Tag: Lunt 60mm

Sun transit of ISS 2022-08-21

On 21st of August 2022 was a special day. Around noon the international space station made the transit across the Sun. I was ready and managed to capture it. The transit itself took only 0.4 seconds and the frame rate of my camera was only 20 FPS, so I captured only 8 frames. In total, I captured 2000 frames, out of which I selected the best 75% and stacked them together. The ISS was added from the transit frames as separated layers.

And here is just the stack without ISS:

TelescopeLunt 60mm
Aperture60 mm
Focal length420 mm
MountRainbow Astro RST 135
CameraZWO ASI 178MM
FiltersDouble stack
Exposure2000x3.5ms, Gain 149, bin 1x1, 75% selected
Date2022-08-21

Sun

I always wanted to capture the brightest object in the sky. However, it’s not as easy as you think. If you purchase any “normal” telescope, many unmissable warnings are covering the whole telescope not to point it to the sun, unless you want to get blind. This means if you want to observe or photograph the Sun, you need a dedicated telescope for that. There are basically two companies manufacturing dedicated solar telescopes: Coronado and Lunt. The third option is to purchase any refractor and use the DayStar filter called QUARK. The third option is probably the cheapest way (depends on the selection of the refractor), but it has a feature, which I don’t like. The filter is equipped with the Barlow lens. This makes it nearly impossible to observe or photograph the whole disk. This was for me no-go and I started to decide between Coronado and Lunt. Based on pictures on astrobin.com I decided on Lunt. The next dilemma is the aperture – the bigger the better, but in the case of solar telescopes, the price grows exponentially with the aperture. In the end, I decided on 60 mm. Next decision: single or double stack. Here again the more stack the better, at least in terms of what you can see on the surface. Here is a very nice feature of the small Lunt telescope – the double stack is basically achieved by screwing the front filter in front of the telescope. This is a very fast way to turn the single stack, which is great for observation of the prominences, into the double stack, which is excellent for observing the surface. So I decided on the double stack.

The first experience with the single stack was great. The prominences were nicely visible. Moreover, even the surface had a clearly detectable structure. Then I screwed the double stack in front and the troubles started. Basically, the image was significantly worse compared to the single stack. After the discussion with Lunt, I am returning the front filter and waiting for the replacement.

Here is the stack of 540 images captured by FireCapture, processed by Autostakkert!, Registax, PixInsight, and LightRoom.

Technical details:

TelescopeLunt 60mm
Aperture60 mm
Focal length420 mm
MountRainbow Astro RST 135
Autoguidingno
CameraZWO ASI 178MM
Correctorno
FiltersNo
Exposure1000x7ms, Gain 0, bin 1x1,
Date2021-08-21