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Polaris 130 Secondary Adjustment


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#1 Hophead_LWC

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Posted 12 December 2019 - 09:03 PM

I am new to the hobby and trying to get the best out of my first scope, a Polaris 130EQ. It seems to be a decent starter scope with good reviews, but I'm having trouble with collimation.

My question is: can the secondary mirror be adjusted away from the primary, toward the spider?

While trying to collimate per the instructions from Meade, I am unable to center the secondary mirror when viewed through the focuser tube. The secondary appears to be too far toward the primary mirror, viewed with and without a collimation cap. Since I don't understand exactly how such an adjustment is made, I wanted to ask the experts in this forum. I assume any forward/back adjustment involves the center screw, but somewhere I had read a stern (perhaps overly dire) warning to not touch that screw! I have a picture in mind of what I think needs to happen, but I'd rather be safe than drop a mirror.

 

I've uploaded a couple of photos showing how the secondary looks with and without the collimation cap. Hopefully they are helpful!

 

CC1 20191204_002122.jpg

DT1 20191206_185851.jpg

 

I like the Polaris 130 and I want to push it as far as it can go. I find myself getting hooked on the hobby and have just bought an LX85 8" ACF...but I still want to dial in the 130 as a more portable option.

I appreciate any advice from the community!

 

Thanks,

Ken


Ken

#2 MistrBadgr

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Posted 13 December 2019 - 08:24 PM

Hi Ken!

 

What you have to do is slowly back off each of the three small collimation screws a tiny little bit, then tighten the center screw.  Repeat the process until the mirror is where you want it.

 

Hope this helps!

 

Bill


Bill Steen, Sky Hunters' Haven Observatory, Broken Arrow, Oklahoma

#3 Hophead_LWC

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Posted 15 December 2019 - 05:53 PM

Thanks Bill, that's what I was hoping to hear.

 

I got a response from Meade customer service (delay was my fault). I did not have the photos to send them initially, and without the photos their response was to leave the center screw adjustment at the factory setting, that the offset is necessary for fast reflectors. This is contrary to the collimation instructions in the manual and everywhere else I've found, fast focal ratio or not, which state that the secondary should be centered when viewed through the focuser. It's my understanding that once collimated, the reflection of the secondary will appear closer to the primary for a fast focal ratio Newt.

 

On the other hand, I understand that (partial) offset truly is the secondary being positioned slightly closer to the primary (not centered in the focuser), so the response from customer service makes sense.

 

So it seems to me that I have contradicting instructions, or something just has not clicked in my brain. I think once it clicks for me, it will have been a worthwhile learning experience.

 

I appreciate any advice to help it click in my head.

 

Thanks!

Ken


Ken




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