Secondary mirror position

[JKB]

Does anyone know if my SW 150p should have the secondary mirror off-center? The reason I ask is that it is! It is currently further from the Focuser and I noticed it when looking to collimate (not done yet though)

I know Astro Baby mentioned some telescopes did have off center secondaries.

Any advice welcomed as always

Cheers

[John]

A degree of secondary offset is normal for fast newtonians.

[scotttumsh01]

All a bit confusing for me, hope mine is ok, i get clear images so im sure mine is ok, i use a collimating cap on my 150p

[sixela]

The mirror can but can also not be physically offset away from the focuser. The only really "important" thing is to centre the actual secondary outline (not its reflection) under the focuser, and to be honest, even that's not that important for visual observation, as long as you see the entire primary reflection when you look through the empty focuser from somewhere close to the middle of the focal plane (i.e. where the moon gives a focused image if you point the scope to the moon and hold a piece of paper in front of the focuser).

The sihouette reflection of the secondary in the primary's reflection that you see when you peer through the empty focuser tube is in any case offset towards the primary (i.e. away from where you see the focuser tube intrude in the primary's reflection when you rack it in.)

[JKB]

Thanks John, but is there a rule as to how much offset? or is each manufacturer different?

Will it make much difference if I centre the 2ndary then collimate?

Thanks