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Is a 2x Barlow enough to bring a BV into focus?

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3 replies to this topic

#1 Kim2010

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Posted 09 February 2024 - 01:47 PM

So using my 100ED apo, I can't bring my WO BV into focus. Looks like I need more backfocus.

 

Now I bought a Maxbright II BV finally (yay!), and I am thinking if using a 2x Barlow be enough to bring the BV to focus on my 100ED. Would it be?


Edited by Kim2010, 09 February 2024 - 01:48 PM.


#2 vtornado

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Posted 09 February 2024 - 02:16 PM

On my Orion 100 F9 ED yes it is enough.  I know our tubes are related, but I'm not sure about tube length and focuser height.   Another issue has to do with the postion of the barlow element in the housing.  Maybe they all don't work.  IIRC I used a gso shorty. which has a longer body than the Orion shorty and Meade TV telenegative.  I have the Williams optics BV that came with two OCSs and they did not have enough in-focus relief.


Edited by vtornado, 09 February 2024 - 02:18 PM.

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#3 betacygni

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Posted 09 February 2024 - 07:30 PM

Generally speaking the more magnification, the further back the point of focus becomes and the more likely you will be able to reach focus. Note however that barlows not designed specifically for binoviewers will give higher mags when binoviewed. For example my TV 2x Barlow gives about 3x with binoviewers.

Is there a particular reason you’re not wanting to use the Baader glasspaths? The 1.7x model with a baader t2 diagonal should reach focus in nearly any refractor.

Edited by betacygni, 09 February 2024 - 07:32 PM.

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#4 Kim2010

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Posted 10 February 2024 - 08:46 AM

Yay! It worked! :) My Maxbright II worked with 100ED when I used a 2x Celestron Barlow :)




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