KG3 IR Absorption vs IR Blocking filters? Same?

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Re: KG3 IR Absorption vs IR Blocking filters? Same?

Post by MalVeauX » Sat May 26, 2018 3:14 pm

Hrm, if that filter works (Baader 2458475B) as an ERF (blocking IR, and other wavelengths, but keeping UV), then further narrowing it with my 395nm filter, I could then use the two 393nm filters to further narrow it down maybe. The thing I have to figure out is just how to manage the heat from a 120mm aperture with this.

I look forwarding seeing how the baader blue filter works as an ERF. If it does, I'll have to consider it. If I can get away from using IR only blocking/absorbing filters, like the KG series, that would be good. I just need to be able to use it on large apertures. Even if I had to do the blue then an additional IR blocker/reflector, then the 395nm, then the 393nm, that would be fine.

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Re: KG3 IR Absorption vs IR Blocking filters? Same?

Post by TheSkyBurner » Sat May 26, 2018 5:13 pm

If the transmission graph is honest, then the b-ccd filter blocks everything below 380nm. It does not specify optical density however so it could be od1 which is very weak. It also does not specify focal length so it could mean anything really. It is also intended for night time astrophotography so the intensity of ir/uv glare at night is totally different.

I ordered a second one from agena , a 1.25”.so now they are sold out. I am going to do a burn test on this thing to figure out once and for all if baader planetarium is telling the truth and how deep this heat blocking goes. If it burns a sheet of paper or brown leaf or black plastic on an f5 scope. Then it is totally weaksauce. If 2 filters burn a sheet of paper at f/5. Then it is not a good filter coating and something else entirely would have to be used with it like a circular polarizer to have manual control over the intensity.


I already know for a fact that the beloptik filter burns paper at f5 and so does the b&w filter, and also a lumicon ir block filter. I havent tried any ir/uv combos with color filters but that is on the list of things to do now because it is important

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Re: KG3 IR Absorption vs IR Blocking filters? Same?

Post by TheSkyBurner » Sat May 26, 2018 5:13 pm

They daystar website recommends using astrofilm or neutral density filters on scopes 120mm and above. So they obviously know ir/uv is also a problem at kline. Lunt specifies not to use their filter on anything above 100mm. So there is a clear damage threshhold that needs to be over come, and currently not a single company sells a prefab kline erf without a custom special order. So although you want a lunt or daystar filter to replace what you have it seems like you might still damage their primary filter.

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Re: KG3 IR Absorption vs IR Blocking filters? Same?

Post by MalVeauX » Sat May 26, 2018 6:03 pm

The Quark manual (updated) states it can go up to 150mm with just the Quark Calcium & a UV/IR cut filter.

Lunt limited to 100mm makes sense, but over 100mm, an ERF could be employed (Aires?).

I'm very interested to see how a Baader Blue CCD filter -> UV/IR block -> paper burn goes.

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Re: KG3 IR Absorption vs IR Blocking filters? Same?

Post by TheSkyBurner » Sat May 26, 2018 7:37 pm

Im wondering if the light is reflected back out the front of the refractor if it will cause a double image or haze interference against the back element that lowers overall contrast .

http://www.daystarfilters.com/calcium.shtml

"DayStar recommends use of IDAS Brand UV/IR filters in rear-mounted configuration on refractors only. The IDAS Brand UV/IR cut filter has been tested to pass 3933Å light, but reflects UV and IR light back out the front of the telescope unfocused. This application is called a "hot mirror". The UV/IR cut filter must be installed before the FIRST SURFACE which encounters concentrated light such as the diagonal or barlow; whichever comes first. This application cannot be used in SCT application, as the OTA and secondary will gain heat and possibly cause failure of the adhesive of the secondary mirror."
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Re: KG3 IR Absorption vs IR Blocking filters? Same?

Post by MalVeauX » Sat May 26, 2018 9:11 pm

Hrm,

I doubt the reflected heat is an issue. This is done with internal ERF's in some systems, and the Quark Chromosphere does it too, it reflects the heat back out. I don't get haze or anything in my Quark and I use the UV/IR cut filter. Other people using whatever etalon and internal ERF's are also reflecting heat back out.

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Re: KG3 IR Absorption vs IR Blocking filters? Same?

Post by christian viladrich » Sun May 27, 2018 8:27 pm

I might be a little bit off topic, but as an information, I use a 50 mm Blue Astronomik filter placed 220 mm ahead of the focus for Ca K imaging with my TOA 150.
The filter is slighlty tilted to avoid reflections.
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Re: KG3 IR Absorption vs IR Blocking filters? Same?

Post by TheSkyBurner » Sun May 27, 2018 11:37 pm

These SChneider Kreutznach 010 filters UV absorption filters maybe required on 150mm + aperture telescopes using sub aperture blue filters.

https://www.ebay.com/itm/B-W-105-mm-UV- ... 0916286072

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Re: KG3 IR Absorption vs IR Blocking filters? Same?

