Useful Reference Objects for UV Test Photos

[Andrea B.]

The typical scene for testing a UV lens often includes

• a Color Checker Passport,
  
• some kind of UV-stable white standard, and
  
• a flower with a known UV-bullseye signature such as a dandelion, rudbeckia or sunflower.
  

I'm sitting here wondering what I could add to that ?? There must be some other ordinary objects out there which would be useful reference objects for UV test photos.

 

BTW, there is also the excellent and interesting UV-pass filter test, not new, but recently revived in the last couple of years by some UV shooters around the web such as Steve Smeed and Enrico Savazzi. This requires an investment in a range of narrow UV-bandpass filters. Those are nice to have, but can be pricey.

 

Anyway, I'm wondering if you have run across any ordinary objects or materials which might be interesting if added to a UV Test Scene?

 

Kindly keep answers brief and on topic. Actual fotos would be nice.

[igoriginal]

Thank you for this! This is a great idea!

 

From my own experiences, I have actually been able to substitute setting "proper UV custom-white-balance" (in camera) to light-grey pavement (when I am not carrying around a small block of PTFE).

 

I did this once, as a desperate "hunch", when I drove far from home to do some UV shots, one day ... and was saddened to discover that I had left my PTFE block at home. :D

 

Custom-white-balancing to light-grey "sidewalk" pavement comes very close to PTFE custom-white-balancing. Close enough to get sufficient "proper UV" coloration that can later be minimally tweaked (if needed at all), in post-photo work, anyway.

 

Perhaps there are some chemical / compound properties within the cement that is used for sidewalk / pavement work, that permits for this. Either way, this has bailed me out, as an "emergency" custom-white-balancing for UV work.

 

(NOTE: This works, at least, for mirrorless cameras with "shoot-to-set" live-view CWB saving options. Not sure, though, if it would work as well for some optical-based DSLRs with less robust CWB options. I can confirm, at the very least, that this "makeshift" technique works for the micro-4/3 CWB options of Panasonic / Olympus models, as well as the mirrorless Pentax K-01.)

 

As for Steve Smeed's test, I have bought those very same narrow-band-pass filters, to test various lenses. I believe that he calls it the "Sparticle Bandpass Filter Test." I haven't set up my acquired filters, yet, to test my own lenses ... but I plan to soon. This is definitely the second-best way to test a lens's UV-transmission bandwidth, outside of plunking down $$$$ for a spectrometer.

 

(For those who are new to this very handy idea, it is talked about here: http://www.nikonians.org/forums/dcboard.php?az=show_topic&forum=214&topic_id=2130&mesg_id=2130 )

[igoriginal]

Speaking of other "UV-consistent" targets for testing ... I have noticed that the "chrome" parts of automobiles (such as chrome and silver-colored reflective hubcaps) show up as a deep "purple", when an image is properly UV custom-white-balanced.

 

(I discovered this consistency, across all automobile "chrome", when doing a forensics test for imperfections in automobile paint.)

 

Take a look at this photo comparison, below:

 

(Note: The only reason the truck also shows up as purple, under properly white-balanced UV colors, is because its paint job also coincidentally happened to be "silver.")

 

This was taken with a Kuribayashi / Kyoei 35mm F/3.5 lens, with a known useful UV-transmission down to about 325nm, according to Steve Smeed's Sparticle Bandpass Filter test.

[igoriginal]

So, from what I can gather ... highly-reflective chrome and silver surfaces will appear deeply and vividly PURPLE, under properly custom-white-balanced UV-only images taken with sufficiently capable UV-transmissive lenses.

 

Perhaps, then, such objects can be included in "UV color" assessment?

[Alaun]

Combustion in burners is often controlled by the UV-emission.

So, a candle might be an object/source with a to some degree reproducable light spectrum.

 

(did not record the settigs, GH3-UVIR and Baader with UV-Nikkor, out of camera WB, very high ISO setting: 25600)

 

 

second one, which is better showing the yellow UV pattern around

 

 

Werner

 

 

EDIT: had put in the wrong picture and put in a second one

[Andrea B.]

OK, I'm going to shoot some Easter Jellybeans, some pecans and maybe some sugar.