Tag Archives: tracking

Not Eclipsed!

The total Lunar Eclipse of February, 2018 reminded me of my travails from my first effort to shoot an eclipse in 2010.

My First Eclipse Attempt: 2010

In December 2010, I was crestfallen to see the weather reports. The last total eclipse of the moon visible from North America until 2014… and the weather everywhere within a reasonable 3-4 hour drive was predicted to be 90% clouds and worse. It seemed my eclipse was going to be eclipsed by cloud cover.

At about 9:15 PM, PST on December 20th, however, I looked up and saw… THE MOON!  Sure, it was scintillating in a little sucker hole playing with me. But I decided to play along. I hastily hauled out the Canon 5D Mark II, the 70-200mm f/4 IS L lens, the 1.4x Telextender, and the Gitzo carbon fiber tripod. Why those? Because that’s what I found first.

My equipment was scattered about in my office still recovering from the wet weather from earlier in San Jose. Indeed, I did not find the batteries for my Canon 50D camera.

By the time I got set up, I realized that the moon would very soon be contacting the earth’s umbra (darkest part of the shadow). So I quickly got to shooting what I could. Never mind that it was cold and I was not dressed properly.  Soon enough the clouds would come and I could dart into the house to hurriedly collect what I was missing.  The first shot I got was with the moon in the earth’s penumbra. Not particularly remarkable, unfortunately.

Through various breaks in the clouds I was able to get photos from first umbra contact all the way up to totality. Including a serendipitous shot of an airplane headed, probably, to the San Francisco airport or some other place to the north west.

Airplane Transits the Partially Eclipsed Moon
Airplane Transits the Partially Eclipsed Moon

What settings did I use for these shots? f/7.1, ISO 200, and 1/400 of a second exposures. Why so fast? Because, my friends, the moon is BRIGHT. Even partially eclipsed, even already in earths penumbra it is a big bright object. Shooting the moon is a definitive case where your camera absolutely cannot get the right exposure if left to itself. A good exposure must be manually set. I arrived at my settings by a few quick trials. I started at about 1/200th at f/5.6 and noticed that I was getting some over exposed areas (on my LCD screen the overexposed pixels blink white). I then decreased the aperture and continued to tweak the focus.

I wanted the moon images to be as well exposed as possible – especially knowing that the thin clouds were going to dim the image. My goal was to get detail in the moon, I did not care about the clouds or stars. In fact it is impossible – except at a very slender crescent or during a total eclipse to get detail in the moon AND also show stars in the sky. Why? Because the moon is so, SO bright.

I definitely made a slew of mistakes. The most significant one is that I should have put the telephoto lens on my 50D body which is a 1.6 crop camera. Had I done that all my moon images would have been about twice the size of what I actually got. Not having my camera all packed away in my bag meant some lost opportunities here.

I also thought  that perhaps the 5D would have been a good choice to get a sequence of shots showing the progression of the eclipse. The idea was to get the moon in the bottom corner of the frame and take a series of shots as it moved to the upper left of the frame. This also did not work for several reasons. The first problem was that the cloud “holes” came at irregular intervals – so spreading them across the frame evenly was not going to happen. The second problem was purely my failure to correctly guess the path the moon would follow in the sky.  Had I been a little smarter I’d have switched lenses when I realized the timelapse path was not going to work. But instead I tried again a few times.

I also realized that when the eclipse was total, the moon was going to be quite dim and the superior high ISO performance of the 5D II was needed. For the totally eclipsed shot, the ISO was ramped all the way up to 1600 and the exposure dropped from 1/400 to 1/6 of a second. That is a HUGE difference. The slower exposure meant that details in the moon would be blurred and the stars at this telephoto range would become dashes rather than dots.

