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Review of the new ZWO Narrowband filters - comparison to the old ZWO and Astrodon filters

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#1 cfosterstars

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Posted 27 July 2018 - 01:57 PM

I previously posted several thread on the issues that I had with reflections and artifacts with my 36mm ZWO filters. The main issue was light leakage and internal reflections that lead to very poor flat frames and artifacts in stacked images that would not easily be removed with various gradient removal tools such as pixinsight DBE. I also posted on the more generic issue of internal reflections in my OTA and how that was also effecting the quality of my images. Here are a bunch of the background threads if you want more of the history:

 

On reducing reflections in your imaging train:

 

https://www.cloudyni...trodon-filters/

 

https://www.cloudyni...cuser-drawtube/

 

https://www.cloudyni...-filter-bevels/

 

To get to the point where I could get reasonable images, I had to debug a lot of issues. The main issue was that the ZWO filters were not fully coated to the edge. For the 1.25" filters that came in filter cells, much of this gap was covered by the cell itself. Also most buyers of the ZWO cameras and filter were getting the 1.25" filters since for the most part they were large enough so that vignetting was not an issue and they were less costly. I had the 36mm unmounted filters and along with the 31mm unmounted filters, the uncoated edge of the filters lead to a lot of leakage past the filter that caused lots of reflections and artifacts. Here are posts with a lot of data on this issue:

 

https://www.cloudyni...ing-wrong-here/

 

https://www.cloudyni...ters-seriously/

 

https://www.cloudyni...gs-in-my-flats/

 

Once Sam at ZWO was made aware of how serious an issue this was, ZWO provided a set of rings to mask the filter edges.Sam was very responsive and I received my set of rings within about 10 days of contacting ZWO. I was not the only one who reported on this:

 

https://www.cloudyni...rings-provided/

 

With the rings in place, I used my set of ZWO LRGB and NB filters for a while since it was a big chuck on change to upgrade to Astrodons. Here are some example of images with the first generation ZWO filters:

 

https://www.cloudyni...rs-asi1600mm-c/

 

https://www.cloudyni...th-zwo-filters/

 

I raised a sore subject on Cloudy nights by asking is Astrodon filters were really worth 2-3X the price. I was quite sceptical at first:

 

https://www.cloudyni...ters-seriously/

 

However, a little while after I received my filter rings I had already pulled the trigger on a set of 36mm LRGB and NB astrodon filters. It was shortly after I purchased my Astrodons that the company was sold to farpoint. There was some chatter about quality issues with dirty or poorly packaged filters in this transfer period - apparently from vendors and not from Astrodon itself, but I believe that now these issues are resolved.  However, since I had both complete sets filters on hand, I conducted my own direct comparison between my Astrodon filters and my ZWO filters to document what I saw as the advantage of Astrodon filters over the ZWO filters to help others judge for themselves whether to invest in Astrodons or not. I am a scientist and I like to both do the experimentation myself and see the data. This was my comparison thread:

 

https://www.cloudyni...ontrolled-test/

 

In a nutshell, from my review I felt that the ZWO LRGB filters, with a mask to block the filter edge are usable and will do a decent job with few artifacts. There are some halos around bright stars, but not excessive. For the cost difference (675$ vs. 199$ for 36mm), I feel that the ZWO LRGB filters are worth strong consideration. However, due to the halos on the ZWO narrowband filters combined with the edge leakage, I felt that the narrowband filters were not a good buy.  I used my Astrodons exclusively for about the last six months and have been happy with them. I have made may best images with them. 

 

About a month ago, there was a thread about an new generation of ZWO Narrowband filters being offered on the ZWO website. I took a look, but since I did not have a need it was just for curiosity. About 2 days later, I received an e-mail from Sam telling me about the new filters and asking if I would do a similar test with the new product. I jumped at the chance. I took me a month to collect and analyze the data. We had lots of clouds and a huge hear wave in Austin. I also had some serious issues with some of my equipment, so this took longer than I would have liked.

