Astronomy and Sky Website of Martin Lewis

At home in St.Albans with ‘Fossil Light’ – my home-built 444mm Dobsonian Newtonian Reflector


I am an active planetary imager, telescope builder and sketcher of deep sky objects, living about 35km north of London on the east side of the city of St Albans. I am married with two children.

Most of my observing is done from my back garden. This is relatively free of direct light but is moderately light polluted with a limiting mag is approx 5.3 on best nights and the Milky Way faintly visible overhead in Summer. At this location I have relatively unobscured views S, W and NW.

In my day job I am a principal engineer for Scintacor, a company in Cambridge making scintillation sensors particularly for X-ray detection for medical and dental applications.

I am an active member of the West of London Astronomical Society (WOLAS), being its treasurer and its membership secretary.

Updated 29/11/2015

Main Astronomical Interests

  • Telescope building- especially Dobsonian reflectors
  • Telescope improvement, with a special interest in the thermal optimisation of Newtonians and the optimisation of the movement of Dobsonians
  • High resolution planetary imaging
  • Imaging of ISS and Shuttle
  • Sketching of Deep Sky Objects, especially planetary nebulae and galaxy groups


I have been interested in things happening in the sky for as long as I can remember. My interest in astronomy, however, started at about the age of 8 when my father first showed me the stars and told me fantastic stories about the gods and creatures that were immortalised in the constellations.

At the time we used a pair of heavy-weight Russian Zenith 10×50 binoculars looking at things like the moons of Jupiter and the Pleiades. I clearly remember personally ‘discovering’ the Double cluster in Perseus from my parent’s back garden in Finchley, North London, with those binoculars! This was the 60’s, a time when the Milky Way was readily visible from such an urban location

When I was about 9 years old I had my first scope. This was a cheap, wobbly, overpowered 50mm refractor which was stopped down to 10mm to reduce colour fringing. With this I stared in astonishment at a tiny perfect Saturn with the rings full open. This made a much deeper impression on me than anything I had seen with the binoculars. To this day I am not a subscriber to the idea that a pair of binoculars always beats a small telescope.

My first ‘proper’ scope was a £35,  3″ refractor, bought via an advert in Exchange & Mart from a Mr. Woods of Ealing. This had optical issues and for a £10 upgrade I got a ‘better objective’. This was my first taste of telescope problems, but I ended up with 3″ f15 refractor of superb optical quality. I still have that scope as well as the tiny 9mm and 15mm Huygens eyepieces, with the incredibly short eye relief, that I used to observe the planets.

With that refractor I observed the night sky every night I could from the back garden in Finchley and started sketching the planets and many deep sky objects at the eyepiece. It wasn’t long before the refractor ‘improvements’ started, including a foray into building an equatorial mount. The set-up and use of this mount severely hampered my visual observing and gave me a distaste for inappropriate equatorial mounts which I harbour to this day (see photo of the scope set up at my parents garden in Finchley, N.London).

My interest in astronomy came to focus in 1977 when I studied for ‘O’ level Astronomy on my own and submitted several observing projects.  A few years later I went off to University. An astronomy course and the dense maths this called for unfortunately stifled my interest in the heavens and other interests took priority.

I resurfaced in 1989 when visiting County Donegal in Ireland for a wedding.  Comet Austin was in the sky and I rose at 5am and crept through a silent house to go and see it. The thrill of being under a pristine sky in a strange place, at a time when I would normally be fast asleep, gave me such rush of excitement. I can feel it now when I think back. I was hooked again!

10″ Dark Star Dobsonian

The 3″ rapidly went through another reincarnation, but now with a job I was able to use my wages and up-size. The Dobsonian revolution had passed me by but I made up for lost time and bought a 10″ Dark Star Dobsonian from Telescope House. More optical problems ensued requiring some refiguring work on the primary and a new secondary, but the jump in aperture was incredible. 10 times the light collecting area allowed me to see spiral structure in galaxies, resolve globulars and see much more planetary detail than I had ever seen before. I loved the ease of use of the Dobsonian with its great stability and simple construction but I wanted to squeeze every last drop of performance out of it. More telescope rebuilding followed and I gleaned much useful experience especially in understanding how thermal management issues affect telescope performance.

In 1993 I decided I needed a much larger scope- specifically to see and sketch more detail in more Deep Sky Objects. I wanted a scope that would disassemble and fit into the back of my car and yet be quick and easy assemble at an observing location. The idea was that I would be able to transport it to dark sky sites and set up and observe from there. Thus began a 3 year, 3000 hour project to build my own 18″ Dobsonian called Fossil Light. You can read more about that scope here.

Although the 18″ scope gave me fantastic views of deep sky objects and enabled me to sketch far more detail than had been possible with the 10″ I was only using the scope a few times a year. This would be occasional trips to the West of London AS (WOLAS) observing location in the Chilterns, the Equinox Autumn Sky camp and a spring WOLAS trip to a UK dark sky sight. I had sold the 10″ a few years earlier and I needed a smaller scope that was quicker to set up and which would be good on planets

A trip to David Hinds in Tring revealed that he still had a 222mm mirror set which was still unsold after he had given up his mirror making activities. A year and a half later this smaller scope, again a Dobsonian, was finished. The the scope is designed to be easy and quick to set up in garden to increase the time spend each year actually observing. The scope has Argo Navis digital setting circles to speed up finding of objects and is regularly used from my main observing location in back garden of my house in St Albans.

In 2005 I had a go at webcam imaging of planets with the 222mm by collecting short videos whilst the planets drifted through the field of view of the undriven scope. Later that year encouraged by the drift imaging results I built an equatorial platform to sit the scope on and enable longer avis to be collected. This worked well and so started my interest in high resolution imaging of the planets. The results of my endeavours can be seen here. As well as imaging the planets I have also tried imaging the ISS and Space Shuttle and results of this work can be found in the ISS and Shuttle gallery.

I have now moved on from my imaging with my 222mm dobsonian and now image with my 444mm dobsonian, Fossil Light, which previously was used exclusively for deep sky visual work. The use of this larger scope has moved my imaging capabilities on tremendously as I hope you can see from my images especially showcased here.

In addition to planetary imaging, in recent years I have also built an all-sky camera to do time-lapse sequences of the slowly rotating sky which I feel nicely conveys the beauty and tranquility of the night sky. You can see examples of my all-sky videos here.