Despite it's advantage, many first-time telescope buyers shy away from an EQ-mount because of horror stories about the time needed to setup such a mount. And possibly because such an odd-shaped rig with weights & knobs looks intimidating & complicated.
While it is true, this step of polar-alignment can be very tedious & time-consuming, this usually refers to very high-precision setups (permanent pier or observatory). Casual observers can finish it a lot more quickly.

And of course, not every observer needs that same high amount of precision & effort and when performing polar alignment of his setup. It is important to distinguish the intended purpose. Startrails invisible when shot with a 50mm "normal" SLR-lens become streaks 50 times longer when shot through a (2500mm) telescope. Plus, usually a telescope's aperture ratio is 4...8 times slower than your SLR lens. Now you would need a setup that's 300x more accurate, if you want to have the same amount of visible error in your images.
That's where some of the stories about time-consuming setup originate -- and as errors get smaller, the effort reduce them takes more time.

"Point the (RA)-axis of your mount (or StarTracker) at Polaris -- DONE". When you read that, it sounds simple. And it really IS THAT EASY but it also is NOT ACCURATE, though for many users it is ACCURATE ENOUGH. Polaris isn't at the CNP (Celestial North Pole), instead Polaris rotates around it, off by 2/3°. That's not much if your startrail image covers 60°x40°, but it is a lot when your FOV is as narrow as the full moon's 1/2°. With the use of a polar-scope with alignment-markings, you can increase precision, but these scope too come with their own drawbacks (more later)

STEP 1 -- applies to all and this may be all you need, to avoid startrails with a wide-angle lens. The advantage is, this works during daylight, doesn't use stars and instead solely relies on accurate mechanical & terrestrial measurements. Tilting the axis / lens based on your latitude and with the help of compass & maps, you point accurately north (don't forget the magnetic declination). The emphasis here is ACCURATE MEASUREMENTS.

If avoiding startrails is your goal and your FOV is wide, a small error isn't a big issue. Vixen's Polar Meter falls in that category and suffers from the same mechanical limitations. Altitude scales don't even show individual degrees. It is ACCURATE ENOUGH for the purpose of avoiding startrails with a wide-angle lens and POLARIE or ASTROTRAC. It's not a tool to align a telescope -- a wide-angle view is more forgiving.
It also helps, if you have prepared for that task in advance -- scout the location on Google Earth to find usable landmarks for orientation. Preferably some due north. If you travel, save the screenshots.


The steps below all are done to further improve accuracy and I recommend those for photographers with narrow FOV (measured in minutes instead of degrees) and long exposures (measured in minutes instead of seconds). You still can choose put in less effort into leveling & polar-alignment to let the GOTO-mount do the necessary (goto & tracking) corrections for you (after a proper multi-star alignment sequence) but sloppy setup still can result in some residual image-rotation errors & elongated stars.

Leveling the tripod's or pier's base isn't a requirement. You can get perfect alignments even if the mount's base is tilted. All that counts is the RA-axis of the mount has to be parallel to the earth's axis. But to get there, you have to measure and make adjustments. With a (perfectly) leveled base, you make an adjustment and only one axis is affected. Simple cause & reaction relationship. The more the base is tilted, the more a single adjustment affects both axis.
Even if you use the GOTO alignment procedures, a properly leveled and north-aligned mount makes life easier to FIND THE ALIGNMENT STARS. If your mount is tilted 1° in each direction, you are 1.41° away from your intended target position -- but you don't know which way. Add to that e.g. a 1° alignment error between the saddle and the OTA or an additional cone-error and you may not even see the alignment star in the wide view of your finder-scope. It also means, later, the GOTO has to do more & bigger adjustments and there casn be image rotation.

If you want to follow my suggestions, you have to make sure the base REALLY IS ACCURATELY LEVELED. To get there, you will have to make very small adjustments and at some point, adjusting the tripod leg's length wasn't practical. Adding $3 worth of screws & wingnuts made life a whole lot easier. Paul Chasse has perfected that idea by adding a swivel foot and send me a triplet for testing : /stargazer95050/29051567. With other tripods, you may have to use thin washers, shims, ... to raise the feet.
Make sure the feet are on solid ground and don't sink in under the weight of the big setup. Spiky tripod feed (or these screws) are the worse. If in doubt, use tiles to spread the weight of the foot over a wider area of grass or sand.

