Baader Astro Solar - holes into the film

[N3ptune]

Hello,

I want to get some advices, I just did an inspection of my Astro Solar filter, I hold it toward the sun and moved it around to see if there are some punctures or holes. Actually I could count 15 micro holes into the film..  It's not possible to see them if not looking at the sun directly, i also can see some of them pointing a strong 500w light.

Now.. these holes are smaller then the tip of a needle, but I can definitely see a ray of sun coming out.

Is this filter bad or should I stop using it?

I don't know how these punctures were created, I am clueless. Maybe they are normal? This filter goes on my 8 inches telescope, has the picture bellow.

thanks

 

[DRT]

You can buy I new sheet of film to replace the film in your filter for not very much money. I would recommend you do that rather than risk your eyesight if one or more of these pinholes proves to be large enough to let too much light through

 

[N3ptune]

I can't say how much pinhole is too much really... it's a sad story.

[Ibbo!]

replace

[N3ptune]

Yeah.. it's serious stuff this filter.. I am going to ask for a free replacement, this is nonsense..

[N3ptune]

But since the pinholes are so small, could I use some sort of UV filter to put on my eyepiece? It could provide maybe the layer of protection required or even more?

[Dr_Ju_ju]

Nope, no hole is too small, just replace the film.

[Ruud]

As long as their total surface remains less than a tiny fraction of a square mm, the holes won't hurt your eyes. (One way to deal with any larger damaged spots is to put a dot of black paint over it.)

Are the punctures new or is it possible they have been there all along? I have a handful of tiny holes in my solar filter that have been there for years. They don't increase in number and they don't have any impact on the image. The Sun's disk has plenty of contrast and no light scatters  into the black space around it. Functionally, the filter is fine.

The first effect of too many micro punctures might be a brighter image of the Sun or, more likely for very small punctures, a haze of scattered light over the image. (Tiny holes, due to diffraction, scatter a lot of the light that they let through.)

[DRT]

7 hours ago, N3ptune said:

Yeah.. it's serious stuff this filter.. I am going to ask for a free replacement, this is nonsense..

Is it new? If so you should definitely do that.

Whilst Ruud's advice is accurate I think it is risky to give or take such advice without actually seeing the filter and examining the holes. If this filter was mine (and wasn't new and capable of being returned) I would replace that film for about £25. That seems a cheap price to pay for guaranteeing keeping your retina intact compared with taking a risk in looking through something you are not 100% certain is safe.

[laudropb]

 I would not risk using the filter. If it is new ask for a replacement, if not buy a filter sheet and replace the old one.

[xtreemchaos]

replace mate, its only a few quid for new sheet, do you have a cat ? cos thay have been known to walk over things and leave small holes from the tips of there claws, you cant take chances with your eyesight.charl.

[N3ptune]

This situation is well known.. I called the shop to see if I could replace the film for a new one because of the pinholes, he knew exactly what I was talking about and said to me it's written inside the manual that some pinholes on the sheet meet factory tolerences and they are not dangerous for my view. My filter is in very good condition.. (It's 7 month old and used 6 times) i don't think it's induced damage, i have to look at a strong light to see the spots.

So i found a manual and it explain's it all page 14. Appendix B Quality information. And like Rudd said, it's possible to block the pinholes with black spot.

http://www.baader-planetarium.uk.com/en/pdf/e_instruction_manual_baader_solar_filter_2015_02_v1_3_WEB.pdf

I could replace the film with another one and get the exact same thing because the manual say in a new conditions some pinholes meet the tolerences.

--> I will bring the filter to the shop and have a few people to look at it.

[DRT]

That is interesting.

The standard wording (presumably supplied by Baader) used by retailers to describe the safety of this film is this...

 

"Eye safety

AstroSolar™ is essentially free from pinholes, since it is coated on both sides, the chance of two pinholes overlapping each other is extremely faint. Pinholes do appear, but to 1 out of 10000 only in optical density 2.5! Baader AstroSolar™ safety film has been approved for eye safety by the National Bureau of Standards in Germany, the PTB. Unlike any other Solar Filter on the market, AstroSolar™ is CE-tested according to EG-Norm 89/686 and EN 169/92 (notified body 0196). All processes connected to this product have been thoroughly tested. Coatings are inspected constantly for consistency to ensure your eye safety!"

