Help Dendrobium and Vanda yellowing :(

[kaarthiik]

Please help!
I am a new Orchid hobbyist, I seen these beautful plants recently. And ordered online after a tough research, I am with them for just 2 weeks and now I am worried. My dends and vandas are yellowing.

First week they were fine, I am from India and the week I recieved the plants, we did not have bright sun the temparatur was 50-55 F during day and 40-45 during nights. Humidity was 80% on average.

This week I had a very bright sun for 4 days, and today I was shoked to see the leaves yello . and few shedded ;(
When there was no sun, I water my dends once a week, but sprayed water on Vanda. On Sunny days, I am wated 2 times in 4 days (as pot was lite)

I did not repot/add fertilizer, Dends were placed on east side of my terrace, able to recieve bright sun.
Now I broght a big sheer to stop dirct light.
Pls help me how to take care...

Please see the pics attached