Sky-Watcher has added a new photographic Newtonian telescope to their range, the Quattro 150P and Sky-Watcher Australia sent me one to try out and review! In this article, I will share my experience and honest opinion on the Quattro 150P.
A brief introduction to the Newtonian telescope
The Newtonian telescope was invented by Sir Isaac Newton in 1668. This popular reflecting design is still widely used today. Reflecting telescopes use two mirrors, a large primary mirror and an angled secondary mirror. Light bounces off the larger primary mirror and onto the smaller secondary mirror, which directs the light towards an eyepiece or camera sensor, where it forms an image.
Reflecting telescopes are commonly used for visual astronomy and amateur and professional astrophotography. Their large apertures offer better resolution and more light-gathering power. They also have zero chromatic aberration. However, reflectors can suffer from optical issues. One such issue is Coma. Coma occurs when stars appear comet-like towards the edge of the image due to light falling inwards from the optical axis. This issue can be fixed by using a Coma Corrector.
Some may say that diffraction spikes are also an optical issue, and technically they would be right. Diffraction spikes are lines of light or light flare that extend out from bright stars. It occurs due to the distortion of light as it enters the optical chamber, this is because the secondary mirror support (sometimes called the spider or veins, or spider veins) interrupts the path the light takes. This effect can look beautiful, I'm a big fan! But if your telescope is not well collimated the diffraction spikes can extend off-centre from the star and cause the starlight to flare off to one side.
The secondary mirror in the Quattro 150P is supported by ultra-thin 0.5mm spider veins. With the support system being thin, the path of light is less interrupted. So, more light is gathered, and diffraction spikes appear thinner and sharper.
About the Quattro 150P
Natively the Quattro 150P has an aperture of F4. Which lets in a lot of light and is sometimes referred to as 'fast'. Its focal length is 600mm. Included in the box is a coma corrector/0.9x reducer. When used, the aperture widens to F3.45 and the focal length changes to about 520mm. But how much of a difference does this wider aperture make?
To get the same amount of data with a single exposure of 60 seconds at F3.45 with a gain of 100 on a telescope that is F5 you would need an exposure of 122 Seconds. If your telescope was F7, you would need to expose your image for around 247 seconds and at F10, it would need to be 490 seconds. Throughout a whole night, the use of an F3.45 telescope vs an F5 telescope will give you twice as much exposure.
Compare the F3.45 and F5 difference with this slideshow
The Quattro 150P retails for AUD 1049.99 . A bargain, if you consider the price includes a coma corrector/reducer which would be around AUD 500.00 if purchased separately.
Included in the box is:
• a solid ultrawide 22mm eye piece
• a 6x30 finder scope
• 2 x tube rings
• 1 x dovetail bar
• a coma corrector/ x0.9 reducer.
View the Sky-Watcher Australia website for more information and specifications.
What's inside
My first impressions
The scope was well packaged. Removing it from the box, I installed the two brackets/rings and attached them to the included dovetail bar. Like the drawtube on my Sky-Watcher 150|750 F5 Black diamond (link to review), the Quattro 150P’s drawtube adapter ring only has two thumbscrews to secure objects. I took the compression ring adapter I brought separately for my other telescope and installed it onto the Quattro. This easy upgrade will set you back around AUD 75.00 depending on where you buy it.
I have the Sky-Watcher Evolux and a compression ring adapter comes standard with this refractor. Sky-Watcher should include it as standard in their reflector range too. Sky-Watcher markets the Quattro as one of their premium photographic telescopes, designed specifically for astrophotography. These telescopes are used with cameras, filters and filter wheels. A compression ring adapter is a better way to secure these accessories.
The first thing to check with any new Newtonian is collimation. The Quattro 150P comes factory-collimated, with the position of the secondary mirror adjusted and the centre of the primary mirror marked with a sticker. Many things can ‘throw out’ collimation, like being transported across the country. A poorly collimated Newtonian will have issues with focusing and star shape. The Quattro seemed to have held collimation well. But the adjustment nobs for the primary mirror were loose. For collimation to hold longer, these need to be tight against the springs. Using a laser collimator, I began my collimation procedure. Once collimation was close, I switched to the Barlow method to fine-tune it. I have been using a Newtonian, and collimating for three years, so the whole process only took a couple of minutes. The term collimation seems to trigger panic in a lot of astrophotographers. It does not take long to learn, and you can install an aperture mask on the primary mirror to help tidy up your stars until you have perfected it as I did in my review of Sky-Watchers 150|750mm Newtonian. Collimation should never be a reason not to invest in this type of telescope considering how great Newtonians are at gathering light, which is the most essential aspect of astrophotography.
Collimation straight from the box
My experience using the Quattro for the first time
When I first opened the box and saw how compact the Quattro was, I immediately knew balancing may be an issue... and I was right.
