8" f6 dob
My eyepieces are made from the waste product of exploding stars. 10XTi 102XLT ST80A(2" Focuser) XW: All; XO: 2.58 Televue: Naglers-T1 Smoothside-full set, 17T4,12T4,Ethos 17,4.7; plossels-40,32,20,17,&7.4mm; Pans-22,24mm; Delos-6,8,12,17.3mm ES100: 5.5,9*,14,20 ES82: full set ES68: 16,20,24,34 NLV: 5,9,10,15 Ortho: HD-7,9; OPS-9,12 Meade RG 7mm Other: Pentax 12.5K(.965), 10mm Parks Zoom: Nag3-6 *=on b/o DAS Dark Site
10" F/4.7 Modified Skywatcher Reflector, 38mm Orion Q70, 17mm Modified Ultima LX, 10mm TeleVue Delos, 7mm Pentax XL.
Quote:...My focuser is fairly squared and I measured the spider vanes to be in the exact center of the tube. My secondary has a classic offset, I think.
Quote:So, looking at the reflections I centered the secondary with the central bolt, always making iterations with the focuser axial alignment. But now I´m stuck in the final step, I think it´s a rotation issue, but I cannot make the two allignments well, it´s seems that at this point I cannot separate at all the tilt-rotation movement.
Quote:Or maybe is the spider? I don´t wan´t to touch the spider any more as it´s delicate and I think this is the best position, centered and with no vanes forced to the side.
Quote:So, should I accept this secondary placement or I can do better?
Quote:And the burned one. Note that the primary is not well alligned yet.
Quote:...I can correct the tilt-rotation to make the primary reflection fit better (see picture) but that affect the focuser axial collimation. What should I do? Stay with this correct visual collimation or with the previous, where the FAA is correct?
Quote:As for the primary, I ment it was not "dead center" under the collimation cap, I can do a little better in the final alignment of the primary.
Quote:Quote:...I can correct the tilt-rotation to make the primary reflection fit better (see picture) but that affect the focuser axial collimation. What should I do? Stay with this correct visual collimation or with the previous, where the FAA is correct?I suggest staying with the correct visual collimation and adjusting the mechanical focuser leveling to correct the focuser axial alignment (focuser is pointing a little too high). If your focuser doesn't have a leveling adjustment, you can try loosening the lower mounting screws and shimming. I've had good luck with thin plastic washers placed between the focuser base and the OTA and secured with the mounting screws.
Quote:...Ok, that´s new to me. My focuser has indeed leveling screws. But, I have to say, I wouldn´t like to start again to deal with the focuser. I think I can live with the FAA a little off, at least for now.
Quote:I´m not sure what you mean with the donut center spot vertical alignment. Thank you for the patience!
XT10 classic with premium optics Tri-knob CR2 focuser
Catseye + Glatter collimation tools
StarBlast 4.5" & 6"
Round Table Platform
Quote:Question - Does a laser collimator always indicate that the secondary is properly angled toward the eyepiece, regardless of whether the secondary is properly placed for a fully illuminated field?
Quote:In other words, if the laser is shining in the primary donut, and the collimator shows that the laser is aligned, is the only question whether the secondary should be raised or lowered? Doesn't an aligned laser mean that the secondary doesn't have to be twisted from side to side?
Quote: Assuming that the secondary is centered, and the focuser is properly aligned, wouldn't tilting the secondary alter the angle at which the secondary faces the focuser?
Quote:It is an iterative process. Starting with positioning the secondary mirror is a good idea. If you have a sight-tube with cross hairs then you can continue with the sight-tube/cheshire combo tool. Of course, you can also use a laser collimator with a plain sight tube.
Quote:an ugly collimation in extra focus
Quote:...I received my chesire/sightube a few days ago, and I certainly don't like it. My main concern is that is long and heavy and won´t go deep into the focuser. I put some tape to prevent play, but its weight produces flexure, I can tell. This make it quite inaccurate. Besides, it won´t be useful to center the secondary under the focuser because there is a huge gap between the secondary and focuser edges and I can´t see the primary clips. I guess this is the wrong lenght for my scope.
Quote:I also have a hard time when focusing the crosshair to perform the FAA and I don´t like the reflection that produces to perform the primary axial collimation, every thing is so tiny and confusing!
Quote:Anyway, while waiting it to arrive I made some last tweeks to the mechanicalls alignments and I improved my collimation cap with a shiny surface. Now is much easier to collimate the primary.This is how my final collimation looks.
Quote:I have the same issue with a Celestron cheshire sight tube. I cannot see the primary clips no matter where the tube is positioned...in ...out...it only shows a small area around the center spot of the primary and not the whole reflection.
Quote:I think this tool is designed for small 4 to 6" telescopes as it is an 1 1/4" size...not 2" in diameter.
Quote:It also wiggles a lot in the focuser when you pull it out.
Quote:...I have an Astrosystems autocollimator. I have taken to using that for the bulk of the work. I know this is not optimal, but it is what I have. I think next week I will buy an Astrosystems 2" sight tube. That should help.