Ok, so I haven't exactly been doing webcam astrophotography for very long but there are some key things that I've figured out pretty quickly.
1. Set up your equipment so that you'll be comfortable
You could be outside for several hours and there are enough things to be doing without grappling with your equipment. Make sure that you have your laptop on a table at a good height and your chair positioned for easy access to both the laptop and the eyepiece. I try to position the telescope at a height that makes it possible to use an eyepiece without needing a diagonal. This minimises the amount of focussing when switching between eyepiece and webcam, which in turn makes it easier to get the target in the field of view of the webcam.
2. Get an UV/IR blocking filter for use with the webcam
It makes for a better image, makes it easier to focus the target and also eliminates the worry of getting dirt onto the webcam chip.
3. Spend the first couple of observing sessions just getting used to the webcam and settings
Try things out, get used to having the extra equipment around and take some videos so that you have something to practice post-processing on.
4. Tend towards under-exposing rather than over-exposing
The default webcam settings will probably over-expose the image. This is fine while trying to locate the target but once found it's best to turn down the gain and/or increase the shutter speed. Increasing the frame-rate is also beneficial.
5. Focus is crucial
If the target isn't focused properly then the final image will suffer for it. Once you've got the right webcam settings, spend a few minutes finding the best possible focus.
6. Get a good number of frames to process
My webcam takes videos at 15 frames/sec and I aim for 4 minutes of material which means around 3600 frames.
7. Let your telescope reach thermal equilibrium before observing
Sometimes it can be a pain thinking about it in advance but it does make a difference if the telescope has been sitting outside for an hour or so before you start taking videos.
8. Get decent alignment on your finderscope
It's never going to be perfect but if you're searching for the target with the telescope than you'll have problems finding it in the webcam. If it's on the cross hairs of the finder than it should be in the field of view of an average eyepiece.
9. Watch how the target moves across the field of view
Getting the target in the field of view of the webcam when using a Barlow is not always easy. I've had most success by positioning the target on the edge of the telescope field of view so that it will move through the centre of the field of view a few seconds later. This gives me enough time to switch the eyepiece for the webcam and wait for the target to appear. This is the only way I've been able to find Mars with a 5x Barlow.
These simple techniques have greatly improved my webcam imaging as we'll see in my next post.
Tuesday 30 March 2010
The Chances of Anything Coming From Mars...
After my first unsuccessful yet instructive attempt at webcam astrophotography it wasn't long before I could have another go. The target was once again Mars but this time I was better prepared for what lay ahead. The million-to-one odds didn't seem unreasonable though...
I had realigned my finderscope during the day and had little difficulty in getting Mars into the field of view of the webcam. I spent a minute or so getting used to tracking the target and then changed the webcam settings to reduce the gain and increase the shutter speed. This makes the image dimmer and much easier to focus as well as stopping it from being over-exposed.
Once I had focussed the image as best I could, I increase the frame rate to the maximum setting. Although the webcam software claimed it could operate at 60 frames/sec it seemed to have an actual maximum of 15 frames/sec. Satisfied with the image I started recording and tracked Mars for 4 minutes. I then followed the same process while using a 2x Barlow which left me with 2 videos to play with in Registax.
Loading the first video into Registax there was an obvious improvement from my first attempt. Even looking at a single frame there were some discernable features. I aligned the frames using centre of gravity alignment and stacked the best 250 or so of the 3600 frames available. The end product wasn't going to win any awards but once I'd tinkered with the layers it was a marked improvement on my previous effort. If nothing else the polar icecap is clearly evident. Unfortunately the higher magnification video wasn't focussed properly so it didn't yield anything useful.
I still had a long way to go but I'll leave you with the best of my images and will return with my latest, and by far the best, Martian observation in a couple of posts time.
I had realigned my finderscope during the day and had little difficulty in getting Mars into the field of view of the webcam. I spent a minute or so getting used to tracking the target and then changed the webcam settings to reduce the gain and increase the shutter speed. This makes the image dimmer and much easier to focus as well as stopping it from being over-exposed.
