I'm Steve, and this blog is about what I'm working on or thinking about right now. At least it was when I wrote it. I'm guessing I've already moved on to something else. ;)
Yesterday, our Cub Scout pack turned out a week in advance of the solar eclipse to learn about science and safety. We also worked on requirements for their 2017 eclipse patch.
BSA Solar Eclipse Patch
The lesson was structured as a “reverse quiz”. The attendees asked canned questions found on randomly drawn slips of paper. Our eccentric instructor answered as best he could. I think he might have been sneaking peeks at his notes. Nobody can keep that much eclipse info in their head at once.
These pictures were frame captures from video taken by the scouts.
These binocular solar filters have been given “professional” facings. Looking for sunspots. One scout’s design adds extra solar shielding from a box making it cooler and removing some internal reflections on the inside of the glasses. Looking for sunspots. Demonstrating a pinhole box viewer. Demonstrating an pinhole box viewer made from paper tubes. What it looks like during totality. Who will be able to see the eclipse on August 21st? What is the pinhole effect? Put on your solar helmet, Box Man! What is the diamond ring effect? There’s a DIY solar filter made from the Silver-Black polymer film from Thousand Oaks Optical on the front end of the telescope. Hopefully the number answering yes will increase this year. Checking out the sunspots. There’s still a sliver! Approaching totality in this video from 1991. Get ready to try something like this during the eclipse!
I used holes from a push pin. You might try something bigger. Maybe a bunch of different sizes to see what works best
They say you should use the full moon to get your initial exposure settings for the totality phase of a solar eclipse. I guess the settings for my setup will be like the ones I used on this picture from last night.
1/100s and 100 ISO Nikon D7100 on the back of a Celestron 90GT 910mm Telescope
The video tests were similar. I liked 1080p30, 1/125s, and 100 ISO.
We’ve been having a lot of rain, clouds, and haze lately. Last night was my best night for the full moon trials. Today, I moved on with the sun trials.
1/125s at ISO 100 Nikon D7100 on the back of a Celestron 90GT 910mm Telescope Thousand Oaks Optical Silver-Black Polymer Filter
Wow. How boring is this? One teeny sunspot? Hmm.. I’m not getting great focus today. Moist atmosphere I think. I did get rid of the light leak by covering the viewfinder. The contrast is great! I also worked to shield the monitor so I could focus without glare in the daylight.
Getting things in focus. Well, technically, I’m centering.
My son took that one. There’s an HDMI port on the camera. I ran it to a 24″ monitor and put that in a box with a black cloth hood. Works for my old eyes.
The monitor in the box
There’s a reticle taped to the frame of the monitor. It helps me keep the sun/moon image centered when there is drift in the tracking. When I see error, I can adjust with the slewing controls on the telescope. The image is a composite of several reticle types I found on the internet. I wanted concentric circles, a cross in the center and a ring with degrees for noting the position of sunspots. I used a similar reticle for the July 11, 1991 eclipse.
Closeup of the reticle. Remember making overhead projector transparencies for presentations? That was before PowerPoint and cheap video projectors. This is pretty much one of those. Who still has the plastic? I didn’t. 5 sheets for $6 on Amazon! This time I used my inkjet printer to add the text and lines. Last time I copied the reticle from a book onto the transparency sheet using the copier at work.
Well, it was bound to happen. He’s been watching me build solar contraptions for quite a while now, and he had his own idea. The idea was to block out as much extraneous light as possible by making a sort of helmet with eclipse goggles to filter the sun. The BM stands for Box Man. You know I’m proud!
How about this one:
Another eclipse viewer
It’s an indirect eclipse viewer: our own collaborative design. We started with ideas gleaned from a Boy’s Life article. There’s a pinhole in aluminum foil at the top of a stack of two paper towel tubes. That puts a ¼” image onto white cardboard at the bottom of this half oatmeal container. The eyepiece is a toilet paper tube pointed at the image. He built it and tested it with some guidance. You aim it by minimizing the shadow of the tall tube on the oatmeal box end.
Selfie showing the DIY filters I made for my binoculars. Of course I can’t see anything dimmer than the Sun though them. 🙂 I used the same construction technique as I did for the telescope filters. The cool eclipse mirror is the one that hangs in the art niche in our hallway.
