What you can see with a compact camera

When I first tried taking some night pictures last year with my A920 I was surprised that they worked at all to be honest. When I enhanced the pictures I noticed some bright pixels which I thought were noise to start with and it took me a few minutes of comparing pictures to work out that they were in fact stars.

Now that's about as far as I got and I haven't thought to much about it until last night. Now when I was taking my test pictures last night the clouds cleared and I could see Ursa Major poking out from behind my house so I thought I'd use that as part of the test. It came out quite clearly and looking at it on this scale you can see the main stars and that's about it.



Today I've been playing around altering exposure, contrast and levels to see what I could see and try to get rid of some of the noise. I then zoomed in to try and see how much of the noise I had gotten rid of. I happened to zoom in on the star Mizar which happens to be a naked eye optical binary and was quite surprised that it seemed to have been captured. I then messed about with the levels a bit more and found that the stars were actually in the right positions and further that I could see objects that I hadn't noticed with the naked eye.

My first attempt got this:



Which is pretty noisy but you can make stuff out on it. I then brought the contrast up quite a bit to take out most of the bright sources:



Which is probably a bit to harsh and got rid of some stuff that was actually there but did at-least get rid of the noise.

Finally I brought the contrast up again and got back some of the noise but probably some objects that are there as well, it's hard to tell.



I'm just really impressed that such a budget camera can capture stuff like this even if it isn't prefect.

Night Photography - What you can do with a digital compact camera

One of the things I'm really keen on doing while I'm out on La Palma is getting some really good night pictures of the dome and surrounding scenery at night. I went out to the WHT last year and spent a night up there and got a few reasonable snaps but I wasn't very well prepared and I wasn't entirely happy with any of them, so this time I'm doing a bit of experimenting first. My plan is to take one of my digital compact cameras and a 35mm SLR. Ideally I'd like to buy a nice new digital SLR but money won't stretch to that at the moment (although I have spent the day drooling over a Fuji S1600 super-zoom which was very reasonably priced and has up to an 8 second exposure but it's still to much!). So I'm stuck with the equipment I've already got.

Now I have a cheep and cheerful Fujifilm FinePix A920 which is fine for snaps (although the JPG compression can be a little bit harsh on very fine detail) and as luck would have it has a shutter speed with goes up to 4 seconds and which behaves very reasonably in dark conditions. This is what I had with me the last time I went out. I also have an old Nixon CoolPix 3200 which I brought back in 2004. Now at the time it was (and still is) a very capable camera and takes nice pictures. Its only drawback these days is it's pixel count but I thought I'd give it a go and compare the difference. Again it has a shutter speed which goes up to 4 seconds.

So first the CoolPix. Now the trouble with most digital compact cameras when you're trying to do this sort of thing is that you just get a bunch of programs and no manual control of anything useful like aptitude and shutter speed control. Basically you have to pick the right program mode and hope it will do what you want. So I tried it out in landscape/night mode and adjusted the resulting jpg in iPhoto. After a bit of fiddling I got this.

Now this is by no means terrible all things being considered but it doesn't seem as good as the pictures I got from the A920 last time I tried this. You can make out stars in this but when I looked at the exposure speed encoded into the JPG it came out as 1/4s which is far to fast for this. I may have another go tomorrow night.

So now onto the A920. I tried this in Night mode and Firework mode and Night mode was by far the best. It gave a 3 to 4 second exposure and with a little adjustment I managed to get quite a nice image. If you compare the two you can see that the A920 photo has far less noise and the definition on buildings is much better (and a big plus the stars are much clearer).

I took this second picture of a tree with stars and again its came out quite well. There's a little bit of noise but the CoolPix failed completely to capture any of the detail from the tree and I only got one of the bright stars visible (again this many have been down to the fast shutter speed and the modes I tried).

I thought I'd try a more conventional shot for a bit of fun (excuse the mess in my garden) and again it's come out quite nicely.

In all three cases with the A920 to manipulate the images in iPhoto 8.1.2 I've only really adjusted the 'Shadows' and 'De-Noise' settings and left it at that.

Now the drawback (apart from noise, etc). Since these images needed post processing you don't get a lot of feedback on the camera display's when you're taking the pictures. Now for me this won't be much of a problem since I'll be able to take a batch of photos then nip back into the observatory and process them and then nip back out and try again which isn't a great problem and at least I get reasonably quick feedback.

