Author Topic: equatorial mounts confusing !  (Read 2628 times)

Jorge Herbert

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Re: equatorial mounts confusing !
« Reply #15 on: January 09, 2018, 03:22:01 PM »
When you truly understand how the sky moves first, then using an equatorial mount will follow naturally.

We all tend to utilize different methods to learn and familiarize ourselves with new concepts, and learning an equatorial mount is sure to have dozens of variations among us. What finally gave me a solid understanding of this ubiquitous mount was when my brother pointed out to me that the sky itself is tilted. It was a radical idea for me – I was 11 at the time. But because my hobby was astronomy, I decided there was nothing wrong with pursuing this idea and getting a broader understanding of where I fit into the grand picture of me with a telescope, looking at these slowly moving celestial objects each night. The fact that I had a long, skinny refractor on a quality mount that was easy to swing around to point wherever I wanted made it easy for me to learn.

If you live in the middle of the Northern Hemisphere like I do, then whether you’re in San Francisco or in Indiana or in New York, the sky is going to be tilted when you look up at it from your backyard. In other words, during the course of each day the sun, moon, planets, and stars will all spin around in the sky, not in a circle parallel to the horizon (as it would look like if you were riding on a carousel), but instead, around a particular star half way up in the sky - that itself will appear to stay still (Polaris). Everything in the sky, no matter where you look, will appear to be spinning around that one star as the day or night progresses.

It’s like you are looking up into the inside of an open, giant, tilted black umbrella; slowly spinning, with all the stars and planets painted onto the inside surface. The middle, or tip of the umbrella – where all those skinny metal bars meet – is where Polaris is.

You want to be able to move up and down, and left-right to point a telescope at anything in the sky. It’s easy to do that with an alt-az mount. But in a tilted sky, as Thomas says, you can tilt the vertical axis so it points right near Polaris (and is now parallel to the earth’s axis/ umbrella shaft) to make it easy to find your way around the sky using coordinates like Ken mentions. Now when you point “straight up” (DEC 90°), it’s actually pointing at Polaris (well, close – actually at the North Celestial Pole). When you go “left-right” (move in RA), you are actually moving in arcs that are parallel to the way all the stars are moving. That means you can track using this one movement. Now you are one with the stars.

With the axis tilted as it is, if you now lower your aim until you’re looking “level” (DEC 0°), you are now looking along the celestial equator, a large arc across the sky with its highest point due south and elevated at an angle that is 90° minus your latitude (this would be the bottom edge of the imaginary hemispherical umbrella).

But the umbrella goes on – it’s actually a whole sphere (the celestial sphere). You can go beyond DEC 0°, and you’d be looking in the Southern Hemisphere, where all the declination values are negative.

The axis pointing at Polaris is called the Polar Axis. The axis allowing you to move to objects circling farther and farther away from Polaris is called the Declination Axis.

I never botherded to learn to convert alt-az to equatorial movements – it was never necessary, and doing that would absolutely confuse me. I use both types of mounts – each has its superb advantages in our hobby.

Steve

unamprodce

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Re: equatorial mounts confusing !
« Reply #16 on: January 10, 2018, 05:03:33 AM »
Quote
So, let's take this apart:<snip>
Wow you cleared up a lot of my questions now I understand how to set the mount up by looking at a star you know and going to your star app and getting the coordinates and then set your telescope up to them coordinates and go from there Is that right

planvelsynchcest

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Re: equatorial mounts confusing !
« Reply #17 on: January 13, 2018, 06:32:32 AM »
Quote
......
AND THAT IS EXACTLY WHY I tell new people NEVER EVER buy an EQ mount, get an AltAZ and I speak from experience.......

This to me seems a questionable statement, as we all know there are many reasons for buying an Eq mount.
Granted, for visual use the Alt Az mounts are often a better solution but for anyone interested in imaging the Eq mounts rule.
It is also almost impossible to buy AltAz mounts with the capacity for heavier setups.

Even for Alt Az users it is important to understand how the EQ mounts work and that an EQ mount, well polar aligned can track using just one motor whereas Alt Az must drive both motors.

Stick with the EQ mount Gunny until you understand how it works

contpeeresto

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Re: equatorial mounts confusing !
« Reply #18 on: January 13, 2018, 06:50:01 AM »
>It is also almost impossible to buy AltAz mounts with the capacity for heavier setups. -- kunama

I can buy a used sky view pro or cg5 mount head for around $125.00 and it can do 15 - 20 lbs.
It can hold a 6" f8 or a 8" f/5 newt.
If someone knows of a atl-az with the same capacity, at the same price I would love to here it.
If I am going to look at the planets I use my sky view pro mount with my 8" f/5 newt. One knob tracking.
I guess I can buy a alt-az goto, but not with that kind of load capacity.

