8 replies to this topic

[John O'Hara]

In preparation for the 2017 total solar eclipse, I recently purchased a mounted Astrozap Baader film filter for my Sky-Watcher 100 ED, and also a sheet of the Baader film to make hand-held naked eye filters with.  When reading the package (for the sheet film), I read the following warning:

 

AstroSolar™ Safety Film reduces the intensity of incident sunlight by a factor of over 100,000. According to current medical research, the filter (when properly used) provides complete protection against thermal damage to the retina (photocoagulation).
Under certain circumstances, any intense source of light (e.g. spotlight, laser beam, welding arc, the sun) can trigger so-called photo-toxic processes in the eye. In extreme cases, such reactions can have an additive effect over time, leading to deterioration of the vision.
Please note: This filter provides protection against solar radiation similar to that offered by welding glasses. However, as long as it is not absolutely certain that even welders glasses completely hinder phototoxic reactions, the same reservations must apply to this solar filter.
Therefore, exercise your own best judgment when using this product.
Although we have never heard of a single case of eye damage in 10 years of sales of this product to thousands of telescope users, and knowing that welders ply their trade for years, while the solar filter’s use can be measured in minutes, we believe it appropriate to inform you of the current state of scientific knowledge.
In any case, it is advisable to interrupt solar observation occasionally and look at other objects. If you have any doubts at all, especially in cases of known excessive eye sensitivity, consult your ophthalmologist or optician.

 

​My first thought is that this is just another legal disclaimer, just in case someone does something stupid.  But then I started wondering if there is any real concern here.  I've never heard of even dedicated solar observers using this film having been harmed.  Of course, I understand the importance of checking the film for pinholes before each use.

 

Thanks,

John

​

Edited by John O'Hara, 06 April 2017 - 01:03 PM.

[George Bailey]

Here is the answer:

 

 

To Dr. George Bailey Mar 28 at 7:11 PM
George,

Thanks for writing. I’m indeed aware of Baader AstroSolar film; I have Baader filters for all my telescopes and binoculars, as it has consistently gotten the highest ratings from Sky & Telescope, where I worked from 1986 to 2008. I have spoken on the phone with Thomas Baader about safety standards. He says his material is NOT certified safe according to the new ISO 12312-2 standard, at least not for use as eclipse glasses for direct viewing. It lets in a little more UV than the ISO standard — which is stricter than the earlier standards — allows. That’s not an issue for aperture filters used with binoculars and telescopes and camera lenses, because the glass in the objective(s) and/or eyepiece(s) filters out the rest of the UV. But for direct viewing, eclipse shades made with Baader AstroSolar film do not meet the ISO 12312-2 standard and are therefore NOT recommended by the AAS and NASA. We have chosen to err on the side of being overly cautious in the interest of public safety.

Baader told me that he is introducing a new, improved filter material for use in eclipse glasses, and that it is currently being tested against the ISO 12312-2 standard. Once certified, it will replace regular AstroSolar film in Baader eclipse shades — but Baader told me he doesn’t plan to sell these shades in the US, at least not for 2017.

Clear skies!

        Rick
--
Dr. Richard Tresch Fienberg
Press Officer, American Astronomical Society

 

 

So in short, if you use it on your scopes/binocs/cameras it meets all standards. 

Just don't look at the Sun directly with it. 

Edited by George Bailey, 06 April 2017 - 01:47 PM.

[John O'Hara]

Thanks, George.  I wonder if the Baader film could be used for naked eye viewing if one is wearing glasses certified to block UV.  My regular glasses, though not sun glasses, are certified to block UV.  I'm thinking that they might clean up the UV that does get through the Baader film.  Also, I'm thinking I'll only use these for the stages of the eclipse leading up to and following totality.  This is not going to be a daily or even montly activitiy (that is, using the Baader film for naked eye viewing.)

 

The problem at this point is that if the new film is not avaible in the use, what else can we used for naked eye viewing? 

[George Bailey]

Look here:  https://eclipse.aas....s/solar-filters

 

I would THINK that UV block eyeglasses would be fine, but I am a chemist, not an optomologist !!!

Edited by George Bailey, 06 April 2017 - 01:55 PM.

[John O'Hara]

I have eclipse glasses with the proper certification, but I wear prescription eyeglasses and they don't work well together.  Thankfully, I do see that the website you provided has some handheld viewers.

 

I guess I'll use the Baader sheet to make a filter for my 6" refractor or binos.  It won't go to waste.

​Thanks again for the information.  My guess is I'd probably be fine using the Baader film for naked eye viewing, at least for short duration.  However, the stakes are just too high.

Edited by John O'Hara, 06 April 2017 - 02:10 PM.

[BYoesle]

A good source for filter data can be found here:

 

http://www.sonnen-filter.de/

 

In Europe, the recommendation is OD 5.0 from < 300 nm to ~ 800 nm, and then OD 2.4 out to ~ 1400 nm:

 

 

Here you can see the transmission of Baader ND 5 film. So just to be safe, using a IR/UV filter can't hurt... and is especially needed with imaging for use of the Continuum filter:

 

 

[George Bailey]

For those who may be scared that the Baader film may be harmful in scopes and binoculars, this is what the AAS says and recommends for the solar eclipse for those optic systems:

 

Solar filters for optics are meant to go over the aperture, i.e., the front opening, and should be used only by experienced observers. The first three sources listed below sell aperture filters made from Baader AstroSolar Safety Film. While this material does not meet the ISO 12312-2 international safety standard for direct viewing of the Sun, it has been safely used by amateur and professional astronomers for several decades for observing and/or imaging the Sun through telescopes, binoculars, and camera lenses.

 

Alpine Astronomical
Astro-Physics, Inc.
Kendrick Astro Instruments
Orion Telescopes & Binoculars (also sells Baader film filters in addition to their glass filters -gb)
Rainbow Symphony (Who, in addition to their orange-color Black Polymer Solar Filters, also sell Baader filters. -gb)

 

While a UV/IR cut is always a good idea for safety back-up in a solar scope, IMHO the same applies to ALL solar filters, not just Baader !!!

 

Too bad we don't have the spectra of the RS or TO (Solarlite) solar filters for comparison. I wonder why TOs is not on the above list.

Edited by George Bailey, 06 April 2017 - 06:49 PM.

[M57Guy]

Sign of the times that what was safe in 2010 became unsafe in 2015.  

 

I asked the family Optometrist (wife) and she agrees the optical glass in objectives and EPs should offer some additional protection against UV, above which the Baader film already provides, and eyeglasses that block UV will also do the job.

[viewer]

Did some searching, the full ISO 12312-2:2015 standard costs about $58, https://www.iso.org/...dard/59289.html

 

Here are some of the criteria, from http://www.eclipseaf...keViewers.shtml:

 

transmission of the filter material used in the viewers: no more than 0.0032% of optical, UVA or UVB radiation, and no more than 3% in the infrared.

 

The Baader film is failing a bit at the ~340nm UV (0.004%) in the graph Bob posted. At the IR ~780nm there also appears to be a bit of shortcoming (also about 0.004%). Above that it looks to be ok, because much more transmission is allowed, even if the Baader scale jumps out of page it looks to be no more than say 0.02% at its peak at about 900nm, a full 3% would be allowed.

 

UVA (315–400nm) and short wave IR mainly go through optics and UVB doesn't, so this may be about what you are getting through the telescope. Personally I feel safer after the search. Of course using it only in the telescope.

Edited by viewer, 09 April 2017 - 09:21 AM.