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Black Anodized Coatings

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#1 calypsob

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Posted 18 February 2019 - 12:04 PM

Your typical black anodized coatings do not block infrared spectrum light, I am not sure if I am the only person seriously bugged by this, or maybe it is something that not alot of people are aware of.

 

I see alot of internal reflection issues lately and while they seem to usually be resolved, I cannot help but wonder how much contrast we are loosing in our images by shooting through black anodized focusers, filters, reducers, and camera bodies lined with black anodized coatings. Sure you can adjust contrast in post processing, but the data that you are loosing to poor contrast before it is recorded by the sensor is un recoverable.

In the past I had taken some example pictures with my dslr and an infrared pass filter, my black anodized telescope was a solid shiny silver behind a 720nm pass filter.

I have not tried a 540nm filter yet but I just ordered one for funzees to see what happens. Imagine the impact this contrast issue would have on Ha and SII.

It would be interesting to see a spectral analysis of generic anodized black to determine exactly where the "black" color drops off. Obviously to our eyes in the visible spectrum this is not an issue. Under infrared though, you have potential to create an ir reflective hotspot at worst and also negatively impact your contrast.

 

Today I found a company that produces a full spectrum anodized coating. Does anyone know anything about this product? https://www.pioneerm...k/optical-black

Would it be logical to start pushing manufacturers to adopt a higher standard coating? I have not intent to fill out an RFQ to get costing on this product, but assuming it is not fiscally unobtanium, maybe we could see something like this 

in our future astro products.

 

If you have a dslr and an infrared pass filter I encourage you to take a snap shot of your gear an upload an image so people can get a better understanding of what I am talking about here.


Edited by calypsob, 18 February 2019 - 12:07 PM.


#2 Jon Rista

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Posted 18 February 2019 - 12:12 PM

You are definitely not the only person bugged by it. So many parts are only anodized, but have no internal microbaffling or flat black paint or anything like that. It is a very serious problem from a reflections standpoint. I have an full set of StellarVue spacers I feel I cannot use, at least not without modification, because they reflect so much light (not just IR, but they reflect a ton of light in general.)

 

Regarding optical black...IIRC, Teleskop Service in Germany uses that, or at least something similar that greatly diffuses light and minimizes reflections, for the internal surfaces of their OTAs. Or at least, for their newts. I am actually much more a fan of dead black paints than just anodization...even the optical black seems to still reflect a bit, including more in IR. I don't understand why internal microbaffling and flat black paint are not standard for all AP parts and accessories that might be exposed to the light path. 


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#3 2ghouls

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Posted 18 February 2019 - 12:55 PM

This was seriously bugging me recently as I had spent big money (for me) on a quad (the now discontinued SVQ86) with an evenly illuminated large imaging circle, but my aggressively stretched flats showed a hotspot. The flats were pretty much correcting, but with certain filters would over-correct. Then I would have to be more aggressive with DBE, and I think that was causing additional problems.

 

Eventually I realized it seemed to be due to some kind of internal reflection interaction between the black anodized spacers and the filters? The telescope internals itself are painted flat black. In any case, I very recently used ScopeStuff flocking material on the inside of all my spacers/adapters (3) and that helped a ton with the hot spot in my flats. Before and after pic of a single flat frame below. It may not have completely solved it, but I thank that it worked enough that I won't have flat over-correction problems anymore.  I have flat black chalkboard paint, but thought I would try the flocking material first as it seemed easier. 

 

screenshot.jpg


Edited by 2ghouls, 18 February 2019 - 12:55 PM.

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#4 Jon Rista

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Posted 18 February 2019 - 01:16 PM

This was seriously bugging me recently as I had spent big money (for me) on a quad (the now discontinued SVQ86) with an evenly illuminated large imaging circle, but my aggressively stretched flats showed a hotspot. The flats were pretty much correcting, but with certain filters would over-correct. Then I would have to be more aggressive with DBE, and I think that was causing additional problems.

 

Eventually I realized it seemed to be due to some kind of internal reflection interaction between the black anodized spacers and the filters? The telescope internals itself are painted flat black. In any case, I very recently used ScopeStuff flocking material on the inside of all my spacers/adapters (3) and that helped a ton with the hot spot in my flats. Before and after pic of a single flat frame below. It may not have completely solved it, but I thank that it worked enough that I won't have flat over-correction problems anymore.  I have flat black chalkboard paint, but thought I would try the flocking material first as it seemed easier. 