 

That first sentence (highlighted by me) does not seem consistent with what you have been told and what is hidden deep in the manual

 

[spaceboy]

I spoke to Baader directly over this some years ago and they basically quoted the manual free from pinholes, since it is coated on both sides

I used several sheets of Baader film in my time and every sheet showed the same under halogen lights or the sun. Unless there is an obvious hole or a hole visible when held up to modestly bright light I wouldn't worry too much about it. Failing that you could get a refractor and Herschel wedge

[CraigT82]

The instructions for my Baader film , purchased 2 months ago, say to draw over any pinholes a permanent marker to seal them up.  That does seem to conflict with the wording on the retailers ads

[N3ptune]

  For me essentially = normally = probably = should be, it can imply pinholes.

I wrote the question to Baader yesterday and they give me an interesting reply, I read it 1 time only, i have to reread it but i paste it anyways because it's interesting.

======================

My question

Hello i have an AstroSolar filter i use on my own 203 mm newtonian telescope to watch the sun, it's a Home made filter. In my close inspection today, (I put the filter toward the sun and move it around to watch if i can see some holes)I could count at least 15 micro holes only visible while pointing the sun, smaller then a point of a needle but i can definitely see a ray of light coming out of these micro holes...

Now what should I do, is this normal for the astrosolar filter? or should i replace the filter for a new one?

Thanks

======================

thank you for contacting us.

AstroSolar Safety Film is CE-tested and was declared safe for solar viewing by the
"PTB" - the technical Bureau of Standards in Germany, a state owned organization.

Those small pinholes that you describe do not have an effect on the
safety of the solar filter. Small cheases are unavoidable during all
the different processes during production, sizing - and mounting
at the filter cell maker and further pinholes may develop over time due to
regular "wear and tear" (fortunately the owners of open tube telescopes
do not regularly look through their primary mirror from the rear side by
holding the mirror up towards the Sun. That would create a lot of grief).

Of the holes you describe each works like a "camera obscura".

By no means the light through such a hole reaches the eye like a laser beam.

Rather it is being dispersed into an "image" of the solar disc (obviously one
with very low resolution, given the small aperture of the "lensless camera").

A number of such "images" will somewhat lighten up the backgrond sky
around the sun, but this does not nearly transport enough focused energy
into the eye to be dangerous in any regard.

As you know, solar filters are around for some considerable time now.

Carl Zeiss had offered the first "objective solar filters" 70 years ago.
Since then all Zeiss solar-filters are accompanied by an instruction sheet,
bearing the following sentence:

"Some tiny uncoated areas of the glass plate result from production
and are not avoidable. Such empty spaces visible in the chromium coating
are within the manufacturing tolerance and do not impair the image quality."

Anyone buying a Celestron glass filter about 10 years ago, could read
the flgw. sentence right on the front side of the box:

"Pinholes and scratches are common in solar filters. If found to be
bothersome opaque with black felt marker."

In all these years we have not heared of a single case were someone would have
damaged her/his eyesight due to using a Zeiss or Celestron solar filter(thank God).

In regard to developing pinholes with prolonged usage, we want to repeate
that the product wears like a high quality telescope mirror, with the added
bonus of being coated on two sides.

Pinholes in double coated thin film have a markedly reduced effect. Much more
prone to pinholes are glass filters. As detailed above, single side coated glass
filters are available since decades from Carl Zeiss - and since a few years also
through many lower class vendors ( some of them discovered that it is possible to
"get by" using straight,unpolished "window-glass").
So in many cases - while the glass may have been treated with a good quality coating
job - it's still window glass, not good for any real work - and coated on one side only.

On glass, a double sided coating would be totally impossible because it would
create all kinds of light scatter and reflection due to the high thickness of
the glass. AstroSolar in turn is very thin (but strong and "unbreakable"!),
so as to exclude any internal light scatter.

The coating technology applied on AstroSolar is much higher advanced than the
regular vapor deposition found on ordinary metallized films as being traded
under the generic name "Mylar".