So next on the list is testing my 35mm SLR. I suspect this will be far more time consuming because I'll have to have film developed but it should be fun at least. My big dilemma now is do I go for slide file and scan slides or do I go for normal print film and hope the lab process the prints correctly.

Into the last two weeks

So perhaps I'd better explain what goes on and what this experiment is in very general terms (and in layman's terms because I'm a Software Engineer not an astronomer). This project is an experiment to test a new adaptive optics system. Now adaptive optics are a way of compensating for distortions in the earth's atmosphere so you can get clearer images from ground based telescopes. It basically works by observing a light source in the part of the sky where you want to observe your target object and by watching how that distorts you can work out how the atmosphere is changing. Once you know this you can use a deformable mirror, basically a mirror that changes shape, to compensate for these distortions and you get a clearer image. Obviously you have to make these measurements may times a second to make this work and at regular intervals, otherwise it doesn't work. Also the time taken to capture your image, calculate the shape of the mirror and the time for the mirror to change must be very short otherwise the atmosphere will have changed to something else and you have to start again. The first experiments in this used stars as the light source to work out how to change the mirror but these days we use lasers and make our own light sources by reflecting laser light off of layers of dust, etc in the atmosphere.

OK, so that's the science bit. In terms of Software Engineering what we have here is a hard real-time system. The data has to flow through the system and meet stringent timing criteria to work. The numbers we're talking about are four cameras, each taking an exposure once every 4ms (250 times a second) which then need to be measured and a shape for the mirror worked out and sent through before the next image has been taken. To do this there are a number of computers, each linked by a fibre-optic bus which allows the data to flow from one computer to another with little delay.

Now the part I'm responsible for (apart from fixing anything that seems to go wrong if nobody else is about) is telemetry. At various points in the system I take the data and then send it via a normal ethernet network to a number of sub-systems which can then use the data to make secondary calculations with slightly less stringent timing constraints. So to recap, I have the job of taking the data flowing though this high capacity fibre-optic network and transferring it to a normal style network (like the kind you'd have around your house say). This is the equivalent of sending a suitcase on a high speed train and at the same time sending an identical suitcase via horse and cart to the same destination and expecting them to arrive at the same time. Some days I have no idea how but I manage to make it work!

So in less that two weeks time we're packing all our equipment up, putting it into a container truck and sending it off to La Palma in the Canary Islands. So this is the last of the time we have left to test anything before we arrive on the Island at the end of August. To say things are hectic is an understatement.

Astronomy

It must be said I've always been a bit of a geek when it comes to science. Way back when I was about 10 this was usually confined to watching Blake's Seven or Star Trek and spouting technobabble but since I was considered a bit thick at primary school and into secondary school due to being dyslexic (which I wasn't really aware of until my early 20s) that's about as far as science went for me.

Then when I was 12 (I think) second term of year 7 anyway and heading towards a life in, if not the remedial class then at least not making the top stream and doing O Levels, the science teacher annoyed me by implying I was less that stellar in the thinking department once two often and I should pay more attention. Now this wasn't completely his fault, poor guy, because by this point I was so bored with secondary school it was untrue so I did have a tendency to sit at the trouble making tables and create havoc. The point he missed, and it was fairly easy to miss, was that I was actually taking everything in that was taught but I just couldn't be bothered to show it (ah, the joys of being a teenager!). I'd also started to read a few popular science books on space and astronomy so I was slightly ahead of the curve he was teaching to.

Anyway the upshot of this was that a few weeks later I sat his end of term test and actually bothered to try and got 93%. This caused three things to happen: 1) the science teacher had to swallow his earlier words and write me a good report card (which I still have and I think its hilarious); 2) Since word was out that I might actually have a brain I stopped hiding my geeky side from everyone (this only lead to some slight playground bullying for a bit); and 3) (and probably most importantly) it got me into the upper stream at school doing O levels (and hence A Levels and hence degree and etc)

But at the time my main science interest was Astronomy. Once the geek was out that's what I wanted to be, or at least in my frighteningly realistic view for a 13 year old, that's what I'd want to be if I was any good at maths, had any chance of going to university and wasn't destined for a blue collar job. Yes, I use to have that little confidence in myself (and probably still do).

So I fell in with the computer geeks at school (by accident really) and that lead on, eventually, to where I am now. Of course the whole Astronomy thing fell by the wayside as an impossible dream and just became a hobby at best.

That is until about 2 years ago when a software job came up in Durham Physics Dept. So in just over a month's time I'm off to La Palma to the William Hershel Telescope to help run an actual experiment. So I guess I'll have something to blog about for a bit...