Sunday, 30 December 2007

The moon by day

Well, there has been another sequence of dark and gloomy nights, so observation chances have been few. However after getting up the other morning I noticed the moon still in the sky at gone 9:00am. I wondered what sort of image that might make. It was quite low in the sky by the time I got things assembled. I took a single picture of it through the telescope. The contrast wasn't very good though.

I tried the movie mode, and stack up a number of images, together with a bit of post processing - and the results were somewhat better.

Doing even more processing and tweaking balances and so on, I got something close to a night image.

Monday, 24 December 2007

Getting to know the moon

After some more shots of the moon, as it waxes to its full extent, I thought it was time to get to know what I was getting images of. I therefore decided to sort out a few features on the moon and see if I could identify them. Taking one of the better large images I set about annotating it with a few of the more obvious features.

Using a number of websites, I was pleased that most of the features I found were visible in my picture. The moon apparently moves around a bit, so it is possible to see more than 50% of it over time. Its necessary to flip the image around a bit to undo what the telescope optics do, but here is the result.

Saturday, 22 December 2007

More of the moon

A clear night appeared after a number of rather overcast, not to say wet evenings. The moon was high and nearly full, so I took the chance to try some more photos.

It is well known that a full moon is not so photogenic as a half moon. You don't get the crater shadows appearing so it is not as clear. Anyway - the results weren't too bad, but the breakthrough tonight was in the processing.

I used registax to stack multiple images from a video of the moon, and this works well. The only trouble is registax can be very slow on the processing. I'd experimented with different forms of conversion from .MOV to .AVI with mixed results. I found a couple of converters that work, 1 produced very grainy results, the other was better. However sometimes it could take over an hour to process a 30s clip. One time I left if running all night to finish.

I looked around for other options, and found the Rad video tools which have a conversion facility as part of the kit. It also has a couple of useful options whereby I can exclude the sound (which isn't needed obviously) and it also allows for an uncompressed output format. I tried this out, and got HUGE AVI files - 700Mb from a 23Mb .MOV file. This is ok, as I only keep the .AVI as temporary files while processing. The good news, registax loves the uncompressed format, and screams through the frames in comparison to the compressed images. The whole thing can now be processed in a few seconds - maybe a minute! Rad video tools is now my new best friend!

Thursday, 20 December 2007

Waxing larger

A number of cloudy nights, and last night was no exception. However early on it was relatively clear and I thought the moon might be worth a couple more snaps.
I'm not sure if it was cloud or mist, but you could see bands of it moving relatively quickly past the moon. It was almost transparent, but not welcome even so! The good thing about using video to capture is that you can take the best frames. You're not dependant on a long exposure that can be ruined by a single glitch.

Anyway, the moon was relatively high in the sky, so that must help with atmospheric distortion. Its also waxed a little so different things are visible.

Anyway, enough with the chatter, lets see what a few hours processing and stacking produced.

Some processing artifacts of the processing are visible on lower and upper parts, but the craters come out pretty well. I must look up some moon maps so I can recognise some of the features I've captured.

Monday, 17 December 2007

Moon shot

Well my telescope and camera are pretty primitive, so the deep sky objects are a bit hit and miss - well ok, they're mostly miss. However the moon is much more tractable - its a lot brighter to start with so doesn't need long exposures.
I tried a couple of shots of the moon with just the camera, mounted on an attachment to keep it still, and the results aren't really that impressive. The camera boasts a 3x optical zoom, but even then its a bit tiny.

Even when zoomed in, its not that good a picture.

The next obvious step is to attach the camera to the telescope and take a picture that way. They come out somewhat better as you might hope.

Its not bad, buts its a little fuzzy around the edges.

However, rather suprisingly you can get some very good images attaching the camera to the telescope and using its video mode. The moon soon drifts out of view, so you can only get about 30-45 seconds worth of images, but they are quite good (although they are taken at 640x480 resolution). What you do is take the video, load it onto the computer, convert from .MOV to .AVI file, and then use the program Registax to process it. This program will lock onto a feature and track it as it moves from frame to frame. Then, it will stack together all the good frame images into one, so reducing noise, and then gives you the option to sharpen it up.
The results are pretty good I have to say, even though I'm still learning what half the settings do.

Now that's more like it!

Sunday, 16 December 2007

Some star pictures

I tried to use the new found techniques to get some pictures of stars - but the equipment wasn't really up to the job. The best I managed was of the Pleiades, which at least gave something half way recognisable. I took a number of images (33 I think) and stacked them with Deep Sky Stacker.

I've still got a lot to learn about the software, but to get much further with deep sky images I probably need something better than my point and shoot digital camera. At best it will take a 3 second exposure, which is not enough to capture anything faint.

On the other hand, in 3 seconds the stars move very little, so the lack of equatorial mount and drive and not noticeable!

Friday, 7 December 2007

Finding out how others do it

After my last experiences with Astronomy and telescopes, I decided that photographing things might be more fun. At least I could show the results rather than just describe them.

Now I'd tried before (March 2007) taking some pictures with a telescope and digital camera of a lunar eclipse. This was a very Heath Robinson setup. The telescope is a very basic reflector that I'd borrowed. The camera was a standard point and shoot digital, hand held up to the eyepiece of the telescope. I was actually very pleased with the results given it was a spur of the moment thing. I worked pretty well until the eclipsing happened too much, then the light levels fell, and I couldn't hold the camera still enough to take anything reasonable without a lot of camera shake and the camera waving a red handed blurring gonna happen sort of icon at me.

