Archive for the ‘Astronomy’ Category

The Caldron and the Laser

11 July 2018

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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Astrophotography Workflow

12 October 2017

Since the last time I blogged about my astrophotography tools things have changed somewhat. I thought I would write up my current workflow, without making it as much an app tutorial as I did last time.

For starters, I no longer use The Photographer’s Ephemeris. Ever since it moved to online only, it’s been pretty much useless to me in the field. It was a great program, and still is, for laying out sight lines, times, and such. Unfortunately, with it being online only, I can’t use it in the field to work out things.

I pretty much rely now on two phone apps and a computer program:

Stellarium: In the field on a laptop or at home, this is my favorite planetarium program. It lets me see what the sky might show on any location, date and time, and conversely allows me to see when a particular sky object might be where I want it for a photograph. Plus it’s great for finding your way around the night sky on site.

Dioptra: An Android only app, it illustrates the adage, “a picture is worth a thousand words.” With it, I can record in one image the desired view from that location, the actual GPS coordinates, and the compass bearing of the view. It records a few other details as well, but those are the ones I focus on.

Sun Surveyor: Available for both Apple and Android, I use this mostly on-site. Its Live View allows me to see the paths of the Milky Way, sun, and moon through the sky superimposed on that location. It’s useful in allowing me to get everything aligned on that spot and ready to take pictures before dark.

Yesterday, I went into the Owyhees with the goal of scouting a location. As can be seen later, the location doesn’t align for the planned photo shoot any time soon but using Stellarium I was able to identify a different possibility that I could take advantage of.

What I list below is pretty much my usual workflow.

Generally, I start out with an idea, which for some reason seems to tend towards shooting from in a canyon to frame the Milky Way or a planet or constellation between canyon walls. This time, I was thinking “Milky Way above Succor Creek.” I know the Succor Creek picnic area is in a narrow canyon (see what I mean?) and there is a bridge that crosses over the creek there. So, off I go into the Owyhees.

A cowboy, in baseball cap, chaps, jeans, jacket, on a brown horse herding three cows and a couple calves under a mostly white cloudy sky alongside the dirt road in the Owyhees.

A working cowboy herding cattle in the Owyhees.

After a relaxing drive, I arrive at the site. I take my camera bag out on the bridge, and position myself centered over Succor Creek. After first turning on the GPS, I pull up the Dioptra app. Once it’s open and I verify I have a GPS lock I wave my phone around in the classic 3 figure 8s to calibrate the compass.

Hmmm. Just had a mental picture of me in a hooded cloak, mystically waving my arms to summon Magnetic and command him to calibrate my compass.

Anyway….

The next step is to simply point the phone camera for the view I want and take a picture. The app then records that view overlaid with all the necessary “notes” I need to work with Stellarium.

A view up a creek with heavy growth of small trees, brush, and grass on both sides. In the far distance a butte sticks up from the horizon visible between the brush, aligned with the center of the creek. Partially white cloudy sky, mostly blue sky. Superimposed is various information from the Dioptra app like a heads-up display.

The output of Dioptra at the bridge over Succor Creek, Owyhees, Malheur County, Oregon.

While it’s hard to see, in the center of the image is a reticle that gives you an aiming point. I usually only use that for direction alignment on some landscape feature that I might want in the end image. Under that is a compass bearing, in this case 138° which is the direction of interest, straight up Succor Creek. Luckily for me, that distant butte is in line with the creek. In the upper left is the latitude, longitude, and altitude of that spot on the bridge. At the bottom is the compass direction. The two angles on the side are useful for getting the camera perfectly level but in this situation I don’t really care about those.

As you can see, one of the current issues with Dioptra is the use of white text and no way to change that. Hopefully, the programmer will be adding an option to change the text color in the future, but for now there are some workarounds. For example, you can change the camera angle to put the text onto a darker background and take a second picture. Or put your hand over the lens. That gives you the first picture showing you the planned view orientation and a second picture that ensures you get all the necessary information.

Similar to previous Dioptra image, but from the middle of a dirt road. Back half of a blue-green blazer visible to left, steep redish brown cliffs to either side of road.

Another Dioptra image, this time on the road to Succor Creek. Note the better visibility of the information upper left.

This is a Dioptra shot at another location. Notice the center information is almost completely lost in the white cloud but the information top left stands out quite nicely. It’s hard to see, but this straight run of the road lines up on 162°, a bit more towards the south and an alternative which would give me those distant rock fingers reaching to the sky.

My next step is to take a few shots with the camera and lenses I am considering using. In this case, I took an image at each end of two zoom lenses, my fisheye (10-17mm) and my regular 18-55mm. I usually use the fisheye for my astrophotography but it’s useful to try the other lenses as well. Sometimes the framing in a different focal length just works better and if you don’t check that, you won’t know that.

Succor Creek test photo, 17mm focal length.

