294mc pro star halo problems - Forums

Topic starter

Jan 8, 2022

Hey!
Need some help/advice on why im getting these horrible halos around stars. I get them on both L-extreme and with IDAS LPS filter. Both are 2" filter which i put in the filter slot in the Redcat 51. Just bought a ZWO filter drawer which i intend to use closer to the camera maybe that will fix it?

Havent tried with just a UV/IR cut filter, since i thought the above two filters would be enough.

See below image:

Dave B

Jan 8, 2022

Halos with the LExtreme is a known cause .

Steven

Jan 8, 2022 · Edited: Jan 8, 2022

In general, halo's are caused most often by the filters. the L-Extreme is kinda known for it.

If you want to rule it out, you could try a long exposure without any filters what so ever. to make sure that the filters are the issue.
If they are, there isn't much you can do about it. A lot of filters have halo's, unless you go for high end and more expensive stuff.

if you still have the halo's while not using the filters, you can (if you have the option) try the camera on a different scope. And that way rule out the camera or the scope.

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AstroTob

Topic starter

Jan 8, 2022

I know about the L-extreme, but didnt except them on the IDAS LPS filter. But i guess i will try with a uv/ir filter and see if i get them. Anyone know if its better to have a 1.25 or 2" one or doesnt it really matter?

andrea tasselli

Frequent contributor

Jan 8, 2022

I know about the L-extreme, but didnt except them on the IDAS LPS filter. But i guess i will try with a uv/ir filter and see if i get them. Anyone know if its better to have a 1.25 or 2" one or doesnt it really matter?

I don't get halos with the L-Pro and L-eNhance so I guess it's an issue with the L-eXtreme. As for the filter size it depends on the filter distance and the f/ratio of the scope. You can check whether they are going to work here:

https://astronomy.tools/calculators/ccd_filter_size

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Andy Wray

Jan 8, 2022 · Edited: Jan 8, 2022

I see a lot of talk about halos due to filters, but just wonder how much of this is caused by heavy post-processing rather than the filters themselves? I'm using cheap ZWO filters and am not seeing the issue.

Well Written Engaging

Mario Paliferro

Jan 9, 2022 · Edited: Jan 9, 2022

It's typical to get those halos with the L-extreme. Try using Dark Arkines, "EZ Decon" for Pixinsight. That should help.

Mike Dobres

Jan 9, 2022

I have tried the 1.25" L-eXtreme with the ASI294MCpro using a Canon 18-55 mm EFS lens, and on a 14" Dobson. I am not having a big issue with halos.

I have the L-eXtreme as close as possible to the cover glass of the 294MCpro. I insert it into a 42 mm filter holder and screw that into the 42-42 adaptor ring that comes with the camera. This way the filter ring is lying directly on top of the camera - that leaves a space of 2-3mm between the sensor cover glass and the filter glass.

Canon 18-55 mm EFS lens
I don't see any obvious halos in this wide field shot - this is the direct Livestack out put from Sharpcap - its only stretched, no sharpening etc. -https://www.cloudynights.com/topic/144516-eaa-image-gallery/?p=11608007

Then even after processing still no obvious halos https://www.astrobin.com/full/vwf2us/0/.

14" Dobson
In this high magnification shot, I only see a slight halo on the very strongest star (at about 8 o clock ,just off center) in the original Livestack output https://www.cloudynights.com/topic/144516-eaa-image-gallery/page-365#entry11612435 which is enhanced when I sharpened in Startools - see final https://astrob.in/po9dj0/0/

With the ZWO UV-IR cut in the same configuration, I dont't see any halos on M42 in the original Livestack or processed versions. https://astrob.in/bdfepa/B/

Bottom line, try moving your filter closer to the sensor.

Hope this helps!

Mike

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Dale Penkala

Jan 9, 2022

I have the IDAS NBZ which is a very close l-extreme filter. I use a Starzona filter drawer system which connects right up close to the camera. When the filter is screwed into the drawer and inserted its about a millimeter away so like others mention try to keep it as close to the camera as possible.
I also have the Optolong L-Pro and do not get any halos with it either.

Dale

Concise

AstroTob

Topic starter

Jan 9, 2022

Andy Wray:
I see a lot of talk about halos due to filters, but just wonder how much of this is caused by heavy post-processing rather than the filters themselves? I'm using cheap ZWO filters and am not seeing the issue.

I think its the filters, the image above is unprocessed, only stacked.

AstroTob

Topic starter

Jan 9, 2022

Mike Dobres:
I have tried the 1.25" L-eXtreme with the ASI294MCpro using a Canon 18-55 mm EFS lens, and on a 14" Dobson. I am not having a big issue with halos.

I have the L-eXtreme as close as possible to the cover glass of the 294MCpro. I insert it into a 42 mm filter holder and screw that into the 42-42 adaptor ring that comes with the camera. This way the filter ring is lying directly on top of the camera - that leaves a space of 2-3mm between the sensor cover glass and the filter glass.