So - given the very basic nature of the setup it looked like things were possible.

Having got the telescope out again now the nights are getting darker and more accessible, I thought I'd have another go. Bad news, the moon is not visible from my garden, and waning fast. However there are some other things to take photos of. Mars is very prominent right now, and I had a go at taking a photo of that.

No chance, wobblesville Arizona, population you... Pressing the shutter button it was a good 2-3 seconds before the click finished, and there was just a blurred mess.

Well OK, it was probably a silly idea, I should wait for the moon again perhaps.

However flicking through some astronomy web sites and shops, wondering idly how much it would be to buy a 'scope of my own, and what do you get for your money I spotted some interesting bits on astrophotography.

For not very much money (well £20 or so) you can get a metal gizmo that sits on the eyepiece and has a couple of metal bits sticking out that allow you to screw the cameras tripod adaptor into, and suddenly the telescope and camera move as one! See the attached - if I had two cameras you could even see the camera in situ.

This was much easier to work with. You can even use the LCD display instead of the view finder. The only issue is that in the dark, without the camera attached, you stand a fairly reasonable chance of poking your eye out with the protruding metal spike - but hey, its a small price to pay.

A clear night arrived, and I had a play around. The results were not altogether as good as I had hoped, but at least there were results.

MarsMars again
Somewhere in Orion,
or maybe the Pleiades
Another Mars

Well - the results are not stellar (groan) but they are at least there.

Then I had the good fortune to notice that the Nottingham Astronomy Society were having a talk by a visiting speaker titled "Digital Astrophotography for Dummies" by Kevin Kilburn. I could perhaps pick up a few tips, perhaps join the society, get to use their 24inch reflector. At the very least I could find out if I was on the right lines. So off to check it out, on a cold, very wet night to see if Kevin has any tips I might use.


He was getting some stunning photographs without any telescope at all, but using a digital SLR camera on a equitorial mount. The secret was to use a digital camera and take multiple exposure, and then use photoshop or similar to remove the street light pollution, and stack the multiple images on top of each other.

The results are excellent. I was well and truly inspired as I left the meeting. He was getting pictures better than a lot of professionals, and using them to propose new theories about the moon and other things. I mean - just look at this example of M31, the Andromeda galaxy, our nearest neighbouring galaxy. Many of these were taken from his own back garden, from which he can see 12 street lights.

This could end up as a relatively expensive night out in the long run...

Friday, 30 November 2007

First Steps

Put me firmly in the class of fair weather astronomers...

I have borrowed a fairly basic reflecting telescope to do some observing. Last Friday was an excellent night to try it out. Although I live in a rather light polluted area, the night sky was crisp and clear. Bright pin pricks of light could clearly be seen through the upstairs window. I went downstairs and stepped outside for a better look, and after a sharp intake of breath, I dashed back in - COLD COLD COLD!!
Observation was terminated before it had really begun.

However, last night, there were only a couple of minor squibs of cloud about, but on the whole things looked pretty good, and the temperature outside was much better. This was much more the way to do it, OK so it would require a coat, but not necessarily Arctic survival gear.

So I went back inside, and lugged out the telescope, set up the tripod, picked the least powerful of the lenses and found Mars with the spotter scope. After a while, I managed to get it well fairly centred, but realised that the cross-hairs which seem like such a good idea, when viewed at night, are black on a black background, with little light, are not in the slightest bit visible in the dark! Even with the least powerful eyepiece, the image has to be pretty much in the centre of the spotter scope to find it.

I went back in to get a more powerful eyepiece, there is only so much you can juggle in one trip...
I installed the eyepiece, and after a bit more hunting managed to re-find Mars, and it agreeably became a small disc, jumping around all over the place as I tried not to touch the telescope and induce any more wild oscillations. Have you ever seen Lissajous Figures on an oscilloscope (do they still use those?) - well that's pretty much what Mars looked like most of the time.

Comet 17P/Holmes - nto that I'd recognise it...
OK - time to try something a bit more tricky, how about that comet 17P/Holmes. I could be like a real astronomer, and casually drop into the conversation my cutting edge observations on the night sky. "Have you seen 17P/Homes perchance? No - oh what a shame..."

I'd already loaded the data into Stellarium and so fired up the laptop on the kitchen table. OK - so its approximately overhead at the moment. If I starts a Mars, and a line up, past Cassiopeia and a bit to the right, yeah that should work.

Went back outside with a couple of the constellations roughly memorised... and WHAT THE...??????

The night sky was now completely overcast, not a single celestial object visible! In the 3-4 minutes I'd been inside a cloud layer had just appeared, as if from nowhere, covering from horizon to horizon. I swear, it was like being on a prank TV program! How did that happen? I went inside and out again to see if I'd been mistaken, but no - complete overcast.

I left the telescope out, and checked occasionally, and about an hour later I could see Mars again in a clear patch of sky. Maybe the overcast was a transient feature. I refocused and re-centred, and then ran inside to get the highest mag. eyepiece. A quick squint to see if it was still centred, and as I watched it there, it slowly and majestically faded completely from view! The overcast was back! This time for good - I wondered if there was anything on TV...

Entering the world of Astrophotography

This blog is a spin off from my open university one, where I first got a little enthused about the idea of taking pictures of stars. As I started exploring more and more, it got a little off topic, so I thought I'd start a new one about my trials with astronomy.