Eclipse Photography – Some Notes for the August Event!

Eclipses are exciting whether they be partial, total or annular. On August 21st of this year, the USA will have an awesome opportunity to see a total solar eclipse pass right across the entire country from Oregon to South Carolina.  People have already got their hotel rooms reserved, rental cars spoken for, and plane tickets purchased. Wherever you choose to go, you are likely to wonder about capturing this event by camera. Here are some thoughts, in no particular order (but I will try to keep it logical).

Never seen an eclipse before?  You might want to consider NOT trying to photograph the eclipse at all!  Sit back and enjoy the event. Total solar eclipses are short in duration, totality, that is. At the location of greatest totality duration (Southeast of St. Louis, MO), the totality lasts only 2m 40.2s… that is just almost about 3 minutes in length. You really want to be looking up at the corona at that point and making all sorts of exclamations!

Determined? You really want to capture this with a camera? Ok! Read on!

Initial Words of Wisdom:

Start planning NOW. Obtain your gear as soon as possible. This accomplishes two things: You will have the better choice of gear with sufficient lead time. Closer to the event, gear will be more difficult to buy. Also, you will have time to do this next important thing: Practice with your gear now!  Learn your camera, inside and out. You want to know ALL there is to know about the equipment you plan to use. Be able to use it without manuals! You WILL NOT have time during totality to learn new things about your gear. Play. Try solar photography on every clear day. Learn what works for you and your equipment now.

Wide Field Photography:

Some of the coolest looking eclipse shots are wide field images taken with fisheye lenses or wide field lenses to capture scenery and the eclipse at the same time. You can even set it up to take images every couple of minutes throughout the whole event and get a lovely series.

A video camera set to wide-field and left attached to a tripod will capture the whole event automatically, and will include sounds of the celebrations around you. Aim, turn on, record. Done. A steady tripod is handy. You might also tape a sign onto the tripod stating “do not disturb”. Check out this video from observers in Queensland for their last total solar eclipse.

Total Solar Eclipse from Queensland Australia

Individual shots: a DSLR or point and shoot camera should be on a tripod. You can take images at short exposure lengths 1/500s or faster depending on your ISO. This will capture the day-lit scenery and the sun. If the camera is well mounted, be sure to aim the middle of your eclipse series towards the center of the frame. Below is a typical wide field setup: a DSLR with 16mm fisheye on a stable tripod. Note that many new DSLRs also have the capability to shoot video <hint hint>.

Wide field imaging setup.

A Nikon D7000 with 16mm fisheye lens for wide field photography. This will capture good images of the surrounding scenery and the eclipse at the same time. No need for a solar filter here. The tripod keeps it all stable.

Below is an image taken with a Nikon D810 at 100 ISO f/8 for 1/640 second exposure. It was resting on a tripod and released manually (i.e. finger on the shutter release button). Shorter exposure times will show less of the scenery, but might show the sun and the corona a little more clearly.

Fisheye image of sun at noon.

This image taken with the setup seen in the photo above, a D7000 ISO100 1/640s f/8 on tripod with 16mm fisheye.

If you have manual focus: set it to manual and focus it onto a distant object and then leave it there. Also, set the ISO, shutter speed and f-stops (aperture) and leave it on manual mode. You will then see the surroundings get darker at totality instead of having the camera keep trying to take properly exposed shots in the darkness of totality.

Many cameras have built in interval timers. Set it up, start the sequence and go enjoy looking at the eclipse!

Telephoto/Telescope:

This gets a little trickier. First and foremost a WARNING: YOU NEED A SOLAR FILTER for your camera and your eyes! DO NOT MESS AROUND HERE. The sun will cause irreversible harm to your eyes if you look at it. It will do more harm more rapidly if you use a telephoto lens without proper filtration!  Got it?!  Good!  This is really important!!!  

Appropriate filters are those made for solar observing and DO NOT include welder’s glass, exposed film negatives, sunglasses, and similar. Good filter material:  Baader Solar Film. You can buy a lot and make a ton of filters for your cameras and friends’ as well.  Buy it NOW or you will find it much more difficult to get closer to eclipse date.

You can buy Baader Solar Film on Amazon.com.

A filter should be placed in front of your lens until just the second before totality. This protects you and the camera and the lens. You can then watch the eclipse as it progresses. I recommend taping the filter onto the lens hood to protect it from being blown off by wind and to prevent interested people from trying to remove it. That is a no no.  Throughout totality and into the moment when Bailey’s Beads are visible, you can take the filter off and shoot without it.

Experiment with your setup and filters well in advance of the eclipse date. Practice using your camera to take solar images. Do this often. Get to know your camera inside and out. Be able to operate it manually without any guide book.

