Sales of the Nikon D4 have been delayed worldwide until at least the middle of March according to Nikon USA. Shipping of the new flagship DSLR has been delayed with rumours suggesting that is due to a firmware upgrade. Nikon USA has simply stated that the mid-March launch is as a result of “minor production delays”, but did not provide any more specific details. Nikon UK on the other hand credited “overwhelming popularity” with the cause for the delay. After the delay, Nikon has been reluctant to give a specific release date.