How to do UV Induced Infrared Fluorescence

[Foxfire]

Happened to have one such IR filter that glows a bit IR when UV is shined on it (Kolari 62 mm K665 Infrared Pro Slim G3). In practice this effect is really not noticeable when attempting UViIRF. Still, i would consider to use UV-cut filter with this particular filter.

 

Don't know if it's possible, but could a UV-cut filter also exhibit IR fluorescence? Better to test i quess.

[Lou Jost]

2 hours ago, Foxfire said:

Happened to have one such IR filter that glows a bit IR when UV is shined on it (Kolari 62 mm K665 Infrared Pro Slim G3). In practice this effect is really not noticeable when attempting UViIRF. Still, i would consider to use UV-cut filter with this particular filter.

 

Don't know if it's possible, but could a UV-cut filter also exhibit IR fluorescence? Better to test i quess.

Incredibly, some of the UV-cut filters do fluoresce.

[ulf]

6 hours ago, Lou Jost said:

Incredibly, some of the UV-cut filters do fluoresce.

They are not "UV-Cut filters" even if used for that. They are long pass filters, from pale yellow, orange, red all the way into IR.

It is only the filters of ionically coloured glass materials that have fluorescence.

 

Filters with a thin coloured filter laminated between glass like filters from Tiffen like Tiffen 8, Tiffen 12 ... don't show any fluoescence.

[ulf]

The very pale yellow Tiffen 2A cut at 405nm.

The Tiffen 2E cut at 415nm.

Neither of them have fluorescence.

None of them are AR-coated as the better Zeiss T* UV, but you get some reduction of the blue colours that are often rather dominant in UVIVF, especially with the 2E

 

[Doug A]

Any advantage in stacking two 2E filters? Couldn't find my, never used, Kodak Wratten 2E gel for months.  Ordered a 77mm Tiffen 2E haze screw in filter. Today the gel reappeared. Trying to get the UVIVF/UVIIF UV Haze filter hierarchy correct in my head. From less to best it is Tiffen 2A, Tiffen 2E, and Zeiss UV?

Thanks for the help,

Doug A

[ulf]

11 hours ago, Doug A said:

Any advantage in stacking two 2E filters? Couldn't find my, never used, Kodak Wratten 2E gel for months.  Ordered a 77mm Tiffen 2E haze screw in filter. Today the gel reappeared. Trying to get the UVIVF/UVIIF UV Haze filter hierarchy correct in my head. From less to best it is Tiffen 2A, Tiffen 2E, and Zeiss UV?

I agree about your grading.

 

I do not think there are any advantage of stacking two 2E Filters.

That will emphasis the weakness of most Tiffen filters. They are not AR coated.

I many reviews they lag in performance to other brands with excellent coating like the Zeiss UV.

Without AR coating there are increased flare from every filter surface...

 

The UV-blocking of both 2A and 2E are quite good in the UV region.

 

[JMC]

As Colin and others have said, the Zeiss T* UV filters are a great option for blocking UV and not fluorescing. Note sure whether I shared it before or not, but last year I published a paper looking at fluorescence of filters and their blocking - https://www.mdpi.com/2313-433X/8/6/162

 

This was something I'd been working on for a couple of years, as it started out as thinking about what would be a good alternative to the no longer available Schott KV-418. Of the filters tested Zeiss T* UV had the best overall combination of UV blocking and low fluorescence (for general use anyway).

 

UVP got a mention in the credits....

[colinbm]

Excellent article thanks Jonathan

[JMC]

6 hours ago, colinbm said:

Excellent article thanks Jonathan

No problem. Glad you like it Colin.

[Doug A]

Very informative paper @JMC. You always write clearly and make things easy, for me, to understand.

Thanks,

Doug A

[JMC]

Thanks Doug.

[Doug A]

First attempt. UVIIRF of cucumber. Kolari Vision modified Pentax K-1 full spectrum with metal Nikon EL-Nikkor 80mm lens. Used Hoya R72 and Tiffen Haze 2E filters. Nemo 365nm torch under cucumber. ISO 100, F11 at 15". Set Pentax as low as it would go on Kelvin scale (2500). White balanced rest of the way in Pentax DCU5/Silkypix. 

Thanks for looking,

Doug A

[colinbm]

Looks good Doug, thanks for showing.

[Doug A]

Thanks @colinbm. A question for @ulf about his fake Zeiss UV filter. Does it have the weird labeling of Japan on the filter ring? The ones I saw have the letter P larger than the other characters. Also read the fake filter boxes have two plastic hinge pins instead of OEM metal. 

 

A very reputable camera dealer has an used Zeiss T* UV for half the normal price. They wouldn't knowingly sell counterfeits, but the fakes might fool them.

Thanks,

Doug A

[ulf]

17 hours ago, Doug A said:

Thanks @colinbm. A question for @ulf about his fake Zeiss UV filter. Does it have the weird labeling of Japan on the filter ring? The ones I saw have the letter P larger than the other characters. Also read the fake filter boxes have two plastic hinge pins instead of OEM metal. 

 

A very reputable camera dealer has an used Zeiss T* UV for half the normal price. They wouldn't knowingly sell counterfeits, but the fakes might fool them.

Thanks,

Doug A

I have no proper Zeiss filter to compare with, but the one I got is a very well made copy.

The letter P on the filter ring is the same size as the other characters. feels engraved and filled with white except for the red T*

The round filter box looks quite proper high quality and have metal hinge pins.

The AR-coating is also top class. Easy to clean and water repellant.

 

I think this fake filter works excellent as a protective filter.

It is only lacking the UV-Cut you have on the proper ones.

Even the hologram seal strips looks legit.

 

Maybe they are made in the proper site, but that someone missed one coating step for UV-cut. They might be supposed to be scrapped and found their way to the market instead.

[Doug A]

Thank you @ulf. This helps a lot. They fixed all the original "inaccuracies", except for cutting UV. Bummer. Rules out the used one for me.  Too much time and trouble to return it, if it doesn't work.

Thank you for the extra information,

Doug A

[Lou Jost]

1 hour ago, Doug A said:

Thank you @ulf. This helps a lot. They fixed all the original "inaccuracies", except for cutting UV. Bummer. Rules out the used one for me.  Too much time and trouble to return it, if it doesn't work.

Thank you for the extra information,

Doug A

There are real ones out there; I got two on eBay and they both work perfectly.

 

[Doug A]

Thanks @ulf and @Lou Jost. Emailed seller and he replied that they'd test it for me, but didn't have a UV light source. Said to send it back under 180 day warranty if it didn't perform properly. Love dealing with UPP. Filter is on the way.

Thanks,

Doug A