Norm- Tourist activities in Antarctica are controlled by IAATO- the International Association of Antarctic Tour Operators. IAATO is a superb example of an industry controlling itself, and very effectively I would add. As a staff member on board a ship owned by a company which is a member of IAATO, one of my many tasks is to make sure we abide by all the IAATO regulations when we land ashore. People who land ashore in Antarctica have to have had an extensive IAATO briefing on how to conduct themselves. We do these on board ship.
Minimum distances to penguins is 5 metres or 15'. They will often approach you closer than this but you may not approach closer. As they are sizeable birds, at 5m a 70-200mm lens works very well. I did use my 400/5.6 for portraits etc. And of course, you attempt to get down to their eye level, which is easier this time of year because the colonies are still covered in snow. In January they become very mucky and stinky with penguin poop and I would not recommend laying down!
For more information look at
www.iaato.org