The 415th Meeting
The 415th Meeting of the Altrincham and District Astronomical Society, held at Timperley Village Club on Friday 7th of April 2006 at 8pm
Those present were:Paul Clark, Kevin Thurstan, Mark Crossley,Richard Bullock, Colin Eaves, Geoffrey Walton,Graham Sinagola, Nick Dixon, Ged Birbeck +2, Chris Suddick, Peter Baugh, Don Utton,Philip Masding Roger Livermore B Hetly ? 1 other,(Total 18)
The chairman Paul Clark opened the meeting by welcoming everyone to the 415th meeting and announced that tonight we were fortunate to have David Ratledge from Bolton AS to give a talk on advances in digital astrophotography. David started by explaining how CCD chips work. He told us some of the advantages of silicon over film were that silicon is ten to twenty times more sensitive, no reciprocity failure and substantial subtraction of light pollution. David then talked about web cams. They are cheap but you need a laptop or computer to run one. They are good for imaging the Moon, planets, sunspots and can be used for double stars.
Next was the digital darkroom he said that he used Iris software which is one of the ones that is free on the internet and that using parts of it he could get two to three times more resolution in the final image which was good for galaxies and planetary nebulae. We then heard about infrared imaging. Infrared imaging done through black glass cuts out all light pollution and penetrates the Milky way’s dust clouds, allowing you to see through the Milky way to otherwise hidden galaxies. It also lets you image quasars and the early universe.
His next topic was digital SLR cameras. One advantage is that they have big CCD chips, in fact the same chip is used in some £500 DSLR cameras as in some £4000 dedicated astro CCD cameras. However they do have some problems of their own, they are poor at the red end of the spectrum as they have a filter over the CCD chip to give better flesh tones, but you can get one over the internet where the filter has been replaced with a clear one. Other problems include generally coming with poor quality lenses, exposure noise, dewing up and difficulty aiming through the viewfinder.
Lastly he spoke about hybrid images where a close up image was pasted onto a wide field image for a more detailed composite image.
We were shown lots of great images throughout the talk and were told if we wanted to see more to visit his website at www.deep-sky.co.uk. Paul thanked him for his talk and we then had a break.
On resuming the meeting Paul Clark showed us four images of Saturn through his 6” scope with a webcam, to show his improvement over the last month. He then talked briefly about the viewing possibilities for the fragmented comet 73P/Shcwassmann-Wachmann over the next couple of months. Following this we went onto society business. The Secretary noted that we had received the new BAA journal and thanked Paul Brierly for donating a book on the moon for the society’s library. He also thanked all those who went to help and support at the recent astronomy evening at Delamere Forest Park. Ged Birbeck reported that as yet we had no prices for the clearing of the obs site. It was stated that there was a card for Tony Aremia, who was in hospital, for anyone who wished to sign it and had not yet done so, sending him our best wishes.
For our next Meeting, on May 5th at 8.00pm, we would be changing venue and trying out the Scout hut. The meeting was then brought to a close.
Those present were:Paul Clark, Kevin Thurstan, Mark Crossley,Richard Bullock, Colin Eaves, Geoffrey Walton,Graham Sinagola, Nick Dixon, Ged Birbeck +2, Chris Suddick, Peter Baugh, Don Utton,Philip Masding Roger Livermore B Hetly ? 1 other,(Total 18)
The chairman Paul Clark opened the meeting by welcoming everyone to the 415th meeting and announced that tonight we were fortunate to have David Ratledge from Bolton AS to give a talk on advances in digital astrophotography. David started by explaining how CCD chips work. He told us some of the advantages of silicon over film were that silicon is ten to twenty times more sensitive, no reciprocity failure and substantial subtraction of light pollution. David then talked about web cams. They are cheap but you need a laptop or computer to run one. They are good for imaging the Moon, planets, sunspots and can be used for double stars.
Next was the digital darkroom he said that he used Iris software which is one of the ones that is free on the internet and that using parts of it he could get two to three times more resolution in the final image which was good for galaxies and planetary nebulae. We then heard about infrared imaging. Infrared imaging done through black glass cuts out all light pollution and penetrates the Milky way’s dust clouds, allowing you to see through the Milky way to otherwise hidden galaxies. It also lets you image quasars and the early universe.
His next topic was digital SLR cameras. One advantage is that they have big CCD chips, in fact the same chip is used in some £500 DSLR cameras as in some £4000 dedicated astro CCD cameras. However they do have some problems of their own, they are poor at the red end of the spectrum as they have a filter over the CCD chip to give better flesh tones, but you can get one over the internet where the filter has been replaced with a clear one. Other problems include generally coming with poor quality lenses, exposure noise, dewing up and difficulty aiming through the viewfinder.
Lastly he spoke about hybrid images where a close up image was pasted onto a wide field image for a more detailed composite image.
We were shown lots of great images throughout the talk and were told if we wanted to see more to visit his website at www.deep-sky.co.uk. Paul thanked him for his talk and we then had a break.
On resuming the meeting Paul Clark showed us four images of Saturn through his 6” scope with a webcam, to show his improvement over the last month. He then talked briefly about the viewing possibilities for the fragmented comet 73P/Shcwassmann-Wachmann over the next couple of months. Following this we went onto society business. The Secretary noted that we had received the new BAA journal and thanked Paul Brierly for donating a book on the moon for the society’s library. He also thanked all those who went to help and support at the recent astronomy evening at Delamere Forest Park. Ged Birbeck reported that as yet we had no prices for the clearing of the obs site. It was stated that there was a card for Tony Aremia, who was in hospital, for anyone who wished to sign it and had not yet done so, sending him our best wishes.
For our next Meeting, on May 5th at 8.00pm, we would be changing venue and trying out the Scout hut. The meeting was then brought to a close.
posted by Mark Crossley at 1:23 PM
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