Grab n Go with a 6" f6.5 Alt Az setup.

[vivid]

Ok, optimised my setup.

ES 152mm f6.5 with rings, Losmandy Vixen universal dovetail, finger and Celestron Vibration supression pads -> Orion large refractor sling bag

Twilight II with 9" pier/extension -> hand carry

In a normal medium sized backpack :
ES82 30mm, ES100 14mm, ES82 6.7mm, in OPT's plastic EP cases
2 filters namely Baader fringe killer and DGM Optics NPB (ala UHC), 1.25" erect image diag (to use when i am bored LOL!)
Losmandy weight system - I use the V series clamp to subtly balance the scope when I change EPs. The counterweight shaft and Losmandy 2.5 pound weight I use it as counterweight in addition to a 1.25kg + 5kg weights secured with cable ties. Managed to tie to the shaft and Losmandy weight so that the cable tie is "free wheeling" even when i am changing Alt and it does not move when i am changing Az. This and the VSP enables me to damp vibrations down to the 0.5 second level (@ 150X.....for 70X and 32X it is literally not an issue at all even with large scope movements), useful during focussing/scope movement.

Total weight : 34kg. No issue for me to take the lift and to my roof. But walking about 100m for 2 of the ob points you will sweat a bit even with my rooftop breeze blowing (my whole rooftop is something like 400 metres length point to point so might have to take it easy if i want to cover 360 deg view LOL!). Setup is about 12 minutes from closing of house door to rooftop reading for ob, should be able to cut 2-3 mins once i am more familar with it.

[cloud_cover]

Mind the back!

[rlow]

Ok, optimised my setup.

ES 152mm f6.5 with rings, Losmandy Vixen universal dovetail, finger and Celestron Vibration supression pads -> Orion large refractor sling bag

Twilight II with 9" pier/extension -> hand carry

In a normal medium sized backpack :
ES82 30mm, ES100 14mm, ES82 6.7mm, in OPT's plastic EP cases
2 filters namely Baader fringe killer and DGM Optics NPB (ala UHC), 1.25" erect image diag (to use when i am bored LOL!)
Losmandy weight system - I use the V series clamp to subtly balance the scope when I change EPs. The counterweight shaft and Losmandy 2.5 pound weight I use it as counterweight in addition to a 1.25kg + 5kg weights secured with cable ties. Managed to tie to the shaft and Losmandy weight so that the cable tie is "free wheeling" even when i am changing Alt and it does not move when i am changing Az. This and the VSP enables me to damp vibrations down to the 0.5 second level (@ 150X.....for 70X and 32X it is literally not an issue at all even with large scope movements), useful during focussing/scope movement.

Total weight : 34kg. No issue for me to take the lift and to my roof. But walking about 100m for 2 of the ob points you will sweat a bit even with my rooftop breeze blowing (my whole rooftop is something like 400 metres length point to point so might have to take it easy if i want to cover 360 deg view LOL!). Setup is about 12 minutes from closing of house door to rooftop reading for ob, should be able to cut 2-3 mins once i am more familar with it.

sounds good...but a picture says a thousand words, so do show us some photos...

[vivid]

Yeah will try to get pictures. I did a second run just now and could feel the strain, not lower back but upper back. Luckily the main ob site is just nearby, just 30m of total walking distance. But to be safe for the back i think would break up into 2 trips on the roof. I cannot use those trolleys that you use for trips to the market/NTUC for the tripod/medium backpack....attracts too much attention up there coz got security somemore.

[weixing]

Hi,
Do show us photo of your new setup...

Have a nice day.

[vivid]

Here it is, this is the new ES AR152 with the longer dewshield. And I got the 9" pier extension so no issue with the big ES100 14mm or ES82 30mm.







Think I might need to change out the 1.25kg weight with 2.5kg weight. Even more stable and less vibration when you tap on the diag. It's heavy but worth it. The 1.25kg is 6 bucks and 5kg is 18 bucks. It may look like it's "wobbly like a pendulum" due to inertia esp in Az but it's not....of course I am talking about tracking or finding an object. When slewing like > 45 deg fast then of course you'd need to manually stop the weights from swinging lah, which thankfully is not often. And thankfully in the dark it does not look bad coz you don't see much of the scope anyway.

[weixing]

Hi,
WOW!! Look quite dangerous to me... May be you should find or make something that will "step down" the weights centre hole, so that can fit into the counter-weight bars. For now, better mark the area around the scope as "no foot zone"...

