Narrowest 393.37 ever by Apollo Lasky

Frankenscope? Let's see it!***be advised that NOTHING in this forum has been safety tested and you are reading and using these posts at your own peril. blah, blah, blah... dont mess around with your eyesight when it comes to solar astronomy. Use appropriate filtration at all times...
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Re: 393.4 bp0.1 - yes it does exist.

Post by krakatoa1883 » Mon Sep 03, 2018 8:28 pm

Thanks Bob for your update. Agree that Baader K-line filter can be an issue as it suffers from ghosting and this may interfere is some way
ghost.jpg
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Although the single stack with Chroma is not comparable with SS/DS PST and also lacks in definition, in terms of contrast of the bright plages it is not so much different from what I get through my 5A Quark calcium. Considering it is a "simple" filter still under development I would say it is a promising result worth of further "tuning".

@Valery - thanks for your advice, I will consider all options before purchasing anything for converting my Mewlon to Calcium imaging.
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Re: 393.4 bp0.1 - yes it does exist.

Post by TheSkyBurner » Mon Sep 03, 2018 9:13 pm

Mark: I truly am sorry, I have nothing against Valery. He does what he does.

Guys, I have made some very powerful friends with this advancement. So all those that see the positive situation developing here I am greatly appreciative.

I am not here to argue or cause fights with anybody or tell people that they are wrong. I have asked for help repeatedly. I am not shy. THIS IS A PROTOTYPE DEVELOPMENT.

I am not trying to sell anybody anything, I get no commission for sending you to chroma. I paid 3rd party engineers, just like Valery does with his ERF. The difference is Valery is trying to make a living off of this, i am giving the information away for free.

I have developed world wide contacts, and now have the attention of some very famous people and even several universities. They are helping me get this thing turned into an etalon. I am only one person with a hobby, yet look how far I have got.



THIS IS THE FIRST STEP TO BUILDING THE CALCIUM ETALON. PERIOD.


It does not take an education, an engineer or even a complete understanding to build something new. It takes an Idea, it takes a new angle of thinking and it takes a leader. Three of my strongest qualities.


I have some VERY good friends at williams optics. I also own Valery's LAST safix. I will have no problems chopping it apart, laser scanning it, then delivering a complete 3d model to some very anxious engineers waiting for my skybender project to advance even further.


Valery, i am not here to fight with you, I have asked for your help for literally several years now. I have no secrets and nothing to hide.

Here I have attached the WILLIAMS OPTICS SKYBENDER.......... Maybe I will just go ahead and authorize the placement of a reinvented SAFIX inside of it, have it mass produced, and rebranded entirely.....

This elementary school kid knows how to run a lemonade stand, I also know how to hit back.

I also know how to be a friend.
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Re: 393.4 bp0.1 - yes it does exist.

Post by mdwmark » Tue Sep 04, 2018 2:14 am

Hi group,
The point I was trying to show ,was the Hw of a filter can change depending how it is used and how it is designed. The perfect word calculations is the light is parallel to the filter. The transmission is just for references to show how it decreases with F#.
There are at least 5 company's that I know of that can make a hard coated single cavity .1nm HW filter at K-line. But you would need to order quite a few to get the price down to $1250.
One of the main problems you will come across is that one axis may have a wavelength shift from edge to edge. This would be the side that is facing the center of rotation of the holder. It will get increasingly harder to keep uniform as the CA of the filter just goes from 25mm to 38mm.
The idea of using white light solar film will not work,been there try it. The hard coating can take the heat if you are in the F/25-30 range. Then use a ND filter or color glass to cut the transmission down. The KG3or5 in not a bad idea either.
Bob, I was surprised with your results. You think you may have been off band? This filter should be far superior then any of the one you tried. Just being close to the center, it should have good contrast.
Also do you have a way to measure the CW of the filter? To make sure that it is really at 393.4nm.
This interest in K-line surprises me. I have been offering K-line filters for 35+ years and they have never been that common . These are usually 38.1mm and 50mm etalons, so they have a higher cost. But in the 25mm range, these hard coated filters should be the way to go for imaging.
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Re: 393.4 bp0.1 - yes it does exist.