 

Regardless, this thread is my review of the new ZWO narrowband filters (36mm Ha, SII and OII) vs my astrodon filters. I tried as best I could to make this as fair and thorough an evaluation as I could. If anyone has any request for additional data, let me know and I will see if I can squeeze it in. Even though all the data is collected and analyzed, it is going to take some time to get it all posted. So please bare with me. I will cover:

 

1) unboxing, inspection and mounting of the filters into the filter wheel. 

2) flat frame comparisons

3) stacked, drizzled mono images for the filters 

4) HSO hubble palette processed image comparisons.


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#2 Hubbs

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Posted 27 July 2018 - 02:03 PM

Really looking forward to reading this when the post is done - just curious, I see that ZWO also has 'new' LRGB filters - I know you mention your previous post found the old versions acceptable but was just wondering if you will also be comparing the new LRGB filters as well, or only the narrowband?  Either way it will be a very interesting read!



#3 cfosterstars

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Posted 27 July 2018 - 02:30 PM

Really looking forward to reading this when the post is done - just curious, I see that ZWO also has 'new' LRGB filters - I know you mention your previous post found the old versions acceptable but was just wondering if you will also be comparing the new LRGB filters as well, or only the narrowband?  Either way it will be a very interesting read!

The new LRGB filters are only for 1.25" size. I only have 36mm filter wheels so I cant do such a test. However, If you request to SAM, he could either send me a loaner filter wheel or find a different user to do the test. This review is strictly for the 36mm narrow band filters.



#4 cfosterstars

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Posted 27 July 2018 - 03:07 PM

First prior to doing anything with the ZWO filters, I completed a set of narrowband data from the Sadr region of Cygnus that included the bright star Sadr in the image specifically to see how the filters handled bright stars and how much star halo was present. For the original filters, I used Alnitak and the horsehead nebula, but that was simply not available for imaging. The Sadr region has lots of complex emission and nebulosity so I felt it was a good challenge.  I go into the imaging data later on, but since I did the Astrodon data first and directly prior to this evaluation, I wanted to mention it. 
 
The filters arrived in good shape in a very small box. This seems typically for shipments directly for China. My wife order stuff from China all the time. The filter come packaged individually in separate boxes. This shows the starlight Xpress filter wheel that I have been using with my astrodon filters. The plan here was to keep all other factors that I could control as close to constant as possible. So the ZWO filters were to be mounted in the exact same positions in the exact same filter wheel as the astrodons. The camera was a ZWO ASI1600MM-PRO for both runs. Here are the ZWO filters in their boxes prior to staring the unboxing:
 
01   Starting The installation
 
After opening the filter wheel, this image shows the Astrodon filters prior to removing them from the wheel. The AD LRGB filters are in the top, bottom and right side positions in the wheel and the narrow band filters are in the three positions on the left:
 
02   Removing The AD filters
 
The ZWO filter box were in pristine shape and very clearly labeled:
 
03   New ZWO filter As shipped
 
Each filter box, when you open it, has the filter case inside a plastic bag. Since the filter boxes are unsealed, this makes sense for keeping dust off the case.
 
04   removing The filter case
 
Each filter sit inside a foam recess in a hard plastic case. There is no way that the filter can move around in shipping and is very well protected. the filter is inside a sealed plastic sleeve and folded inside lint free paper. You need to be careful in cutting open the plastic sleeve so as not to cut the paper:
 
05   Opening The Filter Case
 
After unfolding the paper, you can now see the ZWO Ha filter:
 
06   After opening inner sleve
 
The filter was very clean. You can already see major improvements to the filters. First, they are fully coated to the edge and the bevels of the filters are blackened. This should completely eliminate one of the main problems with the original ZWO filters - not coated to the edge with a plain, unpolished or coated bevel. For the get go, I felt that these filters would be a clear step up from the earlier designs:
 
