Quote:
Originally Posted by mental4astro
You might like to see how it fits in your car too.
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Quote:
Originally Posted by Scorpius51
Check to see whether it will fit in your car across the back seat.
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The 8 and the 10 are pretty much the same length but the 10 is fatter. The 8 will be a f/6 so 200mm x 6 = 1200mm focal length and the 10 will be f/5 so 250 x 5 = 1250mm focal length. The shorter ratio will make collimation more critical and increase off-axis coma but these disadvantages are more than offset but the increased light gathering ability, which is proportional to the ratio of the square of the apertures. So 8^2=64 and 10^2=100 so the 10 gathers 100/64 = 1.56 times more light than an 8 - a substantial increase. [If this makes the 10 more attractive you already have aperture fever
.]
One thing which may be on the primary mirror, and should be there, is a centre mark, which aids collimation. It is normally a re-enforcing ring, the things you stick on pieces of paper when putting them into a ring binder so the hole doesn't tear. It doesn't affect the operation of the scope because it is in the shadow of the secondary.