When I showed these filters to my dear son, he commented that he didn’t think they looked very professional. At that moment I had a very “professional” idea…
8/5/17 Update
Some “Sun Shades” for the binocular eclipse filters!
When you are facing the sun for long periods of time, you might benefit from an extra bit of shade. Hence, the shielding disks I added. As I manipulated the binoculars to adjust for eye distance, I realized the disks were kind of “eclipsey”, so I decided to put sun and moon images on them. Well, that simply wasn’t enough drama, so I added faces. The sunglasses idea just tries to bring some sanity back to the whole thing. Totally professional! I can not wait until I whip these out in public! I might need a piece of white “tape” to hide that crack between the glasses halves.
These are the first night-time shots with the D7100. They are looking pretty good! The pictures shown here are cropped from the full frame, but not altered or re-sized.
The Moon
7/27/2017 21:11CDT, D7100+90GT, 1/50s, ISO640
I got back to experimenting with the camera on the telescope. Object tracking is much improved now that I have precisely leveled the tripod with a round spirit level before adding the tracking mount. Here I’ve put the Nikon D7100 on a T-ring in line with, and at the end of, the Celestron 90GT telescope without an eyepiece. I’m getting a 2000 pixel moon image, and that’s good enough for stills in 4K video. Focusing is much easier at night, but it’s still difficult. I plugged an HDMI cable into the camera and hooked it to a computer monitor. The big screen helps my old eyes, but it’s still the same number of pixels being displayed as on the back of the camera. The exposure is not the same when the photo taken vs. setting up the shot. During set up, the camera seems to use a lower shutter speed causing the image to be blown out with highs and it that makes it hard to focus. The shot taken on release comes out much clearer due to the higher shutter speed. If I can get manual control of the set up shutter speed, I can focus better. Camera shake due to wind is still a problem. I’ve added a sandbag suspended under the tripod legs to weigh the telescope tripod down. The bag swings slightly in the breeze but at least it’s not so much of the high frequency shake I was getting before. I might be able to dampen that some by making the bag just touch the ground
I might want a higher ISO to get more depth for the corona during totality, but this seems best for this shot.
Jupiter
7/27/2017 21:24CDT, D7100+90GT, 1/125s, ISO1000
I tried Jupiter using the same setup as the moon shot. We could see two or three of Jupiter’s moons when we used the eyepiece, but I don’t see them here. I used a higher ISO and shutter speed to help freeze the shaking image.
Saturn
7/27/2017 21:28CDT, D7100+90GT, 1/60s, ISO640
The wind died down some, so I could go slower for more color.
OK, so my last sun-addled brainstorm did get me started on a T-shirt logo. Here are my first inklings:
Just getting started
I’m using the hot pink outline to emulate the hydrogen alpha spectrum you see in eclipse prominences, and a nice fuzzy corona. The font is pretty crazy and goes well with the theme. The background subject is going to be a solar eclipse with the sol part of the word over the sun, and luna over the moon.
July 27, 2017
After a lot more work, I think the design is done.
The finished design
I added a starfield background, A hydrogen alpha image of the sun, and a nice, cratery moon. Eclipse aficionados will no doubt realize this image is not representative of an actual solar eclipse. The moon would be a black shadow, and the stars would be washed down into the blacks from the heavy filtering needed to show the sun in this way. And what the heck is that fake lens flare doing way over there on the left? I’m really starting to think this has been Photoshopped. I broke up the word parts with alternating colors. Hopefully it’s appealing.
By the way, It’s weirdly hard to find royalty free images of just stars online. Usually something else has been centered in the foreground. The field I used here came from the top of a NASA photo describing the Catalina Sky Survey (asteroid hunting efforts) on Mt. Lemmon near Tucson.
August 4, 2017
The first one!
The one shown here is a large Hanes tagless. This is the custom shirt where you can fill in the four lines of text with what you want. Note the top line is larger text, and there’s a gap between the 2nd and 3rd.
Here’s a closeup of the dark shirt after one wash.
The dark shirt styles have white ink in the image. While the image is more breathable than typical T-shirt paint, it is less breathable than the other style shirt without the white paint.
But wait, there’s more!
