Tag Archives: eclipse

Geometry and The Moon

Please do not run away. We are about to use adult language here. For example we will be using the word trigonometry. Still here? Good.  Here is a very pedestrian looking lunar eclipse photo taken with a 280mm lens*, cropped.

Near and Distant Neighbors

Very Ordinary Photo of the Lunar Eclipse with the planet Uranus in the lower left.

This past lunar eclipse several of us put our heads together to try to come up with a more creative photo than the one above. We had a trigonometry problem, however. On the West Coast the last moment of totality occurred at 4:24 AM PDT. We were brave enough to be out at any time of night – even if it meant extreme sleepiness in our day jobs but our problem was that the lowest the moon would be in the sky at the last bit of totality was 32.6 degrees above the horizon. We determined that angle using Stellarium, by the way. Unfortunately there is pretty much nowhere to go to get a nice large moon near an interesting object when the moon is almost 33 degrees high.

Wait: Why do we want the moon and the object to be similarly sized? Here is why… we want the moon to be noticeable like the Fantasy version below, not merely “present” like the real photo on the right. Even bigger would be better, right!?

N_281-608714+C_281-8150

Notice above right (Reality) and below how tiny the moon is compared to the building in the foreground?  Indeed, if you see a photo taken from anywhere on the West Coast where the eclipsed moon is significantly lower in the sky or larger than shown against foreground, you know it has been “photoshopped“.

Plan C: San Jose City Hall Eclipse Sequence

In short, it is nigh impossible to get the large moon effect with an altitude (angle) of 32 degrees here is why:

Calculating the Angles

Calculating the Angles

Just how far away do we need to be in order to get the moon the same size as an object of interest:

114.6 x object size

In other words, an object that is one foot tall, requires us to stand 114.6 feet away to make the 1/2 a degree angular size of the moon the same angular size as that 1 foot tall object.  The number “114.6” is from this calculation:

1 / TAN (0.5 degrees)

Yeah, that is trigonometry. Using still more trigonometry it is possible to calculate how high above the horizon a 9 inch tall object has to be so that it is “moon sized”.  We did that for you in the “Calculating the Angles” diagram above. Once you calculate the distance from the camera of 85.9, you can multiply that by the sine of the angle to calculate a height of about 46 feet! Here is the trigonometry:

Height = 85.9′ * SIN (32 deg)

You can go one step farther and calculate the distance from the object with ‘distance = 85.9 * COS(32 deg)’.

Of course after all that calculating you will still need to find a location, have contingency plans for weather and so on. At StarCircleAcademy we have built some tools and put together materials to help in all these endeavors.  We teach these things in our NP111 Catching the Moon Webinar.

The Road To The Temple

Below is where we ended up. This image is from our friend and co-conspirator Andy Morris.

Lunar Eclipse over Temple by Andy Morris of PhotoshopScaresMe

Four of us plotted and schemed to get an interesting shot. Above is Andy Morris’ result.  Click the image and you can read a great article about how he created the shot using Photoshop Skills at his site: PhotoshopScaresMe.com. In fact, it’s a great article which we strongly encourage you to read. You’ll learn how he composited the images together in Photoshop as layers.

The Long Conversation to Pick a Location

Andy has more details including how alcohol played a part in the process. Mostly I, Steven, was the wet blanket explaining why the geometry was all wrong.

  • The Stanford (Hoover) Tower looks like it is shrouded in trees from the needed angle
  • Bank of Italy (formerly BofA) in SJC doesn’t work
  • The main problem with the wind turbines is that the angle to the top of them is something around 12 degrees above the horizon which is 40 moon diameters below the eclipse.
  • Here is why the GG Bridge doesn’t work…
  • This seems to be the best solution I could find: the Coit Tower…
  • Darn. It would appear the coast is out. Forecast calls for Fog from SF to HMB
  • This might make an interesting foreground (see below)… Somebody want to check if they will mind us being on their property in the wee hours?

*Ok, we lied, it was actually a 70-200mm lens with a 1.4 TC on a full frame camera, but the net is the same: 280 effective mm focal length.

Where did you go and what did you get in your planning efforts?  Post a comment and link below… we’d love to see what you came up with!

Plan C: How To Plan a Time Sequence Shot

If you missed the last total lunar eclipse, don’t worry. You’ll have another chance in October, 2014. For that, I’m grateful since as you can see I had some problems with my apparatus (the CamRanger). The battery failed after the 7th shot of the moon you see below, and then it stopped working again after 3 more shots, and needed to be slayed and restarted just as the moon was transitioning to fully eclipsed.

But this column is not about our troubles, it is about how I planned for the lunar eclipse shot you see below.