Post by TheSkyBurner » Tue Sep 04, 2018 2:27 am

mdwmark wrote:
Tue Sep 04, 2018 2:14 am
Hi group,
The point I was trying to show ,was the Hw of a filter can change depending how it is used and how it is designed. The perfect word calculations is the light is parallel to the filter. The transmission is just for references to show how it decreases with F#.
There are at least 5 company's that I know of that can make a hard coated single cavity .1nm HW filter at K-line. But you would need to order quite a few to get the price down to $1250.
One of the main problems you will come across is that one axis may have a wavelength shift from edge to edge. This would be the side that is facing the center of rotation of the holder. It will get increasingly harder to keep uniform as the CA of the filter just goes from 25mm to 38mm.
The idea of using white light solar film will not work,been there try it. The hard coating can take the heat if you are in the F/25-30 range. Then use a ND filter or color glass to cut the transmission down. The KG3or5 in not a bad idea either.
Bob, I was surprised with your results. You think you may have been off band? This filter should be far superior then any of the one you tried. Just being close to the center, it should have good contrast.
Also do you have a way to measure the CW of the filter? To make sure that it is really at 393.4nm.
This interest in K-line surprises me. I have been offering K-line filters for 35+ years and they have never been that common . These are usually 38.1mm and 50mm etalons, so they have a higher cost. But in the 25mm range, these hard coated filters should be the way to go for imaging.
Mark W.
My true interest, Is the future of quantum of computing. Great experiments are going to be completed with this filter, calcium ions and 393nm lasers. The sun is just a distraction hobby.

I dont see why you guys think this does not work with astrosolar film, I have already tested it and captured images with it using only a 90mm aperture. I am just waiting for bob to get somewhere, because why do everything and show off everything myself?

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Re: 393.4 bp0.1 - yes it does exist.

Post by TheSkyBurner » Tue Sep 04, 2018 2:45 am

consider the following information, directly from baader planetarium . (note that this says PROTUBERANCES - which are prominences,. impossible with astrofilm right? Yet here it is done and published by baader planetarium.de, using a garbage nikon camera.)

nd3.8, not nd5. Obviously the intensity is not the same as a true ERf system, but to say this will not image using astrofilm3.8 is literally wrong. I will post my images when Bob is done doing his thing.

https://astrosolar.com/de/informationen ... ha/#halpha

"Note from Baader Planetarium: What we have always considered impossible and have always answered in such a way with inquiries to our Narrowband filters, that succeeded in this admission of a customer. His wonderful single shot shows some shadowy protuberances on the edge of the sun - and a plane in the middle. This experiment works photographically, visually the solar disk would fade the protuberances, we have to advise against visual experiments of this kind for eye protection reasons! "

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Re: 393.4 bp0.1 - yes it does exist.

Post by Valery » Tue Sep 04, 2018 3:05 am

mdwmark wrote:
Tue Sep 04, 2018 2:14 am

There are at least 5 company's that I know of that can make a hard coated single cavity .1nm HW filter at K-line. But you would need to order quite a few to get the price down to $1250.


This interest in K-line surprises me. I have been offering K-line filters for 35+ years and they have never been that common. These are usually 38.1mm and 50mm etalons, so they have a higher cost. But in the 25mm range, these hard coated filters should be the way to go for imaging.
I know the sixth which can make a 0,1 - 0,15nm 1" filter much cheaper if a quantity is 100 or more in order.


This interest is as high as Lunt sells his CaK filters. Due to specific details size and their structures CaK starts to be really interesting only at a very high resolution. Minimal diameter of a telescope for such impressive CaK pictures is 150mm which is equal in resolution to a 250mm telescope in Ha. The larger the aperture, the more interesting CaK images become.
However all the major details are well seen on the pictures taken with a single PST filter (paired with K-line Baader) or single Lunt CaK. Double stacking improves the contrast very little, much less than in H-a double stacking. This is because PST and Lunt filters already have very steep sides with effectively supressed skirt.

It was my wrong expectation that at subangstom FWHM we will be able to image new details - filaments and fibrills as well as bushes of spiculaes. As leading pros astronomers explained me, this is not the case with the CaK.
Such a new for Ca details can be imaged only at 8542,1A line and only if the filter will have very steep sides, well supressed parasitic skirt and FWHM will be 0,25A maxumum (much better if 0,15A). I believe these requirements are too strict and even two 0,7A etalons being DS will show almost as much as professional filters. I have a solid factual evidences what kind of filter will be enough for a new view of the sun in a Ca. And this is infrared Ca II I line.