Eclipse imaging setup.

The telephoto setup: a D200 with 300mm telephoto. There is a Baader solar film filter on the front. A right angle viewfinder is attached. This was a windy day! The sturdy tripod helped a lot.

Tripod: You need one with telephoto lenses.  You need a sturdy one.  The sturdier, the better. For a 300mm lens on a full frame (FX) camera, I use a Manfrotto MT055XPRO3 055 Aluminium 3-Section Tripod with Horizontal Column.  There is also the issue of the tripod head. I use one with slow motion controls, also a Manfrotto item: Manfrotto 405 Pro Digital Geared Head. These are not inexpensive items! Whatever you use, the ability to slowly move the pointing as the earth rotates is very helpful. It just has to be stable as a rock.

A word about tracking: Some of you will be tempted to go find an astronomical tracking mount for this event… thinking that you can mount the camera onto the mount and just let the thing track through the event automatically. If you have not done this before, avoid the temptation. A good tracking mount is much more expensive, as it has to be massive to hold your lens and camera combination. Alignment with the earth’s rotational north pole is not easy in daytime. You will need batteries or another power source to drive it. Just no. It is EASY to manually track the sun in a camera’s viewfinder. Keep it simple. Travel lighter. Save money. If you’re a pro and plan on doing this, then you already know what you are up against. No need to discuss this any more.

Lens:  A DSLR and a telephoto from 300mm up will be great. 300-400mm lenses are more than adequate for some excellent photography…. There is no need for a massive telescope with 8” open aperture and 1200mm of focal length. The sun is bright. The sun is also large at some 0.5 angular degree in diameter. If you use a zoom lens, be sure that you can lock the zoom feature. Use duct tape if it does not have a locking feature. Some of them will zoom in or out on their own due to gravity! Not fun if you are trying to keep things equal throughout the event.

Here is an image taken through a 300mm telephoto using a Baader solar film filter. It has been cropped but kept at 100% scale from the camera:

Partial eclipse image

Partial phase of the 1 August 2008 eclipse seen from Novosibirsk, Russian Federation. Nikon D200 and 300mm telephoto, iso1000 1/5000s f/7.1

Camera: The camera will be better if it has manual controls and manual focus. Having a remote shutter release is good in that it will reduce vibrations. Setting focus: With the solar filter on, focus on the edge (limb) of the sun until it is crystal/razor sharp. You might even have a couple sunspots to focus on. Most camera’s autofocus systems will do this nicely. Once focused, switch the camera and lens to manual focus and DO NOT touch it throughout the event. If your camera has mirror lockup mode, you can use that if you wish to reduce more vibration, but you will have to look through the viewfinder occasionally to center the sun, and that requires a mirror.  I never bothered with the mirror lockup feature for eclipses, and my images were fine.  Why setting to manual? You should expect to change the shutter speed and maybe even the aperture throughout the eclipse in order to get best exposures. The moon covering the sun will dim the event, little by little. As totality is reached, you will want to try to capture the inner corona and flares/prominences with short exposures… and then use longer exposures to capture the outer corona, requiring longer exposures. You will be VERY busy at totality.

Large zoom lens setup.

A Nikon D810a with 200-500mm zoom, right angle finder and home made Baader film solar filter. This is the limit for the tripod before things get too shaky. Add a GPS receiver and remote shutter control, and this is a perfect setup.

Working end of D810a and zoom.

The working end of the D810a and massive zoom lens. The right angle finder allows one to be looking away from the sun while taking photos. Add the shade of a rimmed hat and the extended cardboard from the filter assembly, and taking solar photos is a snap!

File Types: Most modern DSLRs, and digital cameras in general, allow one to select various modes of shooting: High, Medium, Low resolution, Raw, NEF, etc. My recommendation is to have your camera shoot both high resolution Raw images and JPGs as well.  Depending on your camera make/model, this will result in raw images of type NEF, RAW, or CRW and also store JPGs. These raw images can be edited much more cleanly than JPGs. Images will be large! Have memory to handle this. My last eclipse trip saw 350 images in all from eclipse start to finish. Also turn off any compression modes and image processing (sharpening, etc) that cameras are likely to do. Set your camera’s time and date as accurately as you can using Universal Time. If you have a GPS attached, then this will be taken care of for you.

Totality: Much has already been written about what you can expect to see during totality. You have to decide what you are going to do, and in what priority. Some will want to just look up and enjoy. Others will want to take as many photos as possible. Assuming you are going to take as many photos as possible, read on.

