Hi Dennis and welcome on board! I deleted your other post in GRD forum. But I probably should not as it's more GRDII than GX100 problem. I will move this post to GRD forum and leave the track of the post also here.
As for your problem, I too noticed some weird behaviors of Ricoh file numbering. While the last number is apparently stored in camera, the sequence is somehow continued also if you use different cards with different last number, not matching the actual file sequence recorded in camera. And more, from time to time, the file numbering gets mad and starts naming the files with underscore sign instead of "R" letter
In any case, the real (correct) number of taken files (actual shutter count) is recorded both in camera internal memory and in exif!
If you want to fix the file numbering without resetting anything, do this...
- At first, check the actual shutter count of your GRDII
- switch the camera to Scene mode and press and hold the Macro and Play button (at least 1-2secs).- Now erase all files from your actual card, except the very last (newest) photo.
- in the appeared menu see the SH row. It's your actual GRDII shutter count. Write this number down.
- Replace last four digits of the file name (of this last photo) with the number found in SH row, but preserve the number of digits in the file name!
In other words, change this R0016525.jpg to this R0010001.jpg. Your actual shutter count is probably higher, but I guess not over two-three digits number? In case the number of shots is under or equal 99, the file number should be R00100xx.jpg, If it's under or equal 999, then the number should be R0010xxx.jpg and so on.
Unfortuantely, this procedure does not fix the "underscore" problem and the first three digits after R (underscore) may be different in case of higher shutter count. For example, I did the same thing like you, using the SD card from different camera, which shutter count was beyond 8000 files. And my first three digits are 007 (Bond..James Bond). I guess resetting the camera to factory defaults could fix the file numbering as well? But only if you use new or newly formatted card. But I did not try this yet.