We are back at our normal venue from 3rd Sept. 2021 |
This page lists our monthly meetings. For other events open to the general public, see our Events page
Dates are set well in advance but the 'content' of the meeting is only updated (from our 'meetings database') when details are entered, so 'blank' or 'TBA' may be shown when data has not yet been entered (please be assured that the meeting will take place and a talk on (some) Subject will be delivered by (some) Speaker ! )
During the COVID-19 restrictions, all meetings are being held on-line using ZOOM. Meetings are normally held at the Church Hall (aka 'The Soltau Center') of St James-the-Less, Stubbings, Maidenhead SL6 6QW, from 7.30 (for a ZOOM link, or map and directions, see the About MAS (Where we meet) page
The Main Topic is usually delivered by an invited guest speaker. We aim to provide a diverse range of subjects linked (in some way) to Astronomy - whilst the 'Second Session' is typically delivered by one of our members. If time allows, the evening concludes with a short 'What to see this month'.
Details of a typical evening (times are approximate) :- 7.30pm. The evening starts with the Chairman delivering any important Announcements and then introducing the main speaker. 7.45pm (latest). Main Topic Speaker gets up and the lights are turned off. If you arrive after 7.45, please enter the Hall by the first door (on the right, after the entrance) and please be extra careful when finding a seat at the back of the Hall as members often setup telescopes there ! 8.45-9pm +. Coffee break during which visitors often chat with members who have set-up their telescopes at the back of the hall. If the weather is good, sometimes members will nip out for a quick look at the sky. Smoking is permitted outside the Hall, however smokers are asked to avoid any 'observers' (smoke particles always seem to get into optical equipment, no matter how well 'sealed' it may be) 9.15pm (at the latest). The 'Second Session' then runs for about 45 mins, typically ending with "What's Up !" (what to look out for in the sky this month) 10pm. We aim to clear the hall by 10pm. Post meeting Observing. If the weather is good, the Observing Organiser then leads the way to our chosen observing site, or (if the weather looks even a slight bit 'iffy) members sneak off to the local Pub instead :-)
Next meeting :
(-) 7 Nov 2025 Exoplanet Observation - (Adrian Jones)
Friday, 7th November 2025 - Exoplanet Observation" by Adrian Jones
All our indoor Meetings are open to the public, however non-members are asked to make a contribution of £2 toward the hall hire costs (this may be collected at the door on arrival, or left at the 'Tea hatch' at half time).
This note last modified: 7th Aug 2025 21:14.
(+) 5 Dec 2025 Christmas Quiz - (members)
(+) 2 Jan 2026 Telescope Parade - (members)
(+) 6 Feb 2026 When Galaxies Were Born ? - (Professor Richard Ellis)
(+) 6 Mar 2026 TBA
(+) 3 Apr 2026 TBA
(+) 1 May 2026 TBA
(+) 5 Jun 2026 MAS 69th AGM - (Annual General Meeting)
Meetings Archive |
The meetings archive gives an 'overview' of the Society activities over the past 10 years (see also the Events page).
Members have access to the full 'History of MAS' (including AGM minutes going back to 1957) along with full names and photos
The MAS 'year' runs from September of one year to June of the following. The end of year AGM in June elects the Committee for the following year (there are no meetings in July and August - although often members will meet informally at the local pub - which gives the new Committee time to 'get a grip' on running the Society)
The "short cuts" (in the 'title bar', at the very top of this page) will take you to the June AGM entry for the end of that MAS year
The Maidenhead Astronomical Society meetings archive (last 10 years only)
Missed a meeting, or can't remember when a topic was last covered ? Here is the archive of past MAS meetings.
Note that this list covers only our monthly meetings and AGM's. Reports on Observing and Other Events are separate pages
If notes were taken at the meeting, the date below is underlined and shown with a '(+)' = click to see the notes (if no '(+)' is shown, no notes were taken - or, more likely, the webmaster hasn't found them and posted them up yet :-) )
(-) 3 Oct 2025 Visual Astronomy and the Human Eye - (David Hayes (Zoom))
Friday, 3rd October 2025 - Visual Astronomy and the Human Eye by David Hayes (via Zoom)
In a first for MAS, tonight's speaker delivered his talk to the meeting via Zoom. This required access to the Hall's WiFi which went smoothly, although the signal strength in the Hall was low. Half way through the talk, David restarted the session to avoid the 40 minute limit, the restart also going smoothly.
David Hayes
David covered a number of areas of visual observing, with much focus on the human eye :-)
He started by pointing out that the human eyes can still beat the camera, especially for sensitivity and resolution. Further, our brains can still beat computers (except when it comes to long exposure stacking).
