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IDAS Filter Comparison Test Report

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#1 jimthompson

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Posted 09 November 2021 - 10:53 PM

Good evening all,

 

It has been a while since I posted anything here.  I thought some of you might be interested in my latest filter test report.  In it I test and compare a large selection of IDAS brand filters, including the new NBZ.

 

http://karmalimbo.co...son_Nov2021.pdf

 

Cheers!

 

Jim T.


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#2 EmeraldHills

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Posted 09 November 2021 - 11:17 PM

Jim Thompson. This is amazing. When I grow up, I want to be as cool as you are. Wow. I hope the world realizes what a great contribution you're making to the science.

Have you ever had a chance to look at the Celestron Light Pollution filter? I'm using the one custom-designed for the RASA 11. It was EXTREMELY expensive. For the money, it sure seems to lean toward a green tint. I have to SERIOUSLY tweak the color sliders in SharpCap (EAA) to enjoy the view. Would you guess that that is normal?

 

I really enjoy your videos, brother. I learn so much from you.

 

Doug



#3 jimthompson

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Posted 09 November 2021 - 11:41 PM

Hi Doug,

 

Are you talking about this filter?:

 

https://www.celestro...5ca2cf08a&_ss=r

 

If so, I would have thought it would perform similar to an IDAS LPS-P2 which has good white balance but not a whole lot of light pollution reduction.  By your description of the image being very green it sounds more like you have this filter:

 

https://www.celestro...5ca2cf08a&_ss=r

 

Having a wider O-III pass band so as to also pass H-beta has an unfortunate additional effect of allowing a lot more green light in.  This is the same issue people have with white balancing the Optolong L-eNhance.  If the spectrum plots available on the Celestron website are to be believed, this filter does not perform as well as the L-eNhance.  The Celestron website says the filter will work on their f/2 RASA, but as far as I can tell the pass band are not pre-shifted like the NBZ, so in fact the filter will not perform well on a RASA ... the green biased white balance would be worse in a RASA since little Halpha would be getting through the band shifted filter.

 

Celestron used to sell filters made by Baader, but not anymore.  From what I can tell they are cheaply made knock-offs now.

 

Cheers,

 

Jim T.


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#4 Tfer

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Posted 09 November 2021 - 11:53 PM

The EAO1 filter just hit my wish list!



#5 EmeraldHills

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Posted 10 November 2021 - 07:17 AM

Hi Jim. Thanks for taking time to respond. The filter I picked up with my RASA 11 is this:

 

https://www.celestro...rograph-rasa-11

 

Did I waste my money?

 

I do pretty much exclusively EAA, so I don't ever need anything for narrow-band astrophotography. But I liked the fact that I could "set it and forget it" for everything by leaving it in the built-in optical window in the RASA. But I'll admit - I do have a hard time with a bias toward green in many/most of my observations. I have to adjust the Sharpcap color balance filters a LOT to find balance.

 

 

 

Hi Doug,

 

Are you talking about this filter?:

 

https://www.celestro...5ca2cf08a&_ss=r

 

If so, I would have thought it would perform similar to an IDAS LPS-P2 which has good white balance but not a whole lot of light pollution reduction.  By your description of the image being very green it sounds more like you have this filter:

 

https://www.celestro...5ca2cf08a&_ss=r

 

Having a wider O-III pass band so as to also pass H-beta has an unfortunate additional effect of allowing a lot more green light in.  This is the same issue people have with white balancing the Optolong L-eNhance.  If the spectrum plots available on the Celestron website are to be believed, this filter does not perform as well as the L-eNhance.  The Celestron website says the filter will work on their f/2 RASA, but as far as I can tell the pass band are not pre-shifted like the NBZ, so in fact the filter will not perform well on a RASA ... the green biased white balance would be worse in a RASA since little Halpha would be getting through the band shifted filter.

 

Celestron used to sell filters made by Baader, but not anymore.  From what I can tell they are cheaply made knock-offs now.

 

Cheers,

 

Jim T.



