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HD-60 Eyepiece Twist Barrel


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#1 gspie

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Posted 11 May 2012 - 03:49 AM

I have a 25mm HD-60 eyepiece (came with my LX800).I noticed that the barrel twists, and the eyepiece gets a bit longer-- what is the purpose of the twisting barrel?
LX850 with 10" ACF OTA and Takahashi FS 60C OTA -- SBIG STT-8300M CCD with FW8G-STT Self Guiding Filter Wheel and SBIG AO-8 Adaptive Optics -- Camera Control and Image Calibration with Maxim DL/CCD Pro, Image processing with PixInsight, and final composition with Photoshop CS5

http://home.comcast....ie/astroweb.htm

#2 Meade

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Posted 11 May 2012 - 10:42 AM

The extending barrel helps to block out stray light while observing.

#3 gspie

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Posted 11 May 2012 - 01:37 PM

I think you misunderstood -- I'm not talking about the rubber cup -- if your twist the barrel, it gets longer -- the end that goes into the diagonal has a black segment that gets longer the more you twist -- up to 3/8"
LX850 with 10" ACF OTA and Takahashi FS 60C OTA -- SBIG STT-8300M CCD with FW8G-STT Self Guiding Filter Wheel and SBIG AO-8 Adaptive Optics -- Camera Control and Image Calibration with Maxim DL/CCD Pro, Image processing with PixInsight, and final composition with Photoshop CS5

http://home.comcast....ie/astroweb.htm

#4 Cefiar

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Posted 11 May 2012 - 06:45 PM

I think you misunderstood -- I'm not talking about the rubber cup -- if your twist the barrel, it gets longer -- the end that goes into the diagonal has a black segment that gets longer the more you twist -- up to 3/8"

If I'm not mistaken, it's a dioptre adjustment. Some simple Google searches seemed to back up my hypothesis.

This should allow you to adjust the eyepiece slightly to ensure that you can see the image clearly. It also most likely means that if you need glasses that have a small magnification at distances (eg: like bifocals) you won't need to wear them while observing.

Note: Many higher end DSLR cameras have them too, as do most binoculars and the like. Makes perfect sense for this to be on the eyepiece lens of a telescope.

PS: Great to hear you've got your LX800. Congrats!
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#5 gspie

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Posted 11 May 2012 - 11:16 PM

Never thought about it being a diopter since focus is changeable, and there is only the one lens. I would expect a diopter on
Binocular lenses to make up for differences in your eyes focus.

LX850 with 10" ACF OTA and Takahashi FS 60C OTA -- SBIG STT-8300M CCD with FW8G-STT Self Guiding Filter Wheel and SBIG AO-8 Adaptive Optics -- Camera Control and Image Calibration with Maxim DL/CCD Pro, Image processing with PixInsight, and final composition with Photoshop CS5

http://home.comcast....ie/astroweb.htm




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