IDAS D2 filter creates halo around bright stars

[algady]

Hi all,

Recently I got my new Esprit 120 telescope and I wasn't able to use it until last night because of the awful weather that we had!. Last night was clear so I managed to get some images and I noticed that there are halos around bright stars as you can see in the image.
I put the filter between the field flattener and my camera when I captured these images, after some search online I read somewhere that I need to put the filter before the ff but I had no chance to test it yet.
Is there any idea that may help please? The filter suppose to be good quality (very expensive) so I wasn't expecting to get any halos!

This is a single image 120 sec not processed

Thanks

[Nigella Bryant]

I've one, but not used it yet, yeah, place it b4 the ff is the way so I've read. Not between the ff and camera. If you think about it the light path will be more natural if it's put before the ff rather than between. All the filtered light will then be focused through the ff onto the camera sensor. That's my take on it anyway,  lol.

[TerryMcK]

I have the D2 mounted after the field flattener and before the sensor. I don’t get any star halos but the sensor is cooled and I have a dew strap around the field flattener/filter assembly.

Edited March 1, 2020 by TerryMcK

[TerryMcK]

One thing you have to consider with the IDAS D2 is correct orientation. Meaning the male thread M48 has to be camera side, the female M48 thread has to be sky side. On my WO flattener I had to buy a male/male converter to ensure the filter was the correct way around.

[david_taurus83]

I have one and I do get halos when used with my 70mm quad. However, I didn't get halos with my WO 71mm triplet and flattener prior to this! The filter was screwed in front of the flattener then so I think it depends of the design of the optics. M45 stars are very bright anyway. I bet when you stretch it the stars will overpower the halos anyway.

[TerryMcK]

I’ve just seen a review of the D2 on FLO website. This may be of use to you to try the method that reviewer David states.

Our county is full led street lighting, finally decided to invest in an Idas D2 yes expensive but definitely worth the outlay , brown murky images now gone glad I got it now , if you hear reports of it causing halos , the cause for me was to uncheck hot pixels in the cosmetic tab in Deep sky stacker , halos now gone completely around stars . Definitely recommend as the push towards LED lights will increase .

[algady]

Thanks all for your help, I'll try to get some images as soon as I can and see if things changed.

1 hour ago, TerryMcK said:

I’ve just seen a review of the D2 on FLO website. This may be of use to you to try the method that reviewer David states.

Our county is full led street lighting, finally decided to invest in an Idas D2 yes expensive but definitely worth the outlay , brown murky images now gone glad I got it now , if you hear reports of it causing halos , the cause for me was to uncheck hot pixels in the cosmetic tab in Deep sky stacker , halos now gone completely around stars . Definitely recommend as the push towards LED lights will increase .

I saw this before but not sure what he means! shall I check or uncheck that option!

[algady]

Hi, it's clear and I did some tests but unfortunately, no luck!

As far as I understand there are 4 possibilities here, before ff and after ff and fitting it in 2 orientations each time, every time I can clearly see halo around bright stars!

I feel disappointed because it is expensive and has good reviews!

[bottletopburly]

5 hours ago, algady said:

Thanks all for your help, I'll try to get some images as soon as I can and see if things changed.

I saw this before but not sure what he means! shall I check or uncheck that option!

That was my review  btw , I recently stopped using it as it messes the star colours as in I get Aqua stars as it filters the yellow spectrum, so I was going to try just using it for  luminance and add that to unfiltered data just to see if the results were any better.