Red Eyed Susan?

[Cadmium]

Switching to Schott RG665, 665nm longpass filter on the camera lens.

This is getting more interesting now.

1) Simple 665nm IR longpass, with red/blue channel swap (sorry, I could not resist, it looked so much better to me with the swap).

2) Green visual light induced 665nm IR longpass luminescence (LUM). AKA The Pandora Effect.

3) 365nm UV induced 665nm IR longpass luminescence (LUM).

 

 

 

 

[colinbm]

Looking pretty good Steve.

Is the "2) Green visual light induced 665nm IR longpass luminescence (LUM). AKA The Pandora Effect.", narrow band green or a long pass green filter ?

Col

[Cadmium]

Looks like this:

[colinbm]

Thanks Steve, that is why the petals are black in the mono photo ?

Col

[Cadmium]

Partly. The reason the petals are black in the mono photo is:

1) because that part of the flower isn't induced to fluoresce/lum by the green light.

2) because the mono photo is 850nm which has no color difference with the camera sensor

3) there is no reflected IR in the mono photo because there is no IR light, just green light, which only induced the object to fluoresce/lum infrared.

 

I am still unclear if the red in the 665nm flower LUM is red LUM or a trace of visual light leaking through.

I am limited with my green light, I need a stronger bigger green light.

[colinbm]

Thanks Steve

Would a multi Green LED light have a narrower band width ?

Col

[Cadmium]

Narrower than an unfiltered flashlight, but those would still need to be filtered.

[colinbm]

Thanks Steve

[Andrea B.]

I still have some Rudbeckias blooming and I'm now inspired by Steve's work to try some of this cool photography. :D

[Cadmium]

Here is a comparison of 665nm IR LUM and 850nm IR LUM.

[Andy Perrin]

Interesting. Are those using similar camera settings and processing? (In other words, are the petals really darker at 850nm or is that just a processing artifact?)

[Cadmium]

Hi Andy, Yep that was what I was trying to compare there, the difference between the darkness of the two. 850nm is obviously monochrome by nature,

but the 665nm is showing some red luminescence, looks to me.

Settings are the same other than exposure time. 850nm IR LUM requires more exposure time.

[Cadmium]

This time using a sunflower for the subject.

More 365nm UV induced visual fluorescence and IR LUM.

[Andrea B.]

I got nothing from my particular sunflower!! Foo. It might be too old.

 

I did get a bright center from a Rudbeckia though. :D

Used 365-UV LED and various IR pass filters.

[Cadmium]

Hmm, I don't know. Here is my setup.

Absolute darkness. Nothing in the room with any IR or UV.

MTE with U-340 2mm filter on it.

Full spectrum camera with Longpass filter on the lens.

Long exposure.

Paint the flower with the MTE.

I like using 665nm most.

 

Shane pointed out that this is not really truly IR luminescence at -720nm. So we could call it false color IR LUM if we wanted. However, at 850nm we can definitely call it just plain IR LUM.

[Cadmium]

Some things fluoresce more than others. This is to show how luminescent the shell is in IR compared to cadmium.

My original IR Luminescence tests were using some cadmium ceramic pigment stains, which have strong luminescence in IR.

Here is a comparison using three object:

1) stripes of cadmium ceramic stain, high fired, with a clear glaze over the top (top left)

2) shell (top right)

3) old pre-1940's uranium glass marble (front center)

 

These were shot using:

1) normal UVIVF

2) green light induced 850nmm IR luminescence

3) 365nm UV induced 850nm IR luminescence

 

 

Here is another comparison, just to give an idea of the difference in luminescence intensity between the center of the rudbeckia flower and the cadmium ceramic pigment.

[Andrea B.]

Excellent demonstration. Thanks!

 

Love that marble.

 

So cadmium stain or paint is a good test patch for this kind of luminescence.

[Cadmium]

I use cadmium in ceramics, generally mixed with clay, or liquid clay slurry, AKA 'slip' (engobe).

In this test tile, I have several colors of cadmium engobe painted thick on a flat piece of porcelain clay (same clay 'body' formula as the the engobe).

The tile is also glazed with a clear glaze over the top of everything.

Here is a link to the cadmium used in that tile test.

http://www.masoncolor.com/msds.htm

Look down the page for 'Encapsulated", those are the stains containing cadmium.

Click on any one of those to view the 'material safety data sheets' (MSDS).

Cadmium is very toxic, however this material I use is encapsulated, making it possible to work with safely.

Cadmium is used in ceramics for very bright strong reds, oranges, and yellows, even at higher temperatures.

Cadmium fluoresces in IR like a light bulb compared to anything else I have found... so far.

[colinbm]

Hi Steve

I am wondering what this "Encapsulated" process is ?

Could it be that the "Encapsulated" (process) is causing the "Cadmium to fluoresce in IR like a light bulb" ?

Col

[Cadmium]

Here is a link that describes encapsulated stains:

https://digitalfire....ted_stains.html

 

I don't know the answer to your question. This is the only form I have or am willing to experiment with.

Cadmium is used in other art products, paint, etc.. I have seen paint from tubes of oil paint that glow the same way, containing cadmium and other luminescent pigments as well.

The stain does seem to fluoresce even more once the stain is fired, and fused (vitrified).

The test tile fluoresces a bit stronger than the dry pure pigment, and the dry pure pigment is at least three times more condensed than the stain colored engobe,

because the engobe also has a lot of clay, silica, and feldspar in it.

So firing the engobe gives it a stronger fluorescence or luminescence.

[Alaun]

You might look for patent US 4874433 A 'Methods of preparing encapsulated pigments' (a Degussa patent, expired,) describing the process of encapsulating.

 

As the chromophoric substance with Cd seems to come with S, Se, it is not so surprising, they show fluorescence.

[Cadmium]

I was not surprised by it either. Art history and restoration experts use VIIRF to analyze art works.

http://chsopensource...raphy-review-2/

I was only showing the cadmium test tile here as a brightness reference to the other objects.

Just so people would be aware of what to expect if they try this with flowers and such.

I already tried the cadmium a while back separately.

http://www.ultraviol...d-fluorescence/