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"Baader" Solar Filter from China

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#1 ~RA~

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Posted 11 August 2021 - 04:12 PM

So I ordered one of these this morning:

 

https://www.ebay.com...ar=425818849942

 

At the price, I'm thinking if the frame/cell is of decent quality, it's worth it just for that, and if need be I can get some known and reputable film myself to replace what's there. But while I'm waiting weeks for delivery, I wanted to ping the forum and see if anyone else has ordered similar products from eBay (there's a ton) and what your experience has been. Has it been as advertised? Have you found it to be safe to use?

 

Along those lines, how would someone without access to expensive optical instrumentation test the safety of the film, assuming it arrives intact and passes the pinhole test? Obviously UV and IR are the primary concerns, but presumably overall light transmission could be out of spec as well. I'm planning to use it on a 90mm refractor, but may eventually move to something bigger.

 

I'm pretty sensible about eyeball safety, so I'm hoping to forestall the "Why would you risk it?" line of response. As I say, I know I can get replacement film from credible sources, but for now I'm just curious about others' experience with these products, and what precautions and tests could be undertaken for quality assurance.

 

Thanks!



#2 ~RA~

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Posted 28 August 2021 - 02:57 PM

Bump?



#3 MalVeauX

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Posted 28 August 2021 - 03:04 PM

Heya,

 

Hard to say. It says its Baader. But it's also very affordable. Big question mark. Unfortunately, I don't really use these kinds of things for this very reason if visual application is at all a part of it. For visual, I'm pretty strict on what I will use and even then I still question it. Galileo went blind from solar observing with his refractor through clouds and fog.

 

Very best,


Edited by MalVeauX, 28 August 2021 - 03:05 PM.

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#4 Dobs O Fun

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Posted 28 August 2021 - 03:57 PM

Here's what struck me as weird...this comment in the description as if the seller doesn't know what this does:

_______________
Item description from the seller
Directly face the sun to check whether the Bard film has light leakage, and it is strictly prohibited to use it. ...
_______________

Either way I am not yet into solar but your eyesight is nothing to mess with. There maybe a way to check the film before using. Perhaps someone more experienced can tell you more.

If it were me then no. I would buy from a reputable dealer.
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#5 briansalomon1

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Posted 28 August 2021 - 07:08 PM

Several years ago I worked with a US manufacturer of satellite antennas certifying the accuracy of the RF instrumentation they were using to test their antennas, amplifiers, filters etc...

 

One of the antenna components (primary sensor) this manufacturer was using was sourced from China and the Chinese certified every one was tested before shipment and that all met specification.

 

About 50% of these components routinely failed the same test when measured here in the US.

 

It's true Chinese products are priced very low compared to other countries but in China it seems that lying about a product is simply "good business" as long as they keep selling.

 

I think your idea to use the bracket and replace the critical foil is spot-on.


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#6 ~RA~

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Posted 29 August 2021 - 03:19 PM

The tracking on the package is showing as in my state, so odds are good it'll be in my hands sometime this week.

 

I've made solar film filters before, so I'm not a stranger to them. I've improvised cells/housings for a DSLR filter, 70mm binoculars, 60mm and 90mm telescopes, using Thousand Oaks film. I've been happy with the results, and feel good about the safety, but I want to try the more color-neutral Baader film, and I like the looks of the cell on the product I purchased. We'll see.

 

As for taking risks, I'm willing to explore a little and do some sensible investigating. In the present case, I can afford to "take a chance" on the purchase without having to put my eyesight at risk. Asking for group anecdotal experience is helpful, assuming replies are forthcoming, but a safe DIY empirical approach would be best.

 

I'm grateful for all the input so far. I'm still hoping that other members have direct experience with these products from eBay (again, there's a ton, and they do seem to sell). Better yet, I'm hoping for guidance on affordable UV / IR detection methods. I can do more research along those lines, but asking here is a first step in that process.

 

In any case, I've expected all along that I am likely to end up buying the Baader film from a known reputable dealer, in the absence of solid data on the existing. Assuming the cell is solid, I'll still wind up with a good value.

 

On a related note, how many of you regularly insert a UV / IR cut filter in your optical train for visual as a supplemental safeguard behind the objective film? I've seen it recommended, and it makes good sense, but it's not a practice I've adopted yet. Thoughts?


