It depends upon what kind they are. Some Dendrobiums you don't water at all except when they really need it, and others you just slightly decrease the amount of water and frequency of watering. Do you have names of these Dendrobiums?
I am not personally familiar with the named one, so I hope someone else can comment on that. Can you post a pic of the NOID one, full plant? That may help us to determine proper care given the foliage and growth pattern. Thanks!
Sorry my post was supposed to be in mine titled the same thing, or really close to it.It linked me from my email to this one by mistake I guess. Ugh. My post has the actual pics. Of them.