Succor Creek test photo, 10mm focal length.

Succor Creek test photo, 35mm focal length.

Back at the house, I pull up Stellarium on the computer. Using the location function, I enter the latitude, longitude, and altitude. Next, I move the view to the desired compass bearing. I can also set the field of view to match that of the lens I plan to use but I tend to leave that at the default setting unless it’s a site I use regularly and have a landscape for.

Pulling up the time function and setting it to 2300 tonight, I saw that the Milky Way wouldn’t line up with the creek…at all. It would be coming up over the canyon wall to the right. The 10mm focal length image above does show that I could get a decent shot with the fisheye and still be able to have the creek in the image. The creek wouldn’t be going down the middle of the image, though, if I really want to maximize the Milky Way. That creates a potential line that guides the viewers eye away from the Milky Way.

Not good. At all.

So, now I start clicking on the day in the time function, advancing roughly 24 hours per click. As I watch the screen, I notice the moon goes across the scene regularly. A bit of playing with the time and date shows that I could possibly get a shot of the moon high over the distant butte. The creek would guide the eye to the butte and the butte would point up to the moon. With the right moon, Succor Creek would be a ribbon of silver. That’s a decent possibility.

Advancing day by day again, I come up with a shot that doesn’t have the Milky Way, but does have Orion over the distant butte. Hmmm. That’s another possibility. The moon would be up, but hidden by the left cliff wall. The date says 2017/12/6…December 6th. Depending on the weather, that might be fun.

Stellarium, showing Orion above the butte. Succor Creek would be visible vertically in the lower 1/3 center (as seen in previous pictures).

Finally, I get the northern part of the Milky Way aligned…on 2017/12/27. Not as impressive as the main body of the Milky Way, but a possibility. I really want the center band, though, so I continue advancing…to 2018/06/11. Sigh. All the way to next June before I can get that shot.

Hey, Saturn’s there, too, and pretty much right over the butte!

Imagine the 10mm image of Succor Creek above with the Milky Way over it. Saturn would be directly above the butte.

So, now I have a few dates for images that might work at that Succor Creek bridge location. I know what to expect, where to aim the camera, which lens I will probably use, how early I have to be there, and how late I’ll have to stay. It’s a good opportunity to just go camping, too, knowing I’ll have some neat pictures of the night sky as a result.

If the weather cooperates.

K3 First Light – M42

17 December 2014

To paraphrase the narrator in a YA fantasy trilogy, “Say what you will about the Pentax K3. Say that the K3 is fast.”

All images here are shown without any post processing other than to convert from RAW to JPEG. I did resize them smaller to save space but you can still see the noise and M42 for comparison.

Sunday I got up about 0300 to get a drink of water and looked out the window at the night sky. It was so clear, the stars were so bright, I could see Orion, and it was 30° F.

I went back to bed. I lay there, thinking how great the night sky was. I thought about my new camera and how it would be a great chance to check ISO vs shutter speed. I thought about how I would set up that test. I thought how Orion was right there. I thought how I really should go out and take some astrophotos.

After the third time through all that, I thought, “Geez! Quit thinking about it! If I’m going to think about it this much, I should just get up and do it!”

So I did.

M42, the Orion Nebula, aka the Great Nebula in Orion, taken with my new Pentax K3, 400mm, 5 sec., f/5.6, ISO 1600.

M42, the Orion Nebula, aka the Great Nebula in Orion, taken with my new Pentax K3, 400mm, 5 sec., f/5.6, ISO 1600.

I mounted my Tokina 400mm on the K3, set up the tripod, connected the cable release, and went to work. My plan was simple: to run a series of shots to explore the results of different shutter speeds applied to each available ISO suitable for astrophotography.

First of all, this was from my driveway, which is not exactly a dark sky site. The light pollution isn’t all that bad, fortunately, but it’s there: you can’t see the Milky Way, but you can make out M42, the Great Nebula in Orion, as a fuzzy patch.

Given the 400mm’s small field of view, I decided to make M42, the Orion Nebula, my target because it was right there in plain sight, at a comfortable angle, and easy enough to line up on. Since this was just a test to see what I would get, I set up everything and did the shooting without checking each image immediately afterward. After all, I just wanted to see what each combination of ISO and shutter speed would give me. Plus it was 30° F and getting colder.

From experience using my K10D, and to some extent my *ist DL, I knew that I needed to expose for 10 or more seconds to get anything. I wanted to see how much noise there was at the higher ISOs. I decided that I would test with the following string of shots:

ISO: 51200, 25600, 12800, 6400, 3200, and 1600

Shutter speed: 30, 25, 20, 15, 10 seconds

The remaining variables were constant: aperture was wide open at f/5.6 and the focus was manually set. Since this 400mm doesn’t have an autofocus or auto-aperture, the K3 required me to manually enter the focal length. There was no setting on the K3 for 400mm but there was 600mm so I used that. Afterwards, for just the photos posted here, I used an EXIF editor to correct the reported focal length (changed from 600mm to 400mm) and effective focal length (changed from 900mm to 600mm).

