Sunday, August 13, 2017

Taking photos of the sun

There's an eclipse coming in a couple of weeks. I want to take lousy photos of it. But, I also want to avoid burning out my eye like an ant on the sidewalk with a magnifying glass. So, a project.
Problem: The sun is bright. Really bright. Too bright to look at. Too bright to photograph. Both eyes and cameras can be damaged by pointing them at the sun. I'll set up projection rig for most of our eclipse viewing. Its fairly easy. You duct tape a big opaque card over the front of your binoculars with a hole for one side. Then you point the binoculars at the sun and they will project a nice sized image of the sun onto a white card a few feet away. (Caution: Don't look through the binoculars!!) It takes a bit of rejiggering to get things pointed right but it does work. That way you can watch the eclipse while facing away from it -- no blindness, just a bit of eclipse-tan on the back of your neck. Huzzah!
But, of course I will want to take photos. So I need some really, really dark sunglasses for my camera.
There are a number of ways to make it safe to look at the sun. They make sunglasses for eclipse viewing. Its best to stick to companies you know for your eclipse glasses. There are cheap imitations out there that are dangerous to use. One quick spot check you can make is to put them on and look at anything but the sun. If you can see anything at all through them then they aren't dark enough.
You can buy ND filters for your camera that are made for this. They start at around 60 bucks for a screw-on ND 100000 filter and most cost more. So, I decided to try a less expensive do-it yourself alternative.
On thing you can used to safely look at the sun is the lens from a pair of shade 14 welder's goggles. The lens looks like a black glass disk but if you look through it at the sun you will see the sun as a green disk that won't set your retina on fire. Perfect!
For my project I needed the aforementioned welding goggle lens (50mm shade 14) plus a couple of step-down rings to adapt the 50mm lens to the 62mm filter size of my camera lens. Here's my kit:

And here is the mess that I made of it. Happily, epoxy fingerprints will mostly scrape off of glass with a razor blade.

As one might expect, as soon as the glue had set clouds covered the sun which didn't make an appearance for several days. But it did finally come out and I was able to snap a few photos. Here's one of them.
Not bad. I was hoping to see sunspots. But I checked a solar observatory website and there aren't any right now. This proves my filter works perfectly -- there weren't any sunspots and I couldn't see any! Perfection!!

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