What Scope to Get

Equipment
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George Smith avatar
George Smith avatar

I am currently in the process of building an observatory in my back garden. Will be putting a Sywatcher EQ8r mount for the telescope. I have Bortle 7 skies, so I understand this would limit the scope's size. Will mainly be viewing and imaging the planets, however, I will also be doing deep-sky. I will be mainly viewing and imaging the planets, however, I will also be doing deep sky imaging. I have a budget of £8000 for the scope, looking at the Askar 203 APO 203mm f/7 Triplet ED Refractor, the Celestron C11 edge or a 12-16" Orion Optics CT Ultra Newton. Just looking for opinions on what scope would be best for my sky conditions. I like the idea of the refractor having very little maintenance compared to the Newton or SCT needing ollimation on a regular basis.

Thanks
George

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Tony Gondola avatar
Tony Gondola avatar

George Smith · May 2, 2026, 10:07 PM

Bortle 7 skies, so I understand this would limit the scope's size

It’s not the B number that limits your telescope size, it’s the seeing. Typically you want really large apertures for the planets but there’s really no point if your seeing is bad all the time. That’s really what you want to look at.

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George Smith avatar
George Smith avatar

Tony Gondola · May 2, 2026, 11:58 PM

George Smith · May 2, 2026, 10:07 PM

Bortle 7 skies, so I understand this would limit the scope's size

It’s not the B number that limits your telescope size, it’s the seeing. Typically you want really large apertures for the planets but there’s really no point of your seeing is bad all the time. That’s really what you want to look at.

Thanks Tony, my seeing is mixed. I am near the sea, so sometimes seeing is ok

andrea tasselli avatar
andrea tasselli avatar

George Smith · May 2, 2026, 10:07 PM

I am currently in the process of building an observatory in my back garden. Will be putting a Sywatcher EQ8r mount for the telescope. I have Bortle 7 skies, so I understand this would limit the scope's size. Will mainly be viewing and imaging the planets, however, I will also be doing deep-sky. I will be mainly viewing and imaging the planets, however, I will also be doing deep sky imaging. I have a budget of £8000 for the scope, looking at the Askar 203 APO 203mm f/7 Triplet ED Refractor, the Celestron C11 edge or a 12-16" Orion Optics CT Ultra Newton. Just looking for opinions on what scope would be best for my sky conditions. I like the idea of the refractor having very little maintenance compared to the Newton or SCT needing ollimation on a regular basis.

Thanks
George

For planets the largest aperture you can afford, so at least a 12” scope (or larger). Orion UK newts are very good at holding collimation once dialled in so “on regular basis” it’s actually maybe twice a year (I own two of them). I mistrust C11 as per long habit so the only other option here is the C14 but that is a really an handful for DSOs given it’s focale length. Refractors of that size are really a no-go area. There is no limit on scope size if you are willing to optimize the image scale to match your seeing conditions.