Sunday, October 19, 2014

DSLR Solar Observing Test and Sunspots October 19, 2014

Using my home made solar filter attachment for my DSLR, I did my first solar observing test today. I couldn't have asked for anything more for a first try! How exciting! Not only do I have a ballpark set of numbers camera settings to use on the partial eclipse, but I was able to observe and identify sunspots for the first time ever!

canon T5i sun photo
Canon T5i, stack of 15 frames each at ISO 100, 300mm, f/7.1, 1/15 sec

sunspots DSLR 300mm
Same as above with sunspot active regions labeled. 2192 recently produced a large solar flare (link).
So this solar observing test also prompted me to learn a little more about sunspot naming or labeling. It turns out, "There is no naming or numbering system for sunspots. There is a system for numbering active regions, however. An active region can contain one or more spots. The National Oceanic and Atmospheric Administration (NOAA) numbers active regions consecutively as they are observed on the Sun" (source).

During this test, the sky wasn't totally clear - but I was still able to observe sunspots. Can't wait to try it again when the sky is perfectly blue.

observing conditions
Sky conditions during my solar observing test
I looked up the sunspot active regions on the SOHO website and easily compared it to my photos. Here is a side by side version. I had to rotate my sun to match the orientation of the SDO image.

sunspots and active regions
Comparing my photo to the SDO image at the same time, you can clearly see the two large active regions, and faintly make out the two tiny ones in between. They are more apparent if I crank the contrast but it ruins the look of the image. 

I learned a lot about taking photos in the daytime. It was really difficult trying to focus on the sun, but I used the live view method of zooming in and manually adjusting while looking at the large LCD screen. The reflection on the screen was so bad, I had to cover myself and the back of the camera with a jacket in order to see it clearly. I felt like one of those old-timey photographers with the hood over the back of the camera.

taking photos of the sun
Whatever gets the job done!

Also, in case you were wondering what the photos look like straight out of the camera, here is an untouched shot prior to stacking and cropping. It still has a pleasing orange color because I'm using black polymer instead of Mylar. To compare, I think the telescopes had Mylar filters for the transit of Venus event that I photographed with my iPhone through the eyepiece.

sunspots DSLR at 300mm
Single frame straight from Canon T5i, ISO 100, 300mm, f/7.1, 1/15 sec

home made solar filter or DSLR
Here's another look at my home made solar filter, it looks pretty good in the daylight

Saturday, October 18, 2014

$10 DIY Solar Filter for DSLR Camera

I made a solar filter that fits over my DSLR lens for $10 and it only took me about 10 minutes. I made it to photograph the partial solar eclipse that will be visible for much of the western and Midwestern US on October 23, 2014.

The only real cost was for the 4"x4" sheet of Thousand Oaks Optical black polymer solar filter. You can by it in bulk to bring the cost per square inch down, but this 4 inch section is more than enough for what I'm making and was about the same price as a pack of 5 solar eclipse cardboard viewing glasses. I chose this over Mylar because it is supposed to make the sun appear a more natural orange rather than blue-green.

I've read other posts about making ones out of CDs or x-ray paper or whatever - I wouldn't skimp on this just in case. It's just $10 and shipping took 1 day, don't mess around, just get a sheet of the good stuff. It still beats a threaded camera filter for $50-$65 using the exact same black polymer.

how to make solar filter for camera
Final product fits snug on lens and holds the black polymer filter in place

This is the final product, and the photos below show the sequence of making it out of tape and a black school folder.

solar filter arrives in the mail
Thousand Oaks Optical black polymer solar filter arrives in the mail

thousand oaks optical black polymer
Black polymer solar filter 4"x4" sheet

trace camera lens circumference
Used the lens base cover to approximate the size of the viewer

trace camera lens circumference
Traced it with a pen and cut it out

school folder on floor
Made 4" squares on a school folder

cutting out folder
And cut them out

how to make a solar filter for camera
Cut a strip of the folder and rolled it up to wrap around the lens for size

solar filter for camera lens
Wrapped it around and taped it to size

solar filter for camera
Cut wings on one end and bent them flat. Taped the flaps between cardboard and folder

Flaps are taped down to cardboard and folder taped over that to cover

make a quick solar filter

easy solar filter for camera
Put the solar filter uncut between the sandwich made of folder and cardboard

diy paper solar filter holder
Taped all around to hold in place. Now my solar filter is uncut and un-damaged and held in place

Thursday, October 16, 2014

Take iPhone Solar Eclipse Photo with One Simple Trick

Ok so if you're like me, you love snapping pics with your iPhone, and you love solar eclipses, but you can't figure out how to take a solar eclipse photo with your iPhone. Well, you could get a telephoto lens, a solar filter, and a tripod - or you could take advantage of one neat trick about the lens flare on an iPhone.

