wchen

@mike_halliwellThank you very much! Will do.

@mike_halliwellRight. Fortunately, I had one left so I could compare. The two screws are the same as shown on Fig 15 on D810 repair manual. Now I need to find a new one for the one I borrowed. Tough task.

The picture ...

Out of town for a few days and not able to response to the post. Thank everyone for helpful information and discussion. Sorry I didn't make it clear that the two screws that got lost and loosen were the ones ABOVE the mount; the screws on the mount are all tight and shiny. Please see the picture below (picture from BHphoto; trimmed and marked by me). I guess there is a space between the mount assembly and the front plate, and the two screws prevent the assembly from tilting forward with weight, hence the movement when they were gone. They could get loosen overtime with heavy lens mounted (tiny vibration etc). See also Fig 14 and Fig 15 on Page 16 on the manual c.p.m._van_het_kaar linked above. Apparently, there are many types of screws used. I made sure the one I removed from the bottom looked exactly the same as the one left above the mount. It is one about 6mm x 1-1.5mm (NOT exact measures) with fine pitch. I used a Wera ESD PH 0 driver and it fitted. I checked my bag for the screw after the reminding of mike_halliwell but not luck. The camera works without any issue so I will see how things go. I typically leave the lens on the camera during transportation (don't like to mount and unmount the lens in the field). I am a handholding guy, but in the field, I would carry the camera by reversing the setup, so the lens would rest on my arm, or grabbing the setup by the lens, thus not put too much weight on the mount. The bad: after about 6 years doing these with relatively heavy lens (first with a AFS 300mm f4 with TC-14II and then 500 PF), some of the tendons of my arms got damaged, and would hurt with certain hand activities. The good: I became careful, and the tendons are slowly recovering.

About three weeks ago I found that my 500 PF would pull the right side (close to the grip) of the mount of my D850 slightly forward, and the mount would make some grumpy noise. I left the heavy lens mounted when not in use and in transfer, so I thought I might have damaged the mount. Therefore, I was thinking about sending the camera to Nikon to see if anything got loose inside. Today I looked at the camera carefully, and there was a small hole above the mount: there should have a screw, but it was gone. The screw at the left was also very loose and ready to drop off. I tried to get a body screw from my now rarely used D7200, but they are different from that particular one used on D850. So, I finally removed one at the bottom of D850 to fill the hole above the mount as a temporary solution. Hopefully none of you have "screwed up" like this, and you might want to check those two screws if you mount a heavy lens often.

Bird and the mountain. Nikon D850 with 300mm f4 PF lens.

Adorama has the deal in stock in case anyone interested. https://www.adorama.com/ilxlcf164gab.html

Oh, and a dedicated Export or Convert button (I didn't see it.)

Tried it and it worked nicely. The only thing I miss so far is it doesn't have those small icons for individual adjustments. I had to keep scrolling up and down with the sidebar. I found those icons on NX-D to be very convenient: one click and I was there. Nikon should bring them over to the Studio in a update, and there is space for them already.

Bosque del Apache National Wildlife Refuge again, with Nikon D7200 and 50mm f1.2 AIS, snapped before their mom caught up (not my kids.) :) The kids must be looking into a better world after the pandemic that I failed to see. I made many trips to the refuge in last three months because it was safe to walk around in the wild and I could practice my skills as a "camera holder" (what my teenage daughter dubbed me.)

Bosque del Apache National Wildlife Refuge last Sunday evening. It was chilly (about minus 8C) and windy that made my fingers ache and clumsy even with gloves on. Only a few people were there having some chill fun. With Nikon D7200 and 28mm f2 AI lens.

It is sandhill crane season here in New Mexico. Nikon D850, 500mm PF at f5.6, cropped.

Nikon SP, 50mm f1.4 SC, and Kodak Gold 200.

Hi bgelfand, thank you very much for your suggestion. I will look at it.

Hi Dieter, thank you for your further response. The camera is two years old so it is out of warranty. I live in NM. I will ask Nikon for estimation of repair cost. If the camera requires a lot of work from Nikon, it may not be worth a trip to their service center. The camera still takes G lenses, so it is useful. But I use manual lenses a lot (this was why I started with Nikon), it is going to be quite inconvenient. I used a D200 for seven years and a D7000 for three years before D7200 and never experienced such a major problem. As you said, the issue makes a good excuse for a new purchase. Thank you. Time for an FF. :)