tisdag 16 augusti 2016

Vibration damping the EQ3 aluminium tripod

The EQ3 mount with the aluminium tripod is generally considered not to be suitable for astrophotography. Still, it's a nice, portable mount that, under the right circumstances, can produce relatively good images.
There is an article on cloudynights.com that describes how the tripod can be beefed up. The author of that article increases the weight of the tripod by putting rebar in the upper legs, and a rectangular wooden dowel in the lower legs.
The problem with the tripod is not just a weight problem, but rather a vibration problem.
Filling up the hollow legs with dowels and rebar, doesn't necessarily improve the vibration characteristics of this mount. A person commenting on the cloudynights article, suggested that the legs can also be filled with sand. This will result in both a heavier tripod and different vibration characteristics.
I decided to modify my tripod by inserting wooden dowels in the upper and lower legs. But I also secured these dowels to the plastic and aluminium structure. Hopefully, this will improve the vibration damping of the tripod, without it becoming too heavy.
Wooden dowel cut to size, ready to be inserted in the lower leg
Starting with the lower parts of the legs, I removed all the plastic parts and inserted oak dowels into the aluminium tubes. I noticed that the plastic feet of the tripod are hollow and extend a bit up into the legs. By making the dowels somewhat thinner, and drilling a hole, where the hole in the plastic is, I could fasten the wooden dowel to the plastic foot and later the aluminium leg, and even the top lid of the leg.
Wooden dowel will be secured to the plastic fott and the aluminium leg
Top part of the lower leg
I then inserted two round beech dowels (12 mm diameter) into the lower parts of the legs, making sure there was a tight fit at either end. Unfortunately, it's not possible to fasten these dowels, other than through a tight fix and the small screws that hold the leg spreader in place.
One half of an upper leg

Dowels inside the upper leg
It doesn't take long to get all three legs done.
All three legs completed. Time for reassembly
Finally, reassembling the tripod, it looks as before.
The tripod now weighs 3.6 kg, not much more than before, but it feels steadier.
For a short while I also thought of filling the tripod with sand. I found out that the tripod legs are not sealed at the lower ends, and most of the sand will run out after a while. Filling the tripod, will also make it much heavier. Hopefully, the wooden dowels will improve the damping.
Now all that remains is a clear night to test the tripod.

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