24 replies to this topic

[Raymondhow]

On eBay I found inexpensive filters made of "PET-coated Film for Sun Observing". I'm wondering if that makes a good filter, and is it safe? How does it compare to Baader film? Thanks.

[astrokeith]

A potential minefield!

 

The lists I see dont specify the actual optical density. Thats the first danger & clue.

It's very important that the film is 'stress free' both in manufacture and mounting on the scope. Otherwise it may introduce effects.

 

The principle is good. Many scientific research materials are made this way, but they are specified.

 

Cheap films on eBay or Amazon raise issues. I certainly wouldn't look through one, but possibly for photographic work? They could be transmitting IR or UV!

[steveward53]

Given that genuine Baader Astrosolar Safety film is not expensive by any means I cannot imagine why anyone would even consider trying to save a couple of dollars by gambling on an anonymous product from Fleabay , Amazon , Ali-express , Temu or any of the myriad of "bargain basement" sites out there.

 

Rather than waste time seeking some sort of approval from folks on here ( who I'm 100% confident that to a man will give the same advice) just get the Baader film and save yourself the endless sleepless nights worrying (and the potential risk of eyesight damage.

[cengell]

All great advice in the last 3 post.. I have purchased 2 of these eBay & Aliexpress Solar films and they work, but when I was researching it more there is a standard that NASA specs. does Baddar and Thousand Oaks Optical and Seymour Solar comply YES! I don't recall the ISO# and when I asked the made in China sellers they said they would contact the factory and did not hear back.

 

My thinking now is I got the metal frame which is great and I can remove the made in China film and replace it with the 3 above if it's made in the size which I think they do..

 

Bottom line is it works, but safe as needed unknown, and I have viewed through it and no issues as my plan is imaging so my eye's will be safe.

 

So a suggestion if you like the made in China metal frame like I do then get them and remove the Film and get a quality and tested proven film for the 3 above... 

 

Safety is utmost important. 

 

Christopher

 

P.S the ISO is ISO 12312-2 Compliant.

Edited by cengell, 06 July 2025 - 09:24 AM.

[Raymondhow]

Thanks for the quick feedback guys... pretty much as I expected. Yes safety is #1, so Baader it is. Don't think I wasted my time, because someone Googling on the same question might land on this thread.

 

Clear skies.

[cengell]

Thanks for the quick feedback guys... pretty much as I expected. Yes safety is #1, so Baader it is. Don't think I wasted my time, because someone Googling on the same question might land on this thread.

 

Clear skies.

More info, reason I suggested the Thousand Oaks Optical brand is that's what NASA uses. Also it is the sharpest thin Solar film made? This is why I am ordering some to replace the made in China film..

 

I think you are in the US, so look for Thousand Oaks Optical... Can't beat the quality and price...

 

Please report back as I will as well..

 

Christopher

Christopher

[steveward53]

More info, reason I suggested the Thousand Oaks Optical brand is that's what NASA uses. Also it is the sharpest thin Solar film made? This is why I am ordering some to replace the made in China film..

 

I think you are in the US, so look for Thousand Oaks Optical... Can't beat the quality and price...

 

Please report back as I will as well..

 

Christopher

Christopher

Baader film knocks spots off Thousand Oaks and Seymour solar films as far as clarity and fine details are concerned.

 

I rather think that if NASA uses the TO material it will be for purely 'patriotic' reasons not for quality.

 

I've tried them all and the others are in my opinion best left for eclipse glasses and little else.

Edited by steveward53, 06 July 2025 - 04:01 PM.

[Raymondhow]

I was thinking to go with the Baader AstroSolar Filter from Agena Astro. But was also considering the AstroZap Visual Baader from High Point. (Will be going onto 8" Orion Dob.)

Edited by Raymondhow, 06 July 2025 - 05:16 PM.

[Don W]

Why would you take a chance of damaging your eyes for a few bucks?

 

Get a premade filter from Baader or Thousand Oaks or buy film from them and make your own filter.

 

THE END!