Again, my experiments showed clearly - I can image 95% of CaK details with a cheap PST CaK filter vs DS PST or Lunt CaK filters. Only prominences becomes a bit better seen and spiculaes at the limb.


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Re: 393.4 bp0.1 - yes it does exist.

Post by Valery » Tue Sep 04, 2018 3:57 am

TheSkyBurner wrote:
Tue Sep 04, 2018 2:45 am
consider the following information, directly from baader planetarium . (note that this says PROTUBERANCES - which are prominences,. impossible with astrofilm right? Yet here it is done and published by baader planetarium.de, using a garbage nikon camera.)

nd3.8, not nd5. Obviously the intensity is not the same as a true ERf system, but to say this will not image using astrofilm3.8 is literally wrong. I will post my images when Bob is done doing his thing.

https://astrosolar.com/de/informationen ... ha/#halpha

"Note from Baader Planetarium: What we have always considered impossible and have always answered in such a way with inquiries to our Narrowband filters, that succeeded in this admission of a customer. His wonderful single shot shows some shadowy protuberances on the edge of the sun - and a plane in the middle. This experiment works photographically, visually the solar disk would fade the protuberances, we have to advise against visual experiments of this kind for eye protection reasons! "
From the same page at Baader Planetarium:
"Zur Aufnahmetechnik, das finale Bild besteht aus 2 separaten Belichtungen. Um den extremen Helligkeitsunterschied zu händeln mit zwei unterschiedlichen Belichtungszeiten. Das Bild mit der Oberfläche und dem Flugzeug ist 1/200 sec belichtet (ISO 200), das Bild mit den Protuberanzen 0.3 sec (ISO 200).

Die Bearbeitung habe ich mit Photoshop und Nik-Collektion (plug-in von google für Photoshop) gemacht.

Aufnahmeoptik war das Celestron EHD 11″ mit Reducer (x0.7), Kamera war die Nikon D810a, dazwischen war noch der 3.5nm."

Translates as:
"To capture technique: the final image consists of 2 separate exposures To handle the extreme difference in brightness with two different exposure times The image with the surface and the aircraft is exposed to 1/200 sec (ISO 200), the image with the protuberances 0.3 sec (ISO 200).

The editing I have done with Photoshop and Nik-collection (plug-in from Google for Photoshop).

Recording optics was the Celestron EHD 11 "with Reducer (x0.7), camera was the Nikon D810a, in between was still the 3.5nm."

Peoples, who are willing to work at F/7 and image the protuberances at 0.3sec exposure? Anyone?
Who are willing to downscale your such images in 10x to make them look barely barely acceptable for a quick glance? Anyone?
Who are willing to image the sun chromsphere surface with 0.05nm filter and Astrosolar at F/7 and about 2sec exposure at best and then downsize the image about 10x? Anyone?

Let see how may followers will try to repeat this experience or even go further in to the CaK.


Valery.
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Re: 393.4 bp0.1 - yes it does exist.

Post by Valery » Tue Sep 04, 2018 4:13 am

krakatoa1883 wrote:
Mon Sep 03, 2018 8:28 pm

@Valery - thanks for your advice, I will consider all options before purchasing anything for converting my Mewlon to Calcium imaging.
Even a such one with Astrosolar?

https://astrosolar.com/de/informationen ... ha/#halpha
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Re: 393.4 bp0.1 - yes it does exist.

Post by mdwmark » Tue Sep 04, 2018 6:07 am

My attempts with the nd 3.8 astrosolar film was for visial. I was not trying to image with it. The filter I was using had 75%T and it was to dark for my eyes.
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Re: 393.4 bp0.1 - yes it does exist.

Post by Bob Yoesle » Tue Sep 04, 2018 9:54 am

Hi everyone,

I have a couple of new images from my first run that for some reason didn't process correctly the first time, but had better seeing/resolution. The overall results do not change however:

CT 0.1 nm, exposure 0.100 ms:
CT 0.1.jpg
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PST 0.2 nm, exposure 0.191 ms:
PST 01.jpg
PST 01.jpg (282.06 KiB) Viewed 468 times
There seems to be some weird horizontal lines in the CT image. Not sure the origin of these, but it might be related to the very short exposure near the lower limit of FireCapture's ability to record...?