Canon 18-55 mm EFS lens
I don't see any obvious halos in this wide field shot - this is the direct Livestack out put from Sharpcap - its only stretched, no sharpening etc. -https://www.cloudynights.com/topic/144516-eaa-image-gallery/?p=11608007

Then even after processing still no obvious halos https://www.astrobin.com/full/vwf2us/0/.

14" Dobson
In this high magnification shot, I only see a slight halo on the very strongest star (at about 8 o clock ,just off center) in the original Livestack output https://www.cloudynights.com/topic/144516-eaa-image-gallery/page-365#entry11612435 which is enhanced when I sharpened in Startools - see final https://astrob.in/po9dj0/0/

With the ZWO UV-IR cut in the same configuration, I dont't see any halos on M42 in the original Livestack or processed versions. https://astrob.in/bdfepa/B/

Bottom line, try moving your filter closer to the sensor.

Hope this helps!

Mike

Good to hear, will put the drawer just after camera and see what happens

Now i only need some clear skies for testing!

Jonny Bravo

Jan 9, 2022

Just curious if the image in the OP was only a test to show the halo effect… because you certainly wouldn't want to use either the L-eXtreme or similar filter on the Dark Shark. There is no Ha or O3 to isolate. The only filter you'd want to use on this target is a UV/IR cut.

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Astro Snapshot

Jan 9, 2022

Andy Wray:
I see a lot of talk about halos due to filters, but just wonder how much of this is caused by heavy post-processing rather than the filters themselves? I'm using cheap ZWO filters and am not seeing the issue.

Nope, it's not the processing thing. It's the l-extreme thing.

This is unprocessed (raw stack stretched in Pixinsight, 10 min subs). Can see the halo.

Andy Wray

Jan 9, 2022 · Edited: Jan 9, 2022

Nope, it's not the processing thing. It's the l-extreme thing.

Sorry to all about my jumping to processing being the issue. I guess I will stick to a mono camera and separate filters for now as that doesn't appear to have the same issue as one of these combined filters. Using a mono camera and separate filters does mean that I have to refocus on each filter change, but at least that means that each wavelength ends up with reasonably tight stars. I just wonder if it is possible to create an inexpensive dual-band filter that can actually achieve consistent focus/lack of halos across wavelengths.

Astro Snapshot

Jan 9, 2022

Andy Wray:
Nope, it's not the processing thing. It's the l-extreme thing.

Sorry to all about my jumping to processing being the issue. I guess I will stick to a mono camera and separate filters for now as that doesn't appear to have the same issue as one of these combined filters. Using a mono camera and separate filters does mean that I have to refocus on each filter change, but at least that means that each wavelength ends up with reasonably tight stars. I just wonder if it is possible to create an inexpensive dual-band filter that can actually achieve consistent focus/lack of halos across wavelengths.

No need to be sorry

We all try to figure this out, you said what could be the possible reason, others confirmed/rejected the theory. That’s what the forums is all about, we all learn something new each day

AstroTob

Topic starter

Jan 9, 2022

Just curious if the image in the OP was only a test to show the halo effect... because you certainly wouldn't want to use either the L-eXtreme or similar filter on the Dark Shark. There is no Ha or O3 to isolate. The only filter you'd want to use on this target is a UV/IR cut.

No l-extreme used in the image above, just the IDAS D2 LPS filter since i have some annoying street lamps around, waiting for the uv/ir cut filter to arrive

Werny Michael

Jan 10, 2022

I have a same problem whith Optolong L-extreme and asi 2600mc.
Only on a bright stars.

Peter Myers

Feb 1, 2022

The Halo Formula is:
Distance Traveled = Halo Size X Focal Ratio
Solving for Halo Size:
Halo Size = Distance Traveled divided by focal ratio

Where Distance Traveled:
Is the filter thickness divided by the refractive index (assume 1.5 as a ballpark refractive index but
this is where higher quality filters come in) plus the distance from the filter to the sensor.

Astrodon filters are thin (3mm) and the coatings are of high quality. This is a critical factor in
determining the final halo size. So Astrodon's are famous for their small halo size; they perform
much better than most other filters, but there are limits to what any filter can do. The Distance
Traveled in your system is an important factor as well. Obviously, closer is better. But focal ratio is
another critical factor. That "divided by the focal ratio" is inescapable.

Let’s compare halo size in an f/8 system and an f/2 system. If all the parameters in the f/8 and the f/2
scope are otherwise equal…
Divide the Distance Traveled by 8 (with the f/8 scope) and you get a pretty small halo. Divide the
Distance Traveled by 2 (with the f/2 scope) and the halo is going to be 4 times bigger.

There is no escaping the math. You are going to have some halo even with Astrodon filters if the
distance between filter and sensor is large and/or the focal ratio is fast.

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Sabine Leidinger

Feb 6, 2022

Hi guys, I have almost the same problem but somehow more strange

,... my star halos also appear offset again...

Canon 6D + RedCat51 + Optolong L-Enhance
any ideas why it does the offset thingy?

see here in full resolution:
https://www.astrobin.com/hlzfuf/0/

.... and stretched to hell ;-)