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#7 MalVeauX

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Posted 29 August 2021 - 03:33 PM

 Better yet, I'm hoping for guidance on affordable UV / IR detection methods. I can do more research along those lines, but asking here is a first step in that process.

 

On a related note, how many of you regularly insert a UV / IR cut filter in your optical train for visual as a supplemental safeguard behind the objective film? I've seen it recommended, and it makes good sense, but it's not a practice I've adopted yet. Thoughts?

When in doubt, best practice would be to put a UV/IR block filter in line. As you mentioned people do this even with known filters as just extra precaution. If you want to really cut it out, you use something with KG3 substrate to get the long IR too. Best would be a BelOptik UV/IR for that reason. The film filter is to grind the intensity down to 5% or less and then you can filter the harmful UV/IR wavelengths out with a common UV/IR block filter. I do use UV & IR blocking on most things when its not already there; lots of filters have the IR blocking or UV blocking in my stacks so even if I'm not using an exact UV/IR block filter on its own, I am blocking that when I can.

 

Very best,



#8 Gray

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Posted 29 August 2021 - 03:47 PM

Most Baader stuff I've bought recently was made in Germany except for one item. A T2 1.25 inch focusing eyepiece adapter. It is a Baader part but was manufactured in China. Still it is well made.

#9 ~RA~

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Posted 31 August 2021 - 04:46 PM

The item arrived yesterday. It was nicely packaged, and includes a modest but adequate storage box and a ziplock sleeve for the cell.

 

The cell looks really good, and is just what I hoped it would be. I'm happy with the purchase purely on the basis of that. The aluminum seems nicely machined, and arrived unharmed. Three setscrews with nylon tips have generous latitude for adjustment (the product is sold in different size ranges, and I ordered the 90-112mm for my Celestron 90). There is a sturdy-looking plastic gasket which secures the film, in addition to some visible (but unrecognizable (to me)) adhesive.

 

The integrity of the film looks fine, with no detectable pinholes. As for quality and safety, I have no way of determining this at this time, and therefore CANNOT RECOMMEND the product as is, unless you have the knowledge and access to appropriate testing equipment; or, like me, are willing to purchase solely for the value of the cell.

 

I'll plan to order some of the Baader film from a trusted vendor at a later date. I don't plan to dismantle the current unit until I have replacement film in hand, so I can't yet attest to how nondestructive or difficult that process is. I think the metal cell will be fine, and hopefully the gasket will come out without too much of a fight, and then I'll just need to clean up the old adhesive. We'll see.

 

I still wish I had some way test the film that came with it, but the trust in the source is just too low to risk use without verification.

 

Thanks to all for your thoughts, and happy to have more. @MalVeauX, every time you comment on one of my threads, I wind up chasing down new info and new terms. That's a good thing.


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#10 MalVeauX

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Posted 31 August 2021 - 05:33 PM

Heya,

 

It's likely ok; again if in doubt, just use a UV/IR block filter. Solar film grinds transmission of all wavelengths, and primarily reduces the thermal load (for visual purposes) as well as the luminosity or brightness. We are getting UV & IR and other stuff all day just with our eyes open normally. Obviously concentrated focused beams of the stuff from a stellar source would be bad. But when reduced by 95%+, it's minimal again. Then to further ensure nothing sinister (and invisible) is coming through, use a UV/IR block filter. If only UV or IR was coming through and not visible spectrum, you'd see next to nothing, yet might be getting an eye full of high transmission UV & IR. Right? So if you are blocking it, and still see a disc image, it's only passing visible spectrum and if it's not too bright, then its really low transmission and it's going to be fine. The only real question would then be if it's allowing long IR to pass in any significant value, since standard glass UV/IR block filters don't handle long IR (KG3 does though). I would have a high confidence to use it with UV/IR block filter.

 

But yes, those cells are a great way to get a good platform to make your own higher quality filter system when you need big aperture stuff or using mirror based optics where a wedge cannot be used.

 

Very best,


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#11 George9

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Posted 01 September 2021 - 11:59 AM

Galileo went blind from solar observing with his refractor through clouds and fog.