Plan C: San Jose City Hall Eclipse Sequence

 

The planning began with a list of possible foreground subjects. The San Jose City Hall Rotunda was “Plan C” and the least well researched of my plans. What were plan A and B? Those were one of my favorite lighthouses and a favorite landmark in San Francisco, California. For each arrangement I had to:

  1. Calculate where to stand to make sure the moon would be in an interesting phase above the object. The plan required solving these problems
    1. Determine how high in the sky the moon would be (to know what viewing angle was best)
    2. Determine which DIRECTION I needed to face to capture the moon.
    3. Determine how “wide” a lens I needed to get the sequence I wanted.
  2. Monitor the weather at each location.

After planning all that was left was to make a last-minute decision where the most likely target would have favorable conditions and make any final on-site adjustments.  I had a Plan D, too… but it was also in San Jose so it would have only been chosen had I found some serious obstacle at the City Hall rotunda.

San Jose City Hall Panorama

Calculating the Angles

Determining the angles needed is pretty simple. I used The Photographer’s Ephemeris including all the nifty tricks we teach in our Catching the Moon Webinar. Below you can see a screen shot from the Photographer’s Ephemeris which shows the moon altitude and direction at the beginning of the eclipse. I also moved the time ahead to show the same for the middle of the eclipse.  The moon’s altitude angle (32 to 41 degrees) gave me an idea how close to be to the rotunda to get the moon overhead.  Lower angles allow me to get farther away which allows me to photograph the moon larger relative to the foreground object. This eclipse, however, and the one in October will have the moon high overhead.

Coming up with a Foreground

There is no good substitute for knowing what interesting foregrounds are possible. And also knowing which direction(s) you should be facing.  I knew that the San Jose City Hall Rotunda was generally easterly because I had watched a sun rise through it. I also knew that the eclipse would be at maximum when the moon was in the southern sky so I knew that the range was SE to S directionally.  You can see a diagram from The Photographer’s Ephemeris below for more complete planning.

Calculating Where to Stand

I had to know approximately how tall the foreground object is. For the San Jose City Hall I flat-out guessed.  I found the overall height of the building through Google, and I guess the Rotunda was 60 to 80 feet tall.   My original calculations had me much closer to the building… it was only when I got on site that I realized that there were adaptations that needed to be made.

Watching the Weather

Remember that the Rotunda was plan C.  I kept a close eye on the weather for each of the planned sites.  My favorite weather app is provided by weather.gov – in particular the hourly graphs. We talked about this tool in detail in a prior column.  Why do I like it so much? Because it gives me numbers instead of “partly cloudy”.  It was pretty obvious that the coastal region for Plan A, and the San Francisco Landmark (plan B) were likely to have bad weather – both fog and clouds. Indeed my friends who headed those directions were frustrated by poor visibility.  We had clouds passing through San Jose, but as the weather predictions had read: it got clearest right near totality, and overall was not a hindrance.

Last Minute Adaptation

When I first got to the site, I realized that the Rotunda was taller than I thought. I set up across the street in order to be able to have the moon over the Rotunda… but there were other problems, too. One of the problems is the floodlight on the top of the building. Another was a street light just to the right of where the red marker is in the graph below. These are problems that would only reveal themselves if you visit at night!

And then there are all of those flag posts.  My original guess at the Rotunda Height would have allowed me to stand between the fountain (brown area) and the building… but that clearly didn’t work as the rotunda was too high.  Setting up across the street (and very low) also had its challenges… namely buses and cars that came regularly.  I also realized that I had miscalculated the eclipse time by an hour (forgot it was now daylight savings time).  The miscalculation turned out to be a good thing as it left plenty of time to move around.  It would seem the ideal spot was in the MIDDLE of Santa Clara Street, but that wouldn’t have worked, of course.  Eventually I picked the spot with the red marker as a compromise between altitude of the moon above the structure, removing the glare from the tower lights, the wash-out of the street light, and the many flag poles in the way.

Planning Moonrise

If only my CamRanger had cooperated, I’d have had a continuous sequence of shots of the moon passing over the Rotunda.  There is always October… and maybe Plan A will work for that!

Of course that’s not ALL that was required to get the shot. I also had to composite each of the moon shots into their proper locations. I did that by first taking a panorama of the area, then making sure that when the exposures began I had a piece of the rotunda in each shot so I could properly align the moon over its actual location.  The creation of the image used the Easy HDR method we have previously described.

Fakery Exposed….

In my last article, I discussed Bending Reality and where my personal ethical limits are in relation to photo manipulation. There has been some insightful commentary from very thoughtful people.

In this article I reveal all the ways in which my “Solar Corona, Keck & Subaru” photo (below) can be discounted as a fake.

Solar Corona + Keck & Subaru

Let’s start with the easy things.