Once I had focussed the image as best I could, I increase the frame rate to the maximum setting. Although the webcam software claimed it could operate at 60 frames/sec it seemed to have an actual maximum of 15 frames/sec. Satisfied with the image I started recording and tracked Mars for 4 minutes. I then followed the same process while using a 2x Barlow which left me with 2 videos to play with in Registax.
Loading the first video into Registax there was an obvious improvement from my first attempt. Even looking at a single frame there were some discernable features. I aligned the frames using centre of gravity alignment and stacked the best 250 or so of the 3600 frames available. The end product wasn't going to win any awards but once I'd tinkered with the layers it was a marked improvement on my previous effort. If nothing else the polar icecap is clearly evident. Unfortunately the higher magnification video wasn't focussed properly so it didn't yield anything useful.
I still had a long way to go but I'll leave you with the best of my images and will return with my latest, and by far the best, Martian observation in a couple of posts time.
Sunday 28 March 2010
Starting Out With A Webcam
As I mentioned earlier when it came to moving into 'proper' astrophotography I decided to go down the webcam route. Firstly my suburban location keeps a large proportion of my observing within the solar system and secondly a £50 webcam was much more appealing than a £700 digital SLR camera.
Based on a whole host of recommendations on various websites I managed to track down a secondhand Philips SPC900 webcam on Amazon. The drivers and software I downloaded from the Philips website.
The power of this particular type of webcam is that it is possible to take a video of an object and then stack the individual frames on top of each other to create a much better image. Obviously one doesn't want to be stacking thousands of frames by hand so it's best to use a specialised software package. I downloaded a package called Registax that is widely recommended.
For my first webcam session, the final pieces of the jigsaw were a couple of Barlow lenses. Planetary observing calls for high magnification and narrow field of view so focal extenders are vital. I already had a 2x Barlow and added a 5x Barlow that I ordered from Telescope House.
So I was set-up and ready to go, just waiting for my chance which eventually came on February 9th 2010. Unfortunately this was a moonless night so my options were limited - the easiest target wasn't around, Jupiter was setting a little too early and not visible from my garden, Saturn was rising a little too late. This pretty much left me with Mars which isn't the easiest of first targets. Still you've got to start somewhere!
To sum-up what is about to follow, as an observing session it was a disaster. I did almost everything wrong and didn't produce any images of any quality at all. However I did learn an enormous amount about webcam astrophotography.
The first problem was actually getting the target into the field of view of the webcam. My finderscope clearly wasn't aligned as well as I thought it was - it's one thing to view the target through the telescope but something completely different to get it into the much smaller field of view of the webcam. Add to this the extra clutter of having extra equipment and a laptop to contend with and at times it was rather frustrating.
Once the target was in the field of view there was then the problem of focussing it. Even without a Barlow lens the target would move across the whole field of view in about 15 seconds. This isn't much time to get good focus on a laptop screen. Also the webcam picks up ultraviolet and infrared wavelengths not perceptible to the human eye which adds a haze to the image making it harder to focus.
The other major problem was getting the right webcam settings. I had played around with the settings during the day but this hadn't fully prepared me for picking the appropriate gain, frame rate and shutter speed during an observing session.
Despite these problems I took a number of videos so that I had something to practice with in Registax. Using registax for the first time was a pleasant experience. Although the number of options and controls was slightly intimidating at first, I soon realised that the basics go a long way. I will do a seperate post on my Registax experience in the near future.
For completeness I will include the final processed image from one of my videos. As an image in itself it is rubbish but as a demonstration that one shouldn't expect great things from a debut webcam session it is perfect!
Based on a whole host of recommendations on various websites I managed to track down a secondhand Philips SPC900 webcam on Amazon. The drivers and software I downloaded from the Philips website.
The power of this particular type of webcam is that it is possible to take a video of an object and then stack the individual frames on top of each other to create a much better image. Obviously one doesn't want to be stacking thousands of frames by hand so it's best to use a specialised software package. I downloaded a package called Registax that is widely recommended.
