Using Filters for H-ALPHA Prominences

ASTROVID SolarCam™ CCD VIDEO CAMERA

USING YOUR ASTROVID SolarCam™ (Part 3 Hydrogen-alpha Prominence Detail):

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1.Solar prominences are imaged in Hydrogen alpha light. Solar prominences are much dimmer than the surface detail found on the sun.

2.The majority of observed solar prominences do not change in appearance very quickly. However, you may be able to find one of the changes morphology in rapid time.

3.Gain becomes the more important parameter in imaging solar prominences. An increase of gain will boost the signal bringing out the much fainter prominences. This is done by increasing the manual gain.

4.Increase the manual gain until you see a prominence.

5.You also want to decrease the shutter speed as you make your initial adjustments to allow the promi- nences to come into view.

6.Once a prominence appears on screen you can start to make adjustments to your image.

7.You can see that if the gain is increased you start to lose some of the fine detail (burning it out) but bring out the fainter structures

8.The goal is to adjust the gain so that the most amount of detail can be imaged in the prominence.

9.Again, you will find that you need a balance between gain and shutter speeds. However, this time the gain will be set higher and the shutter speeds will most likely be lower.

10.The Solar Hydrogen -alpha line is a very narrow wavelength in a more atmospheric stable part of the spectrum. The use of slower shutter speeds will not always decrease the resolution of the promi- nences.

11.The human eye has an incredible response to light in terms of dynamic range. The eye can look at ob- jects going from black to bright white in the same image. A camera cannot do that. Cameras have a more limited dynamic range. So often with H-alpha imaging you will not see the prominences and so- lar surface detail at the same time.

12.To better view Solar prominences it is often desirable to increase your image scale. This involves using a Barlow lens or Powermate from TeleVue. A Powermate is a better choice as it is more corrected and will not change your focal point. The only drawback here is that in some of the wide field h-alpha tele- scopes apply a Barlow is not always beneficial. However, on Solar scopes with already longer focal lengths using a Powermate or Barlow lens is generally beneficial.

1.The main filters used for prominences are neutral density filters. However, in long focal lengths they would be less likely to be used than in short wide field telescopes.

2.Again, for neutral density filters you can use a green or blue filter on wide-field telescopes.

3.Because the setups for solar imaging vary so much, some experimentation is need here to determine whether a filter is needed or not for your particular setup.

4.Keeping notes of your results will help in saving time for setup and will lead you to the best possible images.

Enjoy Your Astrovid SolarCam™!!!!

Be sure to try it on the Moon and Planets Also!!!