#6 alphatripleplus

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Posted 10 November 2021 - 07:59 AM

Thanks for the new report, Jim. I will take a closer look, but I'm glad to see you have Bortle 2, Bortle 6 and Bortle 9+ prediction plots of filter performance, which should cover the vast majority of LP scenarios.



#7 roelb

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Posted 10 November 2021 - 05:43 PM

Hi Jim. Thanks for taking time to respond. The filter I picked up with my RASA 11 is this:

 

https://www.celestro...rograph-rasa-11

 

Did I waste my money?

 

I do pretty much exclusively EAA, so I don't ever need anything for narrow-band astrophotography. But I liked the fact that I could "set it and forget it" for everything by leaving it in the built-in optical window in the RASA. But I'll admit - I do have a hard time with a bias toward green in many/most of my observations. I have to adjust the Sharpcap color balance filters a LOT to find balance.

The green color may also depend on the camera used?


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#8 EmeraldHills

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Posted 10 November 2021 - 06:05 PM

ZWO ASI2600 MC Pro?

 

The green color may also depend on the camera used?



#9 Alien Observatory

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Posted 10 November 2021 - 10:20 PM

Just a spectrum comparison between a ASI 071 and a ASI 2600.  Not sure that it relates to anything, but maybe a clue as the 071 was offered as a commercial 35mm camera.  

Pat Utah  smile.gif

Attached Thumbnails

  • ASI071-QE-e1509346837511.jpg
  • ASI2600MC-Pro-1024x680.jpg

Edited by Alien Observatory, 10 November 2021 - 10:30 PM.


#10 EmeraldHills

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Posted 10 November 2021 - 10:49 PM

So sorry, but if I may ask, Alien Observatory - I wonder what we can deduce from these graphs.



#11 Alien Observatory

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Posted 10 November 2021 - 11:27 PM

The Green Sensitivity is much higher in the 2600 compared to the 071.  The Celestron Filters were designed many years before the advent of the 2600 sensor.

 

So it is an ongoing ever changing issue of Filters and Sensor Color sensitivity.  IDAS has been making changes to the color sensitivity for many years as opposed to the stagnant Celestron Filters.  The newer sensors have a much better QE than the older sensors, part of which is attributable to the enhanced Green Sensitivity.  The Color Bayer Matrix is RGGB with 2 Green pixels to 1 Red and 1 Blue Pixel which has been a standard for color cams for decades.

 

Options ?  Try a 071 cam and see if the Green cast problem goes away or find a changeable filter holder for the RASA and try a different filter, or remain as is.   Pat Utah smile.gif


Edited by Alien Observatory, 10 November 2021 - 11:39 PM.


#12 Stargazer3236

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Posted 11 November 2021 - 07:47 AM

Jim, I want to buy the  EAO filter, but on the website, I do not see how I can do that. Is it not for sale anymore?



#13 jimthompson

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Posted 11 November 2021 - 01:10 PM

Jim, I want to buy the  EAO filter, but on the website, I do not see how I can do that. Is it not for sale anymore?

Hi Stargazer,

 

Try this link:

 

https://astrohutech....eaa-and-comets/

 

Cheers,

 

Jim T.


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#14 jimthompson

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Posted 11 November 2021 - 01:53 PM

I see what Alien Observatory is saying.  The sensitivity of the ASI2600 sensor around 500nm, the wavelength for O-III and well in the green part of the spectrum, is quite a bit higher than for the ASI071.  This would suggest that the ASI2600 is more sensitive to green than the ASI071.  However the spectrum shown for the ASI2600 is almost identical to that of the ASI294.  In my testing using an ASI294, all of the multiband (LPS family) IDAS filters had a bluish tint not a greenish tint.  If you refer to Table 3 in my test report, and compare the percentages for each colour channel, you can see that for the NB filters and the EAO1 the green channel is dominant (i.e. a greenish tinted image), but the LPS filters have either a dominant blue channel or blue and green are equally dominant (i.e. blue to cyan tinted image).  If you indeed have the Celestron RASA Light Pollution Imaging filter, it should behave pretty much the same as the IDAS LPS-P2 ... it is essentially a copy of the IDAS filter, much like the Optolong L-Pro is (see attached image).

