Star-hopping with a newtonian on a EQ mount

[hgjevans]

I wonder if I could pick a few brains on the subject of star-hopping with a newtonian on an equatorial mount? I only recently acquired this scope, and I love it already, but it clearly demands a different approach from what I'm used to. Previously I've star-hopped with my binoculars or my little field scope on top of a photographic tripod. And both of those instruments give normal right-way-round views, and so everything is entirely intuitive and easy. But the newtonian, of course, reflects off the primary mirror, and then again off the secondary, so that the image through the eyepiece is very different from what I see either through my binoculars or with direct vision. And I can see that would be easy enough to work with if the scope were on an Alt-Az mount, but on an EQ everything moves in very different directions, and different depending on what part of the sky I'm aiming at, and it changes again when I have to turn the scope in the rings so I can still reach the eyepiece!    

So what I'm really asking is, are there any standard tips or tricks to make it all more intuitive? What I've been doing so far is working out relative RA/Dec coordinates from a starting point and then counting off so many turns of the RA control, so many of Dec to find my target. And that has worked fine, but it's only good for whatever I've planned in advance - every attempt to try to guestimate the number of turns required for something while standing out there by the scope has proved laughably incompetent. [if anyone has ever played the drinking game 'wibbly-wobbly' - well, the results sort of put me in mind me of that.  ]

So, anything I can try to make spontaneous star-hopping more successful? I know a wider field, low magnification eyepice would probably help, but until I've got that, any tips?

[RikM]

There are a few things you could do that would help.

1. fit a Telrad or Rigel QuikFinder illuminated zero power finder. When you have absoloute confidence where your telescope is pointing, star-hopping becomes much easier.

2. fit a right angle correct image optical finder, something like a 9x50 RACI is ideal to use in combination with a Rigel. This gives the same low power view as you would have with your binoculars.

3. if you are up to it, make or buy a Dobsonian base or if the OTA is small enough get an AltAz mount for it. There is no need for equatorial mounting unless you intend to take long exposure images. For visual use, other than tracking planets at very high magnification an AltAz mount will be more comfortable to use.

[Astro Imp]

Oh the joys of the equatorial mount 

As Rik suggests above I sorted this problem with a Telrad (found the 4"riser really handy) and a 9x50 RACI. 

Good luck and clear skies.

[RichM63]

If you are talking about absolute random star hopping for different areas of the sky, (as in Cassiopea/Andromeda, followed by Orion/M45) then you can loosen the clutches and swing the OTA into that area. Tighten them and then use the slo mo' controls to cruise that area.

WARNING YOU MUST HAVE ONE HAND PERMANENTLY ON THE TELESCOPE TUBE IF YOU LOOSEN THE CLUTCHES!!!

It also helps to at least have the N leg pointing North. (not neccessarily Polar aligned) but your movements will then start to form a pattern.

It does become intuitive, yes a nice wide field eye piece does help.

Hint add Telescope and Mount details etc to a Signature, it does help for more precise answers.

[hgjevans]

Thanks everyone. What I really meant was anything to help make the process more intuitive when the image in the eyepiece moves in a way that's hard to reconcile with a straight naked-eye view. For example, if I want to observe M31 through my little spotting scope I just start from Mirach, and then it's about 8 degrees up and over a bit in a certain direction - easy enough. But when I try to translate that kind of approach to an EQ Newtonian... well, 'up' and 'over a bit' obviously  don't correspond to RA and Dec in any consistent way, the view through the eyepice is doing something else again, and as if that weren't enough to confuse me, I'm not even facing the direction I'm trying to point the scope at because I'm looking square into the eyepiece of a Newtonian! 

Don't get me wrong - I love the whole concept of an EQ mount for any number of reasons, and particularly I like being able to guide the scope onto a target using those relative RA/Dec coordinates described above - but that approach needs me to have worked out the coordinates in advance. And of course Murphy's Law dictates that while I'm out observing I'll suddenly feel the urge to try out the scope on some cluster or other that I've not planned to look at, and that's where I'm stymied.

I've got polar alignment nailed - well, close enough for government work at any rate. Apart from that I guess there really just is no substitute for proper planning - and of course I take RichM63's point about experience, and getting used to the process.

Thanks to those who have suggested other kinds of finders - I do have in mind to get a Telrad some day, but for the moment I need to manage as best I can without spending any more money. As it is I can cope with getting the scope onto any reasonably bright naked-eye star as a starting point - it's the bit about navigating from there to some nearby but rather more elusive DSO that I'm trying to sort out.