Unfortunately I can not measure the CWL, all I have is the previous plot supplied by Chroma Tech. Might have to play with the Skybender unit to see if tilting improves performance. The reason I included the Baader K line with the CT is that it seems to work OK with the PST filters, and I wanted to do an "apples to apples" comparison. Next time I will either remove the tilted component as advised earlier, or use the Edmund 400 nm short pass, or possibly nothing at all (all of which might require some additional ND filters to get a longer exposure time.) I will also will try my 2.8 x Klee barlow to get beyond f20 if and when seeing permits...
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Re: 393.4 bp0.1 - yes it does exist.

Post by bart1805 » Tue Sep 04, 2018 10:47 am

Hi Bob, I think I recognize the horizontal links, and think they are indeed caused by the camera in combination with the very short exposure. When you blow up the PST image you seems to see the same pattern.
Gain is zero, gamma neutral?
Would a ND 0.6 or 0.8 or a polariser help to get the exposure longer?
CS! Bart.

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Re: 393.4 bp0.1 - yes it does exist.

Post by krakatoa1883 » Tue Sep 04, 2018 5:11 pm

Valery wrote:
Tue Sep 04, 2018 4:13 am
Even a such one with Astrosolar?

https://astrosolar.com/de/informationen ... ha/#halpha
of course not, at least for H alpha. My calcium H device doesn't show nothing through my Mewlon 210 with full aperture AS 3.8 film, this is the reason I would be very much interested in a filter that could do it. We'll see.
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Re: 393.4 bp0.1 - yes it does exist.

Post by christian viladrich » Tue Sep 04, 2018 6:35 pm

Ok ... I didn't want to jump into this, but it seems there is some misunderstanding about filter transmision and exposure time ;-)

Let's start with the exposure time required for high resolution imaging and a K-Line filter (396 nm, about 8 nm FWHM):

1) With an Hershel diagonal, the exposure time is in the range of 1 ms with the gain of the camera set to the minimum.
Of course, it depends on the sensor, sky transparency, etc. Still 1 ms is a good starting point for the following calculations.

2) If you remember that the transmission of the Hershel diagonal is about 4%, or 1/25, then it is straigtforward to calculate the exposure time with a density filter.

3) Density 3.8, means transmisson = 1/6300. So, if we use an Astrosolar d 3.8 instead of the Hershel diagonal with the K-line, the exposure time will be in the range of 1 ms x 6300 / 25 = 250 ms = 1/4 s.
This is way too long for HR imaging.
Of course, the gain of the camera can be increased to reduce exposure time, but this would reduce the S/N, and no good at all for HR imaging.

4 ) Intermediate conclusion : K-line filter is only for Hershel diagonal (or non aluminized telescope), not for Astrosolar 3.8.

5 ) Now, let's assume we are using a 396 nm / 0.1 nm FWHM filter (and a d= 3.8 Astrosolar) instead of a 396 nm/8 nm . Let's assume the peak transmission of both filters is about the same. The exposure time with the 0.1 FWHM will be about x 80 exposure time of the 8 nm filter, i.e. 1/4 x 80 = 20 s ...

6) If the peak transmission of the 0.1 nm filter is 100% while the peak transmission of the K-line is only 50%, then the exposure time with the 0.1 nm filter is 10 s (with the Astrosolar 3.8) ...

In a nutshell :
- if the target is HR imaging, K-line filter is only with Hershel diagonal or non aluminized Newtonian ;
- still, it is possible to take some K-line images with Astrosolar 3.8 (with long exposure time, high gain, short focal length), but no HR images ;
- going from K-line to Ca K (please remember the K-line filter is not a Ca K filter) still increases the exposure time. This is pratical only with the use of Hershel diagonal, or better with no Hershel at all. In the later case, the heat load should be handle properly, which is an achievement by itself for aperture > 100 mm...
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Re: 393.4 bp0.1 - yes it does exist.

Post by TheSkyBurner » Tue Sep 04, 2018 7:51 pm

The horizontal lines are from the intensity of the light hitting your camera sensor, the sensor is over loaded and it is something i have worked around for 3 years now. Thus the new learning curve for you. The same will happen with your halpha filter and no blocking filter.

Are you guys realizing how difficult this is yet? Just telling someone to coat a filter based on your "textbook" specifications is not going to change the operation of a 90% transmission system with od4 blocking.

Do you guys even know what a stop line notch filter is?

I have stacked filter combinations for 6 years, i dont need a piece of paper, math equation,or text book to show you how adding additional filters works to introduce constructive/destructive interference on the primary coating.

