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Double stars and focal lengths


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Hi,

They say aperture is king, it seems quite obvious when looking for fainter objects.

They also say focal length is better for double star observing.

I have the heritage 130p reflector but was wondering whether or not a skymax 102 would be better for double star observing based on the above calculations?

I look forward to hearing peoples thoughts on this.

Thanks.

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There are two reasons why they say that aperture is king.

More light gathered = more chance of seeing fainter objects. This usually means DSOs, but could also be important if you're observing doubles with a very faint component.
But a larger aperture also means greater resolving power, other things being equal. That's obviously important when observing tight double stars.

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I'm not overkeen on Mak's for double star observing as they tend to have a bright first diffraction ring. This isn't noticeable for lunar or planetary observing. Or on many brighter deep sky objects. However, it is on tight doubles particularly. 

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1 hour ago, CKP said:

Hi,

They say aperture is king, it seems quite obvious when looking for fainter objects.

They also say focal length is better for double star observing.

I have the heritage 130p reflector but was wondering whether or not a skymax 102 would be better for double star observing based on the above calculations?

I look forward to hearing peoples thoughts on this.

Thanks.

The 130p is good enough to show excellent views even with good-quality, relatively expensive eyepieces. A range of 4-10mm EPs would be great for doubles if you can afford them (Pentax XWs, Baader Morpheus, etc).

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2 minutes ago, cajen2 said:

The 130p is good enough to show excellent views even with good-quality, relatively expensive eyepieces. A range of 4-10mm EPs would be great for doubles if you can afford them (Pentax XWs, Baader Morpheus, etc).

I do have a range of bst eyepieces and a x2 Barlow. Hopefully these will be enough, took a while to get this set, I don't really wanna start a new set 😬 

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Quite understand: I started with a BST 8mm myself and it was great EP for the price. My problem is that I wanted a larger FOV, thus the Pentaxes and Morpheus. If narrow fields of view don't bother you, also consider the Vixen NPL and SLV ranges - both excellent for the price. The 30mm NPL makes a very good 'finder' EP for not much money at all.

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