The eye has 4 main parts - the Cornea, a fixed focus 'outer lens' with UV filter, the Iris or Pupil, a variable aperture that opens and closes depending on the light level, then the variable focus Lens (which performs the fine focus) and finally the Fovea, where the image is formed.
The Iris/Pupil has an aperture of around 7mm(1) with a range of f/2.4 to f/11. Our brains 'scan' the image at about 60fps although we can detect a flash as short as 1/200th of a second.
Most of the magic is in the Fovea. This comprises a centre section containing colour sensitive Cones, around 5 mega-pixels. It is surrounded by around 150 mega-pixels of light sensitive Rods (our brains select a portion of this to 'perceive' in detail).
The sensitivity of the Rods is much higher than the Cones - which is why everything looks grey in the dark(2).
Dark adaption means that the sensitivity of both Rods and Cones change depending on light level. Cones first, then after 7 minutes or so of low light, the Rods(2), taking up to 30 minutes(3) to achieve complete dark adaption. Ed. a bright white light - such as a torch - will 'instantly' destroy the chemicals responsible for the sensitivity increase - which a red light does not. Which is why astronomers use red lights in the dark
Combined with the Iris/Pupil this gives us an ISO range of 1 (in bright sun) to 800 (in low light) to over 100,000 (complete dark adaption) !
(1) after age 40 your Pupil looses around 1mm per 10 years.
(2) a genetic disease or Vitamin A deficiency can lead to 'night blindness', the inability of your Rods to increase sensitivity.
(3) the older you are, the longer it takes to achieve complete Dark Adaption.
Of course what you see does not just depend on the physics of your eye. The brain plays a (very) big part.
Whilst our brains can't 'stack' they do take 15 seconds or so to 'see the detail'. 'Averted vision' - looking away from the centre of the telescope eyepiece - can allow our brains to pick up more detail from the (more sensitive) Rods.
Our brains are especially good at 'pattern matching' i.e. seeing what we expect to see. Indeed, sometimes we can't avoid seeing what we expect to see. For example, our brains expect sunlight to be coming from above. David showed us a number of images of moonscapes - when lit from above, craters are seen as craters. But flip the image over, so it's lit from below, and our brain interprets the crater as a dome !
Those with eye defects will find that our brains are able to dynamically 'see with the best eye', using the other eye to 'fill in' enough detail to form a 3d visualisation. Short sighted and long sighted people can take advantage of this by wearing one contact lens with a 'reading' prescription together with one lens of 'distant vision' prescription (something that David does himself !). He notes that this trick will not work with glasses since the lens of a pair of glasses is not next to the Cornea it causes barrel distortion (short sight) or pin cushion distortion - and the brain can't cope with two different distortions.
Next David spoke about eyepieces, showing us a number of examples.
'Exit Pupil' is the cone of light from the eyepiece that enters our eye. This cone varies depending on the telescopes focal length and eyepiece focal length, or (in mm) the telescope aperture divided by the magnification. So the lower the mag. the wider the exit pupil - the higher the mag. the smaller. Exit pupils wider than the Iris/Pupil 7mm (1) mean that the image will not totally enter our eye, whist exit pupils of 1mm or less will show up any 'floaters' or imperfections within our eyes. The 'ideal' exit pupil is 2mm.
'Eye Relief' is the distance from the eyepiece glass to where the exit pupil forms. Long eye relief eyepieces (up to 20mm) are intended for those wearing glasses, however non-glasses wearers can find difficulty achieving a good view. To address this at a public / outreach event, David has a snall tube he fits over the front of his eyepiece to allow non-glasses wearers to place their eye at the optimium position.
A 'Bino-viewer' is a dual eyepiece allowing us to use both eyes at once. When viewing the moon this will result in a '3d effect' (there is actually no paralex - both images are identical - however the brain 'sees what it expects to see'). He notes that with eyepiece focussing (refractors and simple Newtonians) to reach focus a 'Glass Path Corrector' may be needed. Telescopes with moving morror fcus have a much wider focal range and should be fine.
After the Break
Matt
The Photo Competition deadline is midnight after the next meeting (November 7th).
Tomorrow, October 4th, is International Observe the Moon night (but weather forecast is poor). It is to be noted that the following full moon is November 5th.
Alun - What's Up
TBA
All our indoor Meetings are open to the public, however non-members are asked to make a contribution of £2 toward the hall hire costs (this may be collected at the door on arrival, or left at the 'Tea hatch' at half time).
This note last modified: 4th Oct 2025 10:35.