 

I wonder how you are doing your white balancing in Sharpcap?  I typically set the camera Red and Blue channel gains first (located in the "Image Control" tool box), getting them set so the white balance is close.  I then do my final tweaks using the R/G/B sliders in the stacked image histogram view.  If you don't adjust the Red and Blue camera gains up, you will have a very green image regardless of what filter you use, even if you have no filter.  The default setting for the camera R & B gain sliders is 50%.  My R & B gain sliders are normally both above 75%, and can often be maxed out at 100% depending on what filter I am using and the sky conditions.  With those two sliders set properly, you should have lots of colour adjustment available in the live stack window, regardless of the filter you are using.

 

Best Regards,

 

Jim T.

Attached Thumbnails

  • Celestron RASA LPS filter compare.jpg

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#15 descott12

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Posted 11 November 2021 - 04:15 PM

Hey Jim,

Thanks for the awesome report. Very timely as I was wanting to replace my LPS-P2. Never really satisfied with it's performance. I was looking at the EAO-1 but unfortunately it doesn't come in the 2" mounted format.

So in all your experiments I was wondering how the L-Enhnace and L-Extreme stack up against some of these IDAS filters? My use would be mostly EAA with a OSC cameras.

 

Cheers.



#16 EmeraldHills

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Posted 11 November 2021 - 08:41 PM

Jim, I'm heading out in the dark in 20 minutes. I'll try the Red and Blue in Image Control.  I've never even touched them before! Thanks!

Yes - I truly have the Celestron LP filter for RASA 11.

Thanks again.

Doug

 

I see what Alien Observatory is saying.  The sensitivity of the ASI2600 sensor around 500nm, the wavelength for O-III and well in the green part of the spectrum, is quite a bit higher than for the ASI071.  This would suggest that the ASI2600 is more sensitive to green than the ASI071.  However the spectrum shown for the ASI2600 is almost identical to that of the ASI294.  In my testing using an ASI294, all of the multiband (LPS family) IDAS filters had a bluish tint not a greenish tint.  If you refer to Table 3 in my test report, and compare the percentages for each colour channel, you can see that for the NB filters and the EAO1 the green channel is dominant (i.e. a greenish tinted image), but the LPS filters have either a dominant blue channel or blue and green are equally dominant (i.e. blue to cyan tinted image).  If you indeed have the Celestron RASA Light Pollution Imaging filter, it should behave pretty much the same as the IDAS LPS-P2 ... it is essentially a copy of the IDAS filter, much like the Optolong L-Pro is (see attached image).

 

I wonder how you are doing your white balancing in Sharpcap?  I typically set the camera Red and Blue channel gains first (located in the "Image Control" tool box), getting them set so the white balance is close.  I then do my final tweaks using the R/G/B sliders in the stacked image histogram view.  If you don't adjust the Red and Blue camera gains up, you will have a very green image regardless of what filter you use, even if you have no filter.  The default setting for the camera R & B gain sliders is 50%.  My R & B gain sliders are normally both above 75%, and can often be maxed out at 100% depending on what filter I am using and the sky conditions.  With those two sliders set properly, you should have lots of colour adjustment available in the live stack window, regardless of the filter you are using.

 

Best Regards,

 

Jim T.



#17 Tfer

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Posted 11 November 2021 - 10:30 PM

Hi Stargazer,

 

Try this link:

 

https://astrohutech....eaa-and-comets/

 

Cheers,

 

Jim T.

In 2 weeks (payday), I’ll be ordering myself an early Christmas gift.


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#18 EmeraldHills

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Posted 12 November 2021 - 02:29 AM

It DID work better to boost the Reds and Blues up in the Image Controls panel, Jim. The Green is gone! : ) Thanks!



#19 jimthompson

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Posted 12 November 2021 - 10:57 AM

Hey Jim,

Thanks for the awesome report. Very timely as I was wanting to replace my LPS-P2. Never really satisfied with it's performance. I was looking at the EAO-1 but unfortunately it doesn't come in the 2" mounted format.