For my first webcam session, the final pieces of the jigsaw were a couple of Barlow lenses. Planetary observing calls for high magnification and narrow field of view so focal extenders are vital. I already had a 2x Barlow and added a 5x Barlow that I ordered from Telescope House.
So I was set-up and ready to go, just waiting for my chance which eventually came on February 9th 2010. Unfortunately this was a moonless night so my options were limited - the easiest target wasn't around, Jupiter was setting a little too early and not visible from my garden, Saturn was rising a little too late. This pretty much left me with Mars which isn't the easiest of first targets. Still you've got to start somewhere!
To sum-up what is about to follow, as an observing session it was a disaster. I did almost everything wrong and didn't produce any images of any quality at all. However I did learn an enormous amount about webcam astrophotography.
The first problem was actually getting the target into the field of view of the webcam. My finderscope clearly wasn't aligned as well as I thought it was - it's one thing to view the target through the telescope but something completely different to get it into the much smaller field of view of the webcam. Add to this the extra clutter of having extra equipment and a laptop to contend with and at times it was rather frustrating.
Once the target was in the field of view there was then the problem of focussing it. Even without a Barlow lens the target would move across the whole field of view in about 15 seconds. This isn't much time to get good focus on a laptop screen. Also the webcam picks up ultraviolet and infrared wavelengths not perceptible to the human eye which adds a haze to the image making it harder to focus.
The other major problem was getting the right webcam settings. I had played around with the settings during the day but this hadn't fully prepared me for picking the appropriate gain, frame rate and shutter speed during an observing session.
Despite these problems I took a number of videos so that I had something to practice with in Registax. Using registax for the first time was a pleasant experience. Although the number of options and controls was slightly intimidating at first, I soon realised that the basics go a long way. I will do a seperate post on my Registax experience in the near future.
For completeness I will include the final processed image from one of my videos. As an image in itself it is rubbish but as a demonstration that one shouldn't expect great things from a debut webcam session it is perfect!
Saturday 27 March 2010
Partial Lunar Eclipse
A fitting way to round off my early adventures in afocal astrophotography is with the partial lunar eclipse of December 31st 2009.
The viewing conditions weren't particularly good but I did get to watch the eclipse from start to finish over about an hour and a half. As a result my photos aren't particularly sharp but I can't complain since many parts of the UK didn't get to see the eclipse at all. The pick of the bunch is this one, which is and close to maximum shadow and relatively sharp (although still hazy):
Not only did this eclipse mark the end of 2009 but it also marked the end of my main method of astrophotography - the arrival of my webcam was imminent...
The viewing conditions weren't particularly good but I did get to watch the eclipse from start to finish over about an hour and a half. As a result my photos aren't particularly sharp but I can't complain since many parts of the UK didn't get to see the eclipse at all. The pick of the bunch is this one, which is and close to maximum shadow and relatively sharp (although still hazy):
Not only did this eclipse mark the end of 2009 but it also marked the end of my main method of astrophotography - the arrival of my webcam was imminent...
More Afocal Astrophotography
My second attempt at afocal astrophotography was of a very striking half-moon towards the end of November 2009. The pick of the photos is this one:
I particular like the arc of mountains in the upper half of the picture, running from Plato at the top downwards to Eratosthenes. Inside this arc the largest crater is Archimedes.
A couple of points of interest: if you follow the mountains away from Eratosthenes until just before the first obvious gap this is roughly the landing site of Apollo 15, the fourth Moon landing. Secondly to get a feeling of the scale of features on the Moon, Eratosthenes is about 35miles or 58km across which is not far off the size of my home city of Birmingham.
I particular like the arc of mountains in the upper half of the picture, running from Plato at the top downwards to Eratosthenes. Inside this arc the largest crater is Archimedes.
A couple of points of interest: if you follow the mountains away from Eratosthenes until just before the first obvious gap this is roughly the landing site of Apollo 15, the fourth Moon landing. Secondly to get a feeling of the scale of features on the Moon, Eratosthenes is about 35miles or 58km across which is not far off the size of my home city of Birmingham.