  • Right before totality, you have the option to remove the filter and try to capture Bailey’s Beads. With the camera on high-speed multiple exposures, take as many images as you can, as fast as you can. You can also get the Diamond Ring Effect if your timing is good. Another option here: try to get both the beads and the ring effect at the END of totality. It happens on both sides!
  • Remove the filter!
  • Take many photos at many different exposure times. Long exposures will show the outer and fainter corona. Shorter exposures will show the brighter inner corona and prominences. If you take a series of images with a wide range of exposure values, then you can combine them using high dynamic range software to get some amazing imagery.
Inner corona image

A short exposure of the 1-Aug-2008 eclipse. Note the small red prominences and just a hint of the corona. The human eye will see more corona than this photo shows. Nikon D200 300mm iso1000 1/6400s f/7.1

Outer corona image.

Long exposure photo of the same eclipse showing the fainter outer corona. Nikon D200 300mm iso1000 1/160s f/7.1

Gadgets: Below listed are some helpful things to have around. Not all are necessary. Take what you think would be helpful.

  • A good watch.
  • GPS receiver/geotagger attached to the camera: these can log your position and the time onto each image you take. Great if you are doing science or working with the Mega-Movie-Photo-Team.
  • A right angle viewfinder for the camera: this is really helpful, as it allows to look down into the camera viewfinder instead of at the same line as the sun. Combined with a brimmed hat, this is a really nice gadget to have. Some also have 2x magnifiers which help with focusing.
  • Batteries: for all your goodies like the camera, GPS, cell phone, etc. A Charger is also handy. You are not too likely to need to change freshly charged batteries in the middle of the eclipse unless your camera loves to eat them up :-/
  • Extra Memory Cards for the camera.
  • Compass: not all that helpful, but just in case you need to find south…
  • Pencils and pens and notebook.
  • Maps: in case you need to avoid weather, having a paper map of the area is helpful.
  • Bug spray: sometimes bugs can really bug you!  Mosquitoes will come out in at totality.
  • Sunscreen: yep – sun burns are no fun.
  • A brimmed hat: this helps to block sun from your seeing the camera’s field of view properly.
  • A vest with a ton of pockets: to hold tools, parts, lenses.
  • A pocket knife (Swiss Army style with tools): handy to attach tripod screws to camera and many other things.
  • Duct tape: there is always a need for duct tape.
  • Plastic bags: to cover camera and gear against rain and dust.
  • Water and food: keep yourself energized and hydrated.
  • Microfiber cloth and lens dust-off-bulb: helps to clean the optics and the viewfinder window.
  • Your glasses and or contact lenses. Have an extra set.
  • Solar eclipse glasses. These are fun and allow you to see the eclipse with the unaided eye while it is in the partial phase.
  • An odd one: Permission to be where you are located!  Be mindful that it will be easy for you to be tempted to trespass onto lands for which you do not have permission! In case you do venture onto unknown property, bring photo ID with you.

Links to other helpful sites:

SDSS BOSS Plate 6192

Thanks to the fine carpenters at the Academy, we now have our Sloan Digital Sky Survey (SDSS) plate mounted and hanging on my classroom wall. It has been encased in a wooden box filled with ornamental lights, giving it that astronomical view.

SDSS BOSS Plate 6192

The SDSS Plate in its display case. Note the markings which help astronomers identify the various targets.

Information on the plate itself is rather interesting. This is a plate for the Baryon Oscillation Spectroscopic Survey (BOSS) which has the goal of mapping baryon acoustic oscillations signatures by looking at the spectra of some 1.5 million luminous red galaxies. The survey will help astronomers to place limits on the universe’s expansion rate, and more! The plate here was used to hold optical fibers on the SDSS telescope’s focal plane so that each fiber, attached to a hole on the plate, captures light from just one galaxy. That light is then funneled down the fiber optic path to a spectrograph.

 

 

 

The plate has a bunch of markings on it to help astronomers with the data collection process. Fiber optic bundles are grouped together such than each bundle gets a section of the plate bounded by a black border. Blue circles around the openings correspond to the galaxies locations for which spectra are being collected. The black circles around the holes correspond to guide star locations in the field.

The SDSS plate illuminated.

The SDSS plate illuminated.

screenshot-2017-02-14-15-50-12

This is the SDSS field of view for this specific plate. Click on this image to go to the SDSS Navigate tool and have a look around!