1: the chroma filter works via coating interference, It is not a standard bandpass filter that operates through several glass layers for absorption.
2: the coronado filter and lunt filters are not the same. The lunt filter is two filters cemented together for a very specific reason, interference combined with absorption. The coronado filter, purely reflection. Thats why it has the nice blue/purple coating.
3: the chroma hard coated filter is 100% different than the lunt and coronado filters. Totally different, new to everyone. New operating parameters.


I can hand off the torch at my choosing, or leave you all in the dust. I put this in the "modifications" section for a very good reason. To see what you are capable of.

This is entirely about your guys ability to collaborate with each other and function as a team,. Team work is 100% vital to astronomy. This is the one instance where all your math and text books is not going to give you the answer.
You must develop a New way of operation.

Hi Andy, I hope you are reading this and having fun :D


I am working extra hours to pay for a website host, I will put a guide at www.393nm.com

I will stay away from here, due to all the bad mojo. Remember, I am not a vendor.

You will figure it out eventually bob, I am confident.




I will continue to lurk around, but my participation is now just; Overwatch.


(oh hey, i have a supplier for 1.25" 393nm correction lens's with stop line rejector coating just like the pst filters, look at that! How in the world!?)


393nm rejection coating corrector.jpg
393nm rejection coating corrector.jpg (149.73 KiB) Viewed 399 times
393 corrector tint 1.jpg
393 corrector tint 1.jpg (159.26 KiB) Viewed 399 times
393 corrector tint 2.jpg
393 corrector tint 2.jpg (145.02 KiB) Viewed 399 times
393nm corrector lens focal length.jpg
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lemonade anyone?
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Re: 393.4 bp0.1 - yes it does exist.

Post by bart1805 » Tue Sep 04, 2018 8:09 pm

Hi Christian,
Baader sells their K-line with the ND 3.8 Astrosolar. Am I correct that you conclude that with this combination one is not able to obtain HR images?
And if you talk about a wedge, it is without the (almost standard) ND 3.0 I suppose. Correct?
Thanks, Bart.

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Re: 393.4 bp0.1 - yes it does exist.

Post by mdwmark » Wed Sep 05, 2018 8:30 am

Hi Bob,
the only reason I can think of why the .1nm filters has a lower contrast then the PST is that it is not fully blocked. Or it is not on band. There may be a leak in the long side blocking. It is not uncommon to have a blue/green leak that would drop the contrast of the image. Are you using a KG filter to block the IR? The camera could be seeing some IR if you don't.
Mark W.

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Re: 393.4 bp0.1 - yes it does exist.

Post by TheSkyBurner » Wed Sep 05, 2018 1:23 pm

Good

You are not going to get it without the skybender tilting the chroma filter. It was specifically designed to implent there, so yes mark has told you its offband for several days now. Problem 1 established. Problem 2 blocking.

Keep working together. You either continue to help each other, or whats the point?

There are people that want something new and great, with the intention of not sharing it. This is not a house with four walls of privacy so nobody can see what you are hiding, this is public science and learning. It is not a secret business plan to make money.

It is entirely about hitting the K3 center, together. The daystar filter is 5 angstroms, so dont convince yourself it is impossible.

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Re: 393.4 bp0.1 - yes it does exist.

Post by Bob Yoesle » Wed Sep 05, 2018 1:24 pm

Hi Mark,

I used a Baader Blue CCD filter, followed by a KG3, and then the Baader K line as ERF and blocking filters prior to the CT and PST filters. I will next attempt some tests with tilting the CT, and at f25 using a UO Klee barlow if/when my seeing allows. I likely will remove the Baader K line for the remainder of CT filter evaluations, as Dick at Chroma said it would be unnecessary, and I only used it so the comparison with the PST filters was identical - hopefully will get rid of the reflection issue(s).

BTW - Chroma did say they could make a 2 cavity filter @ 0.1 nm, but 3 or more cavities would not be possible for them at such a narrow band pass. This leaves me to wonder what the "magic" is for the Coronado and Lunt filters - wish we had some transmission profiles for those filters...
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Re: 393.4 bp0.1 - yes it does exist.

