Anyone who owns a Nikon DX camera has hear of the 1.5 magnification/crop factor. This crop factor is the ratio of the dimensions of a camera’s imaging area compared to a reference format. The reference format is most often the 35 mm film format or what is called Full Frame (FX) in Nikon digital camera lingo.
The crop factor as described by Ken Rockwell:
If a photo is made with the same lens, but a smaller sensor, it shows a smaller area.
This is why it’s called a crop factor. The smaller sensor is cropping the lens’ image compared to a 35mm film frame. Ditto for what you see through the viewfinder…
…Nothing changes about the lens; it’s simply the amount of the image we get from the back of the lens.
Paul Lester stated in a recent comment that he would love to see two pictures taken from the same spot with the same lens using a D700 and D300 camera. It sounded like an interesting project so I set my tripod up on a cement walkway and proceeded to take two sets of photos using the same 20 mm, 50 mm and 105 mmm prime lenses on both cameras.
All the photos were shot from the exact same spot with the focal point being the first Crape Myrtle tree just to the right of the white mail box at the end of the driveway. The photos have not been post-cropped or altered in any way.
20 MM:
50 MM:
You’ll notice that the D300 photos appear to be cropped compared to the wider field of view (FOV) the D700 provides at the same lens focal length.
There also appears to be a magnification factor with the D300 photos. How can this be if the lens produces the same magnification no mater what camera it’s attached to? The image produced on the small-sensor DX (D300) will be enlarged more to produce output (print or screen) that matches the output of a longer focal length lens on a full-frame/FX (D700) camera. This “enlargement” is a internal system magnification not a true lens magnification but the result is somewhat the same.
In situations where you’re shooting wildlife and need the highest magnification possible you may want to consider the D300 as you’ll be able to get more magnification with a shorter and less expensive focal length lens.
That’s one reason I’m keeping my Nikon D300. It has it’s advantages and is a complimentary companion for the Nikon D700.
You read about the magnification/crop factor of DX cameras but it’s still interesting to view the differences for yourself.
Note: The color mode on the D700 was set to Vivid while the D300 was set to Normal. This accounts for the slightly higher color saturation in the D700 photos.
{ 6 comments… read them below or add one }
Paul 09.08.08 at 9:00 pm
Much thanks, Earl. So there is a magnification and it is readily apparent in all three photos. Interesting. The magnification makes sense, now. Thanks!
Earl Moore 09.09.08 at 7:38 am
@Paul: I enjoyed seeing the results first hand as well. The magnification factor/effect actually becomes more pronounced as the lens focal length becomes longer.
For a Nikon DX with a 20mm lens the magnification factor results in only about 10mm more relative focal length, but with a 105mm lens the magnification factor accounts for an additional 52mm. When you get up to 400-600mm lenses it can become a sizable (200-300mm) increase.
Paul 09.09.08 at 8:02 am
I also noticed that the color saturation of the D700 seems to be higher; however, this could be the effect of having the color modes set differently.
Earl Moore 09.09.08 at 8:17 am
@Paul: You’re exactly right, the D700 was set for Vivid and the D300 was set Normal. I didn’t catch that until after the fact when I viewed the photos.
angel 09.30.08 at 1:31 am
Hey,
What you didn’t say was whether there is a difference of field of view also, if you were to use a dx lens with a dx sensor. Important!
Earl 09.30.08 at 7:26 am
@Angel: Hi. A DX lens or a non-DX lens of the same focal lenghts on a DX Camera (smaller sensor) would give the same results. I say this from what what I’ve read and from my own experience shooting with a DX camera using both DX and non-DX lenses. I noticed no difference in when switching FOV between these lenses.
For testing above I used my prime lenses which are non-DX.
Of note, a DX lens on a Full Frame (FX) camera (large sensor) will result in only part of the sensor being used and a smaller image total pixel count (less than 6mp compared to a normal 12mp+.)
So what’s the advantage of a DX lens? Well, in most cases for the same focal length the cost will be less for a DX lens then a non-DX lens due to to it’s design and construction. They’re designed so manufacturers can offer more affordable lens for DX camera users, resulting in more sales. But, if you think a full frame (FX) camera is in your future you’d be better off in the long run to buy only non-DX lenses.