Gap in my armoury.

[Andrew_B]

On 21/01/2022 at 11:28, Nik271 said:

I've been tempted by the 8 inch edge HD in the past but considering its price bracket I think the StellaLyra RC is the better choice. 6kg vs 8kg is not a big difference, you still need a 10kg class mount to use them comfortably. There is now 8 inch carbon fibre RC which is a kilo lighter but a bit pricier. 

As far as I see the only slight disadvantage of the RC is that its collimation is tricker than a SCT. But there are many online manuals on collimating it nowadays so should not be a big deal if you store it in one location.

RCs also have a very large central obstruction (often around 50%) which reduces overall light gathering and puts a lot of light into the diffraction rings rather than the central Airy disk which reduces contrast for lower frequency detail so they're not a great choice for things like planetary observing or imaging. Apparently you also get a lot of field curvature and astigmatism and as has already been mentioned, an RC is somewhat more sensitive to miscollimation than a Classical Cassegrain, and far more sensitive than a Dall-Kirkham.

[bomberbaz]

18 hours ago, Andrew_B said:

RCs also have a very large central obstruction (often around 50%) which reduces overall light gathering and puts a lot of light into the diffraction rings rather than the central Airy disk which reduces contrast for lower frequency detail so they're not a great choice for things like planetary observing or imaging. Apparently you also get a lot of field curvature and astigmatism and as has already been mentioned, an RC is somewhat more sensitive to miscollimation than a Classical Cassegrain, and far more sensitive than a Dall-Kirkham.

Yeah I think I am settled on an SCT or CC, more likely the latter.