I'd be interested to know how a pack like this works when it's blowing a gale. Unless it's detached from the tripod during viewing, I suspect it will act like a sail, which is why I've never been tempted. I guess if it's only used in a hide, there isn't an issue, but that's very limiting.
Personally, I think it's so quick and easy to attach a scope to a tripod, that while walking I'd rather have the scope in a backpack and the tripod attached to the side of the pack, or in one hand. I bought a Tenba Axis V2 16l for this purpose.
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I can answer that!
On monday I went for a bird count. Not ideal conditions, just past the top of a spring tide, forecast gusting 45+mph winds ( beyond Gale Force ). After the deluges the previous few days and before the next deluges.... so I decided to give it a go.
One part requires me to walk onto a spit of land and look back towards the river mouth, a very exposed and higher elevation than the rest. Yes the tripod was being blown, but I could hardly stand either! No birds visible, except a small few sheltering behind the slightly elevated mudflats.
I continued to the top of the wetland and here it was gusting even more. I really could hardly stand. I made sure the scope and tripod was cradled by my arm around the scope and leg 'inside' the 3 legs of the tripod whilst counting. Though not the best conditions, it enabled me to carry out an amazing count as all the birds were across some scrubby pasture, sheltering. Just before a friend had a reserve largest count of Little Egrets, though some were gone by the time I was there. Heron, Canada Geese and an Egyptian Goose in with the Canada's, plus Moorhen, Widgeon, Shellduck, Curlew etc.
It was amazing to see them all concentrated from across the wetland into such a small area.
It was incredibly windy but I never felt the backpack was making the tripod into a sail, no more than my body was buffeted.
All in all a mad day, but glad I saw what I saw.
I've realised the Mule has an add-on removable pouch at the back that has a drinks holder which enabled me to take a break and drink water. Useful on a 4 hour trip.
Also I've discovered if I deploy the lower legs only, I can reach back and undo the middle legs whilst still on my back therefore taking it off fully extended and 'ready to go' .
Having carried the tripod in my hand or over the shoulder for a few counts, having it on my back really is an improvement.
It allows me to have hands free for bins and to make notes when counting. Deploying it might not be instant but overall this works very well for me.