The nature of our reflection coatings will not be discussed further, but in
hardness they equal an enhanced aluminum coating with quarz protective layer.
We have manufactured such films with comparable coatings for over 20 years
without a single complaint.

Much to the opposite we have tested that those US-made solar filters which use two
layers of film - with the metallized sides facing each other (alike Solar Screen a.o.)
- tend to exhibit a far greater amount of pinholes over time, because two single side
coated films are mounted into one frame, with their metallized sides facing each other.
Consequently these surfaces are rubbing on each other while being subjected to
wind loads during observation. This effect indeed over time produces severe overlapping
scratches in the reflective coatings.

Still overlapping pinholes or pinholes in general are not to be regarded as
dangerous, otherwise Solar Screen at all (not to speak of Carl Zeiss) could never
have dared to market such filters; but when light get's trapped between
two separately metallized layers of film or between a thick glass plate, it leads
to a notable increase of scattered light, trapped between the two reflective
surfaces and creating all sorts of annoying reflections.

We believe that due to the even smaller pinholes with film coating,
and due to the double sided coating process applied on AstroSolar Film,
we are in a position to offer a much safer product than any other company
supplying one side coated filters - while having the least amount of scattered
light ever possible.

With Astrosolar, even a huge scratch on one side cannot have such a desasterous
effect as with a single sided coating, since there still is the inner coating
layer of density ND2.5 present. Of course - such a spot with optical density 2.5 would light up and stand out
very bright against the surrounding two layer coating, having the optical density of ND 5.0
This looks just as if such a spot were completely transparent, but this is not the case!

Given the size of the imperfections that you describe, we can assure you
that you can use your filter in complete safety.

Please take into account that we have set the price for this material so very low,
that everyone could afford just to buy a new piece, rather than clean an
older filter and live with the diminished image contrast of a film torn and
scratched from repeated cleaning operations.

This filter has been tested interferometrically to perform on equal level as
a $ 10000.- apochromatic lens of Carl Zeiss. If one would purchase a standard sheet of  
~ 40x20 inch at $70.- from Astro-Physics or David Hinds Ltd.(our authorized distributors),
it has the same performance - and value - as $ 8000.- in perfect planeparallel glass filters from Zeiss.

A film portion of 100x50 centimeter will probably last you through all of your astronomical life -
for almost all of the telescopes you will ever own.

Please continue to cover pinholes with a black felt marker if found to be bothersome.
If this is being done on the inside of the filter, nothing will hamper the technical appeal once
the filter is mounted on the telescope. Most likely there will not be any difference visible at all.

Please use double tape to affix the film onto any holder that you are conceiving. And make perfectly sure that
your DIY-holder cannot be blown off,

Wishing you a clear view onto our nearest star,

we remain,

Best regards,

Service Team
BAADER PLANETARIUM GMBH

 

 

[N3ptune]

I wonder what Barack obama would say about the subject lol.

[Steve Ward]

My original glass-based filter is covered with "Sharpie" marks blotting out pinholes ( still works fine and safely though ) ... 

Never had an issue personally with the Baader film I now employ , but if I do discover pin-holes in the film I will deal with them the same way.

Good to see Baader putting up such a detailed reply , nothing less than I would expect from such a reliable supplier.

[Ruud]

21 hours ago, N3ptune said:

thank you for contacting us.

AstroSolar Safety Film is CE-tested and was declared safe for solar viewing by the
"PTB" - the technical Bureau of Standards in Germany, a state owned organization.

Those small pinholes that you describe do not have an effect on the
safety of the solar filter. Small cheases are unavoidable during all
the different processes during production, sizing - and mounting
at the filter cell maker and further pinholes may develop over time due to
regular "wear and tear" (fortunately the owners of open tube telescopes
do not regularly look through their primary mirror from the rear side by
holding the mirror up towards the Sun. That would create a lot of grief).

Of the holes you describe each works like a "camera obscura".

By no means the light through such a hole reaches the eye like a laser beam.

Rather it is being dispersed into an "image" of the solar disc (obviously one
with very low resolution, given the small aperture of the "lensless camera").

A number of such "images" will somewhat lighten up the backgrond sky
around the sun, but this does not nearly transport enough focused energy
into the eye to be dangerous in any regard.

