Skywatcher Quattro 8" first light

[Martin Meredith]

I've just acquired a Quattro 8". At f4 this is sold as an "imaging Newtonian" so over the coming weeks and months I hope to evaluate its potential (and pitfalls) for sensor-assisted observing. 

Here are a few first light images to compare with ones I'd taken earlier with my 80mm f6 achromat, mainly to get an idea of resolution, scale, coma (no corrector used) and star bloat. Otherwise the images are not strictly comparable, coming from different sites, temperature etc. All captured with Lodestar-C + LodestarLive v0.10.

Conditions for the Quattro: SQM of 18.45-18.58 (poor!), temp. 26 falling to 23C, humidity 70% rising to 87%.

M27. Left: 80mm single 60s sub; right: Quattro, stack of 2 x 30s. 

NGC6520 + Barnard 86 (The Ink Spot) at 14 deg above the horizon.

Both single 30s subs

Finally, for the Quattro alone, a look at stacking for a fragment of the upper fragment of the Western Veil nebula (the bright star seems to be telling me that my spider vanes are not aligned). From left to right: 1x30, 3x30, 8x30, 16x30. I used an O-III filter for these.

I think the scope has some potential and I'm looking forward to using it at my normal (darker) site soon. For the moment it is completely unmodified apart from the addition of Bob's Knobs for secondary adjustment (which is still a complete pain!), but I plan to flock, add a fan, modify the secondary for smoother operation and add a light shield over the coming weeks.

Cheers

Martin

[Macavity]

Appreciate your efforts to quantify / demonstrate these things in such comprehensive and practical detail.

Interestingly, my carefully "laser calibrated" GSO "Photo Newt" showed a diffraction pattern significantly...

off-center. Sometimes I wonder if it's the canonical (missing?) "secondary offset". Or maybe not to worry!

But I agree(?)! In-focus results with parenthetic "Astrographs" still look rather good for Video Astronomy.

[Martin Meredith]

Thanks Chris. I think the 8" F4 has a lot going for it in theory for sensor-assisted observing with small chips. It will be interesting to share experiences with these scopes. It's a surprisingly stubby little beast too and feels solid on the mount. Bloat was starting to get annoying with the achro and having a single-speed focuser didn't help. Having said that the jury will be out for a while as to which gets used the most  . As a lover of galaxy clusters the shorter FL definitely has a place for me. On the other hand some/all of the Hicksons need the extra resolution. 

BTW Are you referring to single beam laser collimation? I no longer trust it and use an autocollimator instead. Well, actually I get the collimation roughly right first using a sight tube and barlowed laser, then tweak with the autocollimator in place. Knowing when it is perfectly collimated is now no longer an issue but achieving it is...  At present the secondary movements are just too coarse/step-function-like, which I hope to address using the method on one of AstronomyShed's videos.

Martin

[nytecam]

Never was a great fan of refractors [bloat and that..] but love the Quattro images and a winner - well done

[Martin Meredith]

Thanks Maurice. I wouldn't mind seeing some of these objects through a decent 4 or 5-element APO though (if anyone could oblige) before writing off all refractors , although it does seem a bit of waste to be paying for a large flat field only to look at the central portion...

Martin