I have a vixen porta mount maybe it can hold 10 lbs. I have built a pipe mount to get around this restriction,
but I miss my slow motion controls.

bumabbefat

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Re: equatorial mounts confusing !
« Reply #19 on: January 15, 2018, 04:06:19 PM »
Gunny, ya' gotta walk before you can run. Why don't you put the EQ down and step away from the scope. Stick with the dob for the winter, get to know the scope and the sky well and think about the EQ in the spring. Finish one project before you start another. You'll get more out of both that way...

STARKID

omunsopoo

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Re: equatorial mounts confusing !
« Reply #20 on: January 20, 2018, 02:22:08 PM »
Quote
OK say you want to find an object you you’re right assesion is17hr 30 min And your declination is -23.30 The object is the sun and that’s the readings I have current how would I move my telescope and I started having a Polaris centered that’s the kind of questions I have about a equatorial mount my coordinates or 39° north and 86° west

Aha! Now I understand your original question. You want to use your scope's setting circles to locate your targets.

My advice is, don't. First of all, equatorial mounts have numerous benefits, of which the ability to use setting circles to locate objects by RA and Dec is the least by far. Second, using setting circles effectively requires a truly accurate polar alignment, which is much more hassle than the kind of crude alignment needed to track your target by twiddling the RA knob. Finally, the setting circles on budget-priced telescopes are rarely accurate enough to be of much use.

deschwobbmettgod

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Re: equatorial mounts confusing !
« Reply #21 on: January 20, 2018, 09:20:06 PM »
I have a cg4 and svp. I use my circles for short hops

radnatipni

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Re: equatorial mounts confusing !
« Reply #22 on: January 21, 2018, 01:49:12 AM »
Gunny,

These videos may be helpful. I don't own an EQ mount but I have helped others with theirs but I am no expert. These are the videos that helped me.
The first breaks down the set-up and alignment.
The second is about actual use including dealing with odd focuser positions and the meridian flip. (I think that is what it is called.)
Third is more about practical tips

EQUATORIAL MOUNT - References
How to align an Equatorial (EQ) mounthttps://www.youtube....h?v=plx6XXDgf2E
How to use an Equatorial (EQ) mounthttps://www.youtube....h?v=F7HVDKAZ6eM

Practical demonstration of using charts to read RA/DEC for setting circles on your EQ mount
Around 2:30 into the video he talks about a “bluffers” method of using setting circles based on a bright star. This runs through around 6 minutes. Very interesting and likely helpful. I think this is similar to what Ken suggests in post 15 using Vega as a reference star to find Alberio.
https://www.youtube....h?v=geQszAVWMok

Chris Ingram

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Re: equatorial mounts confusing !
« Reply #23 on: January 23, 2018, 12:14:55 PM »
My first scope was similar to the Celestron. Orion and "Eye on the Sky" videos helped me a great deal with the GEM. One thing that I didn't realize when using a reflector on the GEM was that you need to leave the rings loose so that you can spin the OTA as you move to different objects. It seems obvious now but my first couple times trying to use it, I just couldn't figure it out. I'd raise and lower the tripod legs to get the eyepiece in a reasonably comfortable position!

Jeremy Butler

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Re: equatorial mounts confusing !
« Reply #24 on: January 25, 2018, 10:36:32 PM »
Fellow new EQ owner here. I just went through a similar struggle the first time out, but I figured it out relatively quickly. The two videos linked above are great, and there are others. I think at the end of the day it's a matter of having the patience to allow neural plasticity to do its thing. After just an hour or so of use, my brain started to shift from the intuitive up-down/left-right space to a new one centered on the NCP axis. I still need to do it more and give it time, but I am already feeling the increased comfort. One thing I have been doing with mine that helped was playing with it indoors, and mock-hopping using the SkySafari app. It's what you do, when nature gives you 10 days of cloud coverage right after you buy a new setup....
If you get a bit frustrated, remind yourself that forcing your brain to learn something different like this staves off dementia.

nisatourpo

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Re: equatorial mounts confusing !
« Reply #25 on: January 31, 2018, 01:38:53 AM »
I know how to set up the mount looking at Polaris my problem is after that how do I move the scope to the coordinates of the objects I’m trying to fine ......example inclination 23 degrees and a ra 17.30 hours

genssizafa

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Re: equatorial mounts confusing !
« Reply #26 on: January 31, 2018, 02:29:32 AM »
When I first got started 10 years ago I wanted a simple mount that tracks. Something not to heavy or complicated and reliable.
The forums here are full of praise for eyepieces and OTA's. Tracking mounts not so much.
I am ok with Ethos and an Alt/Az.
Dereck

Jimmy Harbaugh

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Re: equatorial mounts confusing !
« Reply #27 on: January 31, 2018, 04:25:51 AM »
I don't exactly know how your mount works but in general here is a cheat sheet.

