Hi Raymond and welcome to the forum!
Some more details will help us to help you make a sound decision:
The R50 comes with a couple of kit lens options, which one precisely do you have?
The needs for architecture and portraiture are quite divergent. For architecture, you want a wide field of view, which means a short focal range, while for portrait you want almost the opposite.
So that suggests either two fixed focal length lenses, one for each application, or a zoom with a wide wide range of focal lengths. Do you have a preference?
What is your budget value in $?
cheers, TREVOR
The mark of good photographer is less what they hold in their hand, it's more what they hold in their head;
"All the variety, all the charm, all the beauty of life is made up of light and shadow", Leo Tolstoy;
"Skill in photography is acquired by practice and not by purchase" Percy W. Harris
