Shetland seems to be blessed with many excellent photographers. Jim Nicholson, Jim Wood, George Petrie, Ivan Hawick, Hugh Harrop & Rob Brookes to name just a few. Like anywhere you have to be out with your camera in all weather & Shetland certainly has quiet a variation in weather conditions even in one day.
The other is opportunity, and Shetland has this in abundance. With minimal tree cover many birds are forced to find other locations and with a good eye these can be seen in unusual open areas. When birds arrive they are often tired and with precautions can be approached closely without disturbing them. Another factor is that many birds are approachable anyway and don't have the fear factor often encountered elsewhere in the UK which is good news if you follow the code of conduct. (See Shetland bird club website).
It also pays to have a large lens which means you can stay further away from the bird, many use their car as a hide and use the wait and see approach. As with any island, but especially Shetland, you are never sure what birds are going to be encountered, especially on migration which makes it even more interesting .
The above photographer who are based on Shetland all year certainly have the patience, skills and understanding as well as devoting plenty of time photographing birds, the results are fantastic . But even the people who visit Sumburgh head to take Puffin photos close up return home very satisfied.