Telescope racks out before focus is met

[orionbman]

I recently bought an Orion 8" f/4.9 reflector telescope with no focuser. I bought a focuser and installed it. While using the telescope, I can not achieve focus with out pulling the eyepiece out of the holder about a 1/4 inch. So the images are almost getting focused, but its just out of the focuser's reach. Everything is collimated as far as I can tell, but I can't do a star test because I can't unfocus enough. Are my mirrors messed up or something? Thanks a lot!

 

[Saiph]

hmmm...you may need to tweak the mirrors a bit, but not sure. Hopefully you don't have a warped secondary (or worse yet primary).<br /><br />A more permanent solution would be to install a spacer at the base of the focuser, a metal ring/tube that fits into the hole,a nd the focuser can fit into. The tube should be, oh, from your description, about an inch or so long.<br /><br />But first, I'd check with different eye-pieces, make sure it isn't just a bad one that's messing you up. <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector.  Goes "bing" when there's stuff.  It also fries eggs at 30 paces, wether you want it to or not actually.  I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>

 

[orionbman]

Do you know where I can get spacers? Or did you mean something homemade? If so, any tips on material or construction? Thanks again.

 

[tfwthom]

Since you are going "cheap and dirty" buying a scope without a focuser...... http://www.telescope.com/shopping/product/detailmain.jsp?itemID=51&itemType=PRODUCT&iMainCat=6&iSubCat=30&iProductID=51 Think Eyepiece Extension Tubes..... not the best answer but will work. Other then upgrading the focuser that you already have.<br /> <div class="Discussion_UserSignature"> <font size="1" color="#3366ff">www.siriuslookers.org</font> </div>

 

[bobw]

You beat me to it. I have been looking around, too, and the shortest one I could find was 1.6 inches for a 1.25" focuser at the first link below. The second link has one 1 inch long for a 2" focuser. I haven't been able to find a focuser spacer to put under the focuser but they may exist.<br /><br />http://www.jimsmobile.com/adapter_comparison.htm#Top<br />http://www.optcorp.com/productList.aspx?mid=171&uid=105-182-220-224 <div class="Discussion_UserSignature"> </div>

 

[Saiph]

that site reminds me: What are you focusing on? Stars, or earth-bound objects. The closer the object, the more you have to rack out the focuser (i.e. extend the eye-peice). If you're focusing on something not to far away with a scope designed for astronomy (objects essentially/practically at infite distances) you can have this problem.<br /><br />If so, try practicing on really distant object (a light pole on a distant hill) instead of something closer. <br /><br />anyway, if that isn't the case, those eye-piece extenstions should do the trick. <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector.  Goes "bing" when there's stuff.  It also fries eggs at 30 paces, wether you want it to or not actually.  I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>