I have a Gitzo GT0531 tripod with a RRS BH-25 ballhead that I use for backpacking and trekking. I'd like to attach a level to this tripod to facilitate shooting panoramas, ideally the bubble level will mount below the ballhead. I'm using this tripod with a Sony RX1 with an EVF attached so using a hot shoe bubble level is out.
Because there is only 1 control on the BH-25 ballhead, it's a bit floppy to do panoramas with the camera in the landscape position and one has to use the camera level and one's judgement to get it close. But in the portrait position, the ball head is fairly solid and works well, if the tripod itself is level.
I've tried the RRS Leveling plate for the BH-40 but it's too large and in the way. One possibility is the Gitzo GLEVEL1 Series 1 Bubble Level which is attached to the lower end of the center column but I can't tell if it might fit on the GT0531. If anyone has the GLEVEL1 Series 1 Bubble Level, I would appreciate it if you could measure the diameter of the mounting hole and email me.
Any other suggestions for a bubble level that might work?