Lens loyalties with full frame
The other issue when swapping formats is lenses. Camera bodies come and go, but lenses are a long-term investment. The Nikon D50 you bought years ago may be obsolete but the lens that came will be just as good today as it was then.
Nikon started off making DX-format DSLRs and a whole range of DX-format lenses to go with them. If you do decide to upgrade to the full frame FX format you’ll almost certainly have to invest heavily in new lenses too.
You can use DX-format lenses on FX-format Nikons, but only in ‘crop’ mode. The camera restricts the sensor area to a DX-sized rectangle in the middle, and you don’t get the benefit of the sensor’s full resolution.
For example, in crop mode, the 36-megapixel D800 produces images of 15.3 megapixels, while the 16-megapixel D600 drops to 6.8 megapixels. So, using your DX lenses is not a long-term solution.
Of course, you may have some FX lenses already, like Nikon’s 70-300mm f/4.5-5.6 telephoto zoom, which is a popular choice for DX-format SLR owners but is actually an FX-format zoom.
If you are considering moving to an FX camera in the future, start investing in FX-format lenses now because they’ll work on any DX-format Nikon DSLR in the meantime. Our photography cheat sheet below illustrates the effect you’ll see when you mix and match full frame and crop-sensor lenses. Click on the infographic to expand the file.
The other big difference between the DX and FX formats is what they mean for angle of view of your lens. The DX sensor captures a smaller image area, which makes it look as if you’re using a lens with a longer focal length.
If you fit a 50mm lens to a DX camera, the pictures look as if they were taken with a 75mm lens. This is the so-called ‘focal factor’. Photographers also talk about ‘equivalent focal lengths’, but really it’s the same thing.
The focal factor of Nikon’s DX sensors is 1.5, which means you multiply the lens’s actual focal length by 1.5 to get its equivalent focal length.
This can work in your favour with DX cameras. If you have a Nikon 300mm f/2.8 lens fitted to a D7000, for example, it effectively becomes a 450mm f/2.8!
If you then invest in a full frame camera like the D800, your 300mm f/2.8 lens will still work fine (it’s an FX-format lens, after all), but it goes back to functioning as an ordinary 300mm.
There are many things to consider when choosing between the DX and FX formats, then, including practical and technical considerations.
PAGE 1: What is full frame?
PAGE 2: Lens loyalties with full frame
PAGE 3: Why the depth of field is different
PAGE 4: How to shoot with a full frame sensor
PAGE 5: How a full frame sensor affects your pictures
PAGE 6: Pros and cons of using a full frame sensor