The Scruffy Astronomer

We've uploaded another video onto the Optics Central YouTube channel. This one is me unboxing the saxon Astroseeker 15075. This is a 6-inch Newtonian on a light computerised alt-azimuth mount. The mount is a nifty little unit, well capable of carrying the weight of the tube. It's a heavier duty mount than the SkyWatcher mini AZGTi, and is capable of taking a heavier tube than the Newtonian here. In fact, this mount is often found with a 127mm Maksutov. The mount can be controlled by the hand controller that's included in the box. Alternatively, because the newest versions of the mount have a built-in WiFi connection, you can also control it using the SynScan app for your phone. The tube is a standard Newtonian, with a parabolic mirror and a focal length of 750mm. This makes it an f/5, meaning it's good for deep-space objects, such as galaxies and nebulas. Star clusters and the Moon are also well within your reach, especially in light polluted areas, but planets wi...

During the latest lockdown in Melbourne, I was at home, but had taken with me a small Newtonian telescope and a guide camera. I was wondering what sort of photo of Jupiter I could get with simple and inexpensive equipment. I put the scope up onto my NEQ6 mount, but it didn't have a finderscope. Complicating matters, the guide camera was set into the focuser of the telescope and it was nicely focused. I didn't want to move it. How was I going to see where the scope was pointed? How was I going to align the scope to the sky? Reusing old equipment I have an old guide scope at home - an Orion. It's not as good as the saxon one, but it does the job. I've also got an ancient illuminated reticule eyepiece which I rescued out a junk bin at an astro meet once. I planned to use this in the guide scope. The eyepiece was filthy. When I looked through it, all I could see was nicely-focused grit and dust across the whole field. I had to pull the eyepiece apart to c...

The imaginary point As we all know, the Earth rotates on its axis. This is why we see the sun rising and setting, as well as the stars moving through the night. But this gives astronomers a challenge. If you have an equatorial mount, it has to be parallel to the Earth's rotation. The more accurate the alignment, the better the mount will perform. Once aligned, you only have to move one axis has to follow a star accurately. The other one can stay still. If the mount is poorly aligned, you'll have to adjust the declination axis occasionally. Of course, this isn't a problem for visual observing. But for photography, a small polar error will ruin your photos. How can you get an accurate alignment? Geometry! I use a computer program called SharpCap to help with my polar aligning. This needs a computer and a camera on the scope. A PoleMaster does pretty much the same thing. SharpCap is very clever. It takes a photo of the polar area, you rotate the RA axis and it take...

Something a bit different today. Occasionally we take great photos that we didn't expect. Often this comes about when something cool happens just as we're pressing the button, and sometimes it's chance. This time it happened when inner-city Melbourne-based Paul was focusing a camera attached to an off-axis guider (OAG). Paul uses a ZWO ASI120MM Mini guide camera on a Celestron OAG attached to a Celestron EdgeHD 1100 with Celestron 0.7X reducer. There's a mouthful! Like the Spanish Inquisition, nobody expects a photo through an OAG... but I'll allow Paul to continue: "I was struggling with focus on my guide camera. I had left my telescope set up after a night of failed attempts at autoguiding on Thursday night. The forecast for Friday was that it was going to cloud over, but around 8pm on Friday evening, the clouds hadn’t yet arrived and the Moon was just “there” waiting to be imaged! "I turned the mount on and selected “Solar System Al...

A long time ago I was a bit of a Formula 1 fan. It was cool to see the things those cars could do, and I was fascinated by all the cutting-edge innovations they came up with. But one season Ferrari, so dominant for so long, had poor performance after poor performance. Eventually they got their act together, but it was a season lost. If they can be the victim of the "cascading failure", I shouldn't have been surprised when it happened to me. To quote Adam Savage, failure is always an option. I normally take my images from the the ASV's dark sky site in central Victoria. But during the lockdown, the site was closed, so I stuck at home, and also stuck with planetary imaging as the trees in my garden prevent my tracking a deep-sky target for a long time. Eight months without a deep-sky photo is cold turkey! When the place reopened, I was off like a shot. It was the time of a full moon, but that didn't fuss me. If my image wasn't great, that was OK, I was going...

I came across this photo a week or two back on the ASV's astrophotography Facebook page. Sam (the photographer) had posted it because of the nice placement of the meteor, and was very modest about the rest of the shot. I was less focused on the meteor and more on the rest. After all, it's the South Celestial Pole, which isn't really photographed much. Why is it that the polar area isn't commonly photographed? To be honest, I'm really not sure, but two reasons come to mind. First, lots of people think it's a bit of a dead zone. And they've got a bit of a point. You can see straight away that the big area between The Emu (that's the Milky Way through the Cross and Carina) and the two Magellanic Clouds is pretty empty. The second reason is a bit technical. "Plate solvers", those clever computer programs that read stars and compare them to a database to determine where the telescope is pointing, have a bit more trouble in the polar area. T...

A while back we sold a Sky-Watcher Esprit to a client. This guy had a slightly old Sky-Watcher HEQ5 mount already, and the Esprit 100 came in under the payload for the HEQ5, so it appeared to be a good match. When he received the telescope, the client found that the Esprit comes with the Losmandy (wide) dovetail plate that the tube rings bolt to. However, the old mount saddle only accepted the Vixen (narrow) plate. This caused us a bit of head scratching. We considered a couple of different solutions, including an adapter (such as Orion part #07952), but that got complex. The simplest solution I could come up with was to change the dovetail plate. The green Sky-Watcher plate is too short, and balancing a scope with a large imaging array (think a full-frame DSLR plus an off-axis guider and camera) isn't possible as you have to slide the scope a long way forward. The dovetail plate has to be longer. Incidentally, for short focal-length refractors, this is a chronic problem. M...

