I bought the Vanguard Alta from Len and then made a multiple device holder for it and can mount both my spotting scope and video camera on it and align them so that the camera stays on the same animal as the spotting scope. What this means is that the tripod head will handle a heavy load very well.
I took this video with the double mount on the Vanguard Alta tripod last week. I am spotting for Phil through the Kowa scope and the camera stays perfectly aligned,
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There was a very heavy fog that morning that as it burned off teh moisture condensed on every optic we had with us and you can see the droplets on the camera lens as blurry spots.