Blurry view in Celestron 114 Telescope

[Dslade05]

After much frustration, I was not able to get a clear image from my 114eq.  I decided that given it is well out of any sort of warranty/return period why not see if I can modify it to work? Prior to this I'd used a laser collimation tool & I know without a doubt the mirrors were lined up perfectly. What I thought was odd is that the laser would be a clean dot in the primary mirror but a blob by the time it got back to the collimation tool. 

So I took the focusing tube apart & removed the Barlow lens that gives it the 1000mm focal length. Tried collimation again, laser came back as a perfect dot. Now the problem was that the focus point was past where I could get with the focusing tube. So I took the whole scope apart, cut 3/4" off the primary mirror end of the body of the scope, re-drilled the mounting holes & put the whole thing back together. So now I've got a 114mm scope with a 500mm focal length.  Re-collimatied it yet again, then tried a number of different eyepieces. 

Where before I couldn't get a clear enough view with a 20mm eyepiece to look at the general outline of my neighbor's grill at 500 yards (I was testing it in the daylight, had to find something to look at! ) I can now get to a 10 mm eyepiece (through a window no less! ) and read the wording on the propane tank. At 500 yards.

I'll be taking it out tomorrow morning before sunrise to see how it does in the night sky, if the wind dies down at all.  Too cold & windy out right now. (MN in February is not a good time to be out)

[laudropb]

Hello and a warm welcome to the SGL. It sounds like you mod has been successful but the final proof will be when you try to focus on a star. Please let us know how you get on.

[Peter Drew]

Your results are at odds with what should be expected from removing the correcting lens from the telescope. The system should now be operating with a short focus spherical mirror. It could be that the spherical abberation introduced by focusing at short range is somehow reducing the effect. It will be interesting to see the performance at night. I would expect to see very spikey stars at best focus. Welcome to SGL. 

[Cornelius Varley]

This type of telescope doesn't collimate well with a laser collimator, the built in corrector lens disperses the returning beam (effectively magnifying the point of light) so they should only be collimated by using a Cheshire collimator or a star or by removing the corrector lens , collimate and then refit the lens. The built in barlow lens is intended to increase the magnification of the telescope and partially correct the spherical aberration of the primary mirror by reducing the FOV (the uncorrected area is outside the FOV). This style of telescope, sometimes incorrectly known as Jones-Bird, is more correctly called a Barlowed reflector, a real Jones-Bird has the corrector placed between the primary and secondary. Without the barlow you probably find that the views are distorted towards the edge of the FOV.

Jones-Bird designs