It is important to be safe but it does not seem Galileo went blind from solar observing, as argued here:

 

https://aty.sdsu.edu...on/Galileo.html

 

(My main worry is not use of reputable commercial white light filters but overuse of calcium H or K line filters visually. They don't look that bright, but they are way bright in energy. No problem trying them out, but they may not be good for long term exposure.)

 

George


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#12 ~RA~

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Posted 01 September 2021 - 01:11 PM

Given your very conservative record regarding safety, I find this interesting, surprising, and more than a little encouraging. It seems to me then, that if one were both extremely budget conscious and value oriented (and safety, of course), the balance tilts towards the outlay of the BelOptik KG3 price, yes?

Where in the train should the UV / IR filter go? Before or after the 1.25" diagonal, or plan to get a larger one to push further upstream away from focus into the tube? Again, this is (currently) for a 90mm frac and for visual. I understand the KG3 is absorptive, and I've read elsewhere   (-;   that they will crack if too close to focus (at higher power, anyway).

 

If I'm following correctly, the solar film serves as an ND filter, and presumably the mirroring acts somewhat as an ERF. One adds a UV / IR cut/block (they're the same thing, right?) for extra confidence against the invisible stuff, and the KG3 extends the cutoff range.

 

Am I in the ballpark?

 

Thanks!

 

It's likely ok; again if in doubt, just use a UV/IR block filter. [\] I would have a high confidence to use it with UV/IR block filter. [\]

 


Edited by ~RA~, 01 September 2021 - 01:14 PM.


#13 ~RA~

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Posted 01 September 2021 - 01:21 PM

It is important to be safe but it does not seem Galileo went blind from solar observing, as argued here:

 

https://aty.sdsu.edu...on/Galileo.html

 

(My main worry is not use of reputable commercial white light filters but overuse of calcium H or K line filters visually. They don't look that bright, but they are way bright in energy. No problem trying them out, but they may not be good for long term exposure.)

 

George

Still reading through it, but that article is a gem right there, and great contribution to this discussion. Many thanks!



#14 MalVeauX

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Posted 01 September 2021 - 01:46 PM

It is important to be safe but it does not seem Galileo went blind from solar observing, as argued here:

Doh, thanks! I had read it somewhere, good to know what it was (or at least thought to be). waytogo.gif

 

Very best,



#15 MalVeauX

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Posted 01 September 2021 - 01:48 PM

 

Given your very conservative record regarding safety, I find this interesting, surprising, and more than a little encouraging. It seems to me then, that if one were both extremely budget conscious and value oriented (and safety, of course), the balance tilts towards the outlay of the BelOptik KG3 price, yes?

Where in the train should the UV / IR filter go? Before or after the 1.25" diagonal, or plan to get a larger one to push further upstream away from focus into the tube? Again, this is (currently) for a 90mm frac and for visual. I understand the KG3 is absorptive, and I've read elsewhere   (-;   that they will crack if too close to focus (at higher power, anyway).

 

If I'm following correctly, the solar film serves as an ND filter, and presumably the mirroring acts somewhat as an ERF. One adds a UV / IR cut/block (they're the same thing, right?) for extra confidence against the invisible stuff, and the KG3 extends the cutoff range.

 

Am I in the ballpark?

 

Thanks!

 

 

 

Solar film -> UV/IR block -> Whatever filter (red? continuum?) -> whatever :)

 

No filter is going to get enough thermal energy to crack behind solar film. No worries about placement in reality.

 

You're in the ballpark. The UV/IR block and/or additional KG3 substrate (you can get a KG3 filter on its own, for cheap, from Andover or Edmund probably, $50 if I recall) to block any unknown and invisible UV & IR which will render it just visible spectrum and low transmission which is safe visually anyways.

 

Very best,
 


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#16 George9

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Posted 01 September 2021 - 06:01 PM

Probably not for this thread, but I wonder if there should be an eye safety thread. I guess the problem is that we (including me) will make mistakes, and someone could hurt themselves following the advice. And CN should not take on the liability. Yet what topic is more important for a solar forum?