Ron Popeil would be proud. In addition to shirts, I also have some stickers that look great on laptops, autos, and eclipse gear.
e·clip·so·lu·na·tic (i-ˈklip-sō-lü-nə-tik) n. Person obsessed with eclipses to the point of insanity – but not quite, as they can probably quit any time. syn: ECLIPSE CRAZY
Identifying the eclipsolunatic in the wild
One easily visible sign is that his hat may be on backwards. Not for lunatic style, but because it interferes with viewfinder work. Another telltale sign is wide open bug eyes. His eyes may be glazed, red, or downright smoking if he forgot to put the safety filter on. Retinal ghosting may have him stumbling around like a drunken fool. He might be a little crazy from the heat and/or “eclipse time crunch” stress. WARNING: Stay well clear of this fellow.
The E-word
As far as I know, the six sylable frankenword eclipsolunatic didn’t exist on the internet before I smashed all the terms together: eclipse, Sol, Luna, lunatic. I did a google search in 2012 and didn’t see one hit. Proof! 😉
That word again came to mind after I had my son take this picture:
I’m … man
Ellipsis Man? Nope, not the series of dots representing an omission. Something else, I just didn’t know what to put there. Where? In the caption? No, right here on my chest! I knew I wanted a new eclipse t-shirt to wear for the coming eclipse, and I thought I’d better figure something out. Yeah, something I could subject the whole family to. What was it? Dangling Preposition Man? No! Keep it together … Man, and stop talking to yourself. OK, OK, you don’t have to be so critical of you.
OK, so let’s take one tiny step back because I know you have questions. And it’s not just questions about sanity. Your real question is: “What is that cape thing in the photo and why would you put that photo out in a public place?” [Nailed it didn’t I?]
Well,
It’s not a cape!
What, again? Another embarrassing picture?
So it looks like a cape, but it’s really something to use as sun shade at the solar telescope. I was really wanting something that’s white on one side and black on the other. The idea is to keep the sun’s rays out and the dark in. The sun had been frying me while viewing and I think it was cooking my brain. I needed some shady relief. The covers they sell for telescopes are pretty expensive. I found this inexpensive silver waterproof barber cape online. It works well draped over a black layer of muslin. Maybe you are looking for a solution yourself? There it is, and that’s my story.
Oh wait, so it actually is a cape then? Yes, yes, but we can restrain our self right? Uh, apparently, not. Dun, dun, da, DUUN!
I did press on to make the logo and the shirt. I never did go back and ask my sidekick to re-take the pictures in the shirt with the, ahem, telescope cover.
After seeing something similar on line, I built this gizmo out of 1/2″ PVC pipe and cable ties. It should help me align to the Sun by maximizing the bright spot in the middle of the shadow. The bottom tubes keep the top tube aligned with the scope tube.
Better than the toilet paper tube ideaZip-tie constructionZip-ties in placeUse an index card to check the aimIt needs to stick out beyond the filter
I set up the scope to see how the filters worked. This is the Celestron 90GT that Santa brought us for Christmas in 2014. It looks a lot like the $189 model from Costco. So far so good. There is a filter on the main scope and one on the smaller spotter scope near the eyepiece.
First Light for the New Solar Filters
First light through the new solar filter I put together. This somewhat unimpressive shot of our star was taken on my Samsung Galaxy S7 pressed against the eyepiece of the Celestron 90GT with my DIY filter on the objective end.
I’m still working on a few things here. First, the focus isn’t great because I need some shade out there so I can see what’s going on. Second, I’m still trying to figure out how to use the solar align feature of the NexStar controller, and the Sun keeps drifting out of frame while I mess around with the camera. Third, with this high magnification, the slightest breeze, camera movement, or hand shake blurs the image. I’ll try lowering the tripod so I can sit on a stool or chair for more stability. This is all stuff that can be worked out. No show stoppers.
I’m happy that the 20mm eyepiece makes the Sun’s image just about fill the view. It seems possible to observe surface details with this setup. I have a 4mm I’ll try, but that might be too much zoom for a steady photo. I’m considering a 30mm or 40mm to pull back a little bit more to gain some margin for alignment error and to see more corona during totality.
Testing with the extension tube and T ring on the DSLR remains.
Standard Scope Eyepiece Setup
I’m working out how to go from the standard setup (pictured above) to one with a camera attached. I hadn’t seen any specific “do it this way” descriptions for the 90GT. The silver tube is the focus tube. It moves in and out of the telescope to set focus. At the pictured distance, the 20mm eyepiece (also pictured) gives a sharp image to my eye. That image can also be photographed with a smartphone against the eyepiece. The next few photos will show the information that was unknown at the time I bought the extension tube and T ring for the camera.