07   darkened bevel
 
The next obvious improvement was that the anti-reflection coating was clearly better. One of my pet peeves with the old ZWO filters was trying to figure out which was the correct orientation for putting them in the filter wheel. The images on the ZWO website were never very clear. Well for the Ha and SII filter, there is no question about which is the correct orientation any more. It is obvious. This is the AR coated side of the Ha filter that should face the OTA:
 
08   Antireflective Coating
 
And this is the camera side of the Ha filter. The correct orientations are also shown on the ZWO website and it is easy to match to the filters in your hand: 
 
09   OTA side Of The filter
 
The OIII filter was different than the Ha and SII. It is full coated and the bevel is darkened, but it looks much more like the first generation filters from an orientation point of view. It requires some attention to detail to determine the correct orientation. It also did not have nearly as strong and AR coating as the Ha and SII filter, but appear better than the 1st generation filters.
 
This is the filter wheel with all three ZWO filters loaded into the upper three filter positions for the camera side of the wheel:
 
10   In The filter wheel camera side

 
and this is the OTA side of the wheel:
 
11   In The filter wheel OTA side
 
With the filter loaded into the wheel, I re-assembled the camera and mounted the filter wheel on the OTA exactly as it was for the Astrodon filters. That night, I focused the OTA and platesolved to match the camera rotation to within 1 degree of the previous camera angle that was used for the AD image acquisition.

 


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#5 CharlesW

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Posted 27 July 2018 - 03:59 PM

Maybe your intent wasn’t to do a side by side between the new ZWOs and the Astrodons but if it was, wouldn’t it have been a little better to load in the two Ha filters and switch back and forth between them over an evening? 



#6 cfosterstars

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Posted 27 July 2018 - 04:34 PM

Maybe your intent wasn’t to do a side by side between the new ZWOs and the Astrodons but if it was, wouldn’t it have been a little better to load in the two Ha filters and switch back and forth between them over an evening? 

I did not do it that way. If you read my previous comparison, I think you will see that the deltas between the filters are not that subtle. I would suggest that if you think this is a better method, you could ask Sam and see if he will send you filter to compare. As it was, this took me a lot of time. 



#7 cfosterstars

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Posted 27 July 2018 - 04:55 PM

After mounting the filters in the filter wheel and attaching it to the OTA, I took images through the OTA with my cell phone camera to look for light leakage. Light leakage and reflections were a serious issue with the original ZWO filters. This lead to very non-uniform flat frames and colored arcs in combined channel images that were very difficult to remove. The leakage was due to the filters not being fully coated to the edge so that light could leak between the edge of the filter and the filter wheel filter slot. The addition of masking rings to block this leakage helped quite a bit. However, I found them somewhat difficult to install and overtime would not lay flat on the filter. This is what the original ZWO filter looked like without the masking rings. The bright leakage is very clear and is very BAD for imaging:
 
LRGB AND NB FILTERS BEFORE MASKING EDGE
 
With the masking rings, the resulting image artifacts could be significantly suppressed. However, for the new filters, without any masking rings, the leakage is basically zero. I even had difficulty taking a good picture through the filter with my cell phone.
 
This is the new ZWO SII filter:
 
12   through The OTA SII Filter
 
This is the new ZWO Ha filter:
 
13   through The OTA Ha Filter
 
This is the new ZWO OIII filter:
 
14   through The OTA OIII filter
 
I previously took similar images for the Astrodon filters:
 
This is the Astrodon SII filter:

 

SII Filter
 
This is the Astrodon Ha filter:
 
Ha Filter
 
This is the Astrodon OIII filter:
 
OIII Filter
 
From a light leakage point of view, the new ZWO narrowband filters are clean. This was evident in the flat frames that I will show next.
 
 

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#8 Der_Pit

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Posted 28 July 2018 - 11:26 AM

One question: You wrote

 

This is the AR coated side of the Ha filter that should face the OTA:

However, ZWO website states

 

if you can see two shadow, this side has anti-reflective coating, and it should face to the camera.