The other day I mentioned that I'd swapped out my guide camera. It turns out it wasn't necessary, and so now I've got an old ASI120MM in reasonable condition. I decided to try setting it up as an all-sky camera. The camera comes with a fish-eye lens, and all you have to do is connect the computer via USB and use some time-lapse software to make a video. I put the camera on a bit of angle iron and attached it to a mini-tripod (see the photo). I was entertaining vague thoughts of putting it onto my mount for an extra view, but I don't think I can run three cameras simultaneously using ASCOM. For image capture I normally use SharpCap 2.9. It's a free download, although more recent versions have become paid software. As always, setting this sort of thing up takes a few goes. There are options that have to be tested out and tweaked, calibrations like dark frame subtraction to be worked out, exposure times to be lengthened or shorted, output formats that work better...

Most high-end mounts attach to the telescope using a dovetail clamp. The telescope itself has a dovetail bar on it, which has a trapezium cross-section. This normally bolts to tube rings, which encircle the tube so they don't crimp it in any one spot, but some light tubes bolt directly to the dovetail. All you have to do is open the clamp on the mount, slide the telescope in so the clamp goes over the dovetail, and wind the clamp shut. Simple. The main advantage of having a clamp is that it keeps your scope parallel with the RA axis on the mount. It also doesn't scratch your dovetail bar. But are there disadvantages? I certainly never thought so. However, last time I was up at the dark sky site I was talking with far better astronomer than I, past ASV president, and general all-round good guy Russell Cockman. Russell was looking at my rig and brought up the subject of dovetail clamps. He asked me if I was scared of using one. This is my previous scope sitting on its mount...

What's the deal with magnification? When using a telescope for visual observations, it's a simple matter to calculate how much bigger everything looks. But with a camera it's more complicated. Here, two concepts  replace magnification: your field of view and your camera's resolution. One of the most common questions people ask me is about the magnification on telescopes. For visual telescopes, it's actually pretty simple. The magnification is just the ratio of the focal length of the main mirror or lens to the focal length of the eyepiece you're using. So, for example, if you've got a telescope with a 900mm focal length, and you use a 20mm eyepiece, the magnification is 900/20, or 45 times. Swap to a 10mm eyepiece and the magnification jumps to 90 times. This is why shorter eyepieces are more powerful. But people also ask me about about magnification when you're using a camera. There's no eyepiece, so it's more complicated.  It's about fie...

The International Space Station is now 20 years old. It orbits the Earth every 90 minutes or so, and while it doesn't go past everyone every time, there are quite a few opportunities to see it - as long as you don't live in Canada, Northern Russia or anywhere in Scandinavia. Mike from Port Macquarie got a fantastic photo earlier this month. It's the best one I've seen so far. I contacted Mike to find out how he did it. ... and you can take a photo like this yourself! The ISS is about 110 metres across. When it goes over soon after sunset or soon before sunrise, it stands out against a dark sky. If the light is at just the right angle, it can be brighter than Venus. The ISS moves at about the apparent speed of an airliner, but it makes no sound, and has no flashing lights. It's quite serene. But Mike's photo was a challenge. It's a bit like photographing an A380 from Melbourne while the plane is flying over Devonport in Tasmania! Mike uses an app called I...

More than anything else, people ask me about polar alignment of beginner equatorial mounts. To be honest, I'm not really sure that beginners need equatorial mounts at all, but that's how a lot of telescopes come. The process seems intimidating and hard to understand, but once you get the idea, it takes about five minutes and you're up and running - especially if you're putting the scope up where you had it last. In this rather lengthy blog (that goes with a video ) I go through the stuff you need to know to get your equatorial mount set up, as well as a load of details you don't need to know, but might be helpful. Before you start Just to keep you on your toes - or maybe to balance the information coming from elsewhere, I live in Australia, which is in the Southern Hemisphere. I can't see Polaris, meaning the procedure might be a little different if you're up North. Some people say that polar alignment is easier in the North, I'm not entirely convinc...

"I can't see anything" This is one of the most common comments - actually, probably the most common comment I get when doing telescope support. Whenever I hear this, my heart sinks a little. It's never a good thing that someone is having this amount of difficulty. There's a danger that I'll lose this person. The other thing is that such a comment doesn't give me anything to work with. it's my job to solve this person's problem, and I've got nowhere to start. In this particular instance, I was chatting with an astronomer who had just got a CMOS camera onto to his scope. He'd got the computer connected, and had checked it was giving him an image (he'd shone a torch down the scope and the screen had gone white). But all he could see was a black screen. This is how I got him going again. Invisible stars Out of focus stars look black. It's not that they're not there, or underexposed, it's just that they're so diffu...

An unusual Barlow that's shipped with (at least some) Celestron StarSense Explorer telescopes has to be assembled in an unusual way in order to be able to focus on stars. We’ve been selling the new Celestron StarSense Explorer telescopes for a few months now. The StarSense Explorer is a nifty new development in the world of beginner to intermediate telescope mounts. It uses the camera on your mobile phone to determine which way the scope is pointed by looking at the stars and consulting a database. It then guides you to whatever you want to look at. Very clever. Of course, our stock sold out before we were able to grab one to use as a display model, so I still have yet to play with one. But that’s not the point of this post. The point is the strange Barlow lens that comes with the StarSense Explorers. A Barlow is inserted into the converging rays of the telescope, making them converge less. Put simply, this pushes the focal point (where the light actually converges) further back fr...