Chasing the ISS with a Canon SX20IS

The International Space Station passed over my house this evening, about to dock with the STS-133 Discovery space shuttle. Though I wasn’t able to see the shuttle (I understand from tweets that it was very close), the ISS pass was pretty bright and lasted for a good few minutes. Fast moving cloud spoilt the first image where the ISS approached from the SSE. However the following three images I hope you’ll agree aren’t too bad despite the weather doing its best to spoil the view.


ISS Pass 1


Here the ISS (the long line, a 32 second exposure), left hand part of the line is passing over Betelgeuse and Bellatrix in Orion. Aldeberan can be seen up to the right and faintly, the Pleiades can be seen.


ISS Pass 2


In this second inage the ISS has passed Orion (whose distinctive outline can be seen on the right of the image) and is approaching Castor and Pollux in Gemini to the upper left.


ISS Pass 3


This final image shoes the ISS track partially obscured by cloud, just before it disappears from view.

I used my Canon SX20IS mounted on a Jessops photographic tripod, taken at ISO100, using CHDK to set a 32 second exposure, at f7.1. I used a two second delay to allow the camera shake to settle down before the shutter engaged. The images have had a small amount of post-processing applied to brighten the scenes slightly.

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Website Update

Just a quick update as to what is going on, as there hasn’t been a posting to my blog for a (unbelieveably) couple of months. I’m working on a substantial update to my website http://www.digitalwaterfalls.co.uk which will consist of a number of tutorials, based on what I have learnt in astronomy and astrophotography.

Watch this this space for announcements before the end of the year…!

Posted by Wordmobi

Beginners Portable Astronomy

Though I’d planned to take my Skywatcher 130 telescope with me on holiday to the highlands of Scotland, unfortunately it turned out too impractical to transport everything we needed for a weeks stay (plus one Greyhound!) so I started looking at alternative options.

Armed with a budget of £100, I started looking into the options. Another smaller telescope seemed the wrong solution, if I was intending to do astrophotography with the smaller ‘scope then I’d have to transport extra bits ‘n pieces. I needed true portability to view the skies, but with the compromise of not being able to attach a camera. So I resolved to achieve two things:-

1. Buy a pair of binoculars to get good views of the skies.
2. Take the digital camera with tripod, but try to get an adapter/bracket to help me utilise both the binoculars and camera on the same tripod.

After looking around, I settled on the ‘Helios Nature Sport Plus’ pair of binoculars, 10×50 wide angle. They came recommended by ‘Sky at Night’ magazine and at £84 with case/neck strap, they fitted nicely into my budget. A suitable camera tripod adapter came in at £9 and I picked up the items from a local dealer, Sherwoods Photographic www.sherwoods-photo.co.uk

Helios Main View.jpg

Out in the field, I’ve found that using the binoculars in daylight, they offer a very high quality view, objects are clear and crisp. The only issue I found with them is the line of the horizon was tinged with a faint reddish/yellow line. However once I fine-adjusted the focus wheel, this disappeared almost completely.

The binoculars have eye-relief caps that twist to extend so that they can be used by glasses-wearers, though I usually take my glasses off any to look through the eye-pieces. Having a rubber coating, the binoculars are easy to handle.

Helios Eye Piece View

For stargazing, I have found the binoculars a very useful pair to use. Jupiter and its four main moons can be seen easily, stars with distinct colouration such as red giants are clear and the field of view is excellent (being 6.5 degrees). Even through light pollution, the arc of stars that form the Milky Way can be distinguished. Satellites have regulary crossed my field of view and even M31 the Andromeda Galaxy can easily be seen.

What I find useful is the ability to grab the binoculars and scan the night sky for five minutes, rather than having to haul the telescope outside and hence feel frustrated that I can’t view the night sky as I would like. It has also proved its worth on holiday to look at scenes and objects in the daytime.

The binoculars come with a useful padded carry case, a short guide how to use the binoculars and a cleaning cloth.

The bracket that allows me to attach the binoculars to a camera tripod has proven useful in two ways, not just whilst attached to the tripod, but has an additional way of holding the binoculars as the bracket attaches via a thumbscrew to the centre screw hole at the front of the binoculars.

In addition to to the binoculars, I also found taking a small field compass, notepad, red LED light and of course several magazines and books with star maps essential for finding my way around the night sky. Useful (for the sake of ease) having a GPS enabled mobile phone to give me my current position also helped star-finding.

I must admit that I was skeptical when I first seriously took up astronomy of the value and usefulness of a pair of binoculars. However after reading a lot of amateur astronomers experiences, magazines and tried it out myself, having a decent pair of ‘bins’ is a worthwhile piece of equipment in the astronomer’s tool kit.

