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maugi88
Pooh-Bah


Reged: 08/25/13

Loc: SE MN
Re: focus shift in LX850 new [Re: cherokeeridge1]
      #6145798 - 10/18/13 11:02 PM

I have been down in the
Dewitt area but not as far as Davenport

Beautiful country.


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Alph
Carpal Tunnel


Reged: 11/23/06

Loc: Melmac
Re: focus shift in LX850 new [Re: cherokeeridge1]
      #6146772 - 10/19/13 02:12 PM

Quote:

I use Focusmax to focus and have noticed a huge difference in the focus position, depending on where I aim the scope.



Just looked at your spreadsheet. If you had temperature compensation enabled then you should turn it off and repeat your tests


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niteman1946
sage


Reged: 02/16/08

Loc: Fort Worth, TX
Re: focus shift in LX850 new [Re: Alph]
      #6147124 - 10/19/13 05:28 PM

Sorry guys, can't help myself. I have a 12" Classic and thought it was the last generation without mirror lock. The GPS model does have the lock feature, and I thought all subsequent SCTs had it. I remember Jason Ware's posts including mention of his LX850 having the mirror lock.

Why would Meade abandon this? Or am I missing something fundamental, and a version of this feature is still there?


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cherokeeridge1
member


Reged: 03/29/11

Re: focus shift in LX850 new [Re: Alph]
      #6147156 - 10/19/13 05:42 PM

I had the temp compensation disabled while doing the focus runs and you can see those focus points in the data but then I factored in temp comp to do the graph. In the data you will see one column for actual focus reading and another for compensated readings. I am now convinced that my primary mirror is moving and that's why I see the large spread as I move the telescope around the sky.

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cherokeeridge1
member


Reged: 03/29/11

Re: focus shift in LX850 new [Re: niteman1946]
      #6147161 - 10/19/13 05:46 PM

I believe that Meade thought the newly designed focus mechanism (dubbed as Crayford like) would not need a lock but they are finding out now that it does. Seems like something that should have been tested before marketing.

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maugi88
Pooh-Bah


Reged: 08/25/13

Loc: SE MN
Re: focus shift in LX850 new [Re: cherokeeridge1]
      #6147515 - 10/19/13 10:15 PM

Cherokeeridge,

Please post your dealing with meade as I have the same scope but no camera to test it.

Upon my conversation with them they are insinuating that this must be a problem with your particular OTA and not the design as a whole.

I am very skeptical of this but want to give meade the benefit of a doubt.

As I have stated I bought my scope for AP but cannot afford the camera for a good year yet. If my mirror moves there is no way I will be able to get the results a high end instrument (which this is supposed to be)should give. Visually I haven't noticed focusing all that often.

Maybe there is a retrofit lock that Meade will offer to fix this. I would be fine with anything that works.


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Alph
Carpal Tunnel


Reged: 11/23/06

Loc: Melmac
Re: focus shift in LX850 new [Re: maugi88]
      #6147649 - 10/19/13 11:36 PM

Quote:

I am very skeptical of this but want to give meade the benefit of a doubt.



Let's not jump the gun. I am skeptical about FocusMax. Manual focusing with MaximDL always worked better for me than FocusMax.


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cherokeeridge1
member


Reged: 03/29/11

Re: focus shift in LX850 [Re: Alph]
      #6147674 - 10/19/13 11:57 PM

Yes, I also am somewhat skeptical of FocusMax sometimes and so in this instance I was also watching the very dim backgound stars to reaffirm my focus point.
I agree about "jumping the gun" and would not presume to say this focus shift will be present on all LX850s. Hopefully not! I can only testify to my own problem.


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