Oh, and yes - I'll put relevant equipment information in a signature in due course, but for the moment the forum rules don't allow me to add one - I think it's another five posts before I can do that. Meanwhile, I'm using the following:

SW200P f/5, EQ5, with the supplied 25mm and 10mm eyepieces, and 2x Barlow;

60mm Nikon field scope with 30x wide field eyepice;

8x42 binoculars.

[bish]

I've always found looking with the bins and a right angled finder works well for me.

[Tinker1947]

Fit a Telrad and print out the free to download Telrad maps, star hop using the Telrad then use a nice low power wide FOV  EP ( 30mm or more) to centre the DSO ect.....

[PorkyB]

If you use a star atlas, a properly aligned EQ mount will move the same way as the atlas grid lines.  Turning the RA knob clockwise will move you to the right on your map, turning the DEC knob will move you up or down on the map (I still can't work out which way, so just turn the know and see which way the scope moves).  If you use Stellarium you can put it into EQ mode and practice these moves.

For example, start at Mirach (naked eye visible) and move up (DEC) by half a finderscope view and forward (RA) by the same amount and you will have Mu-And.  Do the same moves again and you will have M31.  The beauty of an EQ mount is that these move will always work, whatever the position or Andromeda in the sky. 

I really enjoy star hopping with my EQ and use this method to find obscure imaging targets that you can't even see through the eyepiece.  All it needs is patience and practice.

As well as the excellent oculars feature in Stellarium, which lets you see what things look like though you scope, finder, etc. I made a little overlay for my paper atlas with a circle on it which lets me see what will be in a finderscope field of view.  This helps a lot when trying to work out how far to move.

[hgjevans]

For example, start at Mirach (naked eye visible) and move up (DEC) by half a finderscope view and forward (RA) by the same amount and you will have Mu-And.  Do the same moves again and you will have M31.  The beauty of an EQ mount is that these move will always work, whatever the position or Andromeda in the sky. 

Yes, that's sort of what I've been talking about with my 'relative RA/Dec coordinates'. But either approach assumes I've preplanned it and know what the required moves are going to be to get from a given starting point to a given target.

What I'm after here is some way of achieving the same sort of thing on those occasions when I haven't got that information. Say, for example, when I see something through the binoculars that might be worth a closer look. I don't know what it is, but there's a bright enough star nearby to start from, and I can easily see how I would want to move the scope in an Alt/Az sense. But how to translate that movement into RA/Dec movements on the fly is what I'm struggling with. After all, a couple of objects near the celestial equator that are, let's say, two degrees apart would be separated by less than 10min of right ascension. But a similarly close pair nearer the pole might have several hours of RA between them. That's what I'm finding difficult to judge when I'm standing out there at the scope, in the dark, without Stellarium at my finger tips. Yes, I have printed charts, but I'd have to get a light on to be able to see them, and my reading glasses - and I'd still need a magnifying glass to be able to see grid lines well enough to be able to guestimate the moves required. So all in all I was hoping there might be some alternative -  some simple rule of thumb, some ancient received astronomers' wisdom, that would suddenly make navigating a Newtonian telescope across the sky on an equatorial mount as easy as pointing a pair of binoculars at Orion. 

I guess maybe there just isn't, because most responses - and thank you all for your efforts - have revolved around different kinds of finder scopes or Telrads. Which is fine, maybe that really is the best solution; I was just hoping for something that didn't involve spending money! 

[skfboiler]

When I star hop with my 6 inch reflector on an EQ mount I don't have RA/DA in my mind at all.  I just simply loosen the the RA and DA clutches and move the the scope.   For example to find the Dumbbell Nebula, M27, with the clutches unlocked, I find the constellation Sagitta.  The whole constellation fits inside my 6x50 right angle correct image finder.  Through the finder I move the scope to center on gamma Sagittae.  Looking through the finder, I move the scope until gamma Sagitta is on the edge of the finder and M27 is right there.  Then I tighten the clutches and track with the RA slow motion control or with the drive I added.   Again, I am not thinking in RA or DA I'm just moving the scope.   What helped me get a sense of scale is when I made a round disk in conjunction with the star chart I use which is "Pocket Sky Atlas".   You need to know  the field of view of your finder scope in order to make the disk for the star chart you use.  I use the method outlined in the link below.  

 http://washedoutastronomy.com/content/star-hopping-tutorial-lesson-one-m57

[acey]

Loosen the clutches and forget about using the RA/Dec scales. Find the general field using a naked-eye star. Observe the field at high power. Note the direction in which stars drift across the field: this is the celestial east-west line. Celestial north is 90 degrees clockwise from east (i.e. west is on the right with north at the top). Your map will have north at the top; turn it to match the eyepiece view. If your map has a mag limit comparable with that of the scope, and you're fairly close to the target,  put in your lowest power eyepiece and use the map to get to your target. Otherwise use the finder. The view in a Newtonian is rotated with respect to naked-eye view, so rotating the map is all you ever need to do.

