How to do UV Induced Infrared Fluorescence

[Doug A]

Grabbed some pistachios after work and decided to try UVIIF. I was kind of tired and things didn't go as well as expected. First mistake was using stock Pentax 645z. Hey, it works great for UVIVF, so why not here? Because it takes a very long exposure to force enough IR thru the stock sensor filter. Will use full spectrum camera next time.

 

There are other questions.

1. Using Nemo torch or Adaptalux UV arms Is it enough to use a 25 red or Hoya 72 filter on the camera lens? Or is the Tiffen Haze 2E also needed to block UV?

2. Does my custom IR landscape white balance work here? This isn't vital since I shoot Raw, but nice to get in the ballpark. 

Thanks,

Doug A

[ulf]

I can give a few answers based on real facts, even if I have very little personal experience of UVIVF or UVIIF.

 

The Nemo torch is much more powerful than the Adaptalux arms. I had a discussion with the Adaptalux designer about that.

However the square distance rule is always valid. ( the optical power is reduced to 1/4 when the distance increases by 1/2 )

Close enough the Adaptalux arms might be enough.

 

The reason for stacking a Tiffen filter in front of any ionic long pass filter is to block UV.

Most ionic longpass filter materials have their own fluorescence and exposed with enough UV power they might add some unwanted light to the recorded image.

I have just seen that filter fluorescence looking at them and have no idea if they shine in NIR too.

Often the back scattered UV light from the motif is not bright enough, but it is good to know about it.

 

You can see the same material fluorescence in several accidental lenses usable for UV photography.

One of them is the EL-Nikkor 80mm old metal type. Several of it's lens elements becomes hazy whitish of fluorescence under an UV-torch.

 

Hope some of my answers are of use.

[colinbm]

The BEST UV blocking filter is the Zeiss T* UV, no ifs or buts !
https://www.zeiss.com/content/dam/consumer-products/downloads/photography/datasheets/en/filter/datasheet-zeiss-uv-filter-en.pdf

[ulf]

BUT! there are very well made fake copies out there, that look very good, but do not cut UV.

 

I bought one om Aliexpress just to verify that it was a fake. It was.

Except for the low price it looked very authentic.

Box, Hologram-seals, labels, mechanical quality and AR-coating is very good.

Might be a good protective filter.

 

There is a risk that some copies are sold to a higher price.

 

Could easily be verified as OK by testing if it blocks an UV-torch.

 

 

[colinbm]

That can be said about anything Ulf.
Even the news is fake & even women are becoming fake too !
So, Know your product & how to test it !

[colinbm]

@Doug A You might try Cyan induced IR fluorescence too ?

[dabateman]

You may have IR leakage from your light as well. You may want a S8612,  BG39 on the light to block IR. Then a lp IR filter on the camera lens to look for IR.

There is IR in most household lights. So this also has to be done in the dark.

IR fluorescence is weak in most things except cucumbers. If you have one you could try that to get a look. Many flowers alsohave nice UVIIRF.

If your camera allows for dialing in a low Kelvin,  thats what you want. Olympus cameras can dial in to 2000. 2100-2300 is about right for the white balance, a stock preset around there might work, if your camera can't be dialed in low.

 

[Fandyus]

5 hours ago, colinbm said:

@Doug A You might try Cyan induced IR fluorescence too ?

It even works with green. I have tried it myself. Made trichromes with it the other day.

One just needs to put an IR blocker on the lightsource itself, otherwise you risk polluting the result.

[Andrea B.]

 

2. Does my custom IR landscape white balance work here? This isn't vital since I shoot Raw, but nice to get in the ballpark. 

 

Infrared fluorescence, like most fluorescence, has a peak and tends towards the narrowband. It's possible your current WB presets won't work as well as they do on landscapes. But who knows until you try it, right?  I would initially experiment by "clicking around" on the raw photo.  But it is false color, so you can let it be whatever looks nice to you.

[Andrea B.]

Do UV torches really output some IR???

 

I am being very lazy. I'm pretty sure we have discussed this in the past. It's just that if I have to look up one more thing today, I'll prolly fall over in a heap. Spent half he day looking stuff up. Whew!

[Andy Perrin]

7 minutes ago, Andrea B. said:

Do UV torches really output some IR???

That seems very unlikely? I mean it's easy to try the experiment. Just put an IR-passing filter on a converted camera and shine the torch at something IR-reflective that doesn't fluoresce much like PTFE. You should see all black unless the torch emits IR.

[Doug A]

Thanks everyone for all the info. Thanks to @ulf for the warning about filters and EL-Nikkor 80 fluorescence. Hadn't considered that reason for using UV blocker. Surprised there are counterfeit Zeiss filters, even copying the hologram. Wow.

