The math in all this is mind boggling.
First starting with the lens. Nothing changes in the lens. 70-300 full frame is, well, 70-300. However, being a full frame lens it is primarily built for a full frame body/sensor. And simply when it hits a smaller sensor, some of the light is lost around the edges. What's that you say, some lens will get soft around the edges? This is a cure. Expense, but a cure. Best I can say if you're really interested, google FX lens on DX body. There's all sorts of people who can 'splain it better than me but in the end for Nikon there is an approximately 1.5x bump for the lens.
So by Nikon's definition, my 70 - 300 has an equivalent focal length of 105 to 450. Out of the box. PFM (Pure Magic).
To get me the rest of the way, the D7200 has a cute little setting called Image Area. This option disables some of the sensor and in the same manner as above gives the illusion of more zoom in the lens. There is a cost, such as pixel count as represented by the reduced file size - but hey I'm an amateur and this is a hobby. The photos are still awesome.
In the end, does anyone really know what the focal length is? The bigger the number, the bigger the object in the field of view is. More/bigger is better, right? Sometimes yes, sometimes no but I'd rather have it and not need it. Or at least have the option to use it.
So, how does the camera react to this.
This set of shots was taken in Port Huron. One of the river vessels passed under the Blue Water bridge. If I had to guess, the vessel was a mile away.
First image with Nikon's DX Image Size.
Focal Length in 35mm is 450. The Image area is set to DX. Note the lens is 70-300,
Next shot less than a minute later. The Image Area was set to 1.3. Focal Length in 35mm is 600.
The particulars are shown. 1/800 sec, f/8, ISO800, Manual Mode
Both shots are hand held. Enlarged, both shots are very clear. (OK, not as fast as aircraft, but when in Rome...)
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