Bill_de wrote:
You don't need to shoot in crop mode to show what a cropped image would look like. All that's necessary is to show the FF image cropped. The image, I believe, would still have the same pixels per inch. If so, all you need is to do a crop yourself.
Unless I am totally off base, which is very possible.
But, I would expect DX lenses to be tested on DX cameras and FX on FX cameras.
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This is true - but it does help for composition to know where the boundaries are in the viewfinder while shooting !