 

attachicon.gif screenshot.jpg

I had the same problems in the past with spacers. I had to do one thing or another to diffuse the reflections off of anodized parts. I eventually moved to Blue Fireball spacers. Sadly, they have been hard to get ahold of, as they always seem to be sold out (or at least, did in the past), but every Blue Fireball spacer or adapter is internally microbaffled and painted black (although not quite as "flat" black as I think they could be), and have very low reflection. I've got a complete set of M48 and a mostly complete set of M42 Blue Fireball spacers now, and use them whenever I can. 


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#5 calypsob

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Posted 18 February 2019 - 01:21 PM

This was seriously bugging me recently as I had spent big money (for me) on a quad (the now discontinued SVQ86) with an evenly illuminated large imaging circle, but my aggressively stretched flats showed a hotspot. The flats were pretty much correcting, but with certain filters would over-correct. Then I would have to be more aggressive with DBE, and I think that was causing additional problems.

 

Eventually I realized it seemed to be due to some kind of internal reflection interaction between the black anodized spacers and the filters? The telescope internals itself are painted flat black. In any case, I very recently used ScopeStuff flocking material on the inside of all my spacers/adapters (3) and that helped a ton with the hot spot in my flats. Before and after pic of a single flat frame below. It may not have completely solved it, but I thank that it worked enough that I won't have flat over-correction problems anymore.  I have flat black chalkboard paint, but thought I would try the flocking material first as it seemed easier. 

 

attachicon.gif screenshot.jpg

It certainly makes troubleshooting difficult when you have a huge chain of anodized components.

I use a paint called black 2.0 for painting my components, its easy to clean up and sticks to aluminum really well.  I just hate having to paint astronomy grade equipment myself that I just spent alot of money on. 

I think black 3.0 is going to be availible soon https://www.cultureh...ylic-paint-20ml

 

I actually painted the rear cell of my triplet to see if this would eliminate a bad internal reflection that occurs on bright stars, TBD if it worked. 

In the mean time im hoping more manufacturers will take note. I need to try and make some image examples later on.


Edited by calypsob, 18 February 2019 - 01:27 PM.


#6 calypsob

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Posted 18 February 2019 - 01:22 PM

I had the same problems in the past with spacers. I had to do one thing or another to diffuse the reflections off of anodized parts. I eventually moved to Blue Fireball spacers. Sadly, they have been hard to get ahold of, as they always seem to be sold out (or at least, did in the past), but every Blue Fireball spacer or adapter is internally microbaffled and painted black (although not quite as "flat" black as I think they could be), and have very low reflection. I've got a complete set of M48 and a mostly complete set of M42 Blue Fireball spacers now, and use them whenever I can. 

For this exact reason I buy the cheapest spacers I can find, svbony I think? And paint them internally myself.


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#7 calypsob

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Posted 18 February 2019 - 01:23 PM

You are definitely not the only person bugged by it. So many parts are only anodized, but have no internal microbaffling or flat black paint or anything like that. It is a very serious problem from a reflections standpoint. I have an full set of StellarVue spacers I feel I cannot use, at least not without modification, because they reflect so much light (not just IR, but they reflect a ton of light in general.)

 

Regarding optical black...IIRC, Teleskop Service in Germany uses that, or at least something similar that greatly diffuses light and minimizes reflections, for the internal surfaces of their OTAs. Or at least, for their newts. I am actually much more a fan of dead black paints than just anodization...even the optical black seems to still reflect a bit, including more in IR. I don't understand why internal microbaffling and flat black paint are not standard for all AP parts and accessories that might be exposed to the light path. 

That is interesting I have the GPU coma corrector and wonder if they applied the coating to this instrument, I will have to check later on and do a test. 



#8 AIP

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Posted 18 February 2019 - 02:47 PM

Interesting... Someone who has tried some matt black product? a product that works?



#9 pyrasanth

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Posted 18 February 2019 - 03:00 PM

I've just sprayed the inside of my Moravian M68 adaptor with KRYLON Camouflage Paint with Fusion Technology (Black). This is far blacker than the default inner paint.

 

Flocking material works pretty well. I just wish manufacturers paid more attention to this important aspect of astronomy adaptors.


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#10 SXBB

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Posted 18 February 2019 - 03:38 PM

KRYLON Camouflage Paint with Fusion Technology Ultra Flat Black is what Stellarvue told me that they use inside their OTAs.  It's made specifically to not reflect even IR/UV.  I used it inside the dew shield of an AT65EDQ that I used to own and it worked quite well.


