You don’t always need to have long focal lengths to get close up images, this image was taken with a moderately priced Nikkor 70-300mm VR at only 220mm and it is practically full frame.
How did I get an image of a wild Red-breasted Merganser (Mergus serrator) from so close?
Patience. I approached the bird very slowly from the water by sitting on my legs and shuffling them forward and keeping my appearance as small as possible.
Observation. Watching the bird carefully for any sign or alarm or distress. If I noticed the bird show either sign I stopped dead still and waited. When I could see clearly that the bird was relaxed I would inch forward.
The series I have of this bird numbers over 100, it was so relaxed it preened while I photographed it.
It also helped that the bird was in a location where it had become habituated to humans on the beach, that can help with shorter focal lengths.
Then I retreated as slowly & carefully as I approached it without disturbing the Merganser. That felt awesome.
Taken at Fort De Soto’s north beach in Florida.
More Red-breasted Merganser images