1) point the RA axis north as close as you can get it. If you live on a grid system like I do, a lot of streets run N/S, E/W. (this does not mean the telescope tube the mount axis should point north).

2) level the tripod

3) There should be a latitude adjustment on your scope. Set that to your latitude (39).

4) Now point the telescope tube north. If you can see polaris great, get that in the main tube.

5) Now your declication circle should read 90. If if it doesn't make it do so. (don't know how on your scope).

6) Now move your scope in the dec axis, you need to get the dec circle to change when your scope changes.
  some have a locking thumb screw etc. Now we need to use another bright star. Deneb is at RA 20h 40m,
Dec +45.2. So watch the Dec circle and stop when it reads 45, lock the Dec axis down.

7) Now only using the RA axis move the scope to get vega in your sights. Once you get it in your scope,
set your RA axis to 20h 40m.  Your circles are set!

you may have to twink the dec circle a little and reset it to 45.2 when you actually get deneb in your scope.

Now lets say we want to move somewhere else, BEFORE we move the scope, make sure your RA and DEC settings match Deneb. Lets say we want to view the elephant trunk cluster at RA 21 39 and DEC=57.30.
Loosen the Dec clutch or your your slo motion controls to move the scope until your dec circle reads 57.30.
Tighten and do the same with your RA axis to move to 21 39.

When you are done looking at elephant trunk, once again make sure your setting circles are correct, then
move to the next object.

Now you have to be familar with how your mount works, and you can do this in the daytime. All eq mounts work a little differently, and this has to do with when the setting circles move with the scope and when they dont. Some mounts move the circles when you twist the slow motion controls, some don't. Some move the circles when
the clutches are loose, others dont.

You can figure this out in your warm house in the day. So you don't have to learn in the dark when you are freezing.

I hope this helps you.  I use this method all the time as a sort of assisted star hop. I live in heavy light pollution,
and many times I cannot see the object I want in my finder. So I find a nearby star that I can see in the finder,
get my circles set, then use them to guide the scope to the correct location.

If you don't have one I would invest in a 32mm plossl. That will give you the widest field in this scope, which is a big help.

good luck,
don't give up,
VT

ziecouvicog

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Re: equatorial mounts confusing !
« Reply #28 on: January 31, 2018, 11:38:53 AM »
Quote
I know how to set up the mount looking at Polaris my problem is after that how do I move the scope to the coordinates of the objects I’m trying to fine ......example inclination 23 degrees and a ra 17.30 hours

OK, now I understand the issue.

This video is like the others but they don't focus on the set-up. They have the OTA removed and focus on using the scales which is what I think is giving you a challenge.

He uses a known star and dials in its location onto the scales.  Then he turns the mount and reads the scales to find the star they want to find.

At 2 minutes 30 seconds he actually uses the setting circles to find something.
https://www.youtube....h?v=T_TDh68oDp4This one, provided earlier, goes into using the circles and why people are often unsuccessful in finding things. It is not the person's fault, it has to do with how the scales are done on the mount and the error they introduce.  Pick it up around 6 minutes.  This may explain why you may not have been successful in the past. Not your fault!
https://www.youtube....szAVWMok&t=418s

aftilicomp

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Re: equatorial mounts confusing !
« Reply #29 on: January 31, 2018, 01:13:22 PM »
Here is an alternate way to find celestial objects using a Telrad zero power finder and a sky chart. The Telrad has a bull's eye pattern with circles at 4 degrees, 2 degrees, and 1/2 degree circles. Use a chart like the S&T Pocket Sky Atlas that shows the lines of right ascension and declination. Find a brighter reference star in the sky and "measure" your way in Telrad circles to the fainter object.Here is an example: find the star Sirius in your Telrad and scope. Lock both axis. Then unlock the declination axis and swing the OTA north (up) 2 degrees measuring with your Telrad circles. Lock the dec axis. Now unlock the RA axis and slew it to the east (left) about 3 large Telrad circles (about 1 Hour). With a low power wide field eyepiece you will be very close to M46 and M47.If you know the primary stars of the Constellations you can find faint objects using this method.