Filters for white ligh solar imaging with a Herschel wedge
Mikael Joe compared few filters (and here too) for white light solar imaging with a Herschel wedge and TS 102mm f/11 refractor. Joe compared: K-line, Solar Continuum, "He-I" 590nm and "TiO" 705 nm filter. Last two are Omega Optical industry filters.
The 590 nm "He-I" filter was very good in my scope with AstroSolar ND 5.0. The TiO "706 nm" filter was previously used with wedges by few imagers with good results. In my case (and for other imagers) with AstroSolar the TiO filter and any other using infra-red or partially red band gives very low contrast images.
As you can check on the images the Solar Continuum and He-I filter gave most detailed images (nice sharp granulation and spots). Sometimes He-I has a slight advantage. The TiO images are slightly more blurry. What's important with the Herschel wedge - TiO infra-red filter doesn't loose contrast.
It's good to see that newly discovered "He-I" filter (initially I've matched it for He-I emission from some nebulae) proven itself to be very effective with AstroSolar and wedges. Visually it also gives nice yellow images. Infra-red filters that may give images less affected by seeing work only with wedges (and maybe glass solar filters). It would be also interesting to test RG1000 or silicon windows with the wedges - most infra-red filters usable with our cameras.
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