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A (partially) refurbished John Wall 6” Classical Cassegrain

A (partially) refurbished John Wall 6” Classical Cassegrain. Simon Dawes. Assessment. A light Breeze wobbles ‘scope Tripod to tall RA slow motion erratic Too heavy (16kg + tripod) OTA not balanced No clock drive Mirrors need re-aluminiumising Secondary mirror cover stiff

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A (partially) refurbished John Wall 6” Classical Cassegrain

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  1. A (partially) refurbished John Wall 6” Classical Cassegrain Simon Dawes

  2. www.itslifejim.btinternet.co.uk

  3. Assessment • A light Breeze wobbles ‘scope • Tripod to tall • RA slow motion erratic • Too heavy (16kg + tripod) • OTA not balanced • No clock drive • Mirrors need re-aluminiumising • Secondary mirror cover stiff • Allan key needed to change eyepieces • Focus completely lost with each eyepiece change • Eyepiece is a long way out the back of the ‘scope • Inconvenient to view objects www.itslifejim.btinternet.co.uk

  4. Assessment } • A light Breeze wobbles ‘scope • Tripod to tall • RA slow motion erratic • Too heavy (16kg + tripod) • OTA not balanced • No clock drive • Mirrors need re-aluminiumising • Secondary mirror cover stiff • Allan key needed to change eyepieces • Focus completely lost with each eyepiece change • Eyepiece is a long way out the back of the ‘scope • Inconvenient to view objects Mount, Wedge, Tripod www.itslifejim.btinternet.co.uk

  5. Counter weight doesn’t balance scope fully Single unit makes this very top heavy, making mount prone to vibration in a breeze Slow motion causes huge back lash, so not ‘drivable’ William Standing on Stool! Scope too tall adding to leaver effect www.itslifejim.btinternet.co.uk

  6. Wedge added to allow GE Mount www.itslifejim.btinternet.co.uk

  7. www.itslifejim.btinternet.co.uk

  8. Assessment • A light Breeze wobbles ‘scope • Tripod to tall • RA slow motion erratic • Too heavy (16kg + tripod) • OTA not balanced • No clock drive • Mirrors need re-aluminiumising • Secondary mirror cover stiff • Allan key needed to change eyepieces • Focus completely lost with each eyepiece change • Eyepiece is a long way out the back of the ‘scope • Inconvenient to view objects www.itslifejim.btinternet.co.uk

  9. Allan key needed to change eyepieces The idea is that the leaver aids quick eyepiece changing. Eyepieces are permanently mounted in their own tubes HOWEVER Only have 1 tube! Eyepieces too large to store Unable to use eyepieces with other telescopes Completely loose focus with each change From micro densitometer www.itslifejim.btinternet.co.uk

  10. Assessment • A light Breeze wobbles ‘scope • Tripod to tall • RA slow motion erratic • Too heavy (16kg + tripod) • OTA not balanced • No clock drive • Mirrors need re-aluminiumising • Secondary mirror cover stiff • Allan key needed to change eyepieces • Focus completely lost with each eyepiece change • Eyepiece is a long way out the back of the ‘scope • Inconvenient to view objects Correcting prism fixes both of these www.itslifejim.btinternet.co.uk

  11. Still to do • A light Breeze wobbles ‘scope • Tripod to tall • RA slow motion erratic • Too heavy (16kg + tripod) • OTA not balanced • No clock drive • Mirrors need re-aluminiumising • Secondary mirror cover stiff • Allan key needed to change eyepieces • Focus completely lost with each eyepiece change • Eyepiece is a long way out the back of the ‘scope • Inconvenient to view objects www.itslifejim.btinternet.co.uk

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