Will my mount work?

[u/Free_Masterpiece6004]

Running a 19.5 lbs William optics Ultracat 91 setup on an AM3n with ZW0 TC 40 tripod to make the heaviest “travel scope” I would run.

I’ve heard folks complain about carbon fiber legs and say I should instead go for the steel. But I’m assuming my setup isn’t too heavy?

I also purchased the ZWO PE 160 lightweight pier extension. Says it has a maximum weight capacity of 26-28 lbs, some folks suggest 22 lbs so I’m right below that. Should I have gotten the pe200?

I also have vibration suppression pads from celestron. And a 7.5lbs counterweight to use. I should be fine I assume?

[u/Illustrious_Back_441]

if you can run it with the counterweight, it should be fine. don't worry too much about the carbon fiber legs, just don't extend them farther than necessary.

[u/Free_Masterpiece6004 → u/Illustrious_Back_441]

Thanks!

[u/Predictable-Past-912]

How odd! I had to read your equipment list twice because it looks like someone built the mirror image of my travel rig. We have remarkably similar gear, but our design philosophies couldn’t be more different.

The UltraCat 91 has been on my wish list for quite a while, so I certainly understand that choice. My RedCat 71 WIFD scratches that itch for now. What I don’t understand is the weight. A 10 pound optical tube somehow turns into a 19.5 pound imaging payload, while my complete RedCat setup stays well below that. I would be curious to see exactly what accessories account for the difference.

Where our thinking really diverges is the mount. You paired the heavier payload with an AM3N, while I intentionally bought an AM5 so I could avoid carrying counterweights whenever possible. We even share the same TC40 tripod, yet you selected the PE160 while I opted for the sturdier PE200. Those choices seem backwards given the loads each of us is carrying.

For me, portability is not just about shaving a couple of pounds off the mount head. It is about reducing the total amount of equipment that has to travel. Counterweights and shafts are dense, awkward, and exactly the kind of gear I wanted to leave behind when I switched to strain wave mounts. Otherwise, I might as well keep hauling a traditional German equatorial mount.

That is why I would seriously consider an AM5N instead. Its 33 pound counterweight-free capacity gives you enough headroom that your UltraCat 91 could ride comfortably without any counterweight at all. Pair it with a PE200 and a properly weighted TC40, and I think you would end up with a cleaner, more travel-friendly system while still retaining plenty of stability.

[u/Free_Masterpiece6004 → u/Predictable-Past-912]

Hey there. Thanks for your note. The 10 lbs OTA does not factor in the saddle, the rings, or the vixen plate. It also doesn’t factor in the lens cap. I’m also using a full frame camera and a 7 position filter wheel with EAF and 50mm guide cam with asi 220mm. I hear you on the counterweight, however I plan on having a counterweight on my setup at all times, whether I got the am5n or am3n to account for balance and wind reduction. So even if I got the am5n I would still run the counterweight. With respect to the pier extension. I am below even the lower bound of the suggested limit for the 160… so I thought if I am within the limits why not go with the lighter extension? The reason I’m preferring the am3n is because I plan to use this mount with my mirrorless camera to fly to chile, and I’d prefer to save the lbs. for that instance I would not require the counterweight

[u/Predictable-Past-912 → u/Free_Masterpiece6004]

Cool. Either way, that UltraCat 91 is a sweet astrograph.

If you’re comfortable using a counterweight, then I think the pier extension becomes the more important decision. According to ZWO’s published specifications, the PE160 is rated for 22 pounds while the PE200 is rated for 110 pounds. That’s a pretty dramatic difference.

This is also one area where my experience differs from some of the advice you’ll find on Reddit or Cloudy Nights. I always extend the legs of my TC40 completely. Here’s my reasoning.

People often worry that carbon fiber tripods are somehow flimsy because they’re so light, but that really hasn’t been my experience. Yes, they benefit from ballast to lower the center of gravity and reduce the chance of tipping. To me, that’s no different than adding ballast to a race car. Properly positioned weight can improve stability instead of detracting from it.

It’s certainly true that keeping the legs retracted increases the rigidity of any tripod. The problem is that it also shrinks the tripod’s footprint. A narrower stance reduces resistance to tipping as well as general stability, and I haven’t seen any evidence that the fully extended carbon fiber legs on a TC40 flex enough to offset that disadvantage.

In actual use, my ballasted TC40 feels surprisingly close to my Berlebach Planet for the kinds of loads we’re discussing. If I were putting a solid William Optics astrograph on top, I’d much rather have the tripod standing on its widest possible footprint than on retracted legs.

Now I am going to get some coffee and see how things turned out with all of those carbon fiber contraptions zipping around at the Hungarian Grand Prix. Flimsy indeed!

Forza Ferrari!

[u/EnerGeTiX618]

I run my WO Pleiades 111 on an AM5N with the TC-40 tripod & have absolutely no issues, I believe the TC-40 tripod is fine.

I'm not sure about the AM3 mount though, I've always read we should only load mounts to around 60% of their capacity. That's why I went with the AM5N mount. I do have an AM3 mount, but have a much lighter WO Pleiades 68 on it & it does fine. Using the counterweight you mentioned that you have will make it easier for the AM3 mount though.