On another thread, I expressed the thought that if one wanted to have a 120mm (like for a trip where weight & space were at a premium) one could instead use DX mode with the 24-85mm 3.5/4.5G to effectively reach to the 120mm that the traveler was hoping to have for the very occasional longer shot.
One amongst you who whose opinion I value said this in response --
"A small point, perhaps, but to avoid confusing newer members it should be pointed out that engaging the D600's DX Crop Mode does not change the lens' focal length. Crop Mode can be useful, but it simply uses a smaller area of the sensor, of around 10MP. It provides smaller files, but otherwise has the same effect as cropping after the event."
And so for the different question: Does DX mode on a D600 simply crop the FX image, and so taking the same photo in FX & THEN cropping to the same apparent size as the DX image would be either the same or even a better quality image?
I have taken some DX mode shots of surfers with the 70-300mm VR trying to "fill the frame", whereas in FX mode I could not do so, obviously the shots were from the same distance. It SEEMS that the DX shots were more clear, and at any rate, did not suffer. Same apparent result with some racing sailboats. These shots were at distances I could not "reach" well with the FX mode and 300mm lens.
I may be embarrassing myself, but want to learn. If I simply cropped from FX mode to the same apparent size in the frame would I have a better overall image?