Monday 22 March 2010
First Light
As I mentioned in my earlier posts I got back into observing about 5 months ago which means I have quite a lot to catch up on, particularly from an astrophotography point of view.
My first observing session was on 1st November 2009 which happened to be a nearly full moon. I didn't have my webcam back then so had do make do with what was available. I'd seen some impressive results from people doing afocal astrophotography so I thought I'd have a go with my point-and-shoot Olympus digital camera.
For those who don't know, afocal astrophotography is simply holding a camera up to the eyepiece and taking a picture.
I started with a 32mm eyepiece so that I could get the whole of the moon in the field of view. I also used a moon filter to reduce the glare.
After a few minutes of messing around it was very easy to get some decent shots. The pick of the bunch was probably this one...
For something so easy it was hugely satisfying to produce such good results. I tried increasing the magnification but found it much more difficult to align the camera at the eyepiece. Also the photos of smaller sections of the moon were nowhere near as impressive as getting the full moon into the field of view.
So that was my first step into astrophotography. A very small and simple step but one that left me wanting more.
My first observing session was on 1st November 2009 which happened to be a nearly full moon. I didn't have my webcam back then so had do make do with what was available. I'd seen some impressive results from people doing afocal astrophotography so I thought I'd have a go with my point-and-shoot Olympus digital camera.
For those who don't know, afocal astrophotography is simply holding a camera up to the eyepiece and taking a picture.
I started with a 32mm eyepiece so that I could get the whole of the moon in the field of view. I also used a moon filter to reduce the glare.
After a few minutes of messing around it was very easy to get some decent shots. The pick of the bunch was probably this one...
For something so easy it was hugely satisfying to produce such good results. I tried increasing the magnification but found it much more difficult to align the camera at the eyepiece. Also the photos of smaller sections of the moon were nowhere near as impressive as getting the full moon into the field of view.
So that was my first step into astrophotography. A very small and simple step but one that left me wanting more.
Saturday 20 March 2010
Equipment
Buying our first house towards the end of last year was the catalyst for getting back into observing. For the first time in years I have a garden that I can set up in. Plus the cost of some new equipment was less scary when compared to the deposit for the house.
It was a pretty easy decision to buy a Meade LX90. I'd used a Meade Schmidt-Cassegrain telescope at university and always found it a pleasure to observe with. My only real decisions were what aperture and whether to get the ACF (coma-free) version. In the end I settled on 8" for portability and non-ACF since I don't see coma greatly affecting my backyard/solar system based observations. Five months later I am convinced that I made the right choice.
Of course the telescope is only half the story. For a starter set of eyepieces and filters I bought the Revelation Photo-Visual Eyepiece and Filter Kit from Telescope House. This has 5 Plossl eyepieces ranging from 9mm to 32mm, a 2x Barlow, a moon filter, 4 planetary filters and a camera adapter. I also invested in a new diagonal (also by Revelation) since the one supplied with the LX90 isn't brilliant (although it is useful during imaging sessions due to it being easier to attach). A power-supply, red torch and a dew-shield complete my list of initial purchases.
For astro-imaging I've gone down the webcam route. Digital SLRs are too expensive and don't seem to offer anything more when it comes to solar system imaging. I have some experience with manual SLRs and would like to use one in the future but for now I want something quick and easy.
Based on recommendations from most of the websites I consulted, I managed to track down a secondhand Philips SPC900NC webcam on Amazon. It was easy to download the drivers and other software from the Philips website and I bought a webcam adaptor from Telescope House. I also bought an IR/UV filter to remove the haze that can appear on digital images. Now I just need to work out how to use all this stuff!
It was a pretty easy decision to buy a Meade LX90. I'd used a Meade Schmidt-Cassegrain telescope at university and always found it a pleasure to observe with. My only real decisions were what aperture and whether to get the ACF (coma-free) version. In the end I settled on 8" for portability and non-ACF since I don't see coma greatly affecting my backyard/solar system based observations. Five months later I am convinced that I made the right choice.