With an accurately leveled base, setting up the rest of the mount has become one step easier, especially with the iEQ mounts. Thanks to a function which is intended to balance the mount & tube, but I "mis"- use it to determine the accurate "ZERO" position. Based on the GPS coordinates, the iEQ-mount places both axis into (supposedly) horizontal position. If your base is leveled and your "zero"-position is accurate, both axis will be leveled as well -- once the zero-position was accurate, I haven't seen more than +-0.1° error. And that is the accuracy of my angle meter.
During the first setup & after mechanical (alt)-adjustments, the zero-position may not be accurate and the balance-position isn't leveled anymore. If the axis aren't leveled as they should be, loosen the clutches and make adjustments. Afterwards, slew back to zero-position.

Polar alignment & zero-position are intertwined and whenever you make mechanical adjustements to the mount or tripod's feet, that can affect the zero position. With good preparation, these errors are small enough for a mobile setup.
PS : there are additional errors you may want to eliminate :
- collimate the OTA's optical axis to match the saddle / mounting rail -- eliminate the cone error.
- collimate the polarscope to match the RA-axis (if you use it) : -- "How To Focus and Collimate the iEQ45 Polarscope.pdf"


I freely admit, these steps take extra time. But the important part is, these steps SAVE TIME when it is important to an astrophotographer -- after dark. You can improve the setup before nightfall. With proper solar filter & caution, you can even use the sun to do drift alignments. Once the stars become visible, there are several routes to finish the accurate polar alignment. IMO they all perform faster with this preparation.
  • do nothing else : your mechanical preparations already may be accurate enough for your task. Visual observation & wide-angle shots are good examples
  • use GOTO-alignment : your chances of finding the alignment stars improve the more accurate the mount is prepared. The better the polar alignment, the lower the raining field rotation.
  • further refine the mechanical alignment using the polar scope -- as a matter of personal taste, I dislike it because of inconvenience (I'll explain that later, with the tall pier & iEQ mount it became less inconvenient)
  • further refine the mechanical alignment using drift alignment -- there are many description & tools covering that. Drift alignment takes time and is done after sunset -- use of a PC & camera can help to reduce the time needed and simplify the procedure.
  • further refine the mechanical alignment by plate-solving current position
  • use plate-solver to SYNC the scope's position -- given the effort to prepare an accurate setup, the remaining errors may be quite small. I have used both methods but haven't done a comparison if there is a big benefit to further mechanical adjustments over a simple SYNC.

A lot depends what you will be doing later.and what amount of magnification & exposure times you will be using. Without auto-guiding, you rely on the precision of your setup and the optional GOTO-calibration. Auto-guiding (plus GOTO-calibration) can help to make up for some inaccuracies, field-rotation errors still be an issue.

My recommendation is biased -- not because someone paid me but because it eliminates the uncomfortable use of the polar-scope, it works smoothly and it doesn't require any new investments. But that assumption of "doesn't require any new investments" isn't true for everyone.
  • You shoot wide-angle images, you can get away with decent (purely mechanical) polar alignment and don't need all this
  • you can use a combination of good mechanical setup + polar scope -- once you have calibrated that setup
  • If you use a motorized GOTO-mount + dSLR but dont use auto-guiding, you likely don't have the laptop with you and my suggestion is less suitable for you.
  • if you use auto-guiding, you are likely to have a laptop with you and adding the plate-solver and hooking up your SLR can be accomplished quite easily
    ==> you want to see the practical advantage of adding a plate-solver : /stargazer95050/28668501

The optical POLAR SCOPE is a classic accessory to all EQ-mounts. It has Polaris & the stars of the "Big Dipper" marked in its sight and once you have matched all the stars with their markings, you have achieved POLAR ALIGNMENT. And I don't dispute that.-- if the scope is collimated to match the mount. Even with a brand new mount, that is not always the case. Detour : Align a polarscope