Post by TheSkyBurner » Sun May 27, 2018 11:38 pm

Christian, you dont use a UV absorption filter before the astronomic or after? This filter Seems to have very high transmission below 390nm

Reexamining the options at astronomik not sure which blue filter you are using but both seem to transmit very high wavelegnths below 390nm
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Last edited by TheSkyBurner on Mon May 28, 2018 2:18 am, edited 2 times in total.

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Re: KG3 IR Absorption vs IR Blocking filters? Same?

Post by TheSkyBurner » Mon May 28, 2018 2:19 am

looks like the astronomik L1 or L2 filter seem rather great additions to the Blue filters, It is ashame we cannot mail the blue filters somewhere to have them reflective coated for blocking UV up to exactly 387nm with Zero affect on transmission at 393nm. That would be the perfect primary calcium ERF. Especially if it were produced in 200mm diameters!


http://www.astronomik.com/en/uv-und-ir- ... h-m48.html

L1
Image

L2
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Re: KG3 IR Absorption vs IR Blocking filters? Same?

Post by TheSkyBurner » Mon May 28, 2018 2:49 am

if it wasnt for the price and small size, this semrock filter would be the perfect secondary ERF to compliment the blue filter. Would not even need IR UV cut filters before the blue filter.

https://www.semrock.com/FilterDetails.a ... -400/12-25

In all expectations currently, to make a "perfect" K-line erf its going to cost quite a bit to build piece by piece in the end. Probably entirely worth it however similar to the full size halpha erf. Somebody just needs to get on full board with the full size erf mass production. It would be great to have a large aperture dedicated blue light imaging telescope on the market that was diffraction limited below 400nm.

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Re: KG3 IR Absorption vs IR Blocking filters? Same?

Post by TheSkyBurner » Mon May 28, 2018 8:38 pm

So it looks like All IR/UV cut filters are not gonna do anything to protect your filters. Im getting fire out of a stack of 5!

Kinda wish I had the baader planetarium IR/UV cut filter to test, If that one burns its nail in the coffin for any protection.

But im not gonna waste my money, i am confident that its gonna start a fire too.

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Re: KG3 IR Absorption vs IR Blocking filters? Same?

Post by TheSkyBurner » Mon May 28, 2018 8:58 pm

Everything we have been told is a flat out lie.

This is a Single beloptik 2" IR.UV KG3 filter mounted in the nose of a focuser and a 1.25" Baader planetarium G-ccd filter mounted in the nose of a 2" extension.

Totally bogus protection.


G-ccd filter beloptik kg3 FAIL.GIF
G-ccd filter beloptik kg3 FAIL.GIF (6.51 MiB) Viewed 978 times
1.25 baader planetarium g-ccd.jpg
1.25 baader planetarium g-ccd.jpg (182.53 KiB) Viewed 978 times
1.25 baader planetarium g-ccd 2.jpg
1.25 baader planetarium g-ccd 2.jpg (204.41 KiB) Viewed 978 times

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Re: KG3 IR Absorption vs IR Blocking filters? Same?

Post by Merlin66 » Mon May 28, 2018 9:59 pm

What aperture and focal length scope did you use????
"Astronomical Spectroscopy - The Final Frontier" - to boldly go where few amateurs have gone before
https://groups.yahoo.com/neo/groups/ast ... scopy/info
"Astronomical Spectroscopy for Amateurs" and
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Re: KG3 IR Absorption vs IR Blocking filters? Same?

Post by TheSkyBurner » Mon May 28, 2018 10:14 pm

Merlin66 wrote:
Mon May 28, 2018 9:59 pm
What aperture and focal length scope did you use????
120mm objective 1000mm focal length. F8.3 An aperture increase larger than 120mm @f8.3 will greatly increase the burning power, using a faster scope will exponentially increase the burning as well (focal reducers).

So from my perspective, if you are not behind a negative image plane with an Optical density level 5 blocked filter you are going to always damage your filters.

This may explain the ITF failure people are having with blocking filters.

I think narrow band metal oxide filters are the only true form of protection.

I would like to test an objective mounted h-alpha etalon with and without its erf but i do not own one currently.

(obviously at f30 the heat intensity is dramatically lowered)

the lunt calcium systems are meant to operate way below that and so is the CaH quark; that being said there is going to be a problem somewhere down the road with those systems.

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Re: KG3 IR Absorption vs IR Blocking filters? Same?

Post by TheSkyBurner » Tue May 29, 2018 7:52 pm

Here is an OD6 full spectrum blocking filter up to 1200nm at the cost of $405. https://www.semrock.com/filterdetails.a ... -403/95-25
full spectrum blocking.jpg
full spectrum blocking.jpg (84.93 KiB) Viewed 948 times
This full spectrum blocking filter will outperform the baader planetarium / ir uv cut series all the way up to 1280nm, and because you need mutiple baader planetarium filters and IR/UV cut filters on your calcium system to get "total blocking"; then the $405 price tag for this one full spectrum blocking filter is not an issue considering the additional costs needed for the b-ccd to become "heat less" My tests confirm that 4 IR/UV cut filters anywhere in the optical train does nothing for heat blocking. You will always need at least two baader planetarium b-ccd filters to lower the heat level below "burning capability". The heat increases over time as well so a long term exposure is just going to add more heat until maximum thermal loading is reached.