[Charic]

hgjievans.........hi, It makes no difference to Star hopping having a RACI or Telrad fitted to your telescope when your eye is at the eyepiece whilst  viewing.

What does make a difference is practice, practice.practice. It will at some stage almost become second nature when you have it right. There are no magical tricks or shortcuts. Just go out one night without the intention of looking at planet 'X' or star 'Y' and just study for example Polaris, which should stay in the viewfinder without any effort, then just play about moving  too and away from the  target with the telescope. Go to a wider view on a good night with the intent on seeing satellites, and just follow them, after a while, it gets much easier.

I wont ever go back to an EQ mount just for visual observations, just too much setting and fiddling and not enough viewing. 

My eyes see for real, even through my binoculars, but my finderscope inverts and reflects, and the telescope just reflects, the Telrad does nothing? 

It all comes with practice, and it will come.......

[bingevader]

I guess maybe there just isn't, because most responses - and thank you all for your efforts - have revolved around different kinds of finder scopes or Telrads. Which is fine, maybe that really is the best solution; I was just hoping for something that didn't involve spending money! 

I think you hit the nail on the head!

As Charic has just posted, there's no easy way round it, star hopping is just another skill you have to learn.

A bit like steering a boat with a rudder, it becomes second nature eventually.

That's not to say that star hopping is easy mind you!

You just get used to which directions you need to turn things.

As people have already posted, using a low powered EP and knowing its field of view so that you know roughly how many hops to make does help.

I bought a 2nd hand RACI because it's easier on the neck, you still need to know how to star hop.

[hgjevans]

 Looking through the finder, I move the scope until gamma Sagitta is on the edge of the finder and M27 is right there. 

Which edge, though? I mean, there's an entire circle around your finder view. No need to answer that - my point is simply that you already know where it is relative to something that you can place in your finder. I don't have a problem with that so much as those occasions when I'm really not as prepared and not particularly famiiiar with that section of sky.

But one thing is becoming clear to me - people responding are typically doing more with their finders before switching to the main scope than I am. That, I think, might answer some of my problem - I'll need to try that out next clear sky night. But even assuming I get on better with that, I think it will still leave me with some times when I just can't find my target like that, simply because there's a big gulf between the quality of view through my binoculars (which is generally where this process starts for me) and the finder scope. They have broadly similar fields of view, magnifications, exit pupils, and so on, but I see at least an order of magnitude more through the bins than through the finder scope, so their views don't always correspond as well as maybe they should.

[hgjevans]

What does make a difference is practice, practice.practice. It will at some stage almost become second nature when you have it right. There are no magical tricks or shortcuts.

Thanks. Yes - that's making perfect sense. And it does have the big advantage of not costing anything. It's just a pity the available practice time is limited by the weather, although at least I can use the downtime for planning so that the next session is as productive as possible.

Huw.

[hgjevans]

...star hopping is just another skill you have to learn.

A bit like steering a boat with a rudder, it becomes second nature eventually.

Good analogy! Thanks.

Huw.

[Tommohawk]

I'm with the clutch looseners. Ease them off, not fully though and ensure you have good balance. Then grab top and bottom of scope, and move it in the direction you know you want it to go - follow the view with the (long) EP, but don't let what you see determine your direction.

I use goto now, but miss the "thrill of the chase"

[RikM]

I'm with the clutch looseners. Ease them off, not fully though and ensure you have good balance. Then grab top and bottom of scope, and move it in the direction you know you want it to go

That was how I used to do it before I got a Dobsonian. You are using it like a Dob but up on a tripod and the funny axis don't seem to matter as much.

I guess some people like Telrad/Rigel and some don't. I would be well and truly lost without my Rigel. All my 'star hopping' is done through the finders. The field of view through my main scope is just too small.