The other issue I have, it is very inconvenient to use because often the eyepiece is ~3ft above the ground. And you have to stare at an odd angle upwards trying to see stars, all the while you also have to twist knobs to move the mount into position. Did I mention, I wear eyeglasses and the scope hasn't much eye-relief ? Move your eye and you cause parallax errors. All that is a lot of hassle by itself IF YOU CAN SEE THE NORTH STAR.
For observations under a dark sky with eyes well adapted to the darkness, some issues would go away, the hassle of kneeling in front of the scope while adjusting would remain.
When in its "zero" position, the shaft for the declination axis is blocking the view of the polar-scope. That means, you can see Polaris through your telescope but not through the polar-scope. Based on the mount & model, you have to turn the DEC-axis 45° or 90° degree to open a window in that axis but naturally that eliminates the view of Polaris through the main OTA.
PS : these optical polar scopes usually cost another $100...$200 and guess what -- when sold separately, they need CALIBRATION to align with your mount & camera and you are the one to do it. I cannot tell how long these adjustments last and if you have to correct those when you frequently transport the mount.

AlignMaster is a small but helpful tool -- especially helpful if you have your mount connected to a laptop. Based on time & location, it will suggest alignment stars and slew to the expected position. You manually center the star (using eye-piece of camera) and AlignMaster will record the offset. After checking two stars, the tool can determine the error and will aid you in making the mechanical adjustments. To improve accuracy, you should repeat that sequence until the error is small -- e.g. < 1...3 arc- minutes. It is very similar to the GOTO calibration procedures WITH ONE IMPORTANT DIFFERENCE : the corrections are made mechanically to the mount not corrected electronically through the GOTO-electronic.
Additional SW-tools to help with polar alignment : /blog/stargazer95050/781309

Having to FIRST CALIBRATE the polar scope defeats the purpose -- maybe that's another reason, the GOTO-alignment has increased in popularity

The best option, so far, involves image capture and software to perform "Plate Solving". Just like the results you get from submitting your images to /groups/astrometry. To be useful in the field, this tool shouldn't be web-based. Instead it must deliver results within a minute compared to hours for the flickr results ==> Laptop is required. Since I'm imaging & guiding, a laptop already is part of my setup. The software itself is free.
Using your CCD-camera or dSLR, you capture an image and feed it into AstroTortilla and that in turn will calculate position of the the center of the FOV. Adjust the Alt-screw and rotate the mount as needed to get close to the NCP. No need to kneel in the cold dirt to look through the polar-scope. On the left, a screenshot from the close encounter with CNP -- before I ran out of "solvable" stars ("thanks" to light pollution). Any further small adjustments were unsolvable -- bigger adjustments throwing the FOV further away from CNP were just fine as was using a scope with a wider FOV
More on successful & instant "Plate Solving" using a laptop : /stargazer95050/20413811

The crux with my particular setup, the FOV is very narrow and right around the celestial north pole, there aren't that many stars..POLARIS is 2/3° (or 40').away, thus of no use with this very narrow FOV (small camera + long focal length). In startrail images you won't notice that small distance, but at high magnifications, Polaris doesn't even show in my viewfinder (marked red & yellow) when I correctly point at the CNP.
A lens with a wider FOV shouldn't have the same kind of trouble and capture sufficient number of stars. A darker location surely will help. Maybe I also should be using a LPS filter ?

If you are interested in PLATE-SOLVING, there is an alternative to AstroTortilla -- one that is easier to install. Open-source ELBRUS plate solver : or try
Elbrus is a small windows executable ~2MB -- AstroTortilla is a LINUX-tool and you need Cygwin to run it on your Windows-PC. It is free but cost you ~300MB of disk space.
Elbrus database is ~1GB -- AT has more flexibility and you have to choose different catalogs based on the FOV of your scope + camera combo. My selection uses ~3.5GB to cover everything from widefield to narrow FOV with a 600...2000mm focal length.
APT & AstroTortilla work together hand in hand -- similar SequenceGeneratorPro has incorporated Elbrus into their workflow. Both Elbrus & AstroTortilla can be used standalone -- send them a JPG as input.

Hopefully I can get Elbrus to deliver similar good results as AstroTortilla / Astrometry -- for now I have to check Elbrus' results twice and at times there are massive discrepancies !!


1st published -- Dec 2013
update -- May 2014
added ELBRUS & ALIGNMASTER -- Sept 2014

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