Nichia UV LED Lamps

[igoriginal]

BTW, the developing "consensus of opinion" is that our broadband DSLRs probably cannot photograph below 300nm.

 

I would be inclined to postulate, though, that this "opinion" is based primarily on the fact that it is the UV pass filter that is usually the limiting factor, for the clipping of data down to the 300nm line in particular. And not necessarily every single available lens or converted camera.

[Shane]

Why are we to assume that the dyes inside the Bayer Array cannot interact with any bandwidth of radiation?

 

Absorption, reflection, transmission are interactions. When the manufacturer picked the dyes for the Bayer array they didn't care about its UV or IR characteristics because the knew there was an ICF to resolve that.

 

Am I to assume, then, that the Spectrosil 2000 converted "Astrophotography-optimized" camera in my possession is mostly a gimmick?

As I said, not a reality for a consumer camera. If you have a high dollar specialized astrocam optimized for DUV then throw it in front of a double monochromator with a DUV light source and see what the quantum efficiency of your sensor is at that wavelength.

 

You can experiment all you want but testing at that wavelength will not be easy. I have worked with a 220nm DUV source for characterizing luminescence excited at the band gap and the filters are expensive and do not last long.

[Shane]

I would be inclined to postulate, though, that this "opinion" is based primarily on the fact that it is the UV pass filter that is usually the limiting factor, for the clipping of data down to the 300nm line in particular.

 

QE tests on DSLRs with the ICF removed and no lens or filter indicate practical application to around 330nm. You can push it to sub 300nm with non-practical exposure times.

[igoriginal]

Speaking of specialized lenses to photograph in the UV-B, UV-C, and even lower ...

 

... take a look at this interesting discovery: It seems that lens elements made from pure gold can transmit gamma-ray bandwidths, and diffract and focus them into a usable image ... just like the visible range is diffracted and focused with silicon dioxide!

 

http://www.mpg.de/57...es_gamma_optics

[igoriginal]

QE tests on DSLRs with the ICF removed and no lens or filter indicate practical application to around 330nm. You can push it to sub 300nm with non-practical exposure times.

 

Thus, basically, for all intents and purposes ... I should stop racking my mind over less practical theoretics ... and just focus on improving my UV-A photography. Thank you for putting my tireless mind at ease. :D

 

Well, it only comes to show you how easily I get distracted by other tangents. :D

 

(Maybe I can put my 230-400nm range LEDs to good use, by building a "death ray", instead? Haha. Andrea ... about those robotic arms ... do you have a pair I can borrow? Joking.)

[Alex H]

Thanks Shane for such detailed explanation!

[colinbm]

I have just received a Nichia 365nm LED model # NSHU550B.

It is supposed to have a half width of 10nm.

http://www.ledsales.com.au/pdf/nshu550b.pdf

I was told it wasn't very bright....that is true, but the spectrum is sooooo wide ?

About 370nm to 650nm ? Why ?

Col

[Alex H]

Are you accounting for a huge increase of sensitivity of your sensor in the visible range, comparing to UV??? Did You check if there is nothing in your system that can fluoresce under UV light? A tiny spec of paper dust can have a considerable impact.

 

If you did all of this, than please forgive me and ignore my statement.

[colinbm]

That is interesting thanks Alex.

I will have to have a look & check inside the camera & see if their is anything that may fluoresce under UV light.

There is always something more to know & learn :D

Col

[Shane]

If you think it is emitting in the visible then shoot it in complete darkness using the Baader UVIR block filter and see if you get anything.

 

If that is 10nm BP at FWHM, then at FW10% it will be much wider. It is not unusual for these to leak a tiny bit of blue.

 

Also overdriving it will change the peak wavelength.

[colinbm]

Thanks Shane

I'll try again with an Andrea-U filter.

Col

[Johan]

I have been using a 76 LED torch from ebay but I am about to switch to an old flash with gel. For a £25 buy I'm not too unhappy with the ebay torch - it does fluorescence and that's all I want. Gives me purdy reds, oranges, greens, yellows... but cam has to be at iso 6400, 2.8, 1/60 (zoom at 80mm, Pentax K5). Hence the switch to a flash. I have a very old (1970s?) Paffrath Kemper PK UR130Z ringflash and the front cover comes off so I'm just awaiting some gels from eBay to see how well that works. It's a flash with no controls so useless for me... but very very strong so might work out of with the barrier and filter in front.

[JCDowdy]

BTW, the developing "consensus of opinion" is that our broadband DSLRs probably cannot photograph below 300nm.

This is anecdotal and experience-based evidence at this point.

 

If I knew where to go, then I would take my broadbands and pay to have them measured just so we could finally have some facts.

 

I am working on that, when I am ready you are first in line!