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Lunt LS80THa sliding objective tube

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#1 dhkaiser

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Posted 15 January 2020 - 06:31 PM

Anyone have an explanation for the Lunt LS80THa sliding objective tube?  Loosen the thumb screw and the tube slides forward.

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  • LS80THa-Lunt-Solar-Telescope-80mm-8.jpg

Edited by dhkaiser, 15 January 2020 - 07:55 PM.


#2 MalVeauX

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Posted 15 January 2020 - 06:36 PM

To shorten the OTA by sliding the lens shade/shroud back, to fit better in cases.

 

Very best,



#3 dhkaiser

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Posted 15 January 2020 - 06:40 PM

To shorten the OTA by sliding the lens shade/shroud back, to fit better in cases.

 

Very best,

Well it would do that, however it is not a lens hood, the objective lens moves with the sliding tube.



#4 MalVeauX

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Posted 15 January 2020 - 06:42 PM

Well it would do that, however it is not a lens hood, the objective lens moves with the sliding tube.

Hrm... the objective? Or the ERF? Sorry, wish I had a better explanation, don't have one in my hands. My guess is to fit in a case regardless.

 

Very best,



#5 dhkaiser

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Posted 15 January 2020 - 06:54 PM

Object lens at opposite end from focuser...

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#6 petert913

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Posted 15 January 2020 - 07:50 PM

Can't be great for maintaining collimation !



#7 George9

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Posted 15 January 2020 - 10:00 PM

On my older LS80, that's just the dew shield, which slides over the lens cell and rest of the OTA but is not attached to it. Mine doesn't have the screw but otherwise looks similar. 

 

Do you have a recent model with a moving lens, or are you going by the image?

 

George



#8 Cometeer

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Posted 16 January 2020 - 12:11 AM

That is the dewshield. The objective is fixed. The diagram you’ve posted does not contain the dewshield.

#9 bart1805

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Posted 16 January 2020 - 02:41 AM

The diagram is of the 60mm, not the 80mm. The focal length and ratio are both mentioned. The 60mm does not have a dew shield.

#10 dhkaiser

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Posted 16 January 2020 - 04:21 PM

Sorry for slow reply, been on the road today.

 

The question arose yesterday when my friend received his brand new LS80.  No it is not a dew shield, the objective lens moves in and out with the tube.  Lunt answered our inquiry today and said this is a carry over from an earlier design and that it does not matter if the tube is extended or not.  I assume that means the lens attached to the end is a filter not a true objective.


Edited by dhkaiser, 16 January 2020 - 04:22 PM.


#11 gvk

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Posted 17 January 2020 - 01:34 PM

On my LS80THa SS, also brand new, there is no glass or ERF in the sliding lens shade. The only other LS80 that I have seen belonged to a friend, and though a few years old, was identical in configuration to mine.

 

Gerry



#12 twjs

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Posted 18 January 2020 - 06:47 PM

On my LS80THa SS, also brand new, there is no glass or ERF in the sliding lens shade. The only other LS80 that I have seen belonged to a friend, and though a few years old, was identical in configuration to mine.

 

Gerry

Nor mine.



#13 torsinadoc

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Posted 21 January 2020 - 07:52 AM

I don’t understand their response. I owned two different lunt 80s. One early model and one late. Neither had objective lens that moved


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