The Caldron and the Laser

Over the past few weeks, I’ve finally managed to explore a new part of Southwest Idaho and attempt some astrophotography.

I came across mention of the southernmost part of the Snake River and how it was also a mere 40 feet across at that point. Even the name, Caldron Linn, aroused my curiosity. I had to go looking and find where it was and why the name.

A bit of research finally pinpointed where it was on the map: close enough for a day trip. I hit up a friend to see if he wanted to check it out with me and when he found out where it was, he recommended a burger joint in Twin Falls for lunch: the Buffalo Cafe.

Caldron Linn has an interesting history. Linn is an old Scottish word for waterfall. So, essentially the name means Caldron Waterfall. It’s actually a series of waterfalls, three at this time of the year. The best time to go see it appears to be the March-May time frame rather than our late June outing.

Image of Caldron Linn showing the three main falls at the time we were there. For some sense of scale, the bottom falls is 20 to 30 feet.

From the historical roadside sign south of the falls:

In 1811 the Hunt party likened the terrific torrent of the Snake to a boiling caldron, adding the old Scottish word “Linn,” meaning a waterfall. They had lost a man and a canoe in a roaring chute upstream. Finding worse water ahead they abandoned river travel. Next year, another explorer said of Caldron Linn, “Its terrific appearance beggars all description.”

Even with the water low as it was when we visited, it’s still an impressive sight. I could spend all day there just enjoying the place and taking pictures. I definitely intend to return and spend the night. Aside from the wonderful day pictures possible, if I have done my homework properly, the Milky Way rises right up from the waterfalls, or pretty dang close.

Identifying the direction and location of a possible astrophotograph using the Android app Dioptra.

There is no approach to Caldron Linn from the south side, it’s all private land. To get to the falls, you must make the approach from the north. There’s a dirt road that includes a couple of switchbacks as you drop down into the canyon. I would not take a regular car there. Really, I recommend a pickup or SUV with decent clearance instead. Or bikes or quads, of course. Just use common sense!!

Pano of the Caldron Linn area from up on the rim of the canyon. There’s another switchback just left of where this was taken, right where you drop off the rim and start the road down to the caldron.

Now for the laser part….

When I do my astrophotography, one of the difficulties is knowing exactly where my camera is aimed against the black sky and how much of that area is actually going to be covered in the image.

Before I explain my simple technique, let me give you a few, very stern warnings.

First, lasers are dangerous. There’s no question about that. Pointing them into someone’s face risks blinding them or at the very least burning out a section of their sight. Never point a laser device at anyone’s face.

Second, it’s not only dangerous, it’s also illegal to point them at any airplanes. ALWAYS, always scan the sky to make sure there are no flashing, blinking lights moving across your view or near it. If there are, wait until they are gone. If they keep coming and going, just don’t use the laser…better safe than sorry!

Third, do NOT shine your laser through the camera from either end. You risk damaging the optics or the sensor.

The laser pointer is also wonderful for pointing out exactly where in the sky things are. For example, you can point your finger at Cassiopeia and say, “It’s that W on it’s side right there” but with so many stars, which ones make up the W you are referring to? With the laser you can point exactly to each star and draw from star to star, showing them exactly the W you are talking about. Or point out which “star” is Jupiter.

That said, I use my laser pointer to let me see where my camera is generally aimed and then exactly what part of the sky the image will cover. It’s also faster than making an exposure then adjusting the camera until you have what you want.

This is the laser pointer I use. It’s a brilliant green beam from hitting the dust in the air. Red might be better for preserving your night vision, but I’ve not noticed any issues using this green one.

Here’s how I do it:

  1. Eyeball aim the camera in the general direction of my subject by visually aligning the camera lens with the center of the area I want to cover.

  2. Put the laser pointer on the top of the lens and see if it points where I want it to. Adjust as necessary.

  3. While looking through the viewfinder and holding the laser pointer beside the camera, move the laser beam until you see it in the viewfinder.

  4. Move the laser pointer until it points, one at a time, to the four corners of the viewfinder. Hold the laser steady and take a quick look over the camera to see what part of the sky as a whole the beam points to.

  5. Adjust camera as required until the laser pointer, as seen at the viewfinder corners (repeating steps 3 & 4), covers the desired area of the sky.

NOTE, in no instance in the steps above do I point the laser pointer through the camera viewfinder. I hold it beside the camera, point it at my target, and check to see it in the viewfinder.

Steps 3, 4 and 5 actually involve repeatedly looking both through the viewfinder and over the camera at the sky so that I get an accurate idea of what part of the sky is framed in the viewfinder based on where the laser pointer beam is. That lets me know if the composition is what I want.

This is what my laser beam looks like when seen through the viewfinder. Since this was a long exposure (20 seconds), the beam in the image is fatter and dimmer from not being held steady. Visually, it’s actually a pencil thin bright green line out to whatever you’re pointing at.

Check out the above photo of the laser beam as seen when viewed through the viewfinder and you’ll get the idea. Notice how it goes off the image left? That’s because I am using the laser pointer in my left hand near the top left of the camera.

With the same caveats, this process also works well for aiming your telescope at something in the night sky. It’s especially useful if you’re talking with someone else and one of you is trying to tell or show the other where the object of interest is. With the laser pointer, they can point right at it and held on top of your telescope tube, you can quickly point the telescope to the right spot.

That’s it for this posting.

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