The Scruffy Astronomer

6 November 2019 Ever since autoguiding has been an affordable thing, really good astrophotographic images have been easier and easier to get. So what is that? Autoguiding is when you connect a second scope (normally something inexpensive) and a camera to your main scope. This takes photos of stars and sends them to a laptop, which locks onto a star. If the computer sees the guide star wandering even a tiny bit,   it sends correcting information back to the mount. Using autoguiding, as long as you've aligned your mount accurately, you can confidently move from 30 second exposures with nice round stars to 30 minute exposures or more. What's the downside? Urrgh, cables! Until I did some serious cable management, you could hardly see my scope under the cables. It looked like a plate of spaghetti. What's worse, they drag on the ground and catch on things as your mount tracks during the night. Nothing ruins a nice shot as effectively as a snagged cable. Enter the ...

1 November 2019 This remarkable photo was published on the Australian Amateur Astrophotography Facebook page by Kelvin Hennessy. It’s a group of climbers on the Q1 building in Surfers Paradise with the full moon behind them. I had to ask Kelvin how he took it. Kelvin told me that he was inspired by Luke Taylor’s videos of the full moon rising behind the Cape Byron Lighthouse. He wanted to try has own version using the top of the Q1 building as a target. The telescope he used was a saxon 127mm FCD100. This is a triplet refractor which is normally used for astronomical work, as it has virtually no chromatic aberration. For Melbourne residents we have one in our showroom if you want to see it. I was surprised at the mount Kelvin used – it’s a saxon AZ3. You can see it in the photo that Kelvin sent me (and which I’ve brightened heavily). Kelvin says the mount works fine as long as it isn’t windy! I asked Kelvin how he planned the photo. For initial planning, he uses Photograp...

30 October 2019 This is one of those rarer posts where I combine my two interests - birdwatching and astronomy. I've posted before about the surveys birders can help with. Birdlife Australia run a longitudinal survey called Birds on Farms ( https://www.birdlife.org.au/projects/woodland-birds-for-biodiversity/birds-on-farms-wl ). The intention is to get a better understanding of how birds interact with various forms of agriculture, particularly on rural and private properties. I like the citizen science aspect of these surveys. it's a way of making public use of my hobby. I'm not a top-level birder and can't reliably identify every one of the birds I hear. But you don't have to be an expert to get involved. Hear? Yes, most of the time, in a forest, especially, you don't see the birds, but instead hear them. Birds have distinct calls, of course, and most people know a Kookaburra when they hear one, but they also have alarm calls, contact calls, territorial calls, ...

Today’s message is an update on the Tawny Frogmouth nests in my local park. As far as I know, there are three nesting sites at Hays Paddock in East Kew. I’m sorry to have to report that one of the nests has failed. Nest failure isn’t uncommon with Tawnies. Even at the best of times the nest is flimsy, often nothing more than a dozen or so twigs laid across a horizontal fork in the branch. A strong gust of wind will dislodge the platform, sending the young chicks to the ground, but chicks can simply fall off, and I’ve heard that parents can even accidentally knock the chicks out of the nest. I’ve attached a photo of a typical Tawny Frogmouth nest. As you can see, there’s not much to see. I found two dead chicks at the base of the tree a few mornings ago. Being your typical birdo, I took a close-up photo of one of the chicks and asked on the Birding-Aus Facebook page to confirm my ID. The chick was about 10cm in length from beak to tail, and was covered in white down, with no feathe...

28 October 2019 I've been busy blogging on lists lately. The latest one is the " top 10 telescopes for 2019 ". This is different to the Christmas gift list as I wasn't restricted by price (mwa ha ha!) In order to narrow it all down, I split the competition into categories, so I've chosen the following: Two basic scopes Two telescopes for viewing planets One telescope for viewing galaxies and nebulas One scope for short period astrophotography Three scopes for long period astrophotography (can you guess why?) One scope for terrestrial viewing One pair of astronomical binoculars Have a look at my choices and see if you agree or disagree. If you have any other suggestions, let me know in the comments. I'll be particularly interested in hearing from people who have bought scopes and what they think of them. Incidentally, I took the glamour photo of the Esprit 100 while making the unboxing video . Its proud owner knows who he is. He also kno...

24 October 2019 Ever wondered what’s inside your binoculars? Take it from me, there’s some complicated stuff in there. The most important part of the binocular is the pair of prisms between the lenses. Without these, you’d be seeing upside-down. Design and quality of prisms can make a great difference to the quality of the image you see through the binoculars. They can also make a big difference to the look of the binoculars themselves. The older-style “porro” binoculars, with their characteristic zig-zag shape, have largely been displaced by “roof prism” binoculars, which have a straight-through look. This may or may not be a good thing, as while roof prism binoculars are more compact, more robust and easier to waterproof, most of them don’t provide as bright an image as their predecessors. Thanks to our friends at saxon, I got to pull a pair of binoculars apart and investigate the prisms inside them. I’ve written a blog about it (at http://www.opticscentral.com.au/blog/bi...

23 October 2019 Remember a couple of weeks ago I posted my narrowband Helix photo? Well a while later, ASV member Geoff Healey posted a visible light photo of the same object. It's labelled "LRGB". Compare the two photos here. My photo (HOO) is an image captured using two filters that only pick up a pair of highly specific colours. One colour, a pinkish "Hydrogen" is displayed as red on the computer screen, and a teal "Oxygen" is displayed on both the blue and green pixels on the screen. If you look closely, they're quite different. Geoff's images is "true colour" and mine is "false colour". But there are a couple of other differences. You'll note that Geoff's image has lots more stars in it than mine. Geoff's camera accepts the whole spectrum, so it allows a lot more light in, including light near infra-red and ultra-violet. My filters accept light from the nebula but shut out a lot of the rest - to ...