Jewel [C_029690]
Nearly Total – With enough bright area left to form a halo in the clouds

Epilogue:  February, 2018

Sadly I was NOT much better prepared. After studying the weather forecasts, I headed to the coast where it is often really yucky with fog, low clouds, and on-shore winds that bring dampness and salt spray. It was surprisingly clear. My goal was to take a series of shots showing the progression of the eclipse ending at sunrise with the moon hovering over the Pigeon Point Lighthouse. I had done all the calculations as we cover in our Catching the Moon Webinar. (And also somewhat described here)

I imagined something like this effort, but better done.
Plan C: San Jose City Hall Eclipse Sequence

As it came about in 2014, we had to go with plan C due to weather. So I was excited that the weather forecast for the coast was much better in February, 2018. Some oversights on preparation conspired against me. I had not jotted down the proper GPS location and on site I had no cell signal, so couldn’t (re)calculate the spot. That left me wandering about trying to find the little tree and path that was featured on the satellite view… and NOT finding it.

Instead I ended up wandering into a thicket of brush that had an abrupt downward slope. That was fall number 1. Several efforts (and falls) later I tried setting my tripod down THROUGH the gorse all around… only to snap the leg off of my tripod. Now I needed to take  trek back to the car for my backup tripod. (Fortunately I had one!).

Since I got a late start, I scrambled to try to get a couple of series of panoramas on which to overlay the moon trajectory. However the moon was already in complete eclipse by the time I had everything set up. It was only then that I realized I was not getting the details I wanted out of the moon. I was using a 70mm f/4 lens, and the long exposures were streaking the stars and blurring the moon. So while I did get a FEW shots, they weren’t the ones I had imagined. My problem, in a nutshell, was that I was trying to get the moon AND the stars … which I did, but at the cost of streaking and blurring.

Orb to Rule the Night

By the time twilight started to appear, it was obvious that my location was about 1/4 mile distant from where I wanted to be… the little tree that I thought might form the right edge of my panorama was far off. The moon was NOT going to land anywhere near the Pigeon Point Lighthouse, so I packed up and ran up Highway 1 closer to the calculated location. I had to abandon the sequence plans, throw on the big tele-extender and HOPE the moon would survive visibility through the now obvious off-shore fog bank. Of course it didn’t. It fizzled as it got near the target.  I did get a consolation prize of sorts, though. This image hit 80 THOUSAND views in a few days – becoming my most popular photo on Flickr EVER. Sadly it’s not the image I imagined.

It's A Little Bit Broken
Photo from the end of the total eclipse of February, 2018

What Did I Learn?

To get a decent eclipsed moon shot with details, either you need a very fast telephoto lens, or to use a mount to track the moon. I also need to be willing to lose more sleep. I woke up at 3:00 AM, but the 90 minute drive meant that the umbral (dark part) of the eclipse would be starting as I arrived.

I also realized that if I’m going to spend the better part of a day mapping out the moon trajectory toward a landmark like the Pigeon Point Lighthouse, I’d do well to record some GPS locations (where to park, where to stand), and even get a Google map pre-downloaded.

Hopefully you, dear reader, will learn from my mistakes because you won’t have enough time to make them all yourself!

Astrophotography – The Polarie

We have a once-in-a-while webinar on beginning Astrophotography. The purpose of the webinar is to get people acquainted with the tools and techniques required to delve into this interesting genre of night photography.  As we teach in that webinar the single most important piece of equipment you can buy is an Equatorial Mount.  An Equatorial mount is an apparatus that counteracts the rotation of the earth so that your camera can peer at the same place in the sky for long enough to capture an image without streaks. There are many equatorial mounts that range in price from almost nothing (and not even worth nothing) to more expensive than logic would dictate.  For more background please see our survey of Astrophotography Gear.

One of the newer pieces of equipment in the arsenal is a less-than three pound piece of gear called a Polarie.  Here is what it looks like with a ball head attached to its face.

Polarie – Close Up

What Polarie Can Do

As noted earlier, the primary purpose of Polarie is to counteract the effect of the earth’s rotation so that objects in the night sky can be exposed longer without getting streaking. Below are examples of 42 second exposures using an effective focal length of 215 mm. The image at the left is with the Polarie turned on in normal mode, the middle image is the same length exposure but in 1/2 speed mode, and the right is what you get if you use no tracking at all.

Polarie Test - Telephoto

Tracking is less critical when shooting with wider angle lenses. I ran a test with a 200mm telephoto lens because it is a more difficult scenario. For example when shooting the Milky Way, an effective focal length of 10 to 50mm makes more sense.