Have you ever taken a picture of the sun with your iPhone? You'll notice a little white dot in the lens flare. This little white dot actually represents the face of the sun's disk. It becomes apparent when the sun is eclipsed by the moon, and the little white dot becomes a little crescent sun.

how to take eclipse photo with iphone
Left: iPhone photo of the sun not during an eclipse; Right: iPhone sun photo during partial eclipse (I added the arrows)

No solar filters or fancy tricks needed, just point your iPhone at the sun without any additional equipment or lenses and look for the little white dot in the lens flare. BUT DO NOT LOOK AT THE SUN WITH YOUR EYES! ONLY LOOK AT THE SCREEN! - or better yet, don't look at all... just hold your iPhone up and click a few photos, then see if you got it!

If you are going to go the solar filter or solar viewer route, I prefer a 6"x6" Solar Filter Sheet for Telescopes, Binoculars and Cameras rather than getting a 5-pack of solar glasses. This way you can use it for your DSLR or telescope now or in the future, or cut it up and make twice as many DIY eclipse viewing glasses.

Remember, even through solar filter sheets, the sun will still be extremely tiny with the iPhone camera. Other solutions are a DIY sun projector, or even something as simple as a pinhole solar viewer.

What Will October 23 Partial Solar Eclipse Look Like from Indiana?

I haven't seen a partial solar eclipse in a long time, especially not at sunset and not since I moved to Indiana. So what will the partial solar eclipse on October 23, 2014 look like as it sets? Will the eclipse be visible from Indiana? What percent of the sun will be covered, and at what time? Let's find out...

I usually use software like Stellarium to approximate what I can expect to see, at what elevation above the horizon and in what direction. In this case, Stellarium (top below) does give a good approximation of what I can expect, but doesn't give me details like time of maximum eclipse and percentage of totality (is that a term?).

what will eclipse look like indiana october 23
Screenshot from Stellarium showing the partial solar eclipse from Indiana at about 6:25pm ET

what will eclipse look like indiana october 23
Image from Eclipse Calculator
I was really impressed with the information on! It looks like the eclipse will reach its maximum at 6:47pm just minutes before sunset at 6:53pm ET. That's cutting it pretty close! The sun will be just 0.5° above the horizon - that's less than the width of a finger held at arm's length, or about the width of the full moon. You will need an extremely clear view of the horizon, or find some elevation such as the roof of a parking garage.

The partial eclipse begins in Indiana at 5:44pm when the sun is at an elevation of 11.6° - or about the width of your fist held at arm's length. If you want to plan ahead to see if your favorite spot will provide a clear view, you can read my other post with Three Methods to Measure the Elevation of Objects on the Horizon. I'd also recommend the app PhotoPills because it lets you use augmented reality to view the path of the sun at any time on any date.

I have a meeting at 7:00pm sharp, but I think I'm going to try to get a quick view from the roof of a parking garage on the IUPUI campus to see at least part of the eclipse. I was going to try to get a photo at sunset, but there's no way the sun will be dim enough at 6:30pm to photograph or try to view with the naked eye - so it looks like I'll be making a pinhole viewer and trying to snap a quick iPhone pic of the projection. That definitely still counts and it's much safer!

iPhone Bonus! You can actually take an iPhone photo of the eclipse using this one simple trick

Saturday, October 11, 2014

Full Perfect Rainbow at Sunrise

On October 6, 2014 I was having coffee and starring at my backyard (as I tend to do) when I noticed a huge perfect rainbow created by the horizontal light of the sun right as it was rising! I'm not sure if this is true or not, but my impression was that the rainbow was taller and narrower than rainbows later in the day - possibly because the sun was shining directly sideways as it was rising. But I'm not totally sure!

full rainbow over house with pink middle
Panoramic photo with iPhone 5
It was a double rainbow (in some areas) but I love how it looks like a big pink force field over the neighborhood. Indiana is like the rainbow capital of the Midwest I swear!
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