If your dendrobium grew this past season and bloomed like that under your care, then I'd say it's enough light.
It can be a little too much light if the sun directly hits the paph for a long time during the day, but you can tell by the leaves and move away from the window if you see anything happens.
The dendrobium is blooming in my hands for the second time. It might get some direct sun light but it happens during one hour only, and in the early morning.