 

@colinbm point taken about T* UV. Might pick one up just because sizes smaller than my Tiffen Haze 2E 77mm are available. If it is also better that would be another plus. The cyan induced IR fluorescence also looks interesting. 

 

@dabateman I will try the Schott S8612 on the Nemo/Adaptalux. Thanks for the Kelvin tip. Pentax K-1 only dials down to 2500, but that gets closer to the "correct" WB.

 

@Fandyus the trichrome IR fluorescence is great. Still remember the apple image. This will be further in the future.

 

Thanks @Andrea B. for the WB tips.

 

@Andy Perrin appreciate your test for UV torch IR contamination. Easy to test to administer.

 

While composing this post, my email lit up acknowledging, my custom tube linestage has finally shipped. It has moved from Australia to Singapore. Soon it will be in the USA and I'll be very busy listening to music. I'm patient, but over 5 months is a long time to wait. I will return to UVIIF at a later date.

Thanks again everyone,

Doug A

[ulf]

1 hour ago, Doug A said:

Thanks everyone for all the info. Thanks to @ulf for the warning about filters and EL-Nikkor 80 fluorescence. Hadn't considered that reason for using UV blocker. Surprised there are counterfeit Zeiss filters, even copying the hologram. Wow.

 

About the EL-Nikkor it was absolutely not a warning.

It was ment to show that the effect even if visible when shining a torch at the lens elements causing fluorescence do not matter at all. 

Many other accidentally UV-capable lenses do the same and the EL-Nikkor is one of the best. 

 

However the fluorescence from many ionic filter glass materials is stronger and in some situations there might be some effect on the image.

 

Here are the FAKE filters:

https://www.aliexpress.com/item/1005004070717364.html

There are several stores selling them on Aliexpress

 

[Lou Jost]

On 7/26/2023 at 4:24 AM, colinbm said:

The BEST UV blocking filter is the Zeiss T* UV, no ifs or buts !
https://www.zeiss.com/content/dam/consumer-products/downloads/photography/datasheets/en/filter/datasheet-zeiss-uv-filter-en.pdf

I second that.

[Lou Jost]

Here is some full spectrum plant fluorescence, excited by 365nm and dominated by IR.

[colinbm]

Thanks Lou
This is a very bright, colourful image.

[Lou Jost]

Thanks Colin. This would be even more colorful without the IR; there is so much IR fluorescence that it covers up some of the other, more subtle colors.

[Andrea B.]

Lou: stunning photo! Love it.

[Lou Jost]

25 minutes ago, Andrea B. said:

Lou: stunning photo! Love it.

Thank you Andrea. These are mostly liverworts (bright orange-red with blue reproductive parts), mosses (green) and lichens (blue), and a few grasses and other plants (blue/purple/orange).

[Doug A]

Impressive @Lou Jost. So much color. Love it. What filters did you use?

Thanks,

Doug A

[Lou Jost]

29 minutes ago, Doug A said:

Impressive @Lou Jost. So much color. Love it. What filters did you use?

Thanks,

Doug A

Thanks! It was a year or two ago. I think it was the La La UV filter (maybe double thickness) on the flashlight, and Zeiss T* on the camera lens. Sony A7R FS mod. It was a long exposure and I used UV "light painting" , probably a couple of minutes of moving the flashlight around from different angles. That softens the light and eliminates stark shadows. I usually used in-camera long-exposure noise reduction as well; a dark frame of equal exposure length is taken and subtracted from the actual exposure. This works really well.

[Doug A]

@Lou Jost thanks for the extra information. Fabulous capture. I thought UVIIF might have less color than UVIVF. Your image proves that wrong.

Thanks for sharing,

Doug A

[Foxfire]

Additional note that when using UV-cut filter while doing UViIRF it would be better to use it in front of the IR filter, because IR filters might also start to glow IR under UV. This can also be checked/tested.  

[Andy Perrin]

Wow, now that is reallly getting far fetched! Ok we should do the tests. However fluorescing filters and lenses have never been observed to cause actual problems in the history of this site (at least from when I arrived in 2016 or so).

[ulf]

21 minutes ago, Andy Perrin said:

Wow, now that is reallly getting far fetched! Ok we should do the tests. However fluorescing filters and lenses have never been observed to cause actual problems in the history of this site (at least from when I arrived in 2016 or so).

Even if there are no cases observed it is not a bad practice to do so if a good UV cut filter is available.

This is not only true for ionic IR-filters, but for all ionic long pass filters that have a material fluorescence.

 

This is in a way similar to the need for using a lens hood for UV photography.

I never do that, but then I do seldom use dichroic UV-Pass filters, that are more sensitive to stray light disturbances.