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markclaire50

Any real difference between 8" F6 and 10"F5?

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I know these are theoretically different, but in the real world, do members see a difference, sufficient to choose the 10" over the 8"? NOTE the F ratios in my question, in case these make a difference. 

If I also added that I might already have a 180mm mak, would you say go to the 10" or bearing in mind the answer to the first paragraph, still say pick the 8". And why? 

In the case of getting the newt as well as mak, I am aware of the wider field and different viewing experience between the two. Variety is the spice of life! 

Just need to think about cost and storage and justication for using up garage space (usual stuff! ). ? 

Thanks 

Mark

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Our club had a 10" f/6.5 newt for decades, and it showed very sharp (and rather stable) images of Saturn and globular clusters even when its mirrors were pitted at the end of its usable lifetime.

Obviously we've had a number of Meade and Celestron 8" Schimdt-Cassegrains, and some Sky-Watcher 8" and 10" newtonians on the field. Combining the experience from all of these, the 10" is a very worthwhile extra over the 8" diameter.

But the increase between a 180mm and a 200mm (or 203mm in case it's a true 8-incher) is only 23% or 27% more light whereas the 10" gives a 56% increase.

Edited by Ben the Ignorant
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The smallest 2" difference between the two is the focal length.  In my experience, an 8" telescope starts to make most astronomical objects become interesting whereas a 10" really nails them and is probably one of the most effective apertures overall. DSO's have a certain threshold, sometimes increasing the aperture just presents a brighter image of those already resolved without adding much new, I think a 10" hits that "sweet" spot.   ?

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I used to own two Orion Optics (UK) newts, 8" & 10" with similar FOV.
Not greedy. Just avoiding carrying scopes between two houses.

When I stopped travelling, I obviously needed to let one go. But which?
The photo shows both on my D6 mount.

It was actually difficult tell the difference in everyday viewing.
I suppose the 10" might have brought up a fainter object.
I suppose the 10" should have offered a bit more magnification.
However, under the often unsteady and always light polluted UK skies, it was difficult to tell them apart most nights.

At the end of the day I kept the 10". It was marginally (and I mean marginally) better.
What swung it was the better focusser, the mount being up to the job of the heavier scope and not having to transport.

If you are looking to buy new, then the wallet is a big factor.
If you are buying used, then what comes up and where it is are going to be the main influencing factors.
I have feeling that more people find a 10" too big and heavy, so there may be a better choice in the used market.

Sorry no easy or straightforward answers.

David.
 

Dual Europa.jpg

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58 minutes ago, Ben the Ignorant said:

Our club had a 10" f/6.5 newt for decades, and it showed very sharp (and rather stable) images of Saturn and globular clusters even when its mirrors were pitted at the end of its usable lifetime.

Obviously we've had a number of Meade and Celestron 8" Schimdt-Cassegrains, and some Sky-Watcher 8" and 10" newtonians on the field. Combining the experience from all of these, the 10" is a very worthwhile extra over the 8" diameter.

But the increase between a 180mm and a 200mm (or 203mm in case it's a true 8-incher) is only 23% or 27% more light whereas the 10" gives a 56% increase.

Hi Ben. I like the statistical approach you use based on multiple examples to level out variations such as mirror quality between scopes. Thanks. ? 

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