???



#9 cfosterstars

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Posted 28 July 2018 - 01:25 PM

One question: You wrote

 

Quote

This is the AR coated side of the Ha filter that should face the OTA:

However, ZWO website states

 

Quote

if you can see two shadow, this side has anti-reflective coating, and it should face to the camera.

???

 

For the new ZWO filters, the instructions are different for the Ha/SII filter vs. the OIII filter. The "two shadows" applies to the OII and not the Ha dn Sii filters.

 

I had the whole next potion of the review ready to post when my computer crashed!!!



#10 cfosterstars

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Posted 28 July 2018 - 01:48 PM

Next I will show the flatframe comparison between the filters. For generating Flat frames for either of the two sets of filters and my  ZWO ASI1600MM-PRO camera, I used SGP flats calibration wizard to determine flat frame exposures for the three filters for each vendor using my flatman EM panel. For my flatman, I point the OTA to the zenith and park the scope. I use an illumination setting of 200 on the panel and a single layer of tee shirt fabric over the OTA and place the flatman on top of the fabric. I did the Flat Frame capture in the early evening after dark, but before full astronomical dark so that there is no light leakage to affect my flats.  I use a 200 gain for all the NB filters since this is the gain I used for light frames and set the camera temperature to -15C - thats the best the camera can do in the TX summer. The SGP flats calibration wizard determines the exposure conditions for both the flats and dark flats but has to be run independently for the two sets of filters. For the narrowband flats with my Astrodon filters, the exposure times are: 1.67s for OIII, 6.77s for Ha and 11.1s for SII. For the new ZWO NB filters, the optimal exposure times were applicably shorter - which is not surprising since the Astrodon bandpass is 5nm vs 7nm for the ZWO filters. For the ZWO filters, the exposure times were: 1.25s for OIII (74.5%), 4.53s for Ha (66.9%) and 7.18s for SII (64.6%).  Using these same exposure times, I also collect dark flats after full dark with the scope OTA capped to eliminate any possibility of light leakage. For each filter, I collected 40 flat frames and 40 DarkFlat frames. For each set of dark flat frames, I used PI to integrate the frames to generate MasterDarkFlat frames.

 

For the MasterDarkFlat generation I used these setting in PixInsight:
   a. Image Integration
         i. Combination: Average
         ii. Normalization: No Normalization
         iii. Weights: Don’t Care (All = 1)
  b. Pixel Rejection (1)
         i. Rejection Algorithm: Winsorized Sigma Clipping
         ii. Normalization: No Normalization
  c. Pixel Rejection (2)
         i. High and low Sigma = 3.0

  d. Large Scale Pixel Rejection: Low and High - disabled.

 

For Flat Frame Calibration, I use only MasterDarkFlats and I uncheck the Optimize on the MasterDark options. Although less important for short exposures, this significantly reduces effects of AMP glow in the integrated frames. For Flat frame integration and MasterFlat Frame generation, I used these setting in PixInsight. Since I do not use sky flats, I do not use the large scale pixel rejection options:

  a. Image Integration
        i. Combination: Average
        ii. Normalization: Multiplicative
        iii. Weights: Don’t Care (All = 1)
  b. Pixel Rejection (1)
        i. Rejection Algorithm: Winsorized Sigma Clipping
        ii. Normalization: Equalize Fluxes
  c. Pixel Rejection (2)
        i. High and low Sigma = 3.0

  d. Large Scale Pixel Rejection: Low and High - disabled.


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#11 Der_Pit

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Posted 28 July 2018 - 02:02 PM

For the new ZWO filters, the instructions are different for the Ha/SII filter vs. the OIII filter. The "two shadows" applies to the OII and not the Ha dn Sii filters.

Yes, I know.  But they also have the 'mirror side' towards the OTA, and the 'color' side to the cam. And the colored side is the one with AR coating.  That one should always be 'behind' the filter in beam direction.

