parabolic mirror or no parabolic mirror

[luna 2011]

hiya all its me again lol ive just been offerd a skywatcher 130/900 mil focal length for around a 100 squid 3 months old,however i read a review about them and there are 2 versions a 650 or 900.do they have their pros and cons. cheers:cool:

[Capricorn]

The 130/900 will be a spherical mirror, so about f/7.

A 130 from FLO is £157 new. So £100 is a fair price.

Not sure if it is better then the parabolic as the 130P is 650mm FL so with a 5mm eyepiece you would get 130x and a 5mm plossl is as small as makes sense to go. Getting a more costly eyepiece seems a little pointless on a scope costing £100.

A 4mm planetery may work but you will be spending £40 on one. So a fair proportion of the scope cost.

Equally a spherical mirror will not deliver great magnification, probably about the same at the end of the day, being a longer focal length, a 7mm eyepiece would give 130x.-

Both collect the same amount of light.

I cannot see much difference is getting one over the other. However I have not looked through either to compare.

The 130P may be easier to sell later if you get a bigger scope however. So that may be the deciding factor.

[great_bear]

Getting a more costly eyepiece seems a little pointless on a scope costing £100.

Not so sure myself. My Meade SWAs with TeleVue Powermate produce a surprisingly decent view on a 130P OTA - whose value (hard to judge as always sold with mount) must be sub-£100.

I was surprised.