Need help with 4.5" Reflector

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1cooldaddyo

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Last couple of times I've tried it, it appears that I'm seeing the secondary mirror and support arms over everything. A couple of nights ago, I tried looking at a bright star and it looked like I was looking straight down the tube. It was very cold out so I wrote it off as it hadn't had time to adjust to the temperature. <br /><br />This morning, I tried to get a quick look at Jupiter before I left for work (admittedly through a window, just wanted to see what I could see) and the cross was there again. A large black dot on Jupiter with four spokes that tracked with the planet as it moved across the field of view.
 
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MeteorWayne

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AFAIK, the only way to do that is to be WAAAAAAY out of focus.<br /><br />Maybe take it out in the daytime and focus on something distant to get it in the ballpark, then start from there when focusing at night.<br /><br />It's the only thing I can think of <img src="/images/icons/frown.gif" /> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>
 
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heyscottie

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You can also start to see these artifacts at extemely low magnifications, but I can't imagine you are using low magnifications for looking at Jupiter...
 
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1cooldaddyo

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I was at 90x. It could be the focus. Although I could see cloud bands on Jupiter, I could also see the shape of the twigs of the tree in front of my house as Jupiter passed behind them. Assuming its a focusing problem, anything specific I should check. Its an Orion Skyquest Dobsonian. I bought it for the family for Christmas and we've used it successfully several times to view Andromeda galaxy, Orion Nebula, and Saturn (truly surreal!). No guarantees on how its been treated, as sitting on the floor it's well within reach of my 5 year old <img src="/images/icons/blush.gif" />
 
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heyscottie

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If you are seeing Jupiter's cloud bands, you are not wildly out of focus, that's for sure. crazyeddie might have the best suggestion about collimation, but even that sounds iffy to me. I guess you're absolutely sure that there's nothing on the lens itself, right?
 
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1cooldaddyo

Guest
crazyeddie and meteorwayne will have to share the prize. Turns out I had it so far out of focus, everything had bands. At the point where it should have been focused, the collimation is so bad you couldn't see anything. Upon further investigation, I found out that my daughter's "My Little Pony" dolls sometimes hide in the "cave" at the base of the Dobsonian mount, tucked neatly under the primary mirror.
 
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MeteorWayne

Guest
Well, at least you have figured out the problem.<br /><br />I'd suggest collimating, and focusing at the furthest point you can see. Tree, light pole, TV tower, mountaintop. whatever.<br /><br />I'll go into more detail if needed, but hopefully not. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>
 
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heyscottie

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Well, I'm glad we (not including me!) could help out...
 
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