Al's blog

Getting sharp focus with your telescope

Some friends after seeing a strangely cut bit of cardboard in the observatory suggested I write a blog post about it. Those of you who do astrophotography won’t need an introduction to the Bahtinov Mask, but this post might be of interest to the rest.

Getting focus right in astrophotography isn’t easy. Autofocus doesn’t work like it does for normal lenses. And judging it manually is error pone, you can estimate when a star looks like a point, but there is a large margin of error in that estimate, a bright star may look like a sharp point but the fainter stars may still will be blurry. This is especially true in poor seeing where star image blobs can look the same over a large focus range. Read more

By albertw,

Observatory Code!

This morning I got this one line email from the International Astronomical Union Minor Planet Center: Your site is now code Z72. So Cademuir observatory is now officially recognised by the MPC! In order to obtain an observatory code it’s necessary to observe some minor planets (in the 1000-400,000 range) of varying magnitudes, at least a couple of times a night over at least a couple of nights and record their positions to an accuracy Read more

By albertw,

Observatory Lighting

The latest improvement in the observatory is lighting. I needed something that was low power, needed to be red, needed to be white, preferably dimmable, preferably remote control. There didn’t seem to be anything in the local shops, but I found an LED solution on ebay costing a whole $18.90. At that price I’d have to give it a go! Read more

By albertw,

Astrophotography – Flat Frame box

Now that I have the scope in the observatory on a wedge it’s time to start doing a little more astrophotography. And one issue I immediately ran into, especially with the field flattener in place, was the need for decent flat field images. I needed to make a flat box…

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By albertw,

First image in the observatory – M57

I tried taking some deep sky images last night for the first time in several years. Not an ideal setup for my C9.25 – altaz mount, no guiding, no PEC training, no electronic focuser, unmodded Canon 400d and a bright Moon. Given that, I’m happy with the result of 20x30s exposures on one of my favourite objects: Read more

By albertw,

Building an Observatory – Part 7 – First Light! Phase 1 complete!

Well we finally got first light! ok it was sunlight reflected off the clouds but it counts!

The first job today was to drill down into the concrete base to anchor in the 12mm bolts in place. The local building suppliers had Rawl R-KEM which is a two part epoxy that comes in a 300ml tube, it mixes in the nozzle so its easy to apply. With the bolts in place the pier was put in place and leveled: Read more

By albertw,