Using the T Ring by Itself
This camera setup is probably the simplest, and likely best. Slide the diagonal mirror assembly from the back of the scope’s black focus tube end. You’ll be left with a T42 threaded end. Ignore the extension tube that came in the camera adapter kit and just screw the T ring onto the T42 threads. Then you can put the camera on the adapter’s bayonet end. This is the focus tube distance for this configuration.
D7100 on the T Ring
This shows the camera mounted on the focus tube end. I used the camera’s “live view” to keep the mirror up and show the Sun on the display. I found a 1/50th of a second exposure at 640 ISO gave a pretty good image. The sun fills about half the vertical in the DX frame of my D7100. That’s about ideal. I need more experiments with exposure and ISO on the filtered Sun as well as the moon. The moon will help get the right exposure during totality. Since the 90 degree mirror is not in this setup, it’s kind of hard to see the display on the back of the camera when the scope is pointed up and the back of the camera is facing the ground. At higher latitudes, the angle won’t be as extreme. I might want to use an HDMI cable to run to an external monitor (analogous to the Baja setup). That’s going to need an extension cord or inverter depending on where we are.
Finally, the camera is heavy, and the tracking motors won’t hold it. I’m going to need to figure out how to put a counterweight on the opposite end of the telescope tube.
First Light with the D7100 (click for larger image)
This is an unaltered shot from the first test of the D7100 on the back of the scope. 640 ISO and 1/50s
There’s still a focus issue due to the fact that I can’t see the screen very well outside in the daylight. I’m going to have to use some kind of hood or monitor. I also forgot to cover the viewfinder hole again. I bet the light leak from that messed up the contrast some. It could also be due to the cloud passing in front and other atmospheric haze.
Finally, my CCD is filthy! All this lens changing and stuff has really put a lot of junk on it. I see specks on the mirror and CCD when I peer inside the camera. Some of the specs could be on the scope lens too. Guh! I’ll work on cleaning that all up.
Using the 90° and the T Ring
Here is an alternate configuration that uses the extension tube and the 90 degree diagonal. This makes it easier to see the back of the camera when the objective is pointing up. You start from the original setup and slide the eyepiece from the 90 degree diagonal assembly. Then you add the extension tube and T ring. Then you drop the eyepiece into the extension tube and tighten the screw to hold it in. Finally, attach the camera. Again, I’m showing the focus tube distance for focusing on the Sun. I put a bunch of marks on my tube so that I’d know some good places to start hunting focus. The setup has a hard time holding the heavy camera. The whole setup seems pretty strained and sloppy. I expect I’d need to add more weight to the objective side than with the focus tube end setup.
20mm Eyepiece in the Extension Tube
Here’s the eyepiece nestled in the extension tube. With the diagonal and the 20mm eyepiece, it gives about 3x more zoom at the camera CCD than with the “direct T ring on the focus tube end” setup. The sun’s disk is about 1.5x the vertical size of the DX frame on my D7100.
Objective End
Here’s what the input side of the setup looks like. I found I had to angle the main filter so it wouldn’t block the finder scope. I kept getting close to lining up the Sun in the finder scope and then losing the Sun in the finder due to the shadow from the big filter. What is going on? Doh! That was a little frustrating.
Side note: When you are out working on this stuff, make sure you put on your sunscreen. No matter what you do, you’ll end up facing straight into the Sun for a long time!
OK, so I got tired of trying to squint into that little finder scope while getting fried by the Sun. I did figure out if you put a piece of white paper on the ground, and look for this image, you’ll be pointed right at the Sun.
So now I’m thinking of making a simpler finder scope with just an empty toilet paper tube that the Sun shines through when it’s lined up.
Oh…
Wait for it….
Take a picture of yourself through a toilet paper tube and pretend you’re the Sun!This shot may have been altered. 😉
I assembled some cardboard frames to hold sheets of the filter material and attached them to tubes of cardboard that will go over the telescope and finder scope ends that will be pointed toward the sun. Finally, the tubes are set in rigid foam blocks to it able to withstand some handling over the coming years. It’s the same technique I used in 1991.
My T ring and extension tube also arrived. They should allow me to connect my camera to the 90GT telescope.
I’ll be set to take some Sun pictures tomorrow. There’s no eclipse, but I might see some sunspots.
The Front Burner 