Posted by Wordmobi

CHDK for the Canon SX20IS

One of the reasons I purchased the Canon SX20IS as a replacement for my ageing S2IS was the prospect of CHDK being ported. I’d been reading the forums and it seemed that the prospect of a port wasn’t far away.

Thankfully, it seems as though my wishes have been granted as there is a beta version of the SX20 port available on the ‘autobuild’ server. If a build reaches the CHDK autobuild server, its a good indication that the port is almost ‘mature’ and the bugs are gradually being ironed out.

I loaded the current build to a spare SD card (note that it will only load from a bootable SD card, instructions how to this are on the CHDK website) and a quick summary of my findings are as below:-

RAW mode isn’t working just yet as image file sizes don’t correspond to the 4000×3000 resolution.

Scripts act a bit strange, especially the ‘ultra intervalometer’ script I use a lot. At the moment, they can’t be edited, ie. Parameters can’t be changed on the camera, though you can edit them on a PC and the camera will run the script.

Occasionally the CHDK menu disappears and you have to keep reloading it from the shortcut key or the menu button, depending upon how far it drops out.

A minor annoyance is when the mode whell is turned to the ‘C’ position is that the lens fully extends, so you have to retract it. Not a show-stopper though.

However the ‘normal’ CHDK settings (photo menu) are there and work well, such as extended exposure time above the standard 15″. Full control of the ISO value is also there, even going all the way upto ISO5000, though in reality I think the actual result is closer to ISO3200.

CHDK for the SX20 can be found here:

http://chdk.wikia.com/wiki/SX20

Certainly worth monitoring for progress on an incredibly useful tool for the Canon Powershot series.

Astrophotography with the Canon SX20 Part 2

As mentioned in my previous post, now I’m back off holiday I’ve compiled my photos from the SX20 and as per the images below, are some of the results.

Below is a cropped shot of the region around Cassiopeia, the full image (see link – 4000 x 3000 res) also shows (if you look hard enough) M31 in the lower right hand side of the image.

Link to full size image:-

SX20 Cassiopeia / M31

Image Details: ISO800, f4, 15 second exposure.

The next shot shows the Andromeda Galaxy (Messier 31) at about 10x optical zoom:-

Full size image link:-

SX20 Messier 31

… noticeable at this level of zoom, even though the camera settings haven’t changed, are the star trails. Image details:- ISO1600, f5, 15 second exposure.

Overall, even though there is a level of noise in the SX20’s images, it is substantially better than the S2IS’s, which is very pleasing to see.

Astrophotography with the Canon SX20IS Part 1

I’m writing this blog entry whilst still on holiday and not having any means of transferring my digicam pics to my smartphone, so I’ll present the text first and images later.

A holiday to the Scottish Highlands presented itself with an opportunity to take advantage of (potentially) clear dark skies as I usually have to put up with light-polluted skies at home.

I hadn’t really tried out my new Canon SX20IS digicam for some astrophotography, preferring to continue to use my ageing S2IS with CHDK. However the SX20IS really offered a number of advantages over the S2IS such as better ISO capabilities (ISO 800 to 3200) and better resolution. So over a couple of nights, whilst dodging some broken cloud, I managed to obtain some impressive (in my eyes and with my limited photographic ability) images that kicked the S2’s images on the first night into a cocked hat.

As a comparison, on the first night I mainly used the S2IS with CHDK and took a number of exposures 20-32sec in length, ISO400. A lot of noise was picked up and only the brightest stars were picked up. However I was able to save these as RAW images so I may be able to obtain more detail once I get back to my laptop. I took a couple of disappointing shots with the SX20 which only picked up the very brightest stars in Cassiopeia.

However the next night I decided to use the SX20 and after making some aperture changes and setting the ISO value to 1600, this really opened up the quality of the images. Once the broken cloud had nearly completely cleared, I set the camera up on a wooden table on top of the tripod (there were trees all around so I couldn’t get any horizon shots) and started snapping again and Cassiopeia. With the ISO set to 1600, aperture F2.8, manual focus and time 15″, the images taken had substantially less noise than from the S2IS and more stars were picked up by the SX20’s CCD.

As I took more shots and applied the zoom slightly to M31 (Andromeda Galaxy) which I managed to pick up in the image, the aperture adjusted automatically to F4.0. However because I couldn’t see M31 in the viewfinder, it was hit-and-miss (more miss actually) aand couldn’t get a closer image of the object. Even though ISO has more image noise, I’ve been very impressed with the SX20’s ability to take low light shots – and I haven’t even tried the ISO3200 mode yet!

Posted by Wordmobi