 

Sorry to hear about your computer issues :(



#12 cfosterstars

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Posted 28 July 2018 - 02:17 PM

I will start with the SII filter. As I stated in the unboxing above, the Ha and SII filters look very different from the first generation of ZWO filters. 

 

This is a screen capture of the new ZWO SII MasterFlat and the histogram. The histogram looks very symmetric.

 

20   SII Flat histogram
 
With a STF stretch, the new ZWO SII MasterFlat show no artifacts. The full coating of the filter and the blackened bevel that showed no light leakage is producing a very good flat frame.
 
19   MasterFlatSII ZWO 7 18s 200G

 

This is a screen capture of the Astrodon SII MasterFlat and the histogram. The histogram also looks very symmetric.

 

30   AD SII Histogram

 

With a STF stretch, the Astrdon SII MasterFlat also show no artifacts. The Astrodon full coating of the filter and the blackened bevel is also producing a very good flat frame.

 

29   MasterFlatSII 11 1 PRO HS
 
In contrast, this was the histogram of the old ZWO SII MasterFlat. It was very asymmetric.
 
SII Historgram Flipped
 
With a STF stretch, the old ZWO SII MasterFlat show serious ring artifacts due to the gap in the coating of the filter and the uncoated bevel that showed severe light leakage. This flat frame will leave artifacts in your light frames after calibration.
 
MasterFlatSIISTR
 

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#13 cfosterstars

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Posted 28 July 2018 - 02:58 PM

Now for flats for the Ha filters. As with the SII filter, this filter was fully coated and edge bevel blackened with a very strong AR coating:

 

This is a screen capture of the new ZWO Ha MasterFlat and the histogram. The histogram looks very symmetric.

 

16   Ha Flat histogram
 
With a STF stretch, the new ZWO Ha MasterFlat show no artifacts. The full coating of the filter and the blackened bevel that showed no light leakage is producing a very good flat frame.
 
15   MasterFlatHa ZWO 4 53s 200G
 
This is a screen capture of the Astrodon Ha MasterFlat and the histogram. The histogram also looks very symmetric.
 
26   AD Ha Histogram
 
With a STF stretch, the Astrdon Ha MasterFlat also show no artifacts. The Astrodon full coating of the filter and the blackened bevel is also producing a very good flat frame.
 
25   AD MasterFlatHa 6 77 PRO HS

 

In contrast, this was the histogram of the old ZWO Ha MasterFlat. It was very asymmetric.

 

Ha Historgram Flipped

 

With a STF stretch, the old ZWO Ha MasterFlat show serious ring artifacts due to the gap in the coating of the filter and the uncoated bevel that showed severe light leakage. This flat frame will leave artifacts in your light frames after calibration.

 

MasterFlatHaSTR

 


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#14 cfosterstars

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Posted 28 July 2018 - 03:08 PM

Now for flats for the OIII filters. Like the SII and Ha filters, this filter was fully coated and edge bevel blackened. But unlike the SII and Ha, it did not appear to have nearly as strong an AR coating:

 

This is a screen capture of the new ZWO OIII MasterFlat and the histogram. The histogram looks less symmetric than the ZWO SII or Ha filters.

 

18 = OIII Flat histogram
 
With a STF stretch, the new ZWO OIII MasterFlat show no artifacts. The full coating of the filter and the blackened bevel that showed no light leakage is producing a very good flat frame.
 
17   MasterFlatOIII ZWO 1 25s 200G

 

This is a screen capture of the Astrodon OIII MasterFlat and the histogram. The histogram also looks less symmetric than the Astrodon Ha.

 

28   AD OIII Histogram
 
With a STF stretch, the Astrodon OIII MasterFlat also show no artifacts. The Astrodon full coating of the filter and the blackened bevel is also producing a very good flat frame.
 