  1. The EXIF date taken can be seen on Flickr as July 31, 2011. So there is an immediate red flag! Had I left the exposure information intact, there would have been more clues, but I wanted to hide the “iPhone” data!
  2. The implication that this was taken in 1991 fails the following tests:
    1. There were extremely few generally available digital cameras in 1991. Most were less than 1 Mega-pixel. A Hassleblad digital back or a professional TV broadcast camera were among the few that were larger than 1.6 Mpix – the size of the original photo on Flickr.
    2. The Subaru Telescope construction didn’t begin until 1992 and the enclosure wasn’t completed until 1994.
    3. The Keck Telescopes similarly didn’t exist in 1991. The first dome became operational in 1993, and the second in 1996.
  3. The 1991 Total Solar Eclipse was visible in Hawaii near sunrise but this view is facing Northwest as can be determined from Google maps.Now on to the less obvious things:
  4. There is a very suspicious small “orange ring” around the perimeter of the sun. Suspicious because it indicates an annular eclipse, not a total one.
  5. The relative sizes of the sun and foreground are way out of proportion. The eclipsed portion of the sun in this image appears to be slightly larger than the base of the Subaru telescope enclosure. That base is 40 meters wide (131 feet) and 43 meters tall.  For the base of the Subaru to be same angular size as the moon/sun, the photograph would have to be taken 114.6 x 40 meters away. That works out to 2.8 miles to the South East. But…
    1. The view is clearly taken from above since the horizon is visible about 1/2 a degree above the telescopes. The summit is less than 2,000 feet away after that it’s all down hill!
    2. The only way to move far enough away and still look down would be to do so from the air.
  6. The central (dark part) of the eclipse is alarmingly dark relative to the rest of the image. It’s darker, even, than the foreground which lies in shadow. At minimum this would indicate a composite or photo manipulation.
  7. The center is slightly off axis from the diffraction spikes above and below the sun.
  8. There are visible bright reflections off of the Keck domes – more characteristic of an un-eclipsed sun.
  9. If that is REALLY the solar corona it is much more extensive than very sophisticated instruments have observed – even more impressive than NASA photos.

So there you go. Got anything else to add? Please let me know.

PS Is THIS a photo of the Annular Solar Eclipse?

Sequenced Shots (How To)

How on earth did I end up with this:

Annular Eclipse Sequence [C_040079+fives]

What I started with was lots of shots that looked liked these first three images – i.e not much of anything.

As I went along I ended up combining the “specks” into the image at the lower left. I combined the sequence with a shot taken just after sunset (middle bottom) and the result is as shown in the lower right.

We will soon provide the explanation of how to create the result. First we would like to give some clues about how the shot was planned – because, as it turns out, planning is an important part of all sequences like this one!

Avoidable Technical Content

The May 20, Annular Solar eclipse was well documented. Particularly handy is Nasa’s map based application. Choose a spot on earth by clicking on the map and some useful data pops up:

See those highlighted numbers… they tell you that when the eclipse starts it will be 31.5 degrees high in the sky, and when it ends it will be 5 degrees high – about 27 degrees top to bottom.  Allowing another 5 degrees above and say 10 below we need an image that spans 42 degrees in one direction.  Looking at the Azi numbers  The eclipse begins at 270 degrees (due west) and ends at 292.2 degrees (WNW).  So to take that all in and allow a little breathing room we need about 30 degrees.   Thus we know our field of view needs to be somewhere around 42 degrees vertically and 30 degrees horizontally. Already it sounds like we would prefer portrait mode to keep the sun/moon as large as possible. Using one of the many online tools, like the Angular Field of View Calculator by Tawbaware. Canon people might prefer the “easy to click, but perhaps not so easy to understand Canon equipment specific calculator.”

On a full frame camera, the 50 mm lens comes out to 39 x 27 degrees. which would just fit the whole sequence.  I decided to use my 70mm lens – because I already had a solar filter for it. My plan was to wait until I could catch the sun in the upper left of the frame and the foreground I wanted at the bottom. When the sun arrived, I slapped on the solar filter and started automatic 30 second intervals between exposures.

Or Just Go with Luck

Perhaps my first attempt was not so well planned.

Mamma Glows, Baby Shines

I was too interested in keeping Mt Tamalpais in the picture and ALMOST didn’t get the whole moonset. I know better now! Over three years ago I described how I created the image.  The technique is an extension of my previously described Easy HDR method.

To Be Continued…

In Part 2 of this article, we will show you a few helpful little addenda to make the process easier to manage. We will reveal a Photoshop-only method to approach the problem, AND for good measure a nifty tool to make it easy as pie.

Meanwhile if you are intrigued by the moon, you might want to join us from WHEREVER you are on one of our fun, informative, and oh so reasonably priced Moonatic Webinars.  Or maybe the next Photo Manipulation webinar is just your size.