[acey]

 there's a big gulf between the quality of view through my binoculars (which is generally where this process starts for me) and the finder scope. They have broadly similar fields of view, magnifications, exit pupils, and so on, but I see at least an order of magnitude more through the bins than through the finder scope, so their views don't always correspond as well as maybe they should.

You use two eyes with binoculars so you're getting twice as much light entering your visual system - that's why they show more than a scope of equal aperture.

[RichM63]

So now we have the "Loose Clutch Mob".

I can see what you are getting at. A couple of things you might check or try.

1, is your finderscope perfectly aligned with the telescope OTA, this is a daytime activity. Point telescope at a small distant object and then adjust the finder screws to center the object in the finder whilst not moving the telescope or mount. (I use a perching Buzzard).

2, for EQ movement, remember that everything follows an arc and not a straight up/down.

3, practice on the Moon, following the terminator and navigating between craters, you'll very soon get the feel of things.

[hgjevans]

You use two eyes with binoculars so you're getting twice as much light entering your visual system - that's why they show more than a scope of equal aperture.

Understood, but in this case I think it's even more of a difference because the binoculars are top of the range German optics that cost more than double what I paid for the entire scope, mount, finder, eyepieces, etc. Even with one eye shut they show a lot more than the SW 9x50 finder scope does. Don't get me wrong, it's great VFM - far better than it has any right to be for the money, but it's not in the same class, optically speaking.

[hgjevans]

1, is your finderscope perfectly aligned with the telescope OTA, this is a daytime activity. Point telescope at a small distant object and then adjust the finder screws to center the object in the finder whilst not moving the telescope or mount. (I use a perching Buzzard).

Yes, alignment is fine. I do have to check it and realign a tad from time to time, but that's okay, I've got that nailed.

2, for EQ movement, remember that everything follows an arc and not a straight up/down.

Sure - yes, that I think was at least part of what threw me at first - the equatorial grid is nicely intuitive near the equator, but nothing remotely like that as you approach the pole, and to begin with I wasn't even consciously trying to allow for that. Since then I have been trying, but finding it tricky. 

3, practice on the Moon, following the terminator and navigating between craters, you'll very soon get the feel of things.

That does sound like a good idea - perhaps if I start with that, and then move on to a small constellation I already know well - Lyra for instance,and see how it goes.

And if nothing else, all this is at least helping to convince me of the value of preparation!  Thanks again for everyone's contributions. I'll try to make my next questions more straightforward. 

Huw.

[skfboiler]

Once you make that disk the size of the FOV of your finder and follow the method in the link I posted in my previous post you can practice the star hops of the objects you plan on seeing during the day.   Then when night comes you can duplicate what you practiced at the scope.  If you have a nice compact atlas like "Pocket Sky Atlas" you can use at the scope to do the star hops you practiced.  By doing it this way, and looking through the finder, you will know which way to move the scope and by how much.

[PorkyB]

... one thing is becoming clear to me - people responding are typically doing more with their finders before switching to the main scope...

Definitely so.  For me it's Rigel first, to find a naked-eye star as a starting point.  Then do most of the work with the RACI, where everything is the right way up and moves the right way.  By the time I look through the eyepiece I already expect my target to be there.

The funny thing is that I am so used to using an EQ mount that I find using my AZ4 much more difficult.  I find myself turning my star atlas round to work out which way to move the scope to go up the atlas page.  For the same reason I find a Dob difficult to use.  For me an EQ is simple and easily worth the ten minutes of pain to align it.  It just goes to show that we're all different and that you can get used to anything if you put a bit of effort in, although the effort in this case has been mostly enjoyable.

On the subject of doing things the old fashioned way, as well as my non-goto EQ mount, I am a big fan of the paper atlas.  I would never go out without it.  It can be a pain to swap between the atlas (glasses on) and the eyepiece (glasses off), but a cord means that at least I can't drop or lose my specs.  I do occasionally take my laptop out to use Stellarium, but I don't like to do that as the screen spoils my dark vision and the laptop is a dew magnet, so I only use it when I'm looking for something that moves, such as a comet.

[hgjevans]

Once you make that disk the size of the FOV of your finder and follow the method in the link I posted in my previous post you can practice the star hops of the objects you plan on seeing during the day.   Then when night comes you can duplicate what you practiced at the scope.  If you have a nice compact atlas like "Pocket Sky Atlas" you can use at the scope to do the star hops you practiced.  By doing it this way, and looking through the finder, you will know which way to move the scope and by how much.

Thanks, that was good link - and a useful site for those of us with suburban light pollution to contend with.