27   AD MasterFlatOIII 1 67 PRO HS
 
In contrast, this was the histogram of the old ZWO OIII MasterFlat. It was also very asymmetric.

 

OIII Historgram Flipped
 
With a STF stretch, the old ZWO OIII MasterFlat show serious ring artifacts due to the gap in the coating of the filter and the uncoated bevel that showed severe light leakage. This flat frame will leave artifacts in your light frames after calibration.
 
MasterFlatOIIISTR

 


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#15 cfosterstars

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Posted 28 July 2018 - 04:08 PM

After taking flats and dark flat. I imaged the Sadr Region (IC1318) of Cygnus in SHO Hubble Palette for both sets of filters. Each set of acquisition was done sequentially with the Astrodon filters done first and the new ZWO filters done second. These were the acquisition conditions:

 

Imaging telescope or lens:Orion EON 115mm ED APO Triplet Refractor

Imaging camera:ZWO ASI1600MM-Cool

Mount:ORION HDX-110 EG-G

Guiding telescope or lens:Orion 70 mm Multi-Use Finderscope

Guiding camera:ZWO ASI290mm Mini

Focal reducer:William Optics 0.8x Flattener IV

Software:PHD Labs PHD 2 Guiding,  Carte Du Ciel 3.10,  Sequence generator pro

 

Filters: Astrodon 36mm O3 5nm,  Astrodon 36mm Ha 5nm,  Astrodon 36mm SII 5nm

Filters: new ZWO 36mm O3 7nm,  new ZWO 36mm Ha 7nm,  new ZWO 36mm SII 7nm

 

Resolution: 9070x6776

Dates: June 28, 2018,  June 30, 2018,  July 1, 2018

Frames:
36mm Ha: 60x240" (gain: 200.00) -15C bin 1x1
36mm OIII: 60x240" (gain: 200.00) -15C bin 1x1
36mm SII: 60x240" (gain: 200.00) -15C bin 1x1

Integration: 12.0 hours

Darks: ~40

Flats: ~40

Flat darks: ~40

 

RA center: 305.633 degrees

DEC center: 40.456 degrees

Pixel scale: 0.593 arcsec/pixel

Orientation: 180.784 degrees

Field radius: 0.933 degrees

Locations: Backyard, Austin, TX, United States

 

The image processing flow is posted for the most part in this posting:

 

https://www.cloudyni...rocessing-flow/. This post does not yet include the non-linear color manipulation and later processing steps. However, I did do deconvolution on the extracted LUM from the SHO composite for both sets of data:

 

The monochrome MasterLight frames for each filter are shown after calibration, correction, registration,  integration, localnormalization, and drizzle integration. this was followed by registration of the masters, dynamic crop and DBE only. Then these images with stretched to non-linear using the histrogramtransfer process and the STF settings.

 

This is the SII MasterLight Frame for the ZWO filter:

 

23   SadrZWO SIIDRZ HS

 

This is the SII MasterLight Frame for the Astrodon filter:
 
33   SadrSIIDRZ AD DC DBE HS

 

This is the Ha MasterLight Frame for the ZWO filter:

 

21   SadrZWO HaDRZ HS
 
This is the Ha MasterLight Frame for the Astrodon filter:

 

31   SadrHaDRZ AD DC DBE HS

 

This is the OIII MasterLight Frame for the ZWO filter:
 
22   SadrZWO OIIIDRZ HS
 
This is the OIII MasterLight Frame for the Astrodon filter:

 

32   SadrOIIIDRZ AD DC DBE HS

 

One thing to note is that the ASI1600MM-PRO sensor itself does not have an AR coating and that is the sources of the diamond shape interference pattern around the bright star Sadr. All three new ZWO filters are free from the main drawback of the 1st generation filters in terms of arcs or gadient halos that impacted the entire image as a whole.

