The night I realized my telescope was out of focus for 3 months

I kept getting these blurry shots of Jupiter and couldn't figure out why. My neighbor Dave came over last Tuesday and asked if I'd ever checked the collimation on my reflector. I thought 'collimation' was some fancy term I didn't need to worry about, you know? Turns out my primary mirror was way off, and after 5 minutes with a cheap laser collimator, the image snapped right into crystal clear focus. Has anyone else made that same dumb mistake with their scope?

3 comments

3 Comments

torres.blair18d ago

Turns out my primary mirror was way off" - boy does that bring back memories. I did the exact same thing when I first got my 8 inch Dobsonian. I spent two months thinking my eyes were just getting worse or something, blaming the cheap eyepieces that came with it. A buddy at the local astronomy club handed me a collimation cap and showed me how to tweak the secondary mirror with a simple screwdriver. I felt like a complete fool when that sharp image of Saturn showed up for the first time, all those rings I had been missing. Now collimation is the first thing I check before every session, it only takes a couple minutes and saves you so much frustration.

the_holly18d ago

Wait, don't you actually collimate the primary mirror with the adjustment screws on the back though? I always thought the secondary was mostly for getting the reflection centered in the eyepiece tube. It's the primary that needs those tiny tweaks to get the donut shadow perfectly centered in the laser. I learned that one the hard way after messing with the secondary forever and still getting blurry stars.

xena58218d ago

Man, I felt that one in my bones! I had the exact same issue with my 10 inch Dob and it took me forever to realize the secondary mirror was the main problem. @the_holly is right though, once I dialed in both mirrors with a basic laser, everything snapped into perfect focus for the first time.