Of course the telescope is only half the story. For a starter set of eyepieces and filters I bought the Revelation Photo-Visual Eyepiece and Filter Kit from Telescope House. This has 5 Plossl eyepieces ranging from 9mm to 32mm, a 2x Barlow, a moon filter, 4 planetary filters and a camera adapter. I also invested in a new diagonal (also by Revelation) since the one supplied with the LX90 isn't brilliant (although it is useful during imaging sessions due to it being easier to attach). A power-supply, red torch and a dew-shield complete my list of initial purchases.
For astro-imaging I've gone down the webcam route. Digital SLRs are too expensive and don't seem to offer anything more when it comes to solar system imaging. I have some experience with manual SLRs and would like to use one in the future but for now I want something quick and easy.
Based on recommendations from most of the websites I consulted, I managed to track down a secondhand Philips SPC900NC webcam on Amazon. It was easy to download the drivers and other software from the Philips website and I bought a webcam adaptor from Telescope House. I also bought an IR/UV filter to remove the haze that can appear on digital images. Now I just need to work out how to use all this stuff!
Friday 19 March 2010
Why Blog?
Astronomy and blogging go well together.
Firstly a basic observing log is very valuable to an astronomer. I have a detailed log that I keep up to date, but a blog of highlights can make it easier to track my overall progress.
Secondly astronomy involves a lot of trial and error. I have spent many hours trawling through other blogs and websites looking for tips on everything from dew prevention to spectroscopy. Maybe what I'm doing will be useful to someone else or maybe someone will be able to tell me where I'm going wrong!
I will be mostly restricting my posts to descriptions of my own observing sessions, in particular webcam astrophotography and basic spectroscopy. My location in suburban Birmingham limits my targets so you are unlikely to find much deep sky stuff.
Firstly a basic observing log is very valuable to an astronomer. I have a detailed log that I keep up to date, but a blog of highlights can make it easier to track my overall progress.
Secondly astronomy involves a lot of trial and error. I have spent many hours trawling through other blogs and websites looking for tips on everything from dew prevention to spectroscopy. Maybe what I'm doing will be useful to someone else or maybe someone will be able to tell me where I'm going wrong!
I will be mostly restricting my posts to descriptions of my own observing sessions, in particular webcam astrophotography and basic spectroscopy. My location in suburban Birmingham limits my targets so you are unlikely to find much deep sky stuff.
Beginnings
It all started when I was about 8 years old. I was walking back from the local scout group with my dad and I realised that I wanted to do astronomy. I didn't know why but I knew that I did.
Over the subsequent 25 years my relationship with astronomy has been consistently inconsistent. I got my first telescope and barely used it. I would spend a month voraciously reading astronomy books and magazines followed by a year of not reading anything. I toyed with doing an astronomy GCSE and bought a second telescope that gathered dust alongside the first one.
Things started to change in the 90s when I began an astrophysics degree at University College London. It all seemed exciting again and they have some serious telescopes. I imagine it will be quite some time before I get my hands on a 24" refractor again.
But a hobby isn't a hobby when one has to study it. The physics sucked the excitement out of the astro and observing became a chore motivated by exam marks. All in all astronomy had become a bit dull and I took refuge in the mathematics department so I could have an easy life. And astronomy has been in hibernation in my life ever since...
...Until now.
Over the subsequent 25 years my relationship with astronomy has been consistently inconsistent. I got my first telescope and barely used it. I would spend a month voraciously reading astronomy books and magazines followed by a year of not reading anything. I toyed with doing an astronomy GCSE and bought a second telescope that gathered dust alongside the first one.
Things started to change in the 90s when I began an astrophysics degree at University College London. It all seemed exciting again and they have some serious telescopes. I imagine it will be quite some time before I get my hands on a 24" refractor again.
But a hobby isn't a hobby when one has to study it. The physics sucked the excitement out of the astro and observing became a chore motivated by exam marks. All in all astronomy had become a bit dull and I took refuge in the mathematics department so I could have an easy life. And astronomy has been in hibernation in my life ever since...
...Until now.
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