
Cheers
Tom