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#11 AIP

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Posted 18 February 2019 - 04:36 PM

Many thanks pyrasanth and SXBB. I just ordered it for my adapters.

Edited by AIP, 18 February 2019 - 04:37 PM.


#12 Terry White

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Posted 19 February 2019 - 08:20 AM

According to this fellow, flat black paints using pigments and not dyes offer the best absorption of IR. http://diffractionli...eur-telescopes/



#13 Chucke

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Posted 19 February 2019 - 01:21 PM

I don't see that it is much of an issue if you have any filters in the image train.  Any good filter should block IR.



#14 Jon Rista

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Posted 19 February 2019 - 03:54 PM

I don't see that it is much of an issue if you have any filters in the image train.  Any good filter should block IR.

Anodized parts still reflect a ton of visible light as well...it can still be quite a problem with filters.



#15 andysea

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Posted 19 February 2019 - 04:23 PM

I typically paint the interior face of all adapters unless they are already painted.

Sometimes I use a black tape by 3m that is very effective. I like it better than flocking because there is no risk of it releasing little fuzzies that can end up on the sensor. I use the tape for all surfaces for which paint isn't practical or if there is the risk to get it on optical components.

Takahashi is pretty good about that, all the internal parts of their scopes, focusers and adapters are painted flat black. I recently bought a baader adapter and that was also painted on the inside.



#16 AIP

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Posted 25 February 2019 - 02:03 PM

Well... today the paint has arrived

 

40245950803_1e284143c5_c.jpg

 

The M92-M72 takahashi adapter was scratched and painted with permanent marker (fix as it reflects the light)

 

40245950603_9a069eb238_c.jpg

 

So I covered the two threads and painted the adapter

 

33335351238_c0303b694e_c.jpg

 

still a little wet

 

33335351188_6813c1c1b3_b.jpg

 

 

40245950693_36ac28fdc8_b.jpg

 

As I have flats made with the piece unpainted I will now take flats with the piece painted. We will see the difference. I suspect that it will improve a lot

 

I'll post it here

 

Alvaro


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#17 astrovienna

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Posted 25 February 2019 - 04:25 PM

I typically paint the interior face of all adapters unless they are already painted.

Sometimes I use a black tape by 3m that is very effective. I like it better than flocking because there is no risk of it releasing little fuzzies that can end up on the sensor. I use the tape for all surfaces for which paint isn't practical or if there is the risk to get it on optical components.

Takahashi is pretty good about that, all the internal parts of their scopes, focusers and adapters are painted flat black. I recently bought a baader adapter and that was also painted on the inside.

Andy, I like the idea of using tape.  Is this gaffer's tape that you're using?

 

Kevin



#18 ezwheels

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Posted 25 February 2019 - 05:04 PM

I just ordered this Krylon paint last week and painted a bunch of spacers and adaptors. It is very matte and looks professional if you mask the parts you don't want painted. I have no idea if it has an effect on my images yet cause... clouds and stuff.frown.gif



#19 AIP

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Posted 06 March 2019 - 08:57 AM

We continue ...

Amazing some manufacturers how they finish the pieces. Some simply anonize in bright black

The adapters of the SX filter wheel.

As standard, look at the flat part of the interior and the part covered in the inside, reflecting if the light shines:

 

nzg9vs.jpg

 

painting it:

10xcbr8.jpg

 

Already painted:

33asxz9.jpg

 

b6xag6.jpg

 

Another, the CCD camera.

The good thing is that this kind of nose, which can be removed to put the wheel of the same brand directly, can be removed, so it can be painted very comfortably.

More of the same, anonized in bright black. Surface that is completely parallel to the lenses, so any fat star that falls here is reflected. Let's not say the party that is created if a star is positioned right in some corner or edge.

This is how the standard light reflects, with a powerful lamp

 

30l0yls.jpg

167kocx.jpg

vh48yw.jpg

2db54d1.jpg



#20 BillHarris

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Posted 06 March 2019 - 04:52 PM

Years ago I used Krylon Ultra Flat Black similarly. I assume that paint is the same as the Camo paint.
I additionally apply another "mist" layer which reduces the reflection even more.
After applying a base coat and a covering coat, I apply a thin tacky coat which I let dry for less than a minute. Lastly I apply a misting coat with the paint nozzle 24-30" from the work. This applies many small, tacky particles to the tacky paint surface and reduces the reflection more by creating light traps. It can rub off with a cloth, but in practice I've not seen it move around and make a dust.


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