6" Apo Refractor-like for £1300

[Tim]

To quote Arnie:

I have used an f5.9 MN190 for astrophotography over an extended period, and also an f7 6" apo. Didn't use the MN190 for observing much, apart from a few views. One view of M42 I had using it with a cheap  32mm plossl ep will stay with me forever, incredible bright sharp detail in the nebula that was the first time I had a "photographic" view of anything through one of my own scopes. But for a genuine side by side comparison I prefer to do away with the variables introduced by the mk 1 eyeball and compare results from a straight talking camera. I never delete my old individual exposures so if anybody would be interested I can probably track down some photos for a side by side comparison. Bit busy getting the grounds at work ready for my boss's wedding in 2 weeks but after that I can root them out.

John, the scope in your original post looks most interesting!

Tim

[Mr Spock]

I've never looked through a Mak-Newt. I do find the concept very appealing. Is anyone bringing one to SGL2017? Would love a shufti

[michael.h.f.wilkinson]

The key difference affecting planetary performance between the Mak-Newt and SCT designs is the size of the secondary obstruction, assuming for the moment that the optical figure of both scopes is of the same quality. This is typically 33% in the SCT and can be as low as 20% in the MN design. The MN has a much wider FOV, which makes an 8" MN a much better all-round performer. That does come at a cost of weight! The C8 OTA weighs in at only 5.7 kg, or so, much lighter than the MN 86 which tips the scales at 20 kg(!), including dew shield, focuser, and tube rings. Compared to the regular Newtonian (and I had a very good 6" F/8 with 1/10th lambda mirrors and very small CO (23%)), a key difference is that the MN lacks spider vanes, so it doesn't have diffraction spikes. I have never looked through an Intes scope, but they have a reputation of excellent optical figure.

[Peter Drew]

I had to strip down my 5" MN to clean the somewhat mottled surfaces which fortunately scrubbed up well. After doing a basic re-collimate I checked it out via a specular reflection on a distant pylon. Still needs a minor tweak but there was a hard bright Airy disc with faint diffraction ring at 250x. A bit like an APO refractor I thought.