By the way, is the scope in balance position or this is a quick setup for photo taking? My 6" F5 is front heavy, so the mounting point is near the main lens.

Have a nice day.

[Gary]

Thanks for uploading the photos. Really impressive! Do consider bringing it to a clear dark sky soon and let us know how well the optics performed.

[rlow]

Very interesting setup!

Firstly, do you need counterweight? I ask because there are some Alt-az mount which do not, eg. Astroslew 1-4, DM4 & 6 etc. The Astroslew 1 is a very similar, twin mounted type.

If you do, can you attached the weights directly onto the threaded rod? Just use bolts and washers to fix it in place.

And yes, it would be nice if you can bring your setup down to a public event so we can all take a closer look at your setup. For eg, there's an Earth Hour event this Sat. 31 Mar 2012 at Woodlands Waterfront Park.

[vivid]

Hi guys,


Thanks and I am definitely open to suggestions, as some may have better ideas.

There is actually a specialised ADM counterweight solution for such Alt-Az mounts, it is actually pointing “the other way” as compared to this Losmandy VW coz it is not a clamp but a mini dovetail that fits into these vixen saddles. If you look at the pictures you’d know why, coz this is not an official intended use of the regular Losmandy/ADM accessories. http://www.astronomics.com/main/product ... duct_id/VW

It should be this, but I can’t find anybody selling. http://www.cloudynights.com/ubbthreads/ ... er=2661399


That is why I am using the stock Explore scientific dovetail bar together with the Losmandy VW’s shaft secured with a M6 screw and counterweight and not use the clamp, else it’d be pointing inwards. Also if I use the clamp then it’d not be aligned to the central axis of the saddle, making Altitude slewing unbalanced. I will buy and add 1 more cable tie for added safety (ran out of BIG and LONG cable ties LOL!), but it actually is quite safe but of course there is wear n tear. The M6 screw I am searching for a suitable longer one of about 1-inch, for added safety as things become loose during extended usage. But so far I have added a washer and torqued it and it does not come loose at all. Weixing’s idea of “no foot zone” is good if I ever do > 1 pax but so far it is me alone and my preference is to aim 45-90 deg in the scope’s outward direction so it’s very safe.

Robin’s suggestion of just slinging the weights through the central hole, that I have tried before. There is a small problem, because the weights central hole is not slippery so it does not slip until a certain angle, so through the scope the Alt becomes a bit sticky/resistance until the point it slips, and then it causes vibrations. With the cable tie it is constantly slipping, ie the shaft moves but cable tie does not move. With the center hole of the weights resting on the shaft, both the shaft and weights move to a certain point. This is the difference. I have thought of the regular Celestron/Skywatcher weights, the issue is that those holes are slightly bigger than this shaft so if I use the built in tensioners to clamp onto this smaller shaft, it would only be balanced in the Altitude range for a limited range. Not a biggie I guess since for us astro folks we balance from zenith to maybe 30 deg but I did not order with my main order to try which has flat shipping so that’s a small regret as those weights are not much more expensive than the bar bell weights.

This reminds me, I need to google the shear strength of the Stainless steel M6 screws. It might break due to this quite large moment, but these screws are provided with the Losmandy VW weights system so I guess it’s ok.

Ah ha – you guys caught me. It is fast grab n go only at my location’s use. > 100m in a single shot is no go.

I’ll try to get some afocal moon pictures at the EP this weekend so you can see resolution/CA, hope no haze/fog.


The Twilight II is a very close cousin to the Giro series of mounts. I guess on paper it does not need counterweights. I can just run the AR152 without counterweights, but from my testing with weights it is far far smoother with correct balancing. In fact if I may hazard a guess, even a 80mm benefits from a nearly 100% balance in counterweights. If I use only 5kg instead of 5 + 1.25kg, the feel in both Alt and Az is very different. Also the damping times, which I am able to get in the 0.5s range with the correct balance. In my view it is really worth it. I need to have a look at the moon, then l see if I can even do up a youtube vid with say finger rapping on the diag to show the vibrations and damping.

And of course the price of Twilight II is not a DM6 or T-Rex or even a Unistar Deluxe. (and the availability of the 9” extension from OPT is a good convenience due to shipping savings, imagine if I buy stuff from 3 places)