As you know, solar filters are around for some considerable time now.

Carl Zeiss had offered the first "objective solar filters" 70 years ago.
Since then all Zeiss solar-filters are accompanied by an instruction sheet,
bearing the following sentence:

"Some tiny uncoated areas of the glass plate result from production
and are not avoidable. Such empty spaces visible in the chromium coating
are within the manufacturing tolerance and do not impair the image quality."


Anyone buying a Celestron glass filter about 10 years ago, could read
the flgw. sentence right on the front side of the box:

"Pinholes and scratches are common in solar filters. If found to be
bothersome opaque with black felt marker."


In all these years we have not heared of a single case were someone would have
damaged her/his eyesight due to using a Zeiss or Celestron solar filter(thank God).

In regard to developing pinholes with prolonged usage, we want to repeate
that the product wears like a high quality telescope mirror, with the added
bonus of being coated on two sides.

Pinholes in double coated thin film have a markedly reduced effect. Much more
prone to pinholes are glass filters. As detailed above, single side coated glass
filters are available since decades from Carl Zeiss - and since a few years also
through many lower class vendors ( some of them discovered that it is possible to
"get by" using straight,unpolished "window-glass").
So in many cases - while the glass may have been treated with a good quality coating
job - it's still window glass, not good for any real work - and coated on one side only.

On glass, a double sided coating would be totally impossible because it would
create all kinds of light scatter and reflection due to the high thickness of
the glass. AstroSolar in turn is very thin (but strong and "unbreakable"!),
so as to exclude any internal light scatter.

The coating technology applied on AstroSolar is much higher advanced than the
regular vapor deposition found on ordinary metallized films as being traded
under the generic name "Mylar".

The nature of our reflection coatings will not be discussed further, but in
hardness they equal an enhanced aluminum coating with quarz protective layer.
We have manufactured such films with comparable coatings for over 20 years
without a single complaint.

Much to the opposite we have tested that those US-made solar filters which use two
layers of film - with the metallized sides facing each other (alike Solar Screen a.o.)
- tend to exhibit a far greater amount of pinholes over time, because two single side
coated films are mounted into one frame, with their metallized sides facing each other.
Consequently these surfaces are rubbing on each other while being subjected to
wind loads during observation. This effect indeed over time produces severe overlapping
scratches in the reflective coatings.

Still overlapping pinholes or pinholes in general are not to be regarded as
dangerous, otherwise Solar Screen at all (not to speak of Carl Zeiss) could never
have dared to market such filters; but when light get's trapped between
two separately metallized layers of film or between a thick glass plate, it leads
to a notable increase of scattered light, trapped between the two reflective
surfaces and creating all sorts of annoying reflections.

We believe that due to the even smaller pinholes with film coating,
and due to the double sided coating process applied on AstroSolar Film,
we are in a position to offer a much safer product than any other company
supplying one side coated filters - while having the least amount of scattered
light ever possible.

With Astrosolar, even a huge scratch on one side cannot have such a desasterous
effect as with a single sided coating, since there still is the inner coating
layer of density ND2.5 present. Of course - such a spot with optical density 2.5 would light up and stand out
very bright against the surrounding two layer coating, having the optical density of ND 5.0
This looks just as if such a spot were completely transparent, but this is not the case!

Given the size of the imperfections that you describe, we can assure you
that you can use your filter in complete safety.

Please take into account that we have set the price for this material so very low,
that everyone could afford just to buy a new piece, rather than clean an
older filter and live with the diminished image contrast of a film torn and
scratched from repeated cleaning operations.

This filter has been tested interferometrically to perform on equal level as
a $ 10000.- apochromatic lens of Carl Zeiss. If one would purchase a standard sheet of  
~ 40x20 inch at $70.- from Astro-Physics or David Hinds Ltd.(our authorized distributors),
it has the same performance - and value - as $ 8000.- in perfect planeparallel glass filters from Zeiss.

A film portion of 100x50 centimeter will probably last you through all of your astronomical life -
for almost all of the telescopes you will ever own.