 

Nothing wrong with adding a UV-IR cut filter for peace of mind and perhaps safety. But realize that the manufacturers of those filters really don't want you to use them that way. As noted in another thread, Baader, which I respect highly, put a dark blue color filter in a light blue filter cell, mismarking it, and my real light blue filter had a ripple right down the middle. So even the best manufacturers make mistakes, including on UV-IR filters, and there is no reason for them to double check their work because no big harm to a camera. But you start relying on it for eye safety, and there could be a problem. I.e., if you don't trust Lunt, then why trust some no-name UV-IR cut filter maker? Lunt already double-filters all the wavelengths.

 

Would be good to also go through the various wavelengths and their consequences. I think long IR just heats the front of the eye, which may not be a great idea, but that's different from near IR. Therefore one question is whether a set up produces more long IR than waking down the street towards the Sun but not looking at it. 

 

I do use a Beloptic UV-IR cut filter on KG3 when I am not sure about something (an eBay solar purchase being a great example). Under the theory that if the system is bad, I should see it in visible light since everything else is blocked. But I don't add it to my Lunt or DayStar or Solar Spectrum (other than my ERF for the latter two).

 

There's even the infamous Tasco eyepiece solar filter. I did use one way back when. And then I was horrified at the consequences I might have suffered. And then I realized that sure it was plenty safe in my f/15 60mm refractor. The danger would have been if I had ever moved it to another scope.

 

Going into each of these topics and others in detail would be useful if it could be done appropriately.

 

George


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#17 ~RA~

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Posted 02 September 2021 - 01:01 PM

Probably not for this thread, but I wonder if there should be an eye safety thread. I guess the problem is that we (including me) will make mistakes, and someone could hurt themselves following the advice. And CN should not take on the liability. Yet what topic is more important for a solar forum?

 

Nothing wrong with adding a UV-IR cut filter for peace of mind and perhaps safety. But realize that the manufacturers of those filters really don't want you to use them that way. As noted in another thread, Baader, which I respect highly, put a dark blue color filter in a light blue filter cell, mismarking it, and my real light blue filter had a ripple right down the middle. So even the best manufacturers make mistakes, including on UV-IR filters, and there is no reason for them to double check their work because no big harm to a camera. But you start relying on it for eye safety, and there could be a problem. I.e., if you don't trust Lunt, then why trust some no-name UV-IR cut filter maker? Lunt already double-filters all the wavelengths.

 

Would be good to also go through the various wavelengths and their consequences. I think long IR just heats the front of the eye, which may not be a great idea, but that's different from near IR. Therefore one question is whether a set up produces more long IR than waking down the street towards the Sun but not looking at it. 

 

I do use a Beloptic UV-IR cut filter on KG3 when I am not sure about something (an eBay solar purchase being a great example). Under the theory that if the system is bad, I should see it in visible light since everything else is blocked. But I don't add it to my Lunt or DayStar or Solar Spectrum (other than my ERF for the latter two).

 

There's even the infamous Tasco eyepiece solar filter. I did use one way back when. And then I was horrified at the consequences I might have suffered. And then I realized that sure it was plenty safe in my f/15 60mm refractor. The danger would have been if I had ever moved it to another scope.

 

Going into each of these topics and others in detail would be useful if it could be done appropriately.

This. This is exactly what I would want as an outcome.

 

Certain discussions are frowned upon here surrounding eye safety (solar and laser mods) for understandable liability concerns. At the same time, this has the potential to limit access to the many really good minds here capable of open discussion with pointers to reliable source materials.

 

Trust is tricky. Like you say, even the best of the best can make mistakes, so it's good to build in redundancy where possible. Beyond that, it would be great if we all had ready access to simple testing instrumentation. But there's a recursive thing here... a backup filter for redundancy could also be faulty, and an instrument can be poorly calibrated. But the redundancy and testing would offer some safety net against the recursive unknowables. "Trust in Allah, but tie up your camel" applies, so sensible discussion should focus on the "tying of the camel," and in many ways ought to be first order of business.

 

I have so many questions, and we can't all be optical specialists. If ordinary window glass or enough atmosphere adequately filters UV, why doesn't the many layers of glass in a refractor do the same? As for IR, why can't we use a heat sensor/thermopile at points along the image train to assess safety levels? "Don't look at the sun" and "Trust reputable manufacturers" only gets you so far, and it seems to me that for our pursuits having basic instruments of assay should be as common as musicians having tuners.

