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First light with the Lunt LS60THa/B1200CPT


Hughsie

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In previous Summer months I have switched from deep sky astrophotography to solar photography as the lack of any meaningful astronomical darkness makes it tougher to gather good data on night time targets.

Armed with my trusty William Optics Z61 refractor and a DayStar Quark Chromosphere, I can be found on clear days outside in the garden with a black sheet over my head to reduce glare so I can observe the Sun in Hydrogen Alpha on my laptop screen.

With the lockdown in full swing and working from home until the end of September at the earliest, I decided to use the monthly fare I am saving for my commute into London to put towards a new solar scope. I find one of the joys of Solar Imaging is to capture the full disc of the Sun, however, using the Quark this usually entails a nine pane mosaic due to the 4.2x barlow integral to the filter and a bit of luck.

I chose the Lunt LS60THa with an aperture of 60mm, the same aperture as the Z61 and still retaining that portability. Using the Field of View simulator from astronomy.tools I confirmed that my choice of scope/camera produced a nice size full disc with room around the edges should any large prominences appear; well you have to be positive right?!

As well as the full disc I also wanted to be able to capture details of prominences or surface details such as filaments, sun spots and faculae. For this I chose a 2.5x Powermate from Televue as this minimises vignetting and is telecentric producing a ‘flatter’ image. The Lunt also has a choice of blocking filter and here I chose the B1200 over the B600 as the former is designed specifically for imaging.

So why a Lunt over, say, a Coronado Solar scope? The key difference for me was use. The research I undertook revealed that the Coronado is a great solar scope but the views it produces are more ‘3-d’ in effect. In other words it produces fantastic views of the Sun for visual work, but not having a ‘flat’ view doesn’t make it the best choice for taking pictures.

From ordering the Lunt to arrival took over a month as the scope had to come from the US to Germany and then to me. Grant at FLO kept me regularly informed of progress. It is neatly packaged in a protective aluminium case and cut out foam. I also purchased a longer dovetail bar (Lunt 150mm) to mount the Lunt on as this would be easier to achieve balance when attaching to an equatorial mount. The Lunt comes with a clam shell ring to which the dovetail is mounted using bolts with Allen key heads. Maybe it was this scope or maybe it is all of them but the dovetail uses imperial Allen key heads and the scope has metric. Both are produced by Lunt, go figure! So a further purchase of Imperial Allen keys was needed.

Set up is a breeze. Once attached to your mount of choice you then add your solar view finder and camera/eyepiece to the diagonal. If you are one for reading instructions then you will be pleased to learn they are clear and produce the required results first time. If you not an instruction type person then you will be pleased to note they are one page long and fit neatly in your bin.

Filtering the Sun’s harmful rays is achieved through an Etalon built into the scope. I purchased the single Etalon version. Achievement of the required wavelength of 6562.8A to view Hydrogen Alpha is undertaken by a Pressure Tuner. Firstly, you undo the large pressure tuner knob which then sets the pressure to your given altitude. You then screw the knob back on and gradually tighten this whilst viewing the Sun in focus through an eyepiece. As you tighten the knob more details on the Chromosphere come into view and you are done, simple as that. There isn’t really any need to touch this again unless you are going to do something like take it to the top of a mountain!

The great joy of the Lunt over the Quark Chromosphere for me are twofold. First, there is no need for an added cable and battery to warm up the Quark and second you don’t have a huge Quark filter coming our of your diagonal with a camera/eyepiece mounted on top. That always looked too precarious for my liking.

So what does it produce? Well, see for yourself below. Here are two images of the Sun taken on 22 June 2020 using the following additional equipment;

ZWO ASI174mm camera.
SkyWatcher SolarQuest mount.
SharpCap Pro image capturing software.
2.5x Powermate (on the North East limb image).

Each image was produced from 200 frames. For the full disc I was able to use 75% of the 200 frames and for the limb shot I used 25%.

Exposure time on the full disc was 2.649ms and 10.185ms for the limb image. They were taken at 16:17 UT (full disc) and 16:34 UT (limb).

The frames were stacked using the free software AutoStakkert2 and initial curve adjustments and sharpening applied in more free software, this time imPGG. Final adjustments; de-hazing, contrast/brightness, embossing and colouring was added using Affinity Photo.

Overall I am delighted with the Lunt, its speed of set up and build quality are excellent and I am looking forward to many years of good Solar service.

John

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17_34_14_Prom_Col.png

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Great shots.  I've been playing with a Lunt 50 for a while and it's great.  Now I'm waiting waiting waiting for a Solar Quest to arrive from @FLO (patience is a virtue in these times!).

Had to laugh at the dovetail & scope thread mismatch - same thing with the Lunt 50.  I thought it was only me doing something silly, but clearly this must be a deliberate thing to upsell mechanical things.

Enjoy!

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Sounds a sensible use of saved commute money to me.
Interesting to read about your journey and kit.

I have to say something other than WL solar is nipping at my ankles,
but at present it has to remain a for the future item.

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Thanks John for writing this up.  I have found it extremely helpful since I am on the hunt for a Ha Solarscope too.  I was looking for an 80 or 100mm version of the Lunt but this gets exceptionally expensive very quickly!

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