SDSS BOSS Plate 6192/56269
Observed on MJD 56269 (8-December-2012)
Plate center: RA = 7.98654794692993, dec = 16.3795967102051
SDSS BOSS Plate 6192
SDSS BOSS Plate 6192’s field of view as seen by the SDSS
The SDSS then converts all the spectra to plots and measures their z (redshift) values, among other things. One spectra from the many on this plate is below

 

:screenshot-2017-02-14-15-55-00

10 February 2017 Penumbral Lunar Eclipse

Students and community members joined the crowd at the observatory on Friday night (10 February) to enjoy the penumbral lunar eclipse that was gracing our skies that evening. The moon made its way above the trees in the east by 6:15pm, a lovely full moon, so bright that it looked like floodlights had illuminated the soccer fields by the observatory. It was cold!  The thermometer hovered at 11°F and the wind was calm. As people gathered, there was a pulsing of people headed into the Chart House to stay warm, along with those coming back out to view the eclipse’s progress.

This was our first almost-clear evening in quite a while. The day before was the first “snow day” that the Academy had enjoyed in a long time! The new snowfall, well over 10″ deep, had ben plowed from the paths (THANK YOU to our facilities department!), allowing access to the Chart House and Kurtz Dome housing our 16″ SCT telescope. We also had a camera with zoom lens attached, and a pair of tripod-mounted binoculars for people to enjoy.

As predicted, clouds did start rolling in by 7:30pm. With the eclipse hitting maximum at 7:44pm, we had a good view of it before all was obscured. Two good photos below: One of the moon at maximum eclipse, and one of the moonlight causing a 22° ice halo and moondog. Both taken with a D810a and 300mm lens.

moondogseclipse

Magnetometer Testing: Installation and Software Operational

The magnetometer is now installed and running in a test location at the observatory. Both raw data and a continuous plot of data are available online at: http://regulusastro.com/magnetometer/   This URL is likely to change as things become more permanent. At this time, the data correlate well with other magnetometers. We are waiting for a couple of other installations in southern NH to complete before we are able to test thoroughly and make this available for scientific use. Stand by for that!  A typical data plot is below for a quiet day. The green stripe along the bottom indicates quiet conditions. As geomagnetic activity increases, the stripe will turn yellow then red when the K index hits 6 or more.

20161215

Geomagnetic activity from our magnetometer for 2016-December-15, a rather quiet day.

Magnetometer Testing: Geomagnetic Storm Detected

The magnetometer is on a lab bench at this time and running continuously. Typical plots look like the one below from 10-October-2016. Deviations from the 00hour UT moment at the start of the plot are in nT. Time is in UT. Short vertical changes are typically automobiles moving in the area. 10-October was a geomagnetically calm day.

screenshot-2016-10-15-11-34-09

A small CME struck the Earth on 13 October resulting in a G1 level storm and some fabulous aurora for northern latitudes. The Kp index hit 6. The magnetometer detected this storm as can be seen by the plot below.

screenshot-2016-10-15-11-28-56

Getting the plots into Excel: Import the files using space and comma as the delimiters. Create three columns for delta x, y and z. Input an equation that calculates the difference between the current cell and the initial entry (format: =c1-$c$1 which creates an Excel absolute cell reference to c1). Check the data all the way down!  There are corruptions in the readout that might be from the serial to USB converter. Graphs will not plot properly unless those errors are removed. Below is what the sheet will look like when you’re ready to plot. Columns D, F, and H are the calculations of “=c2-$c$2”, “=e2-$e$2”, and “=g2-$g$2” respectively.

screenshot-2016-10-15-11-42-35

Focuser Assembly

Summertime: Time for Repairs and Maintenance

What goes into the repair of a telescope? A lot of time and technical operations.

Our robotic observatory has a 10″ Ritchey–Chrétien optical system. The system focuses by moving the secondary mirror in and out using a very finely controlled motor assembly. After years of hard work, this little assembly got jammed up solidly. The company that made the telescope has moved onto bigger and better things, namely producing to-order optics. Contacting them resulted in contacting an original engineer (James Olson… yes…) who was willing and able to do repairs on the focuser.

The focuser was removed: an intricate couple of hours removing the secondary mirror, detaching all the electronics for the dew heater and focus motor, and then balancing the telescope, since it had lost a lot of mass from its front end. The focuser assembly was then shipped to James in Arizona.

The focuser was taken apart by James, polished, lubricated, re-assembled, and tested for days before he shipped it back to PEA. Once back at its home, the focuser had to be installed back into the spider (24 bolts), the secondary mirror installed onto the end of the focus assembly (three push bolts and three pull bolts), then the whole thing tested for proper movement. A dozen runs of the focuser later, the electronics and mechanics of the system were AOK and ready for the next phase. The next phase?