 

Finally George, you make me wonder if we have the same Tasco. Anyway, good stuff, and thanks for your contributions.



#18 MalVeauX

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Posted 02 September 2021 - 01:45 PM


I have so many questions, and we can't all be optical specialists. If ordinary window glass or enough atmosphere adequately filters UV, why doesn't the many layers of glass in a refractor do the same? As for IR, why can't we use a heat sensor/thermopile at points along the image train to assess safety levels? "Don't look at the sun" and "Trust reputable manufacturers" only gets you so far, and it seems to me that for our pursuits having basic instruments of assay should be as common as musicians having tuners.

 

 

It is unfortunately that many discussions simply cannot happen here due to the ToS and regarding commercial solar equipment and may safety discussions on this equipment involves knowing the parts inside and transmission of them, etc, which doesn't come from a white paper or commercial graph. It comes from people who opened these up and measured things. So all of that is forbidden around here. So yea, very unfortunate, and it all comes down to basically telling people something is safe or not and it gets left at that with some minor discussion. A super thread regrading safety would be great, but it would be ignored by the very people who need it, as they would just post first, and then get a link to it later from someone... The stickies here on this forum are ancient, nearly irrelevant, and the few good links in the stickies are completely ignored by the intended audience (evidenced by the threads that are started on the very subjects). Just being realistic about forum behavior.

 

Regarding your questions.... keep in mind, you cannot even look at the sun with your naked eye, and your pupil constricts to as small as it can go, and it's still too bright. So naturally, any optic that consolidates that energy into a small focused area is going to be much more intense. Refractor glass is about transmission, it refocuses light and consolidates it at the focal plane at very, very high transmission, it doesn't block light, it's purpose is to transmit all of it as best as it can. It's so good at it that the glass doesn't get hot, testimant to how good it transmits all of it (unlike a mirror, which does get hot, because it can't reflect it all and absorbs some and gets hot). Your eyes when looking around are seeing reflected light from objects. Not just staring at the star with the atmosphere and air as your filter. Looking at the reflected light around you after its already been filtered and lots of the UV & IR absorbed and visible light reflected, is nothing like looking directly at the star with your eyes--which is obviously not safe. So naturally, anything pointed at the sun that collects light would be even more so a problem in terms of what's unsafe about it. And even more intense. Thus, we need a way to decrease intensity and filter out the dangerous wavelengths that are invisible to our eyes, yet carry energy (UV & IR). Visible spectrum carries a lot of energy too, mind, more than UV does. But we can see visible spectrum and when its too intense we perceive it as too bright and our eye protects itself and shuts. So for visible spectrum, we simply need to lower intensity, which is easy, when its not too bright, its obvious to your eye, and you're fine. We cannot do that with UV & IR, its not visible spectrum to our eye, so we wouldn't know its too bright or intense. So we filter it out completely so that it's not even an option or question, or at least filter it to a very low amount. Remember, it has to be a low amount because an optic that consolidates that energy intensifies it over a smaller surface area, so its a lot more than one might think by the end of the imaging train of an optic. It's a lot easier to simply block IR all together, since you cannot see it anyway, than it is to try to measure thermal properties (which would be different in every single sample of a scope and different apertures, designs, etc, making it too variable, and too prone to risk). Again, so much simpler to block wavelengths that your eye cannot see, that's already taking out the energy and no need to measure it, it's just not there in a meaningful load, which is way simpler and safer for a population with zero information or education on the subject.

 

Even the moon is too bright to look at in a scope at low power with a big aperture! And the moon is absolutely reflecting IR at you!

 

Bottom line is, block UV & IR as much as possible and it will be a lot safer because you can't see those wavelengths. Then, grind transmission enough so that the image is not too bright to where you can look at it.

