TIL Prizm Lens don't block any infrared

[Dbninc]

I now have a full spectrum camera.

I've had this Pentax Q10 for a while as a nice little pocket interchangeable lens camera that can also shoot raw files like my bigger cameras. Just 12 megapixels is kind of dated now days (the cam is from 2010), but still does very decent quality for the small 1/2.3" sensor.

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Basically the 'baby' digital version of my 1980s Pentax MX (which was considered one of the smallest SLR they made with a bright viewfinder).

I got it really cheap as they were originally rather expensive and people weren't going to pay $800 for a small 1/2.3" sensor. As a result the lens came cheap now. It's now at the point where I couldn't even sell the whole kit for more than 150, so I wondered... can it be full spectrum.

Apparently it can, and rather easily too... you simply cut the IR Cut glass from the matte box it's suspended in. So that's what I did. Basically lose automatic dust removal, and the ability to shoot 'normal' pictures unless you put a hot-mirror filter in front of the lens.

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So now it can see full spectrum. I don't own a UV-only-passing filter, but I have a Schott BG3 Dual Bandpass filter which allows UV and IR light in, but blocks out visible light. I never bothered using it because none of my cameras could see UV, and I already had much better filters for strictly passing the IR side. But it was on sale so I got it long time ago anyways just in case I did get something that could use it.

It'll show between about 225nm to about 450nm above 0.25+ light transmission, basically all of UV-A and UV-B, and a fair bit of UV-C. Also shows Infrared from about 720nm beyond.

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Today is bright and sunny, so I went outside. With a UV/IR dual bandpass filter you see the blues of UV, but also Infrared light, giving you sort of that "Goldie" look straight out of the camera.

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Then when I put the Prizm Shallow Water lens in front, it blocks out the UV (all the blue above).

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So test wise to damaged lens, it would be mostly sufficient, especially if I use a blacklight (no IR transmission at all).

For me to strictly only see UV A/B/C thru the camera without any purple/blue visible light (that little bit of range between 400nm and 450nm), I would need to buy this guy Hoya U-340 52mm x 2mm thick UV Pass Ultraviolet Dual Band IR Filter | eBay so that it only covers the UV passing range.

This is fascinating stuff, you have a pm incoming

 

[KarlBlessing]

This is fascinating stuff, you have a pm incoming

Got your pm. But doesn't seem like I'm able to reply yet (need to be a member for 14 days). My signature's personal website does have some social links and I would be down for that now that the capability to see it is here.

 

[KarlBlessing]

Well they do definitely block 100% of all UV, noticed my car windshield blocks some, with the side windows blocking none or just about none. (according to this article about 5 years ago, most cars including high end ones, block around 95-98 of UV-A, but side windows usually nothing).

 

[Dbninc]

Well they do definitely block 100% of all UV, noticed my car windshield blocks some, with the side windows blocking none or just about none. (according to this article about 5 years ago, most cars including high end ones, block around 95-98 of UV-A, but side windows usually nothing).



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This lens only shows UV light, correct? What are these splotches, differences in the coating on the rear of the lens?

 

[KarlBlessing]

This lens only shows UV light, correct? What are these splotches, differences in the coating on the rear of the lens?

Reflection of the UV light behind me coming in from the car's side and rear window (it's easier to see as a video because you can see the reflection changing as the angle is tilted).

No UV light is getting thru the lens at all, but it is reflecting it off the back easily, but we usually don't have UV light coming from our face side.

 

[KarlBlessing]

Pending when I actually get some kind of 'holder' set up and probably smooth flat paper to act as the shadow cast (though ideally parallel with the lens would be best if I get the light source as direct as possible).

The only thing flash-wise I have that emits any amount of UV is my old 750W studio strobe (seems I would need a special UV enhanced xenon flash for best bright artificial result), as opposed to using one of my 365nm or 395nm UV flashlights.

This is the Prizm Low Light, about as transparent as you can get besides just clear. It has 75% Visible Light Transmission, but still advertised as blocking all UV 400nm and below. Well... it does.

I consider it total blockage when the ripples in the opaque microfiber cloth give the same darkness of shadows as the lens does.

 

[Scythe]

Great research

 

[Ventruck]

Great thread.