The flower is a night blooming cereus. It won't fully open until 10 or 11 pm and begins very slowly opening shortly after sunset. I just photographed mine and used a black velvet background and off camera constant light the first night. Unfortunately I had to move it inside for the shot as it started to rain buckets outside. I also did a time lapse which turned out just ok. I was lucky enough to have another bloom the next night. That time I set up my iPhone to do a video. Same setup: black velvet background draped over all the extra stems and clutter, constant light about 2' away inside a soft box adjusted not eliminate shadows within the flower. The iPhone video turned out better than the time lapse, no post processing necessary and fascinating to watch - more interesting than a single still photo.

I have the Nikkor 200-500mm lens and bought an Apecase large professional lens case. Not only does the lens fit but I can also use it as a carry case for the lens with the D850 attached. https://apecase.com/product/acprolc18/.

I found a lens at a good price on eBay sold by a vendor called Downtown Photo. Has anyone had experience with this vendor and are they reputable.

Thanks again. I appreciate your information and now look forward to using this thing I bought.

The grip is a Nikon and the lock is off.

Thank you for your speedy response. Yes, the AF-L/AE-L was set to ON and I see that it does act as BBF. Because of some hand injury issues it is difficult for me to use BBF, is there a way to turn that off and use the shutter in vertical mode for auto-focus?

I'm hoping someone can answer a question that has me frustrated: I bought a Nikon MB-D15 Battery Pack to use with a D7100 from an acquaintance who hadn't ever used the battery pack. It was originally purchased new and hadn't ever been used. I put it on my camera and played around with it a bit but couldn't get the camera to auto-focus when the grip was used in the vertical position. The controls wheels worked so I could change shutter and aperture settings but the focus only worked when the camera was in Manual mode. Is this how the battery pack works in vertical position or is there setting or two I'm missing? Anyone have an answer?