Clairelm1 Posted July 12, 2016 Share Posted July 12, 2016 Hi guys, total newbie here. I received my telescope last Wednesday for my birthday but have been unable to use it due to cloud cover. I had to collimate it as the secondary was all over the place and I got a collimating cap today so have sorted that (i think it looks right anyway). Surprised myself when I looked out the window before to see partially blue skies and the moon in the distance, so of course off to the telescope I ran. Found the moon with the 20mm, it focused OK enough, although I feel like there was a slight blur to the edges, is this normal? Maybe my collimation is off? Also, please forgive my idiocy here, I am sure its the most basic of questions. But why when I put the 10mm lens in did the image reverse itself? I have just received a couple of books I ordered, so I hope to not keep asking such stupid questions. Many thanks for any help I get. p.s does anyone use olympus EM10 MkII and know which T ring I need? Link to comment Share on other sites More sharing options...
John Posted July 12, 2016 Share Posted July 12, 2016 The normal view through a newtonian telescope is up and down and left and right reversed. The normal view through a refractor, a maksutov-cassegrain or a schmidt-cassegrain is up and down correct but left and right reversed. Astronomers are very concerned about maintaining light (many targets are rather faint !) and therefore resisted putting additional lenses / prisms into telescopes to give an image like we see with our eyes. Link to comment Share on other sites More sharing options...
Clairelm1 Posted July 12, 2016 Author Share Posted July 12, 2016 4 minutes ago, John said: The normal view through a newtonian telescope is up and down and left and right reversed. The normal view through a refractor, a maksutov-cassegrain or a schmidt-cassegrain is up and down correct but left and right reversed. Astronomers are very concerned about maintaining light (many targets are rather faint !) and therefore resisted putting additional lenses / prisms into telesopes to give an image like we see with our eyes. through the 20mm it looked 'normal' and then reversed with the 10mm, why is this? I am using the Celestron Astromaster 130 so its Newtonian. Link to comment Share on other sites More sharing options...
John Posted July 12, 2016 Share Posted July 12, 2016 Just now, Clairelm1 said: through the 20mm it looked 'normal' and then reversed with the 10mm, why is this? I am using the Celestron Astromaster 130 so its Newtonian. It should look the same through both eyepieces (larger in the 10mm) unless the 20mm is an erecting eyepiece which you do get with some scopes. Link to comment Share on other sites More sharing options...
Clairelm1 Posted July 12, 2016 Author Share Posted July 12, 2016 They are definitely the other way round, so I guess its an erecting eyepiece. Many thanks. Link to comment Share on other sites More sharing options...
Knighty2112 Posted July 12, 2016 Share Posted July 12, 2016 Depending on what scope you have, the 20mm EP may be an erecting EP, so views through it are as you would normally see. Some telescope manufacturers supply one of these with some scopes to allow you to use the scope for daytime views also. Normally for astronomy as John says the views are not normally normal and will be reversed in some way, either east or west, or up and down etc. i have a couple of erecting EPs supplies with different scope, but rarely use them. Link to comment Share on other sites More sharing options...
Clairelm1 Posted July 12, 2016 Author Share Posted July 12, 2016 Just now, Knighty2112 said: Depending on what scope you have, the 20mm EP may be an erecting EP, so views through it are as you would normally see. Some telescope manufacturers supply one of these with some scopes to allow you to use the scope for daytime views also. Normally for astronomy as John says the views are not normally normal and will be reversed in some way, either east or west, or up and down etc. i have a couple of erecting EPs supplies with different scope, but rarely use them. Thank you, this makes sense to me now when I imagine the path the image takes through the scope to my eyepiece. The 20mm lens is erecting and my other lens are normal (non-erecting?) whatever the correct term is. Again apologies, idiot newbie here Link to comment Share on other sites More sharing options...
Peter Drew Posted July 12, 2016 Share Posted July 12, 2016 The "normal" view through a refractor, Maksutov or Schmidt- Cassegrain is the same as that of a Newtonian, upside down and left to right reversed. It is the addition of the almost universal use of a star diagonal that changes the upside down to correct side up. I'm sure this is what John meant. Link to comment Share on other sites More sharing options...
John Posted July 12, 2016 Share Posted July 12, 2016 11 minutes ago, Peter Drew said: The "normal" view through a refractor, Maksutov or Schmidt- Cassegrain is the same as that of a Newtonian, upside down and left to right reversed. It is the addition of the almost universal use of a star diagonal that changes the upside down to correct side up. I'm sure this is what John meant. Quite right Peter. I know the Japanese like to observe "straight through" but I've always found a star diagonal essential to avoiding a cricked neck with scopes with the eyepiece at the lower end of the scope I should have qualified my post to include my assumption that a star diagonal was in use with those scope designs. Link to comment Share on other sites More sharing options...
Clairelm1 Posted July 12, 2016 Author Share Posted July 12, 2016 you do realise you guys are totally confusing me I'm only on page 10 of "Turn left at Orion" Link to comment Share on other sites More sharing options...
John Posted July 12, 2016 Share Posted July 12, 2016 Just now, Clairelm1 said: you do realise you guys are totally confusing me I'm only on page 10 of "Turn left at Orion" I so envy you the discoveries that you are going to make as you progress through that great guide Link to comment Share on other sites More sharing options...
Clairelm1 Posted July 12, 2016 Author Share Posted July 12, 2016 1 minute ago, John said: I so envy you the discoveries that you are going to make as you progress through that great guide I am excited, now if the clouds could kindly disperse Link to comment Share on other sites More sharing options...
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