If you're a DYI person you can try this
1st - get a phone case that you can attach Velcro to the back.
2nd- find a flat peice of plastic about 1/8" thick (I used a cheap plastic spreader/putty tool) cut to the size of your phone case and cut a hole the size of your camera lens, then attach Velcro to one side.
3rd- (this is the little more difficult part) find a peice of tubing to fit the diameter of you optics eye peice (I used a pvc fitting for one and a vitamin bottle cut down for another). Center the tubing on the hole for the camera lenses on your plastic plate and glue it on the opposite side of the Velcro.
Now you can have your phone in your pocket and when you need the adapter just put it on you optic and attach your phone with the Velcro.