A Critical Look At Polarie

I purchased only the Polarie unit (about $400 USD) not any of the accessories. The unit is deceptively heavy at almost 3 pounds but at that weight it is still – and by far – the lightest equatorial mount you can find. The only other device in its weight class at present is the Astrotrac with a starting price about twice as much. The Astrotrac does come with a better tripod mount, however at a total cost of around $1300 USD.  I paired up the Polarie with my Canon 50D and the 70-200 f/4 lens.  The addition of a Giottos ball head brings the total weight of the equipment attached to Polarie to about 6 pounds.

The Positives

  • Inexpensive
  • Good instruction manual
  • Mostly easy to set up and to use
  • Suitable for a beginner
  • Good power for the price.
  • Can be powered with mini USB (or two AA batteries). Claimed life is 4 hours on AA batteries but mine lasted at least 6 hours using rechargeable batteries.
  • Compact and MUCH lighter than almost everything else.
  • Can be used in Northern or Southern latitudes.
  • Tracks at star, solar or lunar rates (and yes, they are all different) as well as a 1/2 speed rate which should be good for Landscape Astrophotography.

The Negatives

  • The back plate can be unscrewed to peer through the axis of the motor and also houses a built-in magnetic compass but the plate is almost flush to the Polarie body and it is quite hard to grip.
  • The inclinometer (angle measurement device on the side) seems like a good idea except that the markings are so small and coarse that to my eyes it is illegible.  The lighted inclinometer *might* help if the North Star is obscured by trees or such.
  • The front plate has a 1/4″ retractable bolt and attaches awkwardly to the motor plate with two thumbscrews that are hard to reach once a head is on the motor plate. I would have preferred that Polarie supply a 1/4 to 3/8″ adapter since most good heads attach via 3/8″ bolts.
  • The battery compartment door is a nail buster to open.
  • Since Polarie will certainly be used with a DSLR camera, Vixen really missed an opportunity to add a remote release cord – I see no jack for one.
  • Not sure what the point of the flash shoe is. I do see the Vixen has another (much larger) inclinometer that can be attached there, but you may be able to do better using an application on your smart phone.
  • The optional polar alignment scope is expensive, and bulky. It’s also complicated to operate because you must remove the ball head and camera from the device. BUT the weight of the camera and ball head is likely to create enough “sag” that the careful measurements will be wasted.  We like the SkyTracker much better in this regard.

There is a sight hole to line up Polaris – the North star. I used only that method to align Polarie and got fair results. To get really long exposures one of two methods will need to be undertaken to increase the alignment accuracy: either invest in a Polarie polar alignment scope at almost double the cost or do drift alignment. Drift alignment is not simple and probably would frustrate the aspiring astrophotographer. The Polarie can be purchased with an optional ratcheting tripod base which might be a good idea, however the stated load capacity of the bundled tripod seems too low to use with a heavy camera.

Noteworthy

Remember that you will need at least two heads and you’ll want them both to be ball heads for optimum configurability. The head on the tripod should be sturdy – see below for why.  Below I refer to tripod head – the apparatus that joins the tripod to the Polarie, and to the Polarie head – which is the hardware used to attach a camera to the Polarie.

Problem Areas

In addition to the negatives listed above, there are several other sources of problems including every point where one element attaches to another. For example: the Polarie base if not attached securely to the tripod head can rotate.  If using quick release plates the attachment point creates another source of rotation. If the camera is not securely attached to the Polarie head rotation can occur there, too. All the pieces together may severely tax a cheap tripod head making it difficult to hold up or adjust the load.  In my configuration I found I had to allow some slouching – meaning I had to adjust the camera so it was pointing slightly above my target and then tighten the head so that it would settle to the right place.

What Can You Do With A Polarie?

Maybe we should have put this section first! Some of these things can only be done with a Polarie are highlighted in RED.

