8" Newt for AP

[ChrisV (Chris)]

Originally Posted by cometcatcher

6" F5 is good. I've got one of those. 8" F5 is good too, longer in focal length. 750mm vrs 1000mm. The HEQ5 Pro will easily handle an 8" F5. F4 scopes can be a challenge to collimate. ED Refractors are also a good option. Be like me, have one of each.

Kevin
How hard is it to collimate an f4?
And I agree. My newt and refractor complement each other really well
Chris

[cometcatcher (Kevin)]

Originally Posted by ChrisV

Kevin
How hard is it to collimate an f4?
And I agree. My newt and refractor complement each other really well
Chris

Some people probably have the knack of doing it. I don't. It's not just collimation. Focal plane tilt and focus become much less forgiving also.

[RobF (Rob)]

Originally Posted by cometcatcher

Some people probably have the knack of doing it. I don't. It's not just collimation. Focal plane tilt and focus become much less forgiving also.

Yes, which mightn't bee a problem if the focuser drawtube was rigid, the tube showed no flex, and the secondary assembly rigid. Unfortunately in Chinese OTAs there can be a bit of play in all of these making adjustment (and staying there) harder.

I think my F5 8" is great value, but also expect to have to show some patience and work a little harder to get the best results from it.

[cometcatcher (Kevin)]

Yeah the carbon fiber tubes should help with rigidity. The steel ones flex, a lot. If one really wants F4, CF would be a better choice.