I bought the Walway model (whose link was given above) which holds the phone with a spring compression device. The phone falls out of that easily. Then I bought the Ulazzzi (whose ink was also given). It has a screw that you tighten once the phone is set in it. It is much safer. I have seen another one which is even safer, but can't find it on the internet. PS Use a remote fire for the exposure (via wireless or cable), because pushing the button will make phone move on those lightweight tripods we use for cell phone ...or use 10-15 second delay.

Concerning D750 shutter release recall. Mine was finally recalled after 3+ years. I had noticed that occasionally it made a bright exposure even though all the settings were the same as photos in before and after the bad one, even when I did a burst series of shots at the same time. This might occur once in 4,000 shots but might occur once in 300 shots occasionally and then recur. It probably did it 50 times. But Nikon replaced the shutter mechanism. That is good because mine already had over 90k exposures on it. They also cleaned it completely, inside and out (including cleaning the sensor). All for free. So if you are thinking of buying one and it is used, ask the seller if it has been serviced for that issue. If not, go to Nikon and see it's serial number is on the "recall" list. I'd buy it and send it for the recall. It took 7-10 days max to get it back. Now it is working & looking like new except for some scratches I had made on the body. It has not repeated the problem, but I have only shot about 2,000 exposures since the recall repair.

I washed and dried both an SD drive and a thumb disk over 3 months ago. Both are still working just fine.