The first new thing I played with was the focus. The Pentax K3 has Live View, and I was eager to try that. My 400mm is fully manual, so I set the camera to manual focus mode. Then I made sure the aperture ring was turned to 5.6, wide open. Next I focused through the eyepiece as best I could, triggered Live View and zoomed in on one of the stars visible. Watching the Live View, I adjusted the focus ring on the 400mm until I had the sharpest possible view of the star. I don’t think it was perfect, but it was definitely at the best possible focus.

The next step was to compose my shot. I was using a cable release to avoid any shaking from pressing the shutter release. For the timing, I wanted it to be consistent, so rather than using Bulb mode I used Manual mode and set the shutter speed to each of the desired values as the shoot went on.

I started with ISO 51200 and 30 seconds. Then I went to 25 seconds, 20 seconds, 15 seconds, and finally 10 seconds. At that point, I dropped the ISO to 25600 and worked my way back up the exposure times. Next, ISO to 12800 and downward on the speeds…you get the idea. I shot all the times against each ISO before changing ISO settings.

At the top of this post I mentioned that the K3 was fast. I’m used to every 30 second exposure needing 30 seconds to store the image to the SD card. Even with my old, non-high speed SD cards, storage to the card even with noise reduction on was still well under 30 seconds. It even seemed to speed up as the shoot went on, perhaps due to the cold?

While changing the ISO, I accidentally went to 5 seconds exposure when I moved the wrong wheel. I was about to change it back to 10 seconds when I decided, “Why not?” So for the end of the downward run at 3200 and the upward start to 1600 ISO, I had two 5 second exposures.

It wasn’t until the next later that morning that I actually looked at the pictures to see what I got. The results, as they say, were nothing short of astounding. For one thing, I flat out did not expect to get the purple/pink of the nebula in the images. I simply had never tried imaging M42 with the 400mm before. Hades, I hadn’t even expected that simply with the 400mm I could achieve a “classic” image of M42! I thought you needed a big telescope for those.

At only 5 seconds of exposure at 1600 ISO, I fully expected the whole image to be black, with maybe a couple of stars showing up. That was NOT the case and I was floored with the result.

The unprocessed (other than to convert from RAW to PNG) 1600 ISO 5 second image is at the top of this post. Even the 3200 image below is awesomeness.

M42 Orion Nebula Pentax K3, 400mm, f/5.6, 5 sec., ISO 3200

M42 Orion Nebula
Pentax K3, 400mm, f/5.6, 5 sec., ISO 3200

There is more noise with the 3200 than the 1600 ISO, as would be expected, but more of the nebula is visible in the 3200 ISO shot, again as expected.

At first I didn’t expect to see star trails, but then I realized that the field of view through the 400mm is so small that it would take less exposure time for the stars to move across the image than for, say, a 135mm lens. Or a 50mm.

At the higher ISOs, the image is actually washed out from being overexposed! I absolutely did not expect that. Things really only start getting visible in the 10 second 51200 ISO exposure.

M42, the Great Nebula in Orion, buried in the overexposure. This is the first image (see text) where M42 is truly visible in a test image. Pentax K3, 400mm, f/5.6, 10 sec., ISO 51200.

M42, the Great Nebula in Orion, buried in the overexposure. This is the first image (see text) where M42 is truly visible in a test image.
Pentax K3, 400mm, f/5.6, 10 sec., ISO 51200.

Working through the images afterwards, it was very noticeable that there is a line in the sand related to noise and it’s at the 12800 ISO vs 6400 ISO point. This is clearly evident in the two images below.

Showing the dividing line between ISO 12800 (left) and ISO 6400 (right). This is the point where the noise level really drops between ISOs. To either side of this line the noise level is gradual, here it's somewhat abrupt.

Showing the dividing line between ISO 12800 (left) and ISO 6400 (right). This is the point where the noise level really drops between ISOs. To either side of this line the noise level is gradual, here it’s somewhat abrupt.

All in all, I am very pleased with my new Pentax K3 camera. I certainly didn’t expect to get such a “classic” image of M42 with just the K3 and my old manual 400mm Tokina. And with the pink/purplish glow of that nebula, to boot! This camera has several tools such as internal stacking that are ideal for astrophotography and I’m really excited to play with them.

Hmmm. I wonder what’s possible with my Classic Celestron C8 mounted on the camera? Or even just with the K3 plus 400mm piggybacked for tracking. ISO 1600 for 3 seconds each, stacked? ISO 3200?

I can’t wait to get out and try again now that I know what this Pentax K3 is capable of.

The best of the season to you all!

See you next year.