 

Both the Ha and SII filters were also free of any obvious star halos that I could see even with aggressive stretching. Furthermore, in terms of detail, sharpness and image quality, I think that the new ZWO SII and Ha are nice filters. The new ZWO OIII filter still shows star halos around Sadr and very weak halos around less bright stars. I assign this to the less strong AR coating of the new OIII.

 

These MasterFrames were combined into Hubble Palette SHO images and I manupulated the colors to the gold/cyan tones. However, this is almost impossible to do exactly the same for two sets of data or even the same set of data if you reprocess so there are differences.

 

Here is the SHO Hubble palette images of the Sadr Region for the two set of filters. Iprocessed the Astrodon filter data first and the ZWO data had the benefit of me having more practice a doing the post processing:

 

This is for the new ZWO filters:

 

24   SadrZWO LSHO
 
This is for the Astrodon filters:

 

34   SadrAD LHSO

 

You can see the reflection arc around Sadr fromthe ZWO OIII filter, but this is dramatically better than the artifacts from the original ZWO filters.

 

There are some things I could do better for this analysis. I) as suggested previously, I could have loaded all the filter int he wheel at the same time and taken the data interwoven to reduce any effects from changes in the conditions. However, since this is mostly a qualitative comparison, I don't this that would change the conclusions of these review. One thing that does nag at me is did I have the filter orientation correct? The one thing about Astrodon filters is that filter orientation is not even mentioned. I am considering put the filters back into the filter wheel at the same time and doing some more side by side comparison from single subframes. The reflections and halos issues do not require long integration times to verify. I would put the filter in the wheel in one orientation and take frames for all filters, then flip the filter orientation and repeat the frames. I still may do this since this issue bothers me.

 

So for the conclusion: First, the quality of Astrodon filters is not the subject of this review nor does this review in any way state that the new ZWO filters are "just as good as Astrodons". I do not say that. Astrodons are the best filters out there and you do pay a lot for that quality. However, many images either cant or choose not to invest that kind of money in equipment. Also many new images want to start out but dont have the budget to get the best. 

 

For those of you who are starting out or who have used DSLR camera or have been doing visual and want to get into astrophotograph, the ZWO ASI cameras are very good cameras at a good price - I have four of them myself. When considering moving from DLSR or getting into AP in general, I highly recommend going to mono with a filter wheel. - its just plain better. If you are going to mono, you will need filters.  These filters are a really good set of filters to start with and maybe even stay with for a very long time. I think that for the price, they are a really decent set of filters and the new Narrowband filters fix the major flaws in the original designs.

 

I would recommend them without hesitation with the clear understanding that they are not totally free of star halos but you can still create very nice images with them. If you look at hubble images, you will see halos.

 

If you have the money, then I recommend considering Astrodon filters. However, you might consider them as an upgrade once you get through the learning curve of AP and mono with filters in general. The saying with Astrodon is that you only cry once.

 

I also have a second ASI1600MM-C camera and I have a set of Baader LRGB and Astronomiks NB filters that I have yet to really try out. I will likely do a similar comparison for those filters in the future. Even I could not stomach paying for a 2nd set of Astrodons. 

 

I hope this review has been valuable to readers out there. Comments and questions welcome.

 

If anyone wants the master light frames to try processing, I can post them in a dropbox.


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#16 dhaval

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Posted 28 July 2018 - 04:41 PM

HI Chris,

Thanks for doing this. This is really helpful.

 

CS!


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#17 Woodbridge_Dave

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Posted 29 July 2018 - 03:39 PM

Thanks for a well designed bias-free test.  In the end, your results are a nice demonstration of conventional thinking about AstroDon vs everything else.  In my opinion, the way an O3 filter performs says a lot about the entire line up.  Based on this, I will still avoid ZWO products.  Just my 2 cents.



#18 pyrasanth

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Posted 30 July 2018 - 06:58 AM

There's a new kid on the block, perhaps not as new, Chroma- The filters are not as expensive as Astrodon and I've currently tested the OIII- no halo whatsoever on any bright stars I've cared to image and that is anything with up to 45 minute exposure on an Atik 460 at 2x2 bin.