Collimation! Having removed everything out on the secondary mirror region, everything was out of alignment. All the optics have to be centered on the optical axis, and aligned perfectly both perpendicularly to the optical axis, and rotationally, as these are a matched pair of mirrors… Sigh. That was a time consuming but worthwhile task. Last night the system was star tested. Success! An image of Altair was used for final touches on collimation, and an image of SS Cygni was used to test scientific data usefulness. SS CYG is now in outburst (huzzah!) and the data are perfect! We have V magnitudes to +/- 0.004. We are back in action!#astronomy #photometry #repairs #observatory #robots#PhillipsExeterAcademy

Focuser Assembly

Focuser Assembly: The secondary mirror is in the black housing inside the telescopes truss tubing.

Focuser Assembly

Focuser Assembly

Focuser Assembly

Focuser Assembly

Electronic Controller for Focuser Assembly

Electronic Controller for Focuser Assembly. This unit controls heaters, fans, focus position and more.

Altair being imaged at perfect focus

Altair being imaged at perfect focus. Success!

Milky Way seen from Cerro Tololo.

Summer Activity

This has been a very busy summer!  Much of my time was spent traveling, so here are some blog posts of those travels for you to enjoy. The trip to Chile was possible with the kind and generous support of the National Science Foundation (NSF), the Astronomy in Chile Educator Ambassador Program (ACEAP), and Phillips Exeter Academy. If you are interested in learning more about the trip or astronomy in Chile, feel free to contact me: jblackwell AT exeter.edu

Arrival in Santiago

Visit to AURA

Under the Stars of Cerro Tololo: Night 1

Under the Stars of Cerro Tololo: Night 2

Panoramic Chile

Cerro Pachón & Gemini South Telescope

Cerro Tololo: A Summit of Telescopes

San Pedro de Atacama and ALMA

 

Final Tests then a New Case

Magnetometer Build Status

An update on the build status of the magnetometer. The board has been tested for correct voltages and other parameters. The three sensors have been wired with filter capacitors and connected for some software testing as well. They have not been placed in any permanent housing, and we are investigating best practices for that. We anticipate installation in the fall term once students are back on campus and we regroup.  Some images:

The completed main board

The completed main board

The display board

The display board

The boards and keyboard attached for testing

The boards and keyboard attached for testing

This is the first boot of the system! Success!

This is the first boot of the system! Success!

Final Tests then a New Case

Final Tests then a New Case

First time operations with all three sensors

First time operations with all three sensors

Initial testing of the logging software

Initial testing of the logging software. A lot has to be done to configure this a little better, but it is good to see it in operation.

9 May 2016 Mercury Transit

The day started out as partly cloudy with a blustery wind up to about 15mph. At 6:30am, the sun was well up, and 45 minutes it both cleared the trees and was to start a morning-long experience with the little planet Mercury crossing its face. Those 45 minutes came and went, and the clouds stayed until about 10am, when things started to clear out. We even had a few strong rain showers, associated with the looming cumulonimbus clouds that were rolling by. The wind picked up, the skies cleared, and the sun came out to play!

We had two telescopes in operation. The newest, the 16″ SCT in the Kurtz Dome was operating with a newly constructed solar filter: Baader solar film and cereal boxes combined with hot melt glue and duct tape. This makes for an excellent off-aperture 6″ screen for the monster scope. The other was our Heliostat which has an inverted Byers fork mount that moves a primary flat mirror to reflect sunlight onto the secondary and then into a 6″ refractor waiting through a hole in the Chart House wall in the library. We had some excellent views and enjoyed visitors from NH and MA as well as several astronomy classes and some members of the astronomy club.

Mercury Transiting the Sun 9 May 2016

9 May Transit of Mercury seen through the 16″ SCT. A Nikon D7000 was used to snap this image which shows the small round dot of Mercury along with two sunspot groups.

16inch_workjing_end

The working end of the 16″ SCT with the D7000 attached for prime focus work.

heliostat_selfie

The heliostat in use. This is also a unique selfie opportunity.

Mercury Transit 9 May 2016

This May we have the opportunity to see the planet Mercury transit across the face of the Sun. The next time to see this event will be in 2019, so don’t miss this!  As with all astronomical studies involving the Sun: DO NOT OBSERVE THE SUN WITHOUT PROPER SAFETY: you only have one pair of eyes, so take care of them.  Only use approved filters for astronomical observation of the Sun and use them properly!  If you are unsure, contact your local astronomy club and ask.

This transit is visible in its entirety from Exeter. Timings are approximately as follows:

Event Time UT Time EDT
External Ingress 11:13 07:13
Internal Ingress 11:16 07:16
Greatest Transit 14:57 10:57
Internal Egress 18:38 14:38
External Egress 18:41 14:41