Optimum enclosed porch humidity level?

[Biiilllll]

I enclosed my screen porch this winter... added lots of CFL's to keep my many various orchid babies happy.... most are doing well even though it is cooooold outside.... a couple of heaters keep the nighttime minimum low temp to the mid 50's... phals are inside where it is warmer.
I have a couple of humidifiers going and usually have humidity levels of 50% to 70%.
Question.... what would you suggest as the optimal humidity level? Thanks for your help! (I have sooooo much to learn!)
Also.... quick plug... don't miss NCPOS show 1/14-1/17 at Daniel Stowe Botanical Garden in Charlotte NC... spectacular facility and lots of very experienced growers exhibiting.

[Donald]

Up here in Massachusetts I have a diverse variety of orchids that have lived quite nicely for the past 8 years in a southeast facing sunroom where the temps range from 60 at night to 74 during the day. The humidity level stays in the low 30s. Presently in bloom are a couple of dendrobiums, eight phals, two psychopsis. Just budding up are a catt and a phrag. Those are my conditions and I think like humans orchids after awhile adapt to different conditions and grow. Summertime finds them all outdoors. Happy growing.

[IncredibleOrchids]

50% - 70% is great! What kinds of orchids do you have?