 

I'm going to buy the Chroma SII shortly and test that and keep the Baader 3.5 nm HA enforced as that seems a good quality filter as well.

 

So we have a good choice of alternatives now which meet all our budget requirements.


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#19 WesC

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Posted 30 July 2018 - 09:34 AM

It’s clear that ZWO has improved the quality of their filters significantly and it seems that they are at least as good as Baader or Astronomik. Astrodon still seems to be the clear winner in the tricky OIII area, but its nice to see such a significant improvement to the ZWOs. waytogo.gif

 

Thanks for the comparison.


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#20 cfosterstars

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Posted 30 July 2018 - 12:17 PM

It’s clear that ZWO has improved the quality of their filters significantly and it seems that they are at least as good as Baader or Astronomik. Astrodon still seems to be the clear winner in the tricky OIII area, but its nice to see such a significant improvement to the ZWOs. waytogo.gif

 

Thanks for the comparison.

Thanks,

 

I am still going to do the orientation test. It still nags me that I may have put the filter in the wrong orientation. Its an easy test, but sky time is precious and I am trying to complete M8 and M20 while I can still see them. But I will get this done. I want to be sure I did this right.


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#21 pointofview_365

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Posted 30 July 2018 - 04:29 PM

There's a new kid on the block, perhaps not as new, Chroma- The filters are not as expensive as Astrodon and I've currently tested the OIII- no halo whatsoever on any bright stars I've cared to image and that is anything with up to 45 minute exposure on an Atik 460 at 2x2 bin.

I'm going to buy the Chroma SII shortly and test that and keep the Baader 3.5 nm HA enforced as that seems a good quality filter as well.

So we have a good choice of alternatives now which meet all our budget requirements.


No way dude. Chroma is a little more expensive. Ask me how I know!

$435.00 vs $620 for 5nm. $650 for the 3nm.


Complete Astrodon tru-balance gen 2 e-series plus NB filters $1980 give or take a dollar. The same kit by Chroma will run $2455.00 give or take a dollar.

Edited by pointofview_365, 30 July 2018 - 04:44 PM.

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#22 pyrasanth

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Posted 31 July 2018 - 02:49 AM

"So we have a good choice of alternatives now which meet all our budget requirements."

 

.....you make your choice and pay your money- that's exactly what the statement means it does not mean cheaper than the others it means we have a choice.



#23 pointofview_365

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Posted 31 July 2018 - 04:45 AM

"So we have a good choice of alternatives now which meet all our budget requirements."

.....you make your choice and pay your money- that's exactly what the statement means it does not mean cheaper than the others it means we have a choice.


Point well said!

#24 pointofview_365

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Posted 31 July 2018 - 04:50 AM

Thanks,

I am still going to do the orientation test. It still nags me that I may have put the filter in the wrong orientation. Its an easy test, but sky time is precious and I am trying to complete M8 and M20 while I can still see them. But I will get this done. I want to be sure I did this right.



Any discernable variable having 2mm and 3mm filters in the same wheel without fine tuning the distance between? Or are you adding a shim/spacer for the 2 filter thicknesses?

#25 pyrasanth

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Posted 31 July 2018 - 06:02 AM

Any discernable variable having 2mm and 3mm filters in the same wheel without fine tuning the distance between? Or are you adding a shim/spacer for the 2 filter thicknesses?

I had to remount my filters last night for the very reason of shimming. When I first had my filter wheels I did not pay much attention to the fact that some filters were thinner than others. The Baader filters are 2.4 mm thick but the LPR filter I bought was only 1.2 mm. It made quite a difference in the focus positions.

 

I can only infer that the shims are offered in different thicknesses to deal with this issue- so my advice is to shim as close as possible to match the thickness of all filters.


Edited by pyrasanth, 31 July 2018 - 06:04 AM.



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