Still need to find a filter that offers od level4 blocking for 1250-1500nm to totally void any heat issues. This 400/12 blocks OD level2 up to 1400 so that is a good start but combined with the full spectrum blocking filter you are looking at $800 which is awful.
https://www.semrock.com/FilterDetails.a ... -400/12-25

The only solution so far is to have a REAL heat blocking filter custom engineered, and this WOULD be possible for large apertures since it wont be anything narrowband. A multi wavelength single coated heat/ultraviolet blocking solar filter that transmits all visible light

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Re: KG3 IR Absorption vs IR Blocking filters? Same?

Post by MalVeauX » Wed May 30, 2018 1:13 am

Interesting,

As soon as the spin off storm from tropical storm Alberto rolls away from me, I'll test some things. When I have my 395nm filters and the two 393nm filters in line, I don't even get a light path on my hand behind it, it blocks so much. I don't even feel heat. But that KG3 before them sure did and cracked.

With my Baader UV/IR cut filter inline with my 120 F8.3, there's warmth in the light path, but it doesn't burn my hand. At least, not a few inches away for a few seconds. Maybe right on it, it will melt stuff. With nothing in the way, I've totally melted plastic caps and started some foam to smoke before...

It probably helps with heat, just enough to not melt the metal/glass/sensor. We're testing the heat on paper, leaves, plastic, etc. Things that will have a higher combustion point as it is. So maybe they're meant to take high temps and this gets it just low enough to not melt.

I'm curious how the blue blocking filter will handle things.

Soon as I get a clear day, I'll test some heat blocking. Wish I had a way to read it with an IR heat sensor or something...

Anything in the $500+ arena, I wouldn't consider, as at that point you can get a Lunt modul, or a smaller ERF made.

Very best,
Last edited by MalVeauX on Wed May 30, 2018 1:38 am, edited 1 time in total.

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Re: KG3 IR Absorption vs IR Blocking filters? Same?

Post by TheSkyBurner » Wed May 30, 2018 1:23 am

The probablem with angstrom imaging is that the wavelengh drifts with thermal loading, so the hotter the filter gets the more off band it goes.

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Re: KG3 IR Absorption vs IR Blocking filters? Same?

Post by Merlin66 » Wed May 30, 2018 1:30 am

Guys,
If you search the forum for "ERF temperature" you'll find some interesting data.....
viewtopic.php?f=9&t=5719&hilit=erf+temperature
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Re: KG3 IR Absorption vs IR Blocking filters? Same?

Post by TheSkyBurner » Wed May 30, 2018 1:31 am

The quark and daystar products are prime examples of using thermal drift to change and tune your filter on and off band with a heating element

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Re: KG3 IR Absorption vs IR Blocking filters? Same?

Post by MalVeauX » Wed May 30, 2018 1:52 am

Very interesting that red + UV/IR block filter. Especially considering the cost of a Lunt blocking or Coronado blocking filter of good diameter size.

Problem with UV/IR with near UV imaging is the UV kills the imaging. My badder UV/IR filter totally killed my ability to see anything when I put it inline with my Skybender loaded with 395nm pass and two 393nm pass filters. Was a grey wall. Pulled out the uv/ir filter and suddenly a disc was there.

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Re: KG3 IR Absorption vs IR Blocking filters? Same?

Post by christian viladrich » Wed May 30, 2018 7:32 pm

FYI, the Astronomik Blue filter cuts wavelength below about 370-390 nm. I'll try to post the curve this WE. This is a quite good ERF filter for Ca K.
Another good ERF for CaK, is the EO 390 nm filter FWHM 40 nm, but it is very expensive.
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Re: KG3 IR Absorption vs IR Blocking filters? Same?

Post by christian viladrich » Wed May 30, 2018 7:39 pm

An image is better than a thousand words ;-)
Here is an example of CaK image taken with the TOA 150 and B Astronomik (internal ERF in front of the FFC), K-line filtre (as additional filter after the FFC) and a Ca K filter :
Image
The K-line filter temperature rises to 35-40°C which is quite reasonable.
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Re: KG3 IR Absorption vs IR Blocking filters? Same?

Post by TheSkyBurner » Wed May 30, 2018 10:36 pm

40c is "cold" so that is fantastic, but i notice you have the FFC which makes your K-line filter behind a negative image plane. Infront of it is a different story temperature wise.

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Re: KG3 IR Absorption vs IR Blocking filters? Same?

Post by christian viladrich » Thu May 31, 2018 6:35 pm

Yes indeed. You have to think carrefully about where to position of the various filters.
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