Post by christian viladrich » Wed Sep 05, 2018 6:42 pm

To Bart :
- Yes, the Hershel wedge is used without any density filter.
- Regarding Baader Planetarium policy, my guess - and this is just a guess - is that they don't want to take any risks. It is impossible for them to know whom they are selling the filters to. Beginners or experienced amateurs looks the same ;-)

You can check at my solar page the exposure time I used for a variety of filter and instrument combinations :
http://astrosurf.com/viladrich/astro/soleil/soleil.html
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Re: 393.4 bp0.1 - yes it does exist.

Post by christian viladrich » Wed Sep 05, 2018 6:47 pm

To Mark and Bob,
The K-line is a marvellous filter to block any leakage outside a 10 nm band arround 396 nm, from 300 nm to 1700 nm.
So the issue should be related to the CWL.
F/25 and some tilt might set the case.
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Re: 393.4 bp0.1 - yes it does exist.

Post by marktownley » Sat Sep 08, 2018 8:17 am

mdwmark wrote:
Fri Aug 31, 2018 4:28 am
What is all this about .1nm or .14nm at K-line. They will both give a great image. With the amount of T ,you will probably need some color glass or an ND filter to drop the transmission down or the exposure will be to fast for the camera.
I ask Bob to check if the spacers where high or low index. So I did a little design for a .1nm single cavity filter.
The design with the high index(2) came out at .09nm in the perfect world(100%). At F/30 it drop to .1nm and the T was 90%, at F/20 the Hw went to .15nm and 78%, then at F/15 it was .27nm and 52%T.
So I flip the design and made the spacer a low index(1.5). The same number of layers gave a .07nm perfect world (100%), at F/30 it drop to .1nm and 68%,at F/20 it was .24nm and 41%T,at F/15 it was .35nm and 25%T.
So either way if you keep this filter near F/30 it will be a killer filter at K-line
If your worried about IR blocking , just add some KG5. That will cut the IR after the 1200nm.
This is the same problem with fast F# you will have with any brand that is a single cavity filter.
Mark W.
Hi Mark,

Given this is a high index filter what does the transmission and bandwidth work out used in a F/10 and F/7 system? I know it is going to be wider bandwidth and lower transmission, just wondering what the numbers actually are?

Thanks

Mark
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Re: 393.4 bp0.1 - yes it does exist.

Post by TheSkyBurner » Sun Sep 09, 2018 2:36 am

Well for what it is worth at this point, I am using a chroma 402etx15 precisely tilted as my single ERF. i am getting awesome results. I may not have the 8000$ SCT telescope to show you a high resolution image, but I can give you some insane prominence images from my $25.00 standard meade 90mm x 800mm achromat with a plastic focuser. (it does have a kg3 filter mounted on the last baffle)

in fact I am getting such great performance with my chroma filter that I am willing to trade both of my pst cak filters to bob for his chroma filter because transmission is king and the coronado filter is only 15% max. They are at this point, antiques. I know exactly where to order them, and which manufacturer supplied them. Nothing special.

it does not matter that this is a single cavity filter. The calcium line is so wide that you just need to hit the actual K3 center to see the difference in contrast. You are either on band, or not.

Two precisely tilted interference reflective bandpass filters = fabry perot etalon.

chroma et402.15x.JPG
chroma et402.15x.JPG (97.3 KiB) Viewed 191 times
chroma et402.15x.jpg
chroma et402.15x.jpg (192.58 KiB) Viewed 194 times

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Re: 393.4 bp0.1 - yes it does exist.

Post by TheSkyBurner » Sun Sep 09, 2018 3:35 am

and for anybody interested , here is stephen ramsdens own pdf with information regarding the width and off band wings.

thanks stephen!
http://www.solarastronomy.org/SolarAtmosphere.pdf

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Re: 393.4 bp0.1 - yes it does exist.

Post by marktownley » Sun Sep 09, 2018 5:52 am

Would love to see the results you are getting. I'm using a tilted 387/10 filter in my CaK system.
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Re: 393.4 bp0.1 - yes it does exist.

Post by Merlin66 » Sun Sep 09, 2018 7:04 am

Guys,
You are confirming my thoughts and experience with filters and etalons.....
You really need to have a spectrograph to allow accurate measurement of CWL and transmission curves.
I can test any filter/ filter combo with a resolution (as measured) <0.02A across the whole solar spectrum (370-8000A), unfortunately I'm in Australia which makes things a bit more difficult.
Building a capable spectrograph is well within the "average" amateur's DIY capability.
Think about it.
"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
"Imaging Sunlight - using a digital spectroheliograph" - Springer

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