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Side by side dual mount question

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#1 schang

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Posted 02 April 2014 - 08:40 AM

I posted one in the DIY section, which did not generate much responses, so I am trying my luck here, with some rephrasing of the questions...

My questions are:

1. Do you think it is a good combination to put a C90 Mak and a bino (or bino-scope) on the same tripod for visual (both for astronomy and terrestrial)?

2. If so, what will be the good way to mount them? Obviously, I do not need a go-to/drive thing, but slow motion knob tracking will be sufficient for my C90. The bino part will be for low mag wide field view, so no need for tracking. The highest mags for the C90 Mak will be around 150X, primarily for solar system/double stars viewing as a grab and go set up.

3. For slow manual tracking of C90, is it better to build an altitude bearing(axis) there, or build it right at the top plate of the tripod?

Thanks.

#2 Hesiod

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Posted 02 April 2014 - 11:31 AM

1)why not? I use often a SCT and a short refractor on the same mount
2)maybe on a dual AZ mount (like the "T" design) or you can use a dual saddle like those APers employ (which however requires an equatorial mount)
3)sorry, I can not understand the question

#3 schang

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Posted 02 April 2014 - 12:11 PM

Thanks for your responses.

About dual saddle, can you be a little more specific?

The number 3 question was about using only one slow motion manual tracking knob for C90 on polar axis. I was thinking that you can do this with ONE knob if the tripod is set due north polar star on its center plate mechanism. If not, then the C90 Mak mount side would require two slow motion control knobs to track. Am I correct?

#4 Midnight Dan

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Posted 02 April 2014 - 12:32 PM

Hi Shien:

Sure, no reason why not. I think a 90mm Mak and binos would make a good pair.

As for slo-mo, I'd suggest that you may not need it. I have a Desertsky Astro DSV-1 with a C5 and a 90mm refractor on it. It does not have slo-mo controls, but I find it's pretty easy to track with if I keep it below 200x. In fact, for most uses, I prefer using the pan handle instead of slo-mo. It's a lot quicker and easier to track with and to slew with. The only time I'd prefer slo-mo is when I start getting close to 200x.

The one thing that's critical if you don't have slo-mo is balance. You want to have clutches set loosely so you can move easily, but you don't want it to sag one way or the other if it's too loose and out of balance.

-Dan

#5 Hesiod

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Posted 02 April 2014 - 12:46 PM

Now I got it (hope...)...taking about an eq? It is not easier to do an altazimuthal "T" design?
Dual saddles are devices which can locked to the mount (or mount's clamp, because usually their main bodies are made according to Vixen or Losmandy standard) and have 2 clamps to bear 2 telescopes (or any other item which employ the right dovetail, be it VIxen or Losmandy)
ex: http://www.scopestuff.com/ss_dmd6.htm

#6 guyroch

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Posted 02 April 2014 - 01:10 PM

About dual saddle, can you be a little more specific?


Good here and better here

Guylain

#7 schang

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Posted 02 April 2014 - 01:28 PM

Hi, Dan:

The only reason I'd think using a slo-mo tracking knob is for higher mag viewing with C90 Mak, where my existing el-cheapo tripod coming with the kit is not quite easy to use for astronomy (though it is fine for spotting/terrestrial). The main issue is it is difficult to have good clamping pressure to move the scope without jerking the view and waiting the scope to settle down. I think balance the scopes on the dual mount tripod can be done (or lock the AZ (panning) axis for stable slo-mo tracking). I am still trying to think it over for a good way to do it. Thanks.

#8 schang

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Posted 02 April 2014 - 01:44 PM

Thanks for the part link, Hesiod and Guylain.

I know it is not easy, but I have time to think it over before I start. I think the AZ T mount will be much easy to do just for slewing with vertical mounted dovetail adapter.






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