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Suitable low power eyepieces for a F4 dobs

  • william coghlan
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17 years 2 months ago #51329 by william coghlan
Suitable low power eyepieces for a F4 dobs was created by william coghlan
I recently bought a second hand dobs in the UK (300mm) for low power deep sky use as well as quick set- up. I already have a few eye pieces (meade 4000 1.25 inch 9.7mm, 26mm; antares 17mm swa and two meade 2 inch eyepieces - a 32mm swa 4000 and a 56mm). Unfortunately the focuser hasn't enough travel to bring either of the 2 inch 'pieces to focus :( Any /all suggestions would be appreciated

Meade LX90 12" LNT
Orion Optics 12" f4 Dobsonian
EPs: currently in transition state
Health: CAF (Chronic Aperture Fever). No known cure. Known to cause Dobs to expand into Obsession.

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17 years 2 months ago #51330 by dave_lillis
Replied by dave_lillis on topic Re: Suitable low power eyepieces for a F4 dobs
Hi,
Is the focus on the inside of the focuser or beyond the focuser (outside) for those eyepieces.

Dave L. on facebook , See my images in flickr
Chairman. Shannonside Astronomy Club (Limerick)

Carrying around my 20" obsession is going to kill me,
but what a way to go. :)
+ 12"LX200, MK67, Meade2045, 4"refractor

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17 years 2 months ago #51331 by william coghlan
Replied by william coghlan on topic Re: Suitable low power eyepieces for a F4 dobs
Afraid I'm not familiar enough with optics in general to answer the question. It's a crayford focuser and judging by the image with the 32mm swa I'd say the focuser would need to move another 5 to 10 mm out at least to bring the image to focus.

Meade LX90 12" LNT
Orion Optics 12" f4 Dobsonian
EPs: currently in transition state
Health: CAF (Chronic Aperture Fever). No known cure. Known to cause Dobs to expand into Obsession.

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17 years 2 months ago #51332 by michaeloconnell
Replied by michaeloconnell on topic Re: Suitable low power eyepieces for a F4 dobs
you could get a 2" extension tube.

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17 years 2 months ago #51334 by william coghlan
Replied by william coghlan on topic Re: Suitable low power eyepieces for a F4 dobs
That's what I thought except I wasn't sure if they existed. Any suggestions where they they can be bought?

Meade LX90 12" LNT
Orion Optics 12" f4 Dobsonian
EPs: currently in transition state
Health: CAF (Chronic Aperture Fever). No known cure. Known to cause Dobs to expand into Obsession.

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17 years 2 months ago #51335 by philiplardner
Replied by philiplardner on topic Re: Suitable low power eyepieces for a F4 dobs
The simple solution is to move the focuser (and secondary) either up or down the tube in the appropriate direction as needed. Cutting a new focuser hole isn't rocket science and it's a lot cheaper than a new eyepiece.

If you can't rack the focuser IN far enough then you need to move it down the tube. If you can't rack it OUT far enough then you need to move it UP the tube.

Phil.

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