Altitude markings for a tri pod

[proflight2000]

Hi all

I am now using my celestron binos 20x80 on a tripod, I can work out Azimuth by using the 360 degree ring on the pan and tilt head, however, tilting the head for altitude is a bit hit and miss as there are no altitude markings. 
 

can anyone offer any ideas as to marking the tilt head for altitude readings? I can mark them but is there an easy way to measure each degree in millimetres to get a rough good guide. So basically if horizon is 0 then does the old clench fist held out to get 10 degrees higher actually work.

many thanks for any ideas.

[M40]

You could try a digital angle finder and spirit level. I bought one from toolstation a few years ago and they work well. I tend to use it to check if a target will clear the neighbours trees but I see no reason why it wouldn't work for your application. All the best.