Talk:Spectrohelioscope

Obsolete?
If you do a Google search, equipment based on band pass filters are widely available while spectrohelioscopes are made in small numbers only by amateurs. There is a spectroheliograph in use at Meudon. I would guess that it can take images at several similar wavelengths at the same time. Man with two legs (talk) 09:27, 31 March 2010 (UTC)
 * I have RV'ed this and this edit. Still an un-supported edit. Citing exsitance is not citing a relaible source for a statement, its synthesis, and also the links are WP:SPAM, wikipedia is not a commercial product guide. The statement is also illogical - a band pass filter and a spectrohelioscope can both show the sun at any given spectral line but only spectrohelioscopes can observe the sun in all visable spectral lines, so a band pass filter would never "superseded" specroheloscopes, they are two different devices that preform overlaping functions but not necessarily the same function. Fountains of Bryn Mawr (talk) 15:53, 1 April 2010 (UTC)
 * On this basis, about 85% of Wikipedia should be deleted. If you do a search, you will not find mass-market suppliers of spectrohelioscopes or probably any suppliers at all. If you know anything about them you will know they are almost always used in the H-alpha band which is the favourite for band pass filters.
 * In short, you know very well that the statement is accurate and you are just Wikilawyering for reasons of your own, and reducing the value of the article in the process. If you really cared about the quality of the article you would have left some sort of link to H-alpha filters because, as you well know, they are highly relevant.  Man with two legs (talk) 16:20, 1 April 2010 (UTC)
 * This is the first time I have ever heard of adherence to WP:V as "Wikilawyering", it is a core content policy. There is very little "value" in un-referenced articles based one "common knowledge" because I (and I assume the editors who wrote WP:V) have found that such articles are invariably wrong  . What the article needs is descriptive references that answer who, what, when, where, why. That this device has similar properties to an H-alpha filter may be encyclopedic but we should try to answer the big questions up front for all aspects of this device, not just how it relates to the sub group of amateur astronomers. Fountains of Bryn Mawr (talk) 16:16, 3 April 2010 (UTC)

Basic information that belongs in this article
If you look at the comments above and the edit history of this article, you can see that I have been prevented from adding information necessary to making this article comprehensive. However, the talk page is about improving the article, which is what this comment is about, and so it will be harder to justify removing this by invoking Wikipedia guidelines. If you think you can incorporate this information into the article without getting reverted, I wish you luck.

1. Spectrohelioscopes were used largely to view the sun in red hydrogen-alpha light -a deep red wavelength which is especially good for viewing solar prominences which are othewise lost in the sun's bright glare. H-alpha light can also be used to view details on the sun's disc which are not visible in white light. (While a spectrohelioscope can be tuned to any wavelength of visible light, H-alpha was the only one mentioned in the spectrohelioscope article in Amateur Telescope Making, Book 1 (fourth edition, pp 192-202))

2. By using other wavelengths, including hydrogen-beta (blue) and calcium-K (borderline ultra violet), additional features are visible on the sun's disc. Calcium-K is difficult for most people to see but is important in solar photography. (Amateur Telescope Making, Book 1 (fourth edition, pp 203-214) describes a spectroheliograph for taking photographs in calcium-K light.)

3. Spectrohelioscopes were historically important but they remain rare because filters are now widely available which can be attached to an ordinary telescope for viewing the sun in hydrogen-alpha light. For any specific wavelength, a filter is much better than a spectrohelioscope because the image is brighter and sharper. A filtered telescope is also much smaller and easier to use. Filters are available for a number of wavelengths but H-alpha filters are by far the most widely available. Man with two legs (talk) 11:01, 8 March 2014 (UTC)