Antlia 1.25" Herschel wedge with 3nm CaK filter

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Antlia 1.25" Herschel wedge with 3nm CaK filter

Post by Merlin66 »

Interesting combo of a wedge plus a 3nm CaK filter.
http://www.antliafilter.com/pd.jsp?id=106


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Re: Antlia 1.25" Herschel wedge with 3nm CaK filter

Post by Montana »

I think Tariq has just bought this, will have to wait and see what he thinks of it.

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Re: Antlia 1.25" Herschel wedge with 3nm CaK filter

Post by christian viladrich »

Well ... well ... It is amazing a manufacturer does not know the difference between a near-UV filter and a Ca K filter. The Antlia filter is just a near-UV filter showing the photosphere, just like Baader K-line, or my Andover 396-5 nm.

The bandpass of a Ca K (of Ca H) filter is less than about 0.4 nm (FWHM). This is what is needed to show the lower parts of the chromosphere.

This beeing said, this is good news to have such a filter. It is an alternative to Baader K-line. Antlia did not provide transmission data beyond 1000 nm, while Baader does. IR blockage can make a difference for solar observation.

More important, there is a very weird feature, they install a diaphragm (i.e. a variable aperture stop) in the diagonal to control the brightness :
Image

Needless to say that such thing is equivalent to stopping down to the diameter of the telescope, and reducing the resolution of the scope accordingly. A very strange idea ...

On top of that, this variable aperture stop is balck, and placed in front of the diagonal, exposed to the full heat load. Another very strange choice ...


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Re: Antlia 1.25" Herschel wedge with 3nm CaK filter

Post by EGRAY_OBSERVATORY »

I did think something strange about the specifications for this particular item, so hopefully Tariq, will be able to prove its' worth with some interesting results.

Could also be a leader in this particular scenario of design... :?:

Might even be interested in getting one for the mini-obsy..

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Re: Antlia 1.25" Herschel wedge with 3nm CaK filter

Post by george9 »

Yes, it is a little odd. Perhaps could be used as the front end to a salvaged CaK PST yellow #1 filter.

I agree it shouldn't say "CaK."

The good news is they warn in bold, "Never look into the sun with the K-Line filter alone, although you don’t perceive it, there is a lot of harmful UV radiation entering your eye." But the description still has confusing sentences like these: "Never use the Solar wedge without the supplied narrowband filter. Otherwise irreparable eye damage can result." Seems to imply visual use is possible with the narrowband filter. It's probably left over from its use with an ND3 filter.

I figure the transmission is around ND3.3: ND1.3 for the Herschel wedge and ND2 for the near-UV filter (3nm/300nm, using the visible spectrum as a reference). Well short of the recommended ND4.5+.

George
Last edited by george9 on Mon Jan 31, 2022 4:38 pm, edited 1 time in total.


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Re: Antlia 1.25" Herschel wedge with 3nm CaK filter

Post by EGRAY_OBSERVATORY »

Thanks George for that added/important information as:-
"Never look into the sun with the K-Line filter alone, although you don’t perceive it, there is a lot of harmful UV radiation entering your eye."

So for Tariq :-

"NEVER LOOK INTO THE SUN WITH THE K-LINE FILTER ALONE, ALTHOUGH YOU DON'T PERCEIVE IT, THERE IS A LOT OF HARMFUL UV RADIATION ENTERING YOUR EYE"... xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

I am still suffering from an eye-problem (nothing to do with viewing the Sun at all), but for two-weeks at the end of last year, was wrongly diagnosed by the Eye Clinic and could have well caused me permanent blindness. The severe headache around that eye a week later then had me attend A&E who could clearly see a more serious problem than "Eye-Strain" and told the Eye-Clinic to see me immediately.
The 8-week course of treatment is working, but blurs the vision during that course...

We responsible Solar-viewers must always adhere to the safe methods available, as unrepairable eye-damage can result...

So always, with great-care must any instructions be clearly printed for the user of any Solar Optical Instrument...

Terry


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Re: Antlia 1.25" Herschel wedge with 3nm CaK filter

Post by TareqPhoto »

Hi all,

Sorry for very late response, as i didn't check out the topics here and just i saw it now, i was so busy since last month and the weather is always changing between super clear to hazy to cloudy and morning/afternoon time i am either sleeping or busy, but i hope i can have time now at least before it is too late and becoming too hot to test mine, i kept thinking about my DSO gear and also about buying Ha solar unit so i forgot about my Antlia.

I don't know which Tariq you are talking about, if me then i will try to do quick tests if i can, i still not sure when and which scope but basically i decided to use my ST80 first, and not sure which camera yet, either ASI174MM or ASI1600MM or my new APS-C sensor the mono, the other mono i have are QHY294M and ASI290MM.


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Re: Antlia 1.25" Herschel wedge with 3nm CaK filter

Post by EGRAY_OBSERVATORY »

Tareq was the correct spelling in my reply

Terry


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Re: Antlia 1.25" Herschel wedge with 3nm CaK filter

Post by TareqPhoto »

EGRAY_OBSERVATORY wrote: Sun Feb 27, 2022 6:13 pm Tareq was the correct spelling in my reply

Terry
It is ok, both can be used, i even saw some write Tarek or Tarik as well, as long you can pronounce it verbally, the last letter is difficult to pronounce for non Arabic people, but i have to assume that ...... I AM THE ONLY "TAREQ" HERE :D :lol:


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Re: Antlia 1.25" Herschel wedge with 3nm CaK filter

Post by TareqPhoto »

I am imaging now with this Antlia, but it is very very difficult, i can't see the view on my computer laptop screen due to the sun backlight or even front light, didn't use any kind of shrouds or protections or boxes, so the focus is like impossible for me to check, i tried the best focus i can but i doubt it is in focus, or maybe the seeing isn't good.

I can see two very clear black spots, but i can't see that filament at sharp details at all, i don't know if stacking will make it clear or sharp later we will see.

Tareq


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Re: Antlia 1.25" Herschel wedge with 3nm CaK filter

Post by EGRAY_OBSERVATORY »

Best to just take some images of what you can see (as the two dark large spots) and process the images in-doors (under cover) and post them here or on the SolarChat page for any of us to comment.

If good or better then keep the focus for the next session..

A Hershel Wedge will not likely show any filaments, as filaments are material leaving the disk and shown in Ha at different temperatures.

Refer to SDO etc., for a better idea of what lines of light show different parts of what each of the different parts of the Sun can be seen with different optics... Much information from both SOLARCHAT-archives and the Internet will tell you more...

Terry


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Re: Antlia 1.25" Herschel wedge with 3nm CaK filter

Post by TareqPhoto »

EGRAY_OBSERVATORY wrote: Mon Feb 28, 2022 11:27 am Best to just take some images of what you can see (as the two dark large spots) and process the images in-doors (under cover) and post them here or on the SolarChat page for any of us to comment.

If good or better then keep the focus for the next session..

A Hershel Wedge will not likely show any filaments, as filaments are material leaving the disk and shown in Ha at different temperatures.

Refer to SDO etc., for a better idea of what lines of light show different parts of what each of the different parts of the Sun can be seen with different optics... Much information from both SOLARCHAT-archives and the Internet will tell you more...

Terry
Will post soon, thank you Terry

Tareq


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Re: Antlia 1.25" Herschel wedge with 3nm CaK filter

Post by TareqPhoto »

Here is my first test ever in this link below

viewtopic.php?f=4&t=35034


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