  • Point the Polarie straight up and use it as an automatic panning motor for a time-lapse.
  • Align Polarie and take a series of shots of the night sky – the sky will stay in the same place in every shot – and any minor movement can be compensated for using Astrophotography procedures.
  • Outfit your lens with a solar filter and track the sun (e.g. for photographing eclipses or solar activity)
  • Track the moon e.g. to catch the space station flying across its face, the slow creep of the terminator, or just to get a time-lapse as the moon sets or rises.
  • Double your exposure on a landscape astrophotography shot by using 1/2 speed mode.

For more hints tips and examples on how to use Polarie, stay tuned to this channel!

My first test of the Polarie was to track the radiant point of the Orionid Meteor shower. My attempt was mostly a bust due to clouds, however note how stable the time-lapse is – and remember this spans almost 14 minutes of real-time.

Here are two more ways I’ve used the Polarie – as a horizontal panning device

As a sky tracking device

Resources for Astrophotography

Original Publication: Oct 12, 2011
Last Revised: Nov 9, 2017

Local Stores (San Francisco Bay Area)

Orion Telescope Center

10555 S De Anza Blvd
Ste 105; Cupertino, CA 95014
(408) 255-8770

Mon-Sat 10 am – 5:30 pm
Sun 12 pm – 5 pm

Equipment Recommendations

There is a lot of gear out there and a lot of thought about what is good / better / best.  For the purpose of my recommendations I’m assuming your interest is primarily Astrophotography and primarily based around using a telephoto lens or a small/lightweight telescope attached to a DSLR. Of course you might succumb to a small telescope. Most of my recommendations are based on personal experience. Some are based on observations of people much wiser than me.  If you decide to get a mount, here are representative alternatives.

OrionMountsCompared

Before we dive into conventional mounts, however, lets take a look a well featured, light-weight solutions.

Approach A: Good, Light and Portable

Astrotrac

AstroTrac TT320X-AG – photo from AstroTrac site.

Since, portable, inexpensive and stable do not all fit into the same category the best solution is the AstroTrac. It is light, well made and moderately priced (from $546 to $1,959 depending on the package – not including shipping). You will be limited to using the AstroTrac with a telephoto lens on a camera unless you buy some dubious additions to turn the AstroTrac into a big scale solution – but since you’re reading this that is probably what you intended anyway. Be sure to get the Polar Scope as it is difficult to align without it! This mount will track at Lunar, Sidereal or Solar rate!  While $546 might sound expensive, for the light weight versatility it’s hard to beat. For a video and more information, see the manufacturer’s page.

Pros: Total schlep weight (tripod, heads, polar scope, battery, AstroTrac) is about 12 pounds (less if you have a lighter tripod); setup is pretty easy; accurate tracking;  maximum load is 33 pound; stops automatically to prevent damage.

Cons: Limited weight; repointing at a different object may compromise the alignment;  2 hours tracking before reset; single drive solution.

Orion Astrophotography Bundle

A possible solution – much cheaper at $180 but also with very significant limitations is the Orion Astrophotography Bundle.  It is a light weight, low load mount with a single axis drive and no alignment scope. At 14 pounds assembled and a load of up to 7 pounds it’s not bad for very wide field astrophotography – but it will never take more than a single camera load. I DO NOT recommend it. For why, please see my review.

Polarie

Another product that has caught my eye is the Polarie device.  Imagine a device about the size of  a DVD slip case only about 3 times as thick.

Polarie Device with Polar scope (image from Amazon) – requires TWO heads and a tripod.

The Polarie device costs about $400 USD, but that doesn’t include the possibly unnecessary polar scope – which is an extra $250 – or a tripod rig to set it all on.  Like the Astrotrac, Polarie is light and portable and runs on conventional batteries.  A competitor is the iOptron Skytracker. Very similar features to the Polarie with a few advantages and disadvantages. The Polarie is a miss, mostly in that the scope is expensive, and requires removing the whole face. Once you put camera gear on it, the distribution of weight changes enough that the alignment via the scope is useless.  It didn’t do a good job managing my Canon 50d with a 70-200 mm lens.

iOptron Sky Tracker

iOptronSkyTracker (requires head, tripod)

Of the Polarie and the $400 Sky Tracker, I prefer the Sky Tracker. It’s better thought out.  The down side is you’ll need to remove the head from your tripod and put this in it’s place then put the head from the tripod on the face of the Sky Tracker.

