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130mm-150mm f/5 portable newtonion?

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#1 Guest_**DONOTDELETE**_*

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Posted 28 January 2004 - 07:43 AM

I currently have a 100mm f/6 refractor and am looking at possible ways of getting a bigger scope that's still portable. How much magnification can this type(130mm-150mm f/5) of scope use on planets? Is it a good type to use, or not any good? I don't know much about reflectors, so I don't even know what questions to ask. But I though since they are a good design for huge sizes they might be very good for smaller sizes too. Please describe what something like this could be used for and some pro's/con's. Thanks in advance.

#2 imjeffp

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Posted 28 January 2004 - 11:01 AM

My Celestron C6-N (C-150HD) fits right in this category, and I regularly use up to 250x (6mm + barlow) on Saturn. I think seeing limits magnification more than aperture for me.

Pros: Reasonably-sized OTA, not overly heavy. Cools quicker than an SCT or Mak. Rides fine on the CG-4. Nice wide views with 32mm Plössl, but higher magnification possible. No false color.

Cons: Slower to cool than a refractor. Collimation more critical in f/5 design than slower scopes. 150mm aperture leads to aperture fever (slippery slope).

I'm very pleased with mine, especially after adding a RA motor.

#3 BCB

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Posted 28 January 2004 - 05:00 PM

The Orion 6" version on the SkyView Pro mount (same darn scope for all intents and purposes), would be the Celestron equivalent, .. I haul mine around the yard quite a bit...

Packing it up for travels a snap too.. 15 min TOPS for complete setup..

Aperature fever is DEFINATE in using a 6. :) I'm a prime sufferer of it, and I've only had mine 2-3 weeks..... :jawdrop:

#4 jmoore

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Posted 28 January 2004 - 05:26 PM

I think jeffp summarized it nicely. The theoretical limit for 130mm and 150mm will be about 260x and 300x, respectively. With either of these aperture sizes, you'll probably be more atmosphere-limited than scope-limited most of the time, such that either scope will let you view the planet at the same mag (somewhere between 150x and 250x). However, there will be those times when atmosphere allows 300x or more...the 6" will get you there...the 5" might not.

Collimation will be important. As long as you keep collimated, planets will look great. I pushed 278x on Saturn the other night with my 8" f/5, and was a amazed at the view. Cool-down, as jeff says, will be longer than a refractor, but with the aperture you're considering, it won't be that long (probably < 1/2 hr in many occasions). My 8" cools sufficiently in under 45 mins usually.



#5 Blair

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Posted 28 January 2004 - 06:33 PM

The Orion 130mm f/5 has a plastic focuser where, (if I remember correctly as it has been a long time since I tried Orion's 6 inch f/5 scope) the 6 inch has a metal focuser. Unless, they have upgraded it in the last year or so. The plastic focuser can flex out of collimation at certain focus points. What I did was I marked the range where my eyepieces came to focus on the focuser and insured the laser dot stayed inside the center of the mirror as I moved the laser collimator through this range. BUT,

I would go with the 6 inch, for sure, if it meets your portability requirment.

#6 Guest_**DONOTDELETE**_*

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Posted 28 January 2004 - 09:18 PM

Thanks for the help everyone! I just need see one in person to make sure the 150mm will work for me. But I'm pretty sure now that this is the scope I'll be getting in a few months(orion).


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