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Explorer 130P or 130M


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So I'm looking at upgrading from my Skylux refactor to a Skywatcher reflector at the end of the month. With a budget of around £250-£280 I'm looking at either the SkyWatcher Explorer 130M or 130P. My question is, is it worth sacrificing the RA motor and getting the 130P which I understand will reduce chromatic aberration and give a clearer view. I'm assuming that I can get the RA motor at a later date for the EQ-2 mount, so effectively getting the best of both worlds.

Also, would the reduced focal length of the 130P be noticeable relating to the longer focal length of the 130M?

Edited by NorfolkGazer
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The 130M has a spherical mirror so it's spherical aberration you should be worried about. I see that 130M has 900mm focal length, so its focal ratio is f/6.9. This is ok for low and moderate power views but you may find that when you use higher magnification the view will be somewhat soft. I think at 130mm diameter a spherical mirror should be at least f/8 to deliver comparable views to a parabolic one.

I would recommend go for the 130P. More compact, lighter and the difference in focal length can be compensated with the use of a Barlow.  

 

Edited by Nik271
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18 minutes ago, NorfolkGazer said:

My question is, is it worth sacrificing the RA motor and getting the 130P which I understand will reduce chromatic aberration and give a clearer view

Both the 130P (130/650) and 130M (130/900) will reduce CA (reflectors don't produce CA). The 130M however, has a spherical primary, so this will give greater spherical aberrations (the image becomes less sharp towards the edge).

21 minutes ago, NorfolkGazer said:

I'm assuming that I can get the RA motor at a later date for the EQ-2 mount, so effectively getting the best of both worlds.

And you can then also choose between the single speed and multi-speed RA drives.

24 minutes ago, NorfolkGazer said:

Also, would the reduced focal length of the 130P be noticeable relating to the longer focal length of the 130M?

Probably not.

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