Please continue to cover pinholes with a black felt marker if found to be bothersome.
If this is being done on the inside of the filter, nothing will hamper the technical appeal once
the filter is mounted on the telescope. Most likely there will not be any difference visible at all.

Please use double tape to affix the film onto any holder that you are conceiving. And make perfectly sure that

your DIY-holder cannot be blown off,

Wishing you a clear view onto our nearest star,

we remain,

 

 

Best regards,

 

Service Team

BAADER PLANETARIUM GMBH

 

 

 

I'm surprised at the fearmongering and the misinformation. Why not just answer the question you pose? The tiny punctures you found aren't dangerous and don't deteriorate the image.

You know, I had two solar filters at one point. An older steel-on-glass filter by Thousand Oaks and a Baader solar film. I got the Baader because it was modern, came with many promises of superiority, and it was not too expensive. So I got it to see if it made any difference. The difference was clear.

I kept the Thousand Oaks. The image quality is identical (both limited by the seeing only), but the glass filter is easy to clean and we have lots of lime trees around (linden), which on sunny days produce tiny sticky droplets that are easily carried by the wind.

The Baader is near-impossible to clean, got sticky, inevitably picked up dust and became a mess. It lasted less than a year. I threw it away. My glass filter is now 26 years old. It is clean and works just fine. And it is a lot cheaper that 26 Baader filters!

And really, Zeiss is not the only one who uses properly polished optical glass rather than windowpanes.

---

Anyway, I always hold my filter up to the Sun for a quick check before I put it on the telescope. My filter is mounted in an aluminium cell that snugly fits over the dew shield of the telescope, but I still tape it in place to make it impossible to come loose by itself. And I explain to everyone around to leave it alone. And also tell them not to remove the lens cap of the finder either.

[N3ptune]

Well me I am kind of glad with the Baader message (It's a strong reply, really), they clearly are proud of their product and they put a true confidence in it. I believe all we need to know is inside, everything is covered, plus this entire thread it's a lot of new and great data for me to figure out the correct way to do.

Ruud I don't know why you think it's a laughing matter.

It seems a few pinholes might not be a big deal but if it gets worse, I need to replace the filter.

 

 

[Ruud]

I thought it was rather a loooooong answer for such a short question!

The reason, btw, for the micro punctures is the vacuum evaporation process used. Tiny specks of dust and other impurities on the substrate cause equally tiny imperfections in the coating. I don't expect that you'll get additional pinprick holes, with the coating between two layers of plastic.

[Steve Ward]

The coating is not between layers , it's on both sides of a single layer ...

And you must have the only 'optically flat' TO glass filter out there then ...

[Ruud]

4 hours ago, Steve Ward said:

The coating is not between layers , it's on both sides of a single layer ...

Oh Thanks! I thought the metallic film was protected on both sides. Maybe I got that impression from the comparison with the quartz overcoated enhanced aluminium.

4 hours ago, Steve Ward said:

And you must have the only 'optically flat' TO glass filter out there then ...

My glass is definitely plan-parallel and polished. I've no idea precisely how flat the surfaces are. I can't make any claims about that.
As I said, the glass is optical glass. That is not so strange. It need not be of a special type. It's just a flat piece of glass used perpendicular to the optical axis, so the refractive index is irrelevant as is the dispersion. But homogeneity and the absence of inclusions are important. It really is not "straight, unpolished window glass". Have you ever tried your telescope through a window? Don't you think you would immediately notice that you were looking through a solar filter made from straight, unpolished window glass? 

I know that it is notoriously difficult to accurately polish flat surfaces. That's why I tried the film filter in the first place, to see if there would be any improvement in the image. I've used both glass and film filters side by side for about half a year. Both filters provided equally sharp images of the Sun. I might have kept both filters had it not been impossible to clean the Baader.

[N3ptune]

I would be suprised the glass filters we buy in a renown shop were made out of low grade glass or something that is not optical grade.. 

[Stub Mandrel]

Look at it his way, the ND5 filter lest through 1/100,000 of the incident light.

0.05mm pinhole lets through about 1/2,000,000 of the light from a 70mm lens.

So 20 pinholes this size would reduce the contrast of the filter by 50% and double the brightness of the image.

I doubt that your pinholes are even that big.