 

Here's a simple breakdown:

 

Solar Energy Distribution.png

 

Our atmosphere already handles a ton for us. But a lot still comes through. Of what comes through, that graph breaks it down to what really matters for us visually or just thermally speaking. As long as we keep in mind that we cannot see UV & IR and that's why they're so dangerous, we wouldn't know they're too bright until it's too late and the damage was done, and understand that visible spectrum carries about the same amount of energy, but we can see it, so we know right away its too bright (blinking, pupil constricting, eye shutting, actual pain, etc) and we can also see when it's not too bright. It really becomes quite simple without any optics or physics knowledge. Literally as simple as, if you can't see it, it can harm you more. So block it! This is with respect to visual of course. Cameras don't care. So block UV & IR. And reduce transmission of all of it.

 

Very best,
 


Edited by MalVeauX, 02 September 2021 - 02:06 PM.

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#19 ~RA~

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Posted 02 September 2021 - 06:24 PM

Marty, I agree with all your points, and I do aim to acquire the UV / IR KG3 before using the eBay filter's questionable film.

 

Some of my last comments were in the context of the Galileo article George referenced. The surprising takeaway for me (and of course, caveat lector) is that staring at the sun is *probably* for *most* people reasonably safe, and that any injury is *probably* recoverable -- UNLESS looking through an improperly filtered telescope.

 

So George's wish for better understanding of implications across wavelengths is one I think we all share. Between you and him, there appears to be a common advocacy for safeguards, but his point about a faulty sample is well taken, which is why I'd love to be able to personally test all the critical components.

 

Say for example my eBay filter is total crap, nothing but a space blanket fitted into a nice cell. (Okay, so I have no idea what a space blanket would or would not filter out, but you get the idea). If I was one of the rare unlucky ones who put a faulty filter in line as a safeguard, and then spent a long time trying to figure out what I was looking at, it could be bad. Small risk, maybe, but potentially dire consequences that I'd love to see minimized.

 

Anyway, I'm still very new around here and finding my way, so nothing I say should be taken as preaching to my betters. As for stickies, maybe they're underutilized or in need of updating. No idea who is in charge of that, but given a good set that is well maintained, it at least gives senior members a valid reason to say RTFM. George's proposal was for an eye safety thread, but if there could be a distillation of well-sourced wisdom, I'd love to see that as a sticky.



#20 MalVeauX

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Posted 02 September 2021 - 06:29 PM

Heya,

 

You can get KG3 pretty inexpensively. A small 25mm x 3mm KG3 is very affordable:

 

https://www.edmundop...ing-glass/9439/

 

You mount it in a 25mm->28mm (1.25") cell and you can thread it to an eyepiece to complete long IR blocking with a standard cheap UV/IR block filter in front of it. Overall very inexpensive to build. The BelOptik one is excellent and of course is already 1.25" standard and one filter, for more cost of course, when its in stock. But there's always options.

 

Very best,


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#21 philmor56

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Posted 04 September 2021 - 12:29 PM

Hi ~RA~

 

I too had the same thoughts as you and I bought this "Astromania" brand filter from Amazon (CA link), for my 72mm grab n' go kit.

 

20210904_130033 - Edited.jpg

 

It looks exactly like the one you bought. (1 manufacturer, many brands perhaps.) Nice construction, and the set screws with the rubber tips were cool, as well was the price.

It was listed as being equipped with Baader film and "Certified by Amazon" for whatever that is worth.

 

Nonetheless, after a visual inspection, and holding it up to the sun, it was clear that the transmission was cut down to a suitable level, and no pin holes/folds or creases were visible.

I decided to check it out, and as always, with an abundance of caution.

I ALWAYS use a UV/IR filter, mounted on the front of my 1.25" diag., for WL visual and imaging.

 

20210904_122055 - Edited.jpg

 

(With my 2" wedge I have a 2" UV/IR filter mounted after the prism on the front of my 2" - 1.25" adapter.)

 

Fortunately I have my old  50mm erect image finder fitted with some real Baader film and put side by side the image was virtually identical. So perhaps they are using Baader film.

 

20210904_121650 - Edited.jpg

 

The supplied set screw provided a nice tight fit, however, redundancy is critical with solar and with the addition of some Velcro strips I feel that the filter is now plenty secure.

 

20210904_121917 - Edited.jpg

 

In closing, I feel that if the transmission is ground down to a comfortable level, and there is no visible damage, with the addition of a good quality UV/IR cut filter, that you are basically safe and ready to go.

