7 replies to this topic

[cfosterstars]

I hope that this is the last in this series of posts on fixing my flats issues predominately associated with my 36mm ZWO filter set. I have a series on posts that cover various aspects of the issue. Instead of a long recap, I am putting links to the previous threads here since they are spread out and there is lots of detail on what I and others went through on this topic. This was the statement of the problem:

 

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

 

Most of the debug is posted in this thread:

 

https://www.cloudyni...ring-artifacts/

 

At the end of this thread, I had resolved the issues with the ZWO filters sufficiently to do adequate correction of my light frames. Eventually I got a new set of filters from Astrodon. The merits of these filters is discussed here:

 

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

 

I then did a comparison between the ZWO filter with all the fixes that I had vs. a new set of Astrodon filters:

 

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

 

This showed as best as I could demonstrate, the performance delta between the ZWO filters and the best in class Astodon filters. I then set out to see of I could make further improvements since my flats were not completely without artifacts. That was covered in these two threads:

 

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

 

and

 

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

 

These were the mechanical fixes to my OTA to further reduce reflections and to show how my flats responded. 

 

This post will show the final results of all of these efforts. There is again a lot of data to post and it will take some time, so please bare with me.

Edited by cfosterstars, 11 February 2018 - 02:24 PM.

[cfosterstars]

This will show the final images through the optical train for each filter and the resulting flat frames. This is with my ORION EON 115mm APO with a Williams Optics Flattener IV. The focuser and flattener have both be flocked and darkened to remove any stray reflections that I could eliminate. The filter wheel is a Starlight Xpress filter wheel with Astrodon 36mm E-series filter LRGB or 5mm Narrow band SII, OIII, and Ha filters.

 

The pictures were taken with my smart phone after the ASI1600MM-C camera was removed and the OTA pointed a a bright, but cloudy sky.

 

The flat were taken with the ASI1600MM-C and an Alnitak Flatman EL panel through two layers of tee shirt material. The Flat times were determined with SGP flats calibration wizard and dark flats were taken for the same exposure time as the flats for calibration. All images were taken at -20C and at a gain of 200, offset of 40 and USB of 90. Each flat was created with 40 flat frames and 40 dark flats and integrated with Pixinsight. The stretched flat used the ScreenTransferFunction stretch and histogram transformation.

 

For the LUM filter:

 

This is the image of the filter though the OTA. Even with blackening the edges of the filter, the filter bevel is still reflecting, but the reflections are significantly reduced from my starting point:

 

 

This is the unstretched LUM flat: Even with the filter bevel reflections, the flat frame is very uniform.

 

 

This is the STF-stretched LUM flat: Outside of a smudge on the flattener and a few dust spots, there are no ring patterns visible. 

 

 

This compares to my initial starting point with the ZWO filters:

 

 

 

For the RED filter:

 

This is the image of the filter though the OTA. Even with blackening the edges of the filter, the filter bevel is still reflecting, but the reflections are significantly reduced from my starting point:

 

 

This is the unstretched RED flat: Even with the filter bevel reflections, the flat frame is very uniform.

 

 

This is the STF-stretched LUM flat: Outside of a smudge on the flattener and a few dust spots, there are no ring patterns visible.

 

 

This compares to my initial starting point with the ZWO filters:

 

 

[cfosterstars]

This is for the GREEN filter:

 

This is the image of the filter though the OTA. Even with blackening the edges of the filter, the filter bevel is still reflecting, but the reflections are significantly reduced from my starting point:

 

 

This is the unstretched GREEN flat: Even with the filter bevel reflections, the flat frame is very uniform.

 

 

This is the STF-stretched GREEN flat: Outside of a smudge on the flattener and a few dust spots, there are no ring patterns visible.

 

 

This compares to my initial starting point with the ZWO filters:

 

 

This is for the BLUE filter:

 

This is the image of the filter though the OTA. Even with blackening the edges of the filter, the filter bevel is still reflecting, but the reflections are significantly reduced from my starting point:

 

 

This is the unstretched BLUE flat: Even with the filter bevel reflections, the flat frame is very uniform.

 

 

This is the STF-stretched BLUE flat: Outside of a smudge on the flattener and a few dust spots, there are no ring patterns visible.

 

 

This compares to my initial starting point with the ZWO filters:

 

 

The improvements in the stretched flats is visible and significant, but the real improvements are seen in the narrowband filters.

 

[cfosterstars]

This is for the OIII filter:

 

This is the image of the filter though the OTA. The edge bevel of the Astrodon filters comes blackened edges. The filter is highly reflective and it was difficult to get a good picture through the filter. The filter bevel is still reflecting slightly, but the reflections and light leakage are significantly reduced from my starting point:

 

 

This is the unstretched OIII flat: the flat frame is very uniform with very little vignetting or other pattern.

 

 

This is the STF-stretched OIII flat: Outside of a smudge on the flattener and a few dust spots, there are no ring patterns visible. I still have some streaks that may need further work, but basically ring free.

