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Best small travel mount? Maybe RST-150H? Share it?

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#1 rms40

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Posted 09 August 2018 - 10:59 AM

I am in the early stages of planning a trip to New Zealand and probably Chile later on. I would like to take a small eq mount for imaging. The smallest eq I had was the AVX. Nice little mount. But you still need to take a tripod and counterweight. That it more trouble than I would want on a long trip. Doable but more weight and size than I would want to lug around.

 

I saw a Rainbow mount at Neaf. I believe it was the RST-10H. It was impressive but expensive. It can hold up to 30 lbs without counterweights, is very small and weighs only 7.5 lbs. It would need a tripod. I would be taking something like my WO Star71 so I wouldn't need a big 2" leg tripod.

 

Has anyone used this mount? If money weren't an object (it is, actually), would this be the ideal small travel mount?

 

I have an idea of getting a group together of like minded travelers that could share a mount like this. It would be easy to ship around to group members for trips. I would only use it for a week or two a year. Are there others that would be interested?

 

Thank you,

 

Randall Martin

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  • rst-150h.jpg

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#2 trurl

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Posted 09 August 2018 - 11:06 AM

Looks like the model is RST-150H:

 

http://www.rainbowas.../mount_rst_150h



#3 sparrowhawk

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Posted 09 August 2018 - 11:58 AM

That looks cool and seems like an interesting idea. 

 

A couple of other ideas for you... My impression was amateur astronomy is popular with Kiwis and there are a fair number of clubs. Many of the people I met were into imaging. You might want to reach out and see if you can connect with someone who can loan you a mount in the country.

 

A variation of that idea. If you are stressed for minimizing space and weight, see if you could ship a mount to one of the clubs (or club member) via DHL, FedEx, or another courier to avoid having to pack it with your luggage. You would also likely find interested buyers in New Zealand if you didn't want to ship it back as used gear is harder to come by locally.

 

Expanding on your idea, maybe more of a club to club exchange?

 

 

Kind regards,

 

Shawn


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#4 jupiter122

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Posted 09 August 2018 - 11:58 AM

I saw it at NEAF. A very very nifty little amount. But the price that was around $6000. Ouch
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#5 photoracer18

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Posted 09 August 2018 - 02:33 PM

With a harmonic drive the price is about right, especially miniaturized. Personally, I would not want to be the first guinea pig.

#6 calypsob

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Posted 09 August 2018 - 04:35 PM

A smart eq pro would be worth investigating. Take time to inspect it for qc issues, a good one will run great with a small scope. The cem25 is not bad either, less compact but under 10lbs
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#7 Simon B

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Posted 09 August 2018 - 05:00 PM

A smart eq pro would be worth investigating. Take time to inspect it for qc issues, a good one will run great with a small scope. The cem25 is not bad either, less compact but under 10lbs

 

I was gonna say this as well - Smarteq pro

 

Also, the Vixen AP mount can be used for...... uh.... AP  grin.gif

 

Can be autoguided too, with the dual motor drives. It's pretty small/lightweight, and has a dedicated travel case.



#8 cuivienor

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Posted 09 August 2018 - 05:20 PM

Alternatively, the Crux Mini is what you may be looking for. https://www.hobym.net/

 

You may want to read this post: https://www.cloudyni...-2#entry7729758 and the thread in general.

 

For something more traditional, I recommend the Vixen AP-WM. Pricey but worth it. Here is a trip I did with it: https://www.cloudyni...ades-widefield/

 

Cheers,

 

Yannick



#9 orlyandico

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Posted 09 August 2018 - 07:49 PM

Hobym and Rainbow Astro are affiliated companies, so the technology is probably the same. But that Crux Mini looks interesting.

 

EDIT: oops, it's $4600. 20" p-p periodic error (6" p-p with PEC). Think I'll pass.



#10 cuivienor

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Posted 09 August 2018 - 07:52 PM

Orly, yep, I'd be in line as well... But here in Japan it is in the vicinity of 4000 USD unfortunately. It does look like an incredible little mount...


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#11 jupiter122

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Posted 09 August 2018 - 08:07 PM

With a harmonic drive the price is about right, especially miniaturized. Personally, I would not want to be the first guinea pig.

It may be worth every penny, but way beyond my budget.



#12 AnakChan

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Posted 09 August 2018 - 08:11 PM

Hobym and Rainbow Astro are affiliated companies, so the technology is probably the same. But that Crux Mini looks interesting.

 

EDIT: oops, it's $4600. 20" p-p periodic error (6" p-p with PEC). Think I'll pass.

I thought Hobym & RainbowAstro were former partners that split?

 

The Crux Mini had a special $400 discount when it was introduced but it was still expensive.

 

In the more miniature scale of harmonic drive mounts/trackers for lighter loads :-

 

1) K-Astec has its own GE1414HD but built for solar tracking.

2) SS-One Traveler

 

I've got #2 reserved hoping to use that as an airline-friendly travel setup with the FSQ-85ED.


Edited by AnakChan, 09 August 2018 - 08:13 PM.


#13 orlyandico

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Posted 10 August 2018 - 12:47 AM

The problem is that the harmonic drives cost $1200 each.

 

Even the China-made ones are $600 each.

 

I have three harmonic drives lying around (ebay specials). I'm going to make a single-axis mount out of one of them for prototyping purposes.