I may still swap out the film, when stocks of Baader are replenished, but at this point I am confident that I have taken all the necessary precautions and that there is no danger or cause for alarm. With the addition of the UV/IR filter I have an inexpensive front mounted solar filter.

 

Hope this helps.

 

Cheers


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#22 ~RA~

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Posted 07 September 2021 - 01:18 PM

Back at keyboard after Labor Day distractions.

 

I'll aim to get the KG3 UV / IR, but in the meantime I'm wondering what would happen if I put my Lunt B600 behind the mystery film.

 

Anyway, I've loved all the input, and am very grateful, and hope this thread may be useful to someone who stumbles on it later.

 

Thanks y'all!



#23 MalVeauX

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Posted 07 September 2021 - 01:22 PM

Back at keyboard after Labor Day distractions.

 

I'll aim to get the KG3 UV / IR, but in the meantime I'm wondering what would happen if I put my Lunt B600 behind the mystery film.

 

Anyway, I've loved all the input, and am very grateful, and hope this thread may be useful to someone who stumbles on it later.

 

Thanks y'all!

 

You would see a dim, red photosphere feature image.

 

Your blocking filter is around 6A bandpass. So it's narrow, but really not that narrow. The film will grind transmission way down, 5% or less left over. The more narrow a filter, the less transmission it will have. So the result will be dim. That said, I've done this. It's mostly photosphere but with good processing you can make out proms at the limb with it if they're bright enough.

 

Here's an example of using two stacked blocking filters (with suitable ERF, solar film for example) and seeing mostly photosphere. I used two 1.7A blocking filters here, and you can make out some filaments but it's mostly photosphere. This won't happen with a single 6A blocking filter, but you get the idea. Even 1.7A stacked will not get you to the chromosphere hardly at all. Chromosphere really happens around 1A or less. So anything above that, is mostly or all photosphere.

 

AR2818_AR2820_AR2821_Photosphere_656nm_1p7A_120mmF10_290MM_81frames_BW_04272021.jpg

 

Very best,
 


Edited by MalVeauX, 07 September 2021 - 01:33 PM.

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#24 ~RA~

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Posted 07 September 2021 - 01:54 PM

[\]  Even 1.7A stacked will not get you to the chromosphere hardly at all. Chromosphere really happens around 1A or less. So anything above that, is mostly or all photosphere.
 

[\]

 

Very best,
 

Sure, I wouldn't have expected anything other than photosphere, so the fact that some chromo gets through at all is interesting.

 

My understanding is the Lunt diagonals have UV and IR blocks, as well as the block for the H wings. I suppose without the latter, the diagonal might serve as the kind of safety net we've been discussing for white light. In any case, I have my LS50 for narrow band, so using my 90mm for continuum with suitable peace of mind is why this thread has been so helpful. Again, I learn pretty much every time you post.


Edited by ~RA~, 07 September 2021 - 01:55 PM.

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#25 ~RA~

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Posted 30 September 2021 - 12:35 PM

I've been wanting to followup with a brief actual-use review, but weather, travel, and a temporarily blank sun has made for delays.

 

Yesterday the sky was mostly clear and seeing was forecast at slightly above 1 arcsec. I put the filter on my 90x660; -> SVBONY UV / IR* -> diagonal -> variable polarizer -> 1.8x Barlow -> Arcturus binoviewers -> twin 30mm EPs.

 

Two very nice ARs gave me solid targets to focus on. Views w/out a polarizer or other ND are bright, but not painfully so -- some dimming helps with contrast. Umbra and penumbra were as crisp and clear as my rig will allow, and I could easily make out plages, esp. along the darkened limb. Faculae were ghostly, but present.

 

I also played around with the views through the Lunt 7-21mm, with similar results.

 

While I haven't been able to compare side-by-side with a known and trusted Baader source, I'm prepared to say I'm happy with the performance of my purchased item. The safety precautions covered in this thread have given me the confidence to carefully proceed. Buyers following this path are advised to assume significant variance in quality control with unknown sources, to employ safety measures accordingly, and include in the budget a fallback to trusted Baader sourced film.

 

Hope this is helpful to others, as it has been for me.

 

RA

 

*I have not yet added the KG3 element, but still plan to. I've ordered a really cheap filter to cannibalize the cell, and will then order the glass.


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