 

 

This compares to my initial starting point with the ZWO filters:

 

 

Compared to the initial ZWO, the ring pattern is completely gone. I dont like the streaks but still a massive improvement.

 

This is for the Ha filter:

 

This is the image of the filter though the OTA. The edge bevel of the Astrodon filters comes blackened edges. The filter is highly reflective and it was difficult to get a good picture through the filter. The filter bevel is still reflecting slightly, but the reflections and light leakage are significantly reduced from my starting point:

 

 

This is the unstretched Ha flat: the flat frame is very uniform with very little vignetting or other pattern.

 

 

This is the STF-stretched Ha flat: Outside of a smudge on the flattener and a few dust spots, there are no ring patterns visible. I still have some streaks that may need further work, but basically ring free.

 

 

This compares to my initial starting point with the ZWO filters:

 

 

Compared to the initial ZWO, the ring pattern is completely gone.

 

This is for the SII filter:

 

This is the image of the filter though the OTA. The edge bevel of the Astrodon filters comes blackened edges. The filter is highly reflective and it was difficult to get a good picture through the filter. The filter bevel is still reflecting slightly, but the reflections and light leakage are significantly reduced from my starting point:

 

 

This is the unstretched Ha flat: the flat frame is very uniform with very little vignetting or other pattern.

 

This is the STF-stretched Ha flat: Outside of a smudge on the flattener and a few dust spots, there are no ring patterns visible. I still have some streaks that may need further work, but basically ring free.

 

 

This compares to my initial starting point with the ZWO filters:

 

 

Dramatically better.

 

[cfosterstars]

So how well do these flats correct my light frames? I can not show that for my Narrowband filters. I have a complete and processed narrowband image set of the Rosetta Nebula - NCG 2237, 2238, 2239 and 2246. The above flats were used to calibrated this data.

 

The data was taken over four nights since I have trees that restrict me to 3.5 hours past meridan. This was taken with:

 

Mount: ORION HDX-110 EQ-G using EQMOD/CdC - Side-by-side

OTA: ORION EON 115mm APO with JMI motorized focuser/PCFC2

Guider: ORION 70mm with ASI290MM-mini/UVIR filter camera/PHD2

Camera: ASI1600MM-COOL

Filters: Starlight Xpress filter wheel with 36mm Astrodon 5nm Ha, OIII and SII

Image Software: Pixinsight (stacking/Calibration/processing); Photoshop CC (processing);

Automation: Sequence Generator Pro; CdC; Maxpoint; 

 

The camera was at -20C with gain of 200, offset of 40 and USB of 90. The lights were calibrated with 50 dark frames, 40 flat frames and 40 dark flat frames using Pixinsight. The data was stacked using localNormalization and 2X drizzle integration. The stack were aligned and cropped. The background gradient was removal done with DBE.

 

For the OIII, this is 59 X 240s frames:

 

 

For the Ha, this was 68 X 240s frames:

 

 

For the SII, this was 71 X 240s frames:

 

 

The flats were very well and the images are clean of artifacts.

 

This is the fully processed Rosetta in HSO Hubble Palette with Super LUM - LSIIHaOIII

 

 

This is really the first time I have done a real decent job on full narrow band using only Pixinsight. Comments and questions are welcome. 

 

I have LRGB data going but still need the GREEN and BLUE channels. The weather has not cooperated, but the LUM and RED data look great.

Edited by cfosterstars, 11 February 2018 - 04:22 PM.

[SandyHouTex]

Any chance you could do a NB of the Horsehead with the ADs?  If you have, did you still have the Alnitak issue?

[cfosterstars]

Any chance you could do a NB of the Horsehead with the ADs?  If you have, did you still have the Alnitak issue?

That is what my LRGB data is. Its a two panel mosaic of the flame/B33 and Alnitak. I also took Ha data, but I was not planning on OIII and SII. I still need to collect GREEN and BLUE data. Right now there is no good weather for the next 10 days at least. Also, I can only get about 3-4 hours per night with my tree issue on Orion currently and it is only getting worse. 

 

Any comments on the Rosetta?

Edited by cfosterstars, 11 February 2018 - 07:16 PM.

[SandyHouTex]

 

Any chance you could do a NB of the Horsehead with the ADs?  If you have, did you still have the Alnitak issue?

That is what my LRGB data is. Its a two panel mosaic of the flame/B33 and Alnitak. I also took Ha data, but I was not planning on OIII and SII. I still need to collect GREEN and BLUE data. Right now there is no good weather for the next 10 days at least. Also, I can only get about 3-4 hours per night with my tree issue on Orion currently and it is only getting worse. 

 

Any comments on the Rosetta?

 

It looks awesome.  I love the Hubble palette because it actually tells you something about what's going on with the chemistry.

 

And thanks for all of your work on the issues you've been having.  It should be made a sticky.  Great info.