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#14 calypsob

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Posted 10 August 2018 - 07:13 AM

Well i guess you could get an astrotrac 360 if you want to spend a ton of money on a small mount. Honestly I cannot see any sense in passing on the smart eq pro, ioptron would have better faster support than any of the other companies and we are talking about undersampled imaging here. You need some degree of precion, im not sure what camera you intend on using. If you autoguide 2.3 um pixels even then you really dont need anything that fancy.

Edited by calypsob, 10 August 2018 - 07:14 AM.


#15 calypsob

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Posted 10 August 2018 - 07:15 AM

The problem is that the harmonic drives cost $1200 each.

Even the China-made ones are $600 each.

I have three harmonic drives lying around (ebay specials). I'm going to make a single-axis mount out of one of them for prototyping purposes.


I hope one day they become more affordable.

#16 orlyandico

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Posted 10 August 2018 - 07:24 AM

I'd have thought the Chinese would drive the price down. For the longest time Harmonic Drive Systems (a division of Toshiba) had a monopoly on these drives, but now China is making them too.

 

But if it (still) costs $600 a pop for the China version.. then there must be some inherent engineering challenge that prevents the price from being driven down.

 

Ye Olde Worm apparently is still the cheapest high-precision option, for all its flaws.


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#17 AnakChan

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Posted 10 August 2018 - 08:00 AM

Sadly for now, one pays premium for portability.



#18 rms40

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Posted 10 August 2018 - 02:25 PM

Wow, lot's of interest in these. The idea of working with someone at the destination is good except that I will be with family and want to be able to setup without having to plan ahead. That is why the ability to take something compact seems appealing.

 

The small Ioptron mounts look good except for needing to take a counterweight. And, the ones I looked at only had 11 lbs capacity vs the 30+ for the Rainbow. Of course, the price is much lower so it might be worth it to deal with the extra weight.

 

Being a business owner myself, I have also thought that maybe I could rent a setup like this to others. I have found that making a business out of a hobby you love can quickly turn the hobby into a job and ruin the enjoyment. So, maybe not! If someone else wants to do that, I may be a good customer.

 

 

Randall


Edited by rms40, 10 August 2018 - 02:57 PM.


#19 Spikey131

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Posted 10 August 2018 - 05:30 PM

For $6000 I could hire a porter to carry my G-11.....


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#20 rms40

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Posted 11 August 2018 - 08:20 AM

Spikey, that is a good one. Ha Ha. Same thing I say about my motorhome. Can stay in a nice hotel for the cost of gas alone. But, it can be convenient. By the way, want to buy a good used motorhome?

 

Back to small mounts...will these harmonic drives track better than a small iOptron like the EQ Pro or CEM25?

 

Randall



#21 rms40

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Posted 11 August 2018 - 08:45 AM

I didn't see this before. They have a picture of the mount and Star71 in a back pack. That is the small scope I have and was thinking about taking on trips. It looks like a great idea....except for the cost. Maybe a good pair of binoculars and visual would be the way to go.

 

This mount would have to track as well as my MYT for me to justify the cost. I could live with the lower capacity if it would track 5+ minutes unguided. Then it could be used as permanent (on pier) and portable mount.

 

Or, we get a group of 20 and share for $300 each. That is a big group.

 

Randall

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#22 cuivienor

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Posted 11 August 2018 - 02:03 PM

+-20" without PEC, and +-3" with PEC makes unguided difficult? Not sure about what the period of a harmonic drive would be though!

#23 orlyandico

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Posted 12 August 2018 - 03:31 AM

The harmonic drive itself has a 24 hour period.

The PE that is seen is actually from the reducer gearhead on the motor. The benefit of the HD system is you don’t need a counterweight.

I’ve seen small surplus harmonic drives on ebay for $100 each.

I’ve already spent $500+ on these surplus drives. Still building... 3D printed parts. Made one last night and it broke.

If I am successful at prototyping I’m considering doing a kickstarter. K-Astec is doing a super limited run and I think I can do something similar. I think there’s enough demand.

Sadly I don’t see the price going much below $3K because even the China drives are $600 a pop and you need two.
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#24 rms40

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Posted 12 August 2018 - 10:49 AM

This has gotten away a bit from best portable travel mount but I am interested in the harmonic drive technology. I know little about it. From what I have read, the harmonic drive is what will allow a telescope mount to have high torque in a small package and operate without needing a counterweight for balance. Is that right?

 

It looks like the harmonic drives are just a "gear box" with high torque for their size. You would need a drive motor to power them. Is there a video or document that would show the parts and operation for a novice? What makes them so expensive? The flexible components?

 

It looks like the harmonic drive technology is what would allow a small, portable travel mount. But, I would want corrected tracking around an arc second if possible (for $6000, I would expect that). Of course, a small guide scope and camera could be taken along. It is just so much easier if you can track unguided.

 

Randall



#25 orlyandico

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Posted 12 August 2018 - 11:05 AM

The harmonic drive has been around since the 1950s and the patents have lapsed.

Unlike a worm drive, a majority (almost all) of the teeth are engaged, which is why it has so much torque and doesn’t need a counterweight (although a CW would allow it to carry more payload by reducing the torque it is subjected to).

I don’t actually know if it inherently has very low PE, because the main drive only turns once in 24 hours when used for RA tracking.

There have been a few mounts made and the comments about their PE leads me to believe that said PE is from the motor reducer and not the HD itself.


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