Experiences with the Baader Planetarium AstroSolar® Safety Film
Not involved into imaging the sun in white light the last few years, the upcoming Venus transit pushed me into a new trial. So I purchased a sheet of AstroSolar® Safety Film from Baader Planetarium ND 5.0, the type with higher density for visual use.
The sheet of film came along with a clear description how to build your own safe solar front filter for your telescope easily. If you follow straight forward the description, there will be no problems at all, even for the unexperienced amateur craftsman. Although the filter ND 5.0 is designated for visual observations, I used it for photography also, thanks to the sensitivity of modern cameras nowadays. Anyway, for photography, the AstroSolar® Film designed for photographic use with its lower density gives you more possibilities e.g application of the Baader Solar Continuum filter and better control for histogram, exposure time etc., as more light is passing through.
Besides the AstroSolar, the images shown, I have taken with the following equipment:
Optic: Takahashi TOA 130S f=1000mm
Camera: The Imaging Source DMK21AU618S (5.6×5.6µm – 640×480 pixel)
Sure, the sensor of the camera used is a little small for the sun – but you can do several shots and combine them in a mosaic for a wider field of view
Filter: 1,25″ Atik manual filter wheel equipped with Astronomik IIc LRGB.
Several tests I have done, showed (to my opinion) that using the R filter, gave slightly better results.
Barlow: 2x 3 element Barlow
Capturing: ICCapture, the software delivered together with the camera, which is doing a good job
Image processing: The avi sequences captured were processed with Registax 6, I have stacked the 250 best images out of 1200. Minor adjustments in the histogram have then been done in Photoshop CS3.
Well, unfortunately the Venus transit was clouded out here in Southern Germany (luckily I observed the previous one in 2004), but anyway I am very pleased of the results that can be obtained with this AstroSolar® Safety Film.
Hope, you like them too
kind regards
Wolfgang