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LP filter Idas D1 vs D2 under LED

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This may not be a very scientific test, just wanted to have a quick feel for my newly acquired idas d2 filter, so took some shots of the LED street light of our street.

In order, first is now filter, 2nd is with Idas D1 and 3rd is with Idas D2. To me D2 doesn't look less bright than the D1, would you agree? I've also tried to look at the mean luminance value of each in GIMP and the D2 came out higher than the D1. What do you think, have I wasted some money?





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I have the d2 certainly makes a difference to me anyway ,our town /county is  probably 90 percent led streetlights 

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To me the D1 looks less bright in those images.

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I find the D2 very good at reducing LP here.


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I found this which might help.


OK I had a chance to do some very rudimentary filter comparisons. It's not all IDAS but is IDAS dominated so will put it into this thread. This is a comparison of the LPS-D1, LPS-D2, LPS-V4, HEUIB II, No Filter, and finally the STC Duo Narrowband.

There is -no- tracking, exposure is 5 mins with ISO2000, and is taken with the A7S RAW downloaded and converted to JPG. Scope is the Takahashi Mewlon 250CRS (2500/F10), therefore pardon the star trails due to gusty winds.


This was from a golf course carpark in Chiba whereby the SQM was 20.27 when the shots were made. it was 21:50 JST and ambient temps were 15.7C (although my Astro A7S cooled the sensor down to -3.9C) and humidity was approx 77%. As mentioned, it was annoyingly windy. There were some LED lights but were literally only 1 foot off the ground but a good 200-300 feet away from me. I was parked next to a 3 story building and next to my car for shielding from the wind. There was a vending machine light on in one of the rooms where my scope was approx 30-40 feet from the window. I don't think it would have contributed much light pollution seeing I'm on such a high focal length scope.


Subject was M97 (planetary Owl Nebula). 


No Filter Used

No Filter.jpg











STC Duo Narrowband

STC Duo NB.jpg

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I think pointing directly at the street lamp is not going to give you a good comparison. If you tried that with a Ha filter you'd still see the lamp. Like above, try on a DSO target with each filter. I'm very happy with my D2 though I only have sodium lamps on my street, LEDs are on the way!

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