So in all your experiments I was wondering how the L-Enhnace and L-Extreme stack up against some of these IDAS filters? My use would be mostly EAA with a OSC cameras.

 

Cheers.

Hi Dave,

 

For ability to increase contrast on emission type nebulae, I would rank the filters in the following order (highest to lowest):  Optolong L-eXtreme, IDAS NBZ, Optolong L-eNhance, IDAS NB1.  The L-eXtreme has slightly narrower pass bands than the NBZ (7nm vs 12nm) so it produces images with noticeably higher contrast, however the L-eXtreme is not optimized for use on fast optics like the NBZ is so it is not recommended for f/4 or faster.  The L-eNhance has a rather wide O-III band compared to its Halpha band, which makes the filter difficult to white balance, but also makes the filter not respond evenly to f-ratio ... Halpha response reduces more rapidly than O-III, causing the colour imbalance to be exaggerated.

 

Regards,

 

Jim T.


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#20 Tfer

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Posted 13 November 2021 - 04:16 PM

Doesn’t ship to Canada…



#21 jimthompson

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Posted 13 November 2021 - 05:44 PM

Doesn’t ship to Canada…

Yes they will, you just have to email the owner, Ted Ishikawa <ted@hutech.com>, directly and request a Paypal invoice including shipping.  I have ordered filters numerous times that way.  Ted is very friendly and helpful.  It is unfortunate that the software for the Astro Hutech E-Store does not seem to handle Canadian addresses correctly.

 

Cheers,

 

Jim T.


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#22 Mikehuerto

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Posted 15 November 2021 - 08:35 AM

Jim

 

Thanks for that very interesting presentation during the November EAA session https://www.youtube....h?v=VPnCYLs5xRo

 

I was wondering about your recommendation for my 4.5 scope. You mentioned the IDAS NBZ, but I note from your image tests, that this will lose a lot of reflection nebulosity (such as running man). Is there something a little bit less restrictive that would work for me to enhance OIII Ha and still catch reflection nebulae........remembering that my light pollution is not that bad at about Bortle 5. Also prefer something that is available as 1.25"... though thats not deal breaker. How would the L extreme perform?

 

Best

 

Mike


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#23 R Botero

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Posted 16 November 2021 - 04:06 AM

Excellent analysis and write up on the IDAS filters!  Thank you for sharing it. waytogo.gif I have used their filters since 2003 as I image from London.  I have the P2 50x50mm version now sitting as my L channel since 2015 and love it.  Mia and Ted at Hutech have always been extremely helpful.  

 

Roberto



#24 jimthompson

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Posted 25 November 2021 - 03:26 PM

Jim

 

Thanks for that very interesting presentation during the November EAA session https://www.youtube....h?v=VPnCYLs5xRo

 

I was wondering about your recommendation for my 4.5 scope. You mentioned the IDAS NBZ, but I note from your image tests, that this will lose a lot of reflection nebulosity (such as running man). Is there something a little bit less restrictive that would work for me to enhance OIII Ha and still catch reflection nebulae........remembering that my light pollution is not that bad at about Bortle 5. Also prefer something that is available as 1.25"... though thats not deal breaker. How would the L extreme perform?

 

Best

 

Mike

Hi Mike,

 

To have better response to reflection nebula but also block as much LP as possible you would need a filter with a wider pass band down around the blue-green part of the spectrum.  A good performing all-purpose filter fitting this bill is the Astronomik UHC.  If you use it by itself you get a good increase of contrast on all object types including galaxies since the filter passes IR.  Then adding a UV/IR cut filter to the UHC will give you even better performance on nebulae at the cost of reduced performance on galaxies.  There is a slightly cheaper alternative available, the Optolong UHC.  It does not perform quite as well as the Astronomik version but it is still pretty good.

 

The Optolong L-eXtreme has pass bands even narrower than the NBZ, so it will perform worse on reflection nebulae.

 

Best Regards,

 

Jim T.




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