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Telescope heating

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#1 John Van Allen

John Van Allen

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Posted 31 May 2020 - 04:56 PM

I own a Televue NP127 non is scope. The club members want to try filming a transit of the ISS next Tuesday using my NP127. They want to use a wedge and I told them I have a full aperature Thousand Oaks mylar filter but they say the wedge produces better images. My concern is letting the suns energy into the OTA and through the objective and then the Petzval corrector before reaching the wedge. Can I have any dangerous build up of heat doing this? 

 

Thanks

John



#2 D_talley

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Posted 31 May 2020 - 05:51 PM

If you do it, make sure to cover the finder scope if one is attached. People forget and burn through the cross hairs. 



#3 rgsalinger

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Posted 31 May 2020 - 06:52 PM

I think a wedge is not a problem. What's a problem are the Etalon Filters that people sell. For some reason these have issues with any Petzval design. See if Televue has opened back up and ask them the question before agreeing. 

Rgrds-Ross



#4 John Van Allen

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Posted 31 May 2020 - 07:32 PM

OK thanks. I will call them tomorrow and post here what they say. I know that the F of the 127mm objective is somewhere around 13 04 15 so the light converges somewhat until it reaches the Petzval lenses and then it departs as an F5.3 into the focuser tube and eyepiece so heating at the Petzval lens group is my concern. 

 

Re finder scope thanks for heads up. I use a red dot finder on the NP127 and rarely use it as the G11 base with Gemini GoTo always gets any object in the FOV of my 40mm eyepiece which is my starter. Thanks 

 

Regards

John




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