It is good a 6" f/5 refractor for DSO?

Hello,

This is my question.A 6" f/5 refractor is good for DSO wide field?
For nebulas, star cluster..

Paulo

Hi Paulo,

For large dim objects, they are great. I have reasonably dark skies, and low power wide field views of the Milky Way are very nice. Small planetaries that require high magnification will not work out as well, as these type of short refractors tend to not hold up to high power views. I use a 31mm Nagler with mine, but it taxes the focuser a bit.

Here's my initial review:

http://www.astromart.com/forums/viewpost.asp?forum_post_id=231758&poll_id=&news_id=&page=

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Paulo martin said:

Hello,

This is my question.A 6" f/5 refractor is good for DSO wide field?
For nebulas, star cluster..

Paulo

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Paulo martin said:

Hello,

This is my question.A 6" f/5 refractor is good for DSO wide field?
For nebulas, star cluster..

Paulo

Ah, someone else starts down the road towards a "Richest Field Telescope"!

My short answer is "yes" depending on what eyepieces you've got or are willing to buy. An f/5 refractor will be pretty hard on eyepieces in terms of astigmatism; this is mitigated somewhat when you are using the scope on DSO's vice stars/planets and at low power, but you'll still probably find that Naglers and other expensive eyepieces work the best on these scopes. Buying an eyepiece that costs significantly more than the scope is not necessarily part of your viewing equation-- but if you've already got these eyepieces, adding an f/5 refractor can be a great way to get a Richest Field view.

I recently picked up an Orion 120mm f/5 here on Astromart, and modified it pretty heavily.
http://www.jimrichberg.com/astronomy/Orion%20ST120.htm

I already had a Nagler 31 and high end 2" diagonal (AP MaxBright), so for a $300 outlay I got a scope that yielded a 4.24 degree field of view at 19 power. This is a useful companion to my big Dob (24" f/4) at deep sky sites, since the big scope can't crack the 1 degree FOV barrier even with the Nagler 31. I've found that the ST120 rendered appreciably better views than smaller refractors (70 and 80mm). The 6" f/5 you're looking at reaches about 0.5 magnitude deeper in terms of light grasp, but at the cost of width of Field of View (3.4 degrees using the Nagler 31).

So yes, I think you're on the right track if you're looking for a dedicated DSO/Rich Field scope, but you might want to crunch the numbers (cost and performance) on slightly smaller (~120mm) refractors as well.

Jim