telescope problem help plz?

Question

i have an 8" Mead Light Bridge.

it came with a 26mm 2" wide Field eye piece, it works perfect.
however, i bought two additionnal eye pieces 12mm 1.5" and 9mm 1.5", but they seem not to work correctly with the adapters or the holders on the telescope, its like they are too far even when i turn the precision knobs to the maximum toward the telescope.
this is what i did :
i try first with the 26mm
- i took away the 26mm eye piece.
- i put the 12mm or the 9mm inside the 2" to 1.5" adapter
- i put the adapter on the telescope in the place of the 26mm 2" eye piece

i see very fuzzy picture, i tried holding the eye piece with my hand without the 1.5" -> 2" adapter and i could get a correct picture. i think the adapter keeps the eye pieces a little bit away from where they are supposed to be. but since the adapter came with the telescope, i don't know what to do?
is it just some matter of calibration or what?

Anonymous · Accepted Answer

It sounds like you have too little in-travel for these eyepieces to reach focus. One solution that may work is a low-profile 2 to 1.25-inch adapter that pushes the eyepiece farther in towards the secondary mirror. Another is to shorten all of the truss poles, if that is possible by an equal amount. If the trusses are not simply a tube, then you should not shorten them, instead contact Meade and see what they would suggest. That is what you would do if you had a conventional truss tube Dob. A solid tube telescope requires that the primary mirror cell be moved towards the secondary mirror  enough for all of your eyepieces to focus, or replacing the stock focuser with a lower profile model.

campbelp2002 · Answer

I would ask Meade if they have different adapters to use with this telescope-eyepiece combination that will allow them to reach focus. Either that or see if they have other eyepieces you could use and if they will take these back in trade for those. If not, then you are faced with modifying the telescope. You could replace the focuser with one having more in-travel (not cheap). Or you could move the main mirror mount a couple inches forward (drilling new screw holes and physically moving the 8 inch primary mirror closer to the Eyepiece) or shorten the truss tubes to make the eyepiece end closer to the primary mirror, but that could end up making the 26mm no longer focus because there is not enough out travel. And a botched job could leave you with a telescope that does not work properly in any number of ways.

Anonymous · Answer

what are you using as a test target? how far away is it?

an astronomical telesscope is intended to look at things that are light years away. my daytime test target is a local ski hill that is 15 km away.

later: are you absolutely sure you put the scope together properly? i haven't seen any reviews that mentioned focusing problems.

Anonymous · Answer

are th 12 and 9 mm eye pieces are of meade series?

meade series eye pieces have 70 degree apparent field of view(FOV), that other eye pieces may not have.

please use meade series eye pieces, I think the range of meade series starts from 15mm.

telescope problem help plz?

4 Answers