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  #21  
Old 23-10-2018, 05:06 PM
astro744
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Reason 1:
I cannot see the return beam spot on the end of the laser collimator because it sits 60mm up into the draw tube as viewed from inside the OTA. If I were able to insert the focuser further into the draw tube as I can do on my GSO focuser I could easily see the spot. Yes there are other collimators available but so are there other focusers.

Reason 2:
The Paracorr type 1 has a 60mm nosepiece. I can only insert 45mm and as a result cannot achieve focus. Again I have no problem with the GSO focuser.

I cannot fathom why a focuser design would provide a stop to prevent accessories being fully inserted other than to prevent items slipping in and hitting the mirror. I cannot think of a single accessory that is 2" diameter along its entire body and if there is one out there it would not be common enough to require this annoying safety feature.

Both of the reasons I mentioned are common applications that other focuser manufacturers have accommodated.
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  #22  
Old 23-10-2018, 05:17 PM
raymo
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Fair enough; I did ask what was different about a Paracorr, and now I know.
cheers raymo
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  #23  
Old 23-10-2018, 05:49 PM
astro744
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Quote:
Originally Posted by raymo View Post
Fair enough; I did ask what was different about a Paracorr, and now I know.
cheers raymo
No worries, raymo. I just had a closer look at the collar that screws into the draw tube and I now know why the stop is there. It isn't because a stop was needed or intended as a safety feature but because extra thickness was needed to accommodate the male thread that goes into the draw tube. If it were possible to leave at 2" I.D. I'm sure it would have been done. My electronic vernier battery is flat so I couldn't measure how close to 2" it is but it does only need a minimal turn down on a lathe.

Anyway, I have digressed here although it is still relevant to comparing GSO with SW. There are many other factors to consider and the focuser is just one of them.

To the OP; whatever you choose, enjoy!
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  #24  
Old 24-10-2018, 07:11 AM
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Allan_L (Allan)
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Quote:
Originally Posted by raymo View Post
I can't fathom out for the life of me why any 2" accessory needs to enter the draw tube at all, the focal point is well outside the draw tube; certainly eyepieces, barlows and collimators don't.
The 2" adaptor allows accessories to slide in about 50mm, how much more do you need?
raymo
I am no techno expert Raymo, but from what I can tell, the whole point of the Paracorr is to get the eyepiece at a particular position hence the micro adjusting height (turntable) to use for different eyepieces. I would think that it needs to be fully seated to achieve this.

http://www.televue.com/pdf/literatur...structions.pdf
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