I mounted the Quattro to my NEQ6 Pro, with my ZWO ASI533, electronic filter wheel and QHY 30mm guide scope and camera, using the included dovetail bar. I went to check the balance, but no matter how I adjusted the telescope, I could not get it to float there. It was too heavy on the front. I found the only way I was able to achieve balance was to piggyback a secondary scope near the primary mirror. Using a larger guide scope than the one I use, such as a 50mm or 60mm, on the back would also work to achieve balance. Maybe a longer dovetail bar would work. I have seen others balance fine when testing the Quattro with only a colour camera attached.
(UPDATE Jan 2024: After some further configuration adjustments, I have been able to achieve a perfectly balanced scope, while still using my mono camera and filter wheel.)
For first light, I did not have an electronic focuser installed. The Quattro 150P dual-speed design focuser means you can use the fine-tune adjustment nobs for a 10:1 speed reduction in the draw tube for precise focus. But, as I turned the focus nobs in and out, the movement wasn’t smooth for me. It made focusing difficult because I couldn’t make precise adjustments. I had to also adjust the screws at the base to tighten the tension as the drawtube kept slipping under the weight of my image train.
After polar aligning, with my luminance filter on, I took a quick 10-second exposure for plate solving. There was some noticeable light leaking in. This is caused by the design of the mounting plate for the primary mirror and made more noticeable by the Quattro’s amazing light-gathering abilities. It is easily fixed; you can 3D print a cap to put over the back of the telescope or you can do what I did and cover it with a black silk shower cap. I then slewed to the Prawn Nebula and all these setbacks were soon forgotten when the first exposure appeared on screen. The detail in my 180-second exposure was amazing!
By morning I had about five hours of total acquisition time on the Prawn Nebula split across my Antlia 3nm Hydrogen, Sulphur and Oxygen filters.
I stacked the image in Astro Pixel Processor and then quickly edited it in Pixinsight and Photoshop. I didn’t capture any RGB data for stars, so I took the stars from a single 180-second Hydrogen image and colourised it yellow. The result speaks for itself. The stars are great and there is great detail in the nebula. This is because the telescope's fast F3.45 aperture allows more light to reach the camera sensor creating a brighter image.
The Quattro’s paraboloidal primary mirror is made from Borosilicate Glass. A paraboloid is a quadric surface. Similar to a cylinder or sphere. It revolves around one axis of symmetry. Parabolic mirrors produce sharp images by focusing parallel light to a single point, correcting spherical aberrations. Unlike spherical mirrors, which often create blurry images due to light reflecting on multiple focal points.
Borosilicate Glass is desired for its ability to cool down quickly and resist thermal shock. So you can start imaging sooner!
I have had a few opportunities to use this scope now and my results continue to amaze me. I did install a ZWO electronic focuser and have had no issue with focusing since.
Gallery of results
Final thoughts
Pros:
Large, fast aperture providing brighter images in less time
Affordable
Includes a coma corrector/reducer
suitable for small and larger sensors
Cons:
Difficult to balance
Light leaks from the primary mirror cell
As a Newtonian user for some time, there was nothing in my experience that I wasn’t prepared for or expecting to a certain degree. However, the biggest setback for me was balancing the telescope. Which I am still irked about today, as I have not figured out an alternative solution, yet!
Setting that aside, I have had consistently good results and the telescope pairs well with my camera and other equipment, I am loving the field of view. I think the scope is great if you are wanting to upgrade your current reflector. There is a learning curve for all beginners starting with any Newtonian, but don't let the Quattro's fast aperture deter you from purchasing it.
The included corrector/reducer works well and doesn’t cause any issues with my stars. It works as well as my Nexus .75 corrector/reducer in fixing coma, the fact that this is included is a major advantage point. The telescope is slightly heavier than my Sky-Watcher Black Diamond but light enough for most EQ mounts. The option choice to upgrade to a carbon fibre tube would be nice. Most Newtonians don’t rank well on portability, but the Quattro 150P is quite compact, if you plan to image or observe the night sky in a field somewhere, and want to do so with a Newtonian, this telescope is a suitable option for you. The price tag is also a huge advantage. I cannot find another telescope with these specifications that includes a coma corrector/reducer at this price point.
In my opinion, as the Quattro is a photographic telescope, Sky-Watcher should ditch the eyepiece and/or finder scope and use the profits to upgrade the focuser to include a compression ring adapter and add a longer dovetail bar – just in case this helps with balancing.
I am obsessed with this little telescope and plan on adding it to my collection. I love being able to produce a workable image in only a few hours even when using different filters because of the Quattro's fast aperture. All my results are well-detailed despite poor seeing most nights. Most often when someone thinks of a Newtonian, they think, big and bulky. I think this scope fills a market void here in Australia and it is a great option for people new to Newtonians and astrophotography or anyone who started with a budget telescope but now wants better, faster optics without the price tag.