The faceplate only “locks down” via that single screw. I found it sometimes slips. Also there is a little slop in the gearing. The good news is that unlike the Polarie with its expensive polar scope, you can actually mount your camera ON the face and make sure there is room to also use the scope to accurately position things.

There is a newer Sky Tracker Pro available which is more like a “real mount”. Haven’t investigated that much.

The advantage of the SkyTracker over most solutions is that it is light and easily portable.

A Canon 50d with a 70-200mm lens was more than it could manage well.

 

iOptron Sky Tracker Pro

We have no experience with this unit, however one of our workshop participants managed to make it work well. iOptron Sky Tracker Pro (no experience)

 

Astro

There is even a new contender rising in the KickStarter arena… it’s called Astro: Time-Lapse Motion Control.  It’s not clear if it will be accurate enough to track at sidereal rate, but I am hopeful.

It’s not designed for astrophotography, but if the rate can be set precisely enough, and a simple alignment done it may work quite well.  It does have a built-in intervalometer, though and as you can see it’s quite compact.

NOTE: I purchased one and found it disappointing.

 

Approach B: Good, Economical

The next bump up in capability is the Orion AstroView Equatorial mount ($250) to which you must add the single or dual drive ($140, recommended) motors for a total outlay of about $390. It’s carry weight is around 31 pounds including batteries but it can handle 12 pounds of payload and you may not need to use all 12 pounds of counterweight. Orion does have mounts in between, but I say skip ’em.  The disadvantage here is that it really can’t take a telescope, there is no autoguider port, and no “GoTo”. But it does come with a polar alignment scope. Tracking accuracy at sidereal rate is pretty good. I haven’t pushed the mount beyond 450 mm so I can’t make final conclusions. One advantage over a normal “tripod” is that the extra weight makes this solution much more stable than a conventional tripod. The latitudes range for use is 18-63 degrees. With some finagling I was able to physically get the angle down to 0 degrees – but you can’t track the RA axis at that angle. Two more drawbacks are that the tripod is lightweight aluminum square tubing with a plastic clamp – it’s begging to fail from overtightening, and the drive motor connectors stick out like sacrificial lambs begging to be broken off when placed down on a hard surface incorrectly.

Approach C: Serious Astrophotographer

Once you move up the value chain you will want to get a “GoTo” scope. This moves you from the $400 neighborhood to the $1400 address which gets an Orion Atlas EQ-G that can support 40 pounds of payload, and costs about 80 pounds in back buckling schlepping to move it around (22 pounds are counterweights).  The good news is a modestly sized telescope can go on this thing – you could even give your toddler a ride. The bad news is there is still plenty you’ll want to buy: an autoguider… and perhaps even a telescope. If that’s where you want to go, perhaps the best bet is the even stronger solution, the Orion Sirius EON 120mm EQ-G GoTo APO at $2800.  None of the above  include an autoguider, or the few miscellaneous parts you’ll need to attach your camera.   If you want a slightly less expensive, lighter system the Sirius mount isn’t a bad deal.

If you KNOW you’re going to put a immodestly sized scope on your mount, you might find yourself in the $4,000 district where a forklift or weightlifting team can help you move the apparatus around. Trust me, $4,000 still isn’t the penthouse suite!

Approach D: Insanely Serious Astrophotographer

Actually I can’t recommend anything in this category because it enters a realm where I’m not willing to go financially. For a down payment on a house you can get a large refractor (or reflector), massively accurate GoTo mount with autoguider, a high-end imaging camera, and a wheelbarrow full of accessories. Names like Losmandy, Takahashi, AstroPhysics and others rule this realm.

Polar Alignment

  • http://www.astronomy-pictures.com/Imaging-Tips.htm#zero
  • http://www.petesastrophotography.com/polaralignment.html
  • http://www.astronomy-pictures.com/Zeroing%20it%20in.%20Using%20a%20DSLR%20or%20CCD%20to%20Align%20Your%20Scope.pdf

Imaging