[cengell]

Why would you take a chance of damaging your eyes for a few bucks?

 

Get a premade filter from Baader or Thousand Oaks or buy film from them and make your own filter.

 

THE END!

Thanks for the advise, so this is what you are suggesting "Baader Solar Sheets" correct? I see Baader has 2 types a 3.8D and a 5.0D and the 5.0D is for viewing and imaging? The 3.8D is NOT for viewing but imaging without telescope and eyepiece's?

 

So get the 5.0D I think is correct?

 

Thank you

Christopher

Edited by cengell, 06 July 2025 - 10:37 PM.

[Raymondhow]

Of the two Baader ready-made filters, think I'm persuaded by the AstroSolar from Agena which claims the film is "mounted entirely stress free". With the Astrozap from High Point, you can see wrinkles in the film right in the picture, which I imagine can be detrimental to the image. 

[steveward53]

Of the two Baader ready-made filters, think I'm persuaded by the AstroSolar from Agena which claims the film is "mounted entirely stress free". With the Astrozap from High Point, you can see wrinkles in the film right in the picture, which I imagine can be detrimental to the image. 

Wrinkles are not only acceptable but recommended by the manufacturer and have no detrimental effect on performance.

 

Having the film stretched taught is ill-advised.

[NuovaApe]

Thanks for the advise, so this is what you are suggesting "Baader Solar Sheets" correct? I see Baader has 2 types a 3.8D and a 5.0D and the 5.0D is for viewing and imaging? The 3.8D is NOT for viewing but imaging without telescope and eyepiece's?

 

So get the 5.0D I think is correct?

 

Thank you

Christopher

Hi Christopher - OD (Optical Density) is a "10 to the power of" value. A small change in OD gives a big change in % transmission.

 

OD5: 10^5 = 100,000, which means it allows through 1/100,000th of the input light.

Or 100/100,000 = 0.001% transmission.

This is for visual, or imaging.

 

OD3.8: 10^3.8 = 6309, which means it allows through 1/6309th of the input light.

Or 100/6309 = 0.016% transmission.

This is for imaging only.

 

Just looking at the numbers - 0.001 vs 0.01 you can tell the OD3.8 is a factor of 10-ish brighter.

The 3.8 is exactly 10^(5 - 3.8) = 15.8, almost 16x brighter.

Dangerously bright for the human eye, but ok for cameras.

 

"The 3.8D is NOT for viewing but imaging without telescope and eyepiece's?"

 

You still need the telescope, but only use a camera and never an eyepiece.

The 16x brightness of the 3.8 means faster exposures and much luckier imaging.

 

I've bought these "unknown quality" solar filters purely for their 3-screw lens cell - far better than I could make from cardboard.

I soaked them in hot water just boiled in the kettle, to soften the glue in the cell.

Then removed the film and replaced with Baader.

 

Ed.

[astrokeith]

By way of choice of film ...

 

The Seestar 50 comes with a solar filter, stated as being Thousand Oaks. I felt the image was 'soft' and so made a Baader replacement (OD5).

The improvement was readily apparent, not just sharpness but now the solar surface granularity being visible too. Others who saw the difference agreed 100% and have also replaced their filters. This too has been reported in various forum postings.

 

I would have expected Thousand Oaks film to be good, based on their reputation for glass filters. I doubt they are manufacturing the film themselves as the process is nothing like the glass deposition process. The Seestar filter is thicker, but brighter (probably nearer OD3.8) and the back side appears black, The black rear side suggests the metal film has been deposited on a sheet that is itself black. Being thick this will produce scattering.

 

Does any one have a Thousand Oaks solar filter that is not from a Seestar and can report on these comments - in particular is the rear side black?

[Don W]

Thanks for the advise, so this is what you are suggesting "Baader Solar Sheets" correct? I see Baader has 2 types a 3.8D and a 5.0D and the 5.0D is for viewing and imaging? The 3.8D is NOT for viewing but imaging without telescope and eyepiece's?

 

So get the 5.0D I think is correct?

 

Thank you

Christopher

Yes, the 5.0d. The other is for imaging.

