Hello!
Yesterday I did some testing with the new Antlia ALP-T dual-narrowband filter - in fact I made a comparison with my Baader 6.5nm Ha and OIII CMOS filters.
Equipment used:
- Skywatcher Esprit 100 (f/5.5, 550mm focal length) with standard SW flattener
- QHY600C-PH CMOS-camera (OSC)
- Skywatcher EQ6-R mount and MGEN-3 autoguider
- N.I.N.A. for acquisition
For each filter a single 600 second exposure was made; the out-of-cam FITS-file was de-bayered in Astro Pixel Processor and stretched identically (black point at the beginning of the histogram mountain, white point at 20,000 and a Gamma of 5).
I then extracted the color channels of the RGB-data and pasted them next to each other into a new greyscale file.
I come to the following conclusion:
- Baader Ha-filter is slightly better in contrast, but the stars of the Antlia Filter are smaller.
- The amount of OIII-signal in the Antlia is considerably higher than in the Baader filter. This results in a much clearer and more contrasty impression of the Antlia RGB image compared to the Baader NB-filter images.
However, this impression could be the result of choosing NGC 2244 as a test target, which has a fairly high amount of OIII emission.
How the Antlia fares against the Baader filter on a true Ha-target (without OIII emission), still needs to be determined.
- While I experienced very unpleasant halos with the Baader Ha-filter from mag. 5 and brighter stars, I did not see any halos when exposing 10 minutes with the Antlia on mag. 1-2 stars like Elnath or Pollux.
I have posted my test shots on my Flickr page, feel free to have a look and commet your thoughts:
Red channel comparison: https://www.flickr.com/photos/147135308@N08/51806200902
Green channel comparison: https://www.flickr.com/photos/147135308@N08/51807517264
Blue channel comparison: https://www.flickr.com/photos/147135308@N08/51807885130
Single 10-minute exposure of NGC2244: https://www.flickr.com/photos/147135308@N08/51805839623
CS
Chris
Yesterday I did some testing with the new Antlia ALP-T dual-narrowband filter - in fact I made a comparison with my Baader 6.5nm Ha and OIII CMOS filters.
Equipment used:
- Skywatcher Esprit 100 (f/5.5, 550mm focal length) with standard SW flattener
- QHY600C-PH CMOS-camera (OSC)
- Skywatcher EQ6-R mount and MGEN-3 autoguider
- N.I.N.A. for acquisition
For each filter a single 600 second exposure was made; the out-of-cam FITS-file was de-bayered in Astro Pixel Processor and stretched identically (black point at the beginning of the histogram mountain, white point at 20,000 and a Gamma of 5).
I then extracted the color channels of the RGB-data and pasted them next to each other into a new greyscale file.
I come to the following conclusion:
- Baader Ha-filter is slightly better in contrast, but the stars of the Antlia Filter are smaller.
- The amount of OIII-signal in the Antlia is considerably higher than in the Baader filter. This results in a much clearer and more contrasty impression of the Antlia RGB image compared to the Baader NB-filter images.
However, this impression could be the result of choosing NGC 2244 as a test target, which has a fairly high amount of OIII emission.
How the Antlia fares against the Baader filter on a true Ha-target (without OIII emission), still needs to be determined.
- While I experienced very unpleasant halos with the Baader Ha-filter from mag. 5 and brighter stars, I did not see any halos when exposing 10 minutes with the Antlia on mag. 1-2 stars like Elnath or Pollux.
I have posted my test shots on my Flickr page, feel free to have a look and commet your thoughts:
Red channel comparison: https://www.flickr.com/photos/147135308@N08/51806200902
Green channel comparison: https://www.flickr.com/photos/147135308@N08/51807517264
Blue channel comparison: https://www.flickr.com/photos/147135308@N08/51807885130
Single 10-minute exposure of NGC2244: https://www.flickr.com/photos/147135308@N08/51805839623
CS
Chris
