zwo asi1600mm pro filter effect.

[redfox1971]

I have my zwo filter wheel connected to my asi1600mm pro when i use my bahtinov mask on the luminance filter the centre spikes seem to be on a strange angle but when using other filters like the red filter they seem fine is this maybe down to the front glass on the asi1600 and the brightness 

[Adam J]

21 hours ago, redfox1971 said:

I have my zwo filter wheel connected to my asi1600mm pro when i use my bahtinov mask on the luminance filter the centre spikes seem to be on a strange angle but when using other filters like the red filter they seem fine is this maybe down to the front glass on the asi1600 and the brightness 

I dont think its the ASI1600mm pro sensor cover glass. Never seen anything like that before. What exact filters and scope are you using?

Also would be useful to see a stack of a completed Lum filter and RGB as seperate channels if possible. I have a feeling about what it may be but I dont want to say without more evidence. 

Adam 

Edited January 19, 2022 by Adam J

[redfox1971]

On 19/01/2022 at 17:42, Adam J said:

I dont think its the ASI1600mm pro sensor cover glass. Never seen anything like that before. What exact filters and scope are you using?

Also would be useful to see a stack of a completed Lum filter and RGB as seperate channels if possible. I have a feeling about what it may be but I dont want to say without more evidence. 

Adam 

Hi Adam thanks for having a look i'm using the williams optics star 71 mark1 connected to the zwo 7 position filter wheel with baader ccd 36mm filters fitted then straight onto the asi1600mm pro heated element fitted to camera.

I've attached some tiff images processed in pixinsight of m81 lrgb witch have been slightly cropped dbe process run  and easy processing script stretched.

Andrew.

masterLight_BIN_1_EXPOSURE_180_00s_FILTER_Blue_Mono_integration_DBE.tif

masterLight_BIN_1_EXPOSURE_180_00s_FILTER_Green_Mono_integration_DBE.tif

masterLight_BIN_1_EXPOSURE_180_00s_FILTER_Lum_Mono_integration_DBE.tif

masterLight_BIN_1_EXPOSURE_180_00s_FILTER_Red_Mono_integration_DBE.tif

[Adam J]

1 hour ago, redfox1971 said:

Hi Adam thanks for having a look i'm using the williams optics star 71 mark1 connected to the zwo 7 position filter wheel with baader ccd 36mm filters fitted then straight onto the asi1600mm pro heated element fitted to camera.

I've attached some tiff images processed in pixinsight of m81 lrgb witch have been slightly cropped dbe process run  and easy processing script stretched.

Andrew.

masterLight_BIN_1_EXPOSURE_180_00s_FILTER_Blue_Mono_integration_DBE.tif 24.61 MB · 2 downloads

masterLight_BIN_1_EXPOSURE_180_00s_FILTER_Green_Mono_integration_DBE.tif 24.61 MB · 1 download

masterLight_BIN_1_EXPOSURE_180_00s_FILTER_Lum_Mono_integration_DBE.tif 24.61 MB · 1 download

masterLight_BIN_1_EXPOSURE_180_00s_FILTER_Red_Mono_integration_DBE.tif 24.61 MB · 0 downloads

Well I was worried about astigmatisum but you will be glad to know that the scope itself looks ok, although you do have slightly pinched ppitics causing the four gaps in your star halo, but I dont think this would be causing the effect you are seeing on the mask spike.

As the effect is only present on the Lum channel I think that we can atribute it to chromatic aberation in the lens. If you have ever used a mask with a OSC camera you would have seen a rainbow effect progressing along each of the diffraction spikes. Like this:

You will notice that the same pattern is present here as in your mono image, but here we see the RGB elements,, your lum shot still contains those elements its just not apparent in mono that this is the case non the less. Green in the middle and Red / Blue either side. The degree of lateral spread in those i.e how twisted they appear is relative to the amount of Chromatic aberation within the imaging scope. You are essentially seeing that the green is in the centre and that the blue and red are shifted slightly away from perfect focus to either side green.

In contrast in a better corrected scope you may see something more like this:

Despite this I would not say that this means the scope is badly corrected its just not fully corrected.

Adam

 

 

 

 

Edited January 20, 2022 by Adam J

[redfox1971]

22 hours ago, Adam J said:

Well I was worried about astigmatisum but you will be glad to know that the scope itself looks ok, although you do have slightly pinched ppitics causing the four gaps in your star halo, but I dont think this would be causing the effect you are seeing on the mask spike.

As the effect is only present on the Lum channel I think that we can atribute it to chromatic aberation in the lens. If you have ever used a mask with a OSC camera you would have seen a rainbow effect progressing along each of the diffraction spikes. Like this:

You will notice that the same pattern is present here as in your mono image, but here we see the RGB elements,, your lum shot still contains those elements its just not apparent in mono that this is the case non the less. Green in the middle and Red / Blue either side. The degree of lateral spread in those i.e how twisted they appear is relative to the amount of Chromatic aberation within the imaging scope. You are essentially seeing that the green is in the centre and that the blue and red are shifted slightly away from perfect focus to either side green.

In contrast in a better corrected scope you may see something more like this:

Despite this I would not say that this means the scope is badly corrected its just not fully corrected.

Adam

 

 

 

 

Thanks for the explanation Adam when williams optics made this model scope they made lots of promises about the quality and a lot of people were let down,having five elements may not help,maybe ok with a dslr but when using filters halos are a problem thanks again.