[Don W]

The one thing everyone needs to know is that the filter MUST block UV radiation. I have seen videos on YouTube where some idiot is making solar filters out of Mylar food packaging. Has it been tested for UV transmission? Absolutely not. Yes they may show sunspots, but if UV is coming through then they may damage their eyes. 

[Raymondhow]

Wrinkles are not only acceptable but recommended by the manufacturer and have no detrimental effect on performance.

 

Having the film stretched taught is ill-advised.

On the AstroZap filter, to me the wrinkles around the edge look like the film has been stretched. 

https://www.highpoin...scopes-az1004-1

Edited by Raymondhow, 07 July 2025 - 03:11 PM.

[steveward53]

On the AstroSolar filter, to me the wrinkles around the edge look like the film has been stretched. 

https://www.highpoin...scopes-az1004-1

If it had been stretched it would resemble a drumskin with a tight , smooth appearance.

 

That image shows it a tad tighter in one direction but nothing to worry about , it looks like pretty much every filter I've ever made from a sheet of film and an embroidery ring ... 

[Raymondhow]

That image shows it a tad tighter in one direction but nothing to worry about , it looks like pretty much every filter I've ever made from a sheet of film and an embroidery ring ... 

It looks a lot like the filter I got from Orion many years ago, which eventually got damaged.

 

This model appears to be less stressed. 

https://agenaastro.c...r-astf-200.html

 

Quite an extensive blurb, claiming it will "perform like a high precision plane-optical window".

[ch-viladrich]

Quite an extensive blurb, claiming it will "perform like a high precision plane-optical window".

This is indeed the case. Here is an image taken with the Astrosolar ND 3.8 and a Mewlon 250:

[steveward53]

Quite an extensive blurb, claiming it will "perform like a high precision plane-optical window".

Fact not hyperbolic claim ... 

[cengell]

Hello all, I have a word of concern! I wrote an email to Badder as I find it interesting that badder does not sell the larger Solar Film 5.0D 250mm x 500mm in the USA, as I can only find the smaller like 200mm max width or smaller..

 

Got a reply that first said, "it's been over 2 years that Baader has had film sold in the USA but could be old stock", or 2, it's not a Badder film as it's been over 2 years, but possible?

 

Also I ordered whats being called "AstroZap - Baader Solar Filters × 1 Fits 215mm-225mm dia. whole ring" and some of the film AstroZap - Baader Solar Sheets × 1 250mm x 500mm.

 

The factory contact is be reached out to see if it's legit?

 

I hope it is real and if storage good should be fine, as I was now sold on the Baader film and safety... 

 

I will report back.

 

Christopher

 

P.S AstroZap may be using Explore Scientific Solar film, but not sure if it's made by Baader? 

Edited by cengell, 07 July 2025 - 05:19 PM.

[Raymondhow]

This is indeed the case. Here is an image taken with the Astrosolar ND 3.8 and a Mewlon 250:

Very nice, I'm sold! 

[steveward53]

Hello all, I have a word of concern! I wrote an email to Badder as I find it interesting that badder does not sell the larger Solar Film 5.0D 250mm x 500mm in the USA, as I can only find the smaller like 200mm max width or smaller..

 

Got a reply that first said, "it's been over 2 years that Baader has had film sold in the USA but could be old stock", or 2, it's not a Badder film as it's been over 2 years, but possible?

 

Also I ordered whats being called "AstroZap - Baader Solar Filters × 1 Fits 215mm-225mm dia. whole ring" and some of the film AstroZap - Baader Solar Sheets × 1 250mm x 500mm.

 

The factory contact is be reached out to see if it's legit?

 

I hope it is real and if storage good should be fine, as I was now sold on the Badder film and safety... 

 

I will report back.

 

Christopher

 

P.S AstroZap may be using Explore Scientific Solar film, but not sure if it's made by Badder? 

BAADER not BADDER.

[cengell]

Got an update: Baader does make this film apparently is a few years old. So should be a real Baader..

 

Thanks

Christopher