Maxscope Safety, care and instructions
One of the central ideas about our Club is hands-on science. Our Star* is no exception. Using images from around the World and outer space is great, but there is no experience like using kit to make optical observations yourself. And there's the thrill of doing something amazing with your own data. Image enhancing programs can make hidden details appear like magic, and animation programs can add your static images together and bring the Sun to life. Even tracings of projected images can be made into flick books to show the rotation on our star.
A Sunspotter image taken by year 7 students
The easiest way to get your own image of the sun is with one of our Sunspotter folded projection telescopes. Once you get the hang of aligning them, you'll be able to see the surface of a star 150 million miles away within seconds. Use a digital camera on automatic exposure and focus. Take a few shots to make sure you get one in pin sharp focus. Its not possible to get a shot from directly above the image surface so the image will come out slightly squashed. Don't worry, it's easy to un-squash it in a program like Photoshop.
The next level of challenge is to use an ETX with a white light filter. Here you have control over focus and will get greater contrast. You can hold a digital camera to the eyepiece.
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A shot taken with a Casio QV3500. Exposure is very important when trying to capture sunspots. I'm not joking when I say that you may find the spot metering setting on digital cameras the most reliable. |
After managing to get an image of sunspots the next is to be able to record the dark, central umbra and the surrounding penumbra. After that is the challenge is to be able to see filament structure in the penumbra. It may be easier to do this with a pencil and a sunspotter! | |
| Now the greatest challenge to image - but the one with the greatest rewards - Hydrogen alpha. First you need to set the telescope up. There is a set of instructions in telescope box. You can either hand hold the cameras to the eyepiece or use one of the photographic attachments. If you are attaching a camera, make sure the tripod ball head is firmly locked. The first indication of success is that you get a red or pink disk image. You may get success with auto focus and auto exposure but you will get better result in manual mode. Here you can get sharper focus and tweak the exposure to show up different features. Focus is critical. | ||
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| Use a fast shutter speed and the red pixels alone register detail on the disk but you do not get details of flares and prominences. ISO100 f5 1/500sec -2EV exposure compensation |
The same image adjusted in photoshop |
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| To get the system in
focus, set the camera focus to manual. The Nikon can be then set
INF and the Casio to the furthest focus. Now zoom in the camera
to the fullest extent. Find a a sunspot or flare and use
the telescope focus ring to get it as sharp as you can. Now zoom
out to a full view or to the maximum optical zoom level.
You have two main choices of exposure. You can use a short exposure that just uses the red pixels on the CCD. This will show sunspots well but will not register the flares. An exposure of 1/500 at ISO100 and F5 should produce a respectable image. Try making longer exposures to capture the flares. The other choice is to over expose the red pixels to the Sun's disk but start to use the green and blue pixels. The filters on the pixels are not perfect and allow a little red light to penetrate. An exposure of up to about 1/8 can work, but you'll need to use a remote attachment for anything longer that 1/30. The advantage with this type of exposure is that you will capture both the faint chromosphere features on the outer edge and those on the disk really well. |
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| When you overexposure the red pixels on the disk gets the green and blue pixels to register detail whilst letting the red pixels capture faint features on the rim. ISO 100 f5 1/30sec -1EV exposure compensation | The same image enhanced in Photoshop | |
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| Even more exposure and other areas of activity are highllighted. ISO 100 f5 1/8sec 1.3 EV exposure compensation | The same image enhanced in Photoshop. | |
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| More results from slow exposures after enhancement | ||
