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UltravioletPhotography

[Filter Test] Hoya U340 with S8612, BG40 and BG39


Andrea B.

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First a Visible and a BaaderU reference photo set of Crocus flowers
 
Equipment:
Nikon D600-broadband + Nikon 105/4.5 UV-Nikkor + Sunlight
 
1. Visible with Baader UV/IR-Cut
[f/11 for 1/400" @ ISO-100]

crocus_visSun_f111-400iso100_20150411wf_145854pn.jpg

 
2. Visible with Baader UV/IR-Cut
[f/22 for 1/400" @ ISO-100]
That f/22 was accidental!

crocus_visSun_f221-400iso100_20150411wf_143723pn.jpg

 
3. Ultraviolet with BaaderU
[f/11 for 1/6" @ ISO-800]
Only made one with BaaderU.

crocus_baadUSun_f111-6iso800_20150411wf_143828pn.jpg

 
 
Now Crocus flowers using the Hoya U340 stacked with IR-blockers.
Not every filter has a pair of photos. The BG38 and B+Ww470 have only one photo.
 
Thickness of the IR blocking filters.
Hoya U340 = 1 mm
S8612 = 1.75 mm
BG40 = 2.0 mm
BG39 = 2.0 mm
Charts for U340 with IR blockers:

 

 

 

 

 

 

NEW!!! as of 14 Apr 2015

 

Note: Someone was 'surprised' that I linked to these charts but they did not show my particular stack. Yes, well. Sigh. I don't have
every
chart combo just yet. I will add them whenever I get them or find time to create them. You can still get a reasonable idea of the bandwidth from the existing charts. I tend to care less about charts than I do results. But ymmv and I'm doing my best to accumulate charts. :D
 
4. Ultraviolet with Hoya U340 + S8612
[f/11 for 1/3" @ ISO-800]

crocus_u340s8612Sun_f111-3iso800_20150411wf_150054pn.jpg

 
5. Ultraviolet with Hoya U340 + S8612
[f/11 for 1/2.5" @ ISO-800]

crocus_u340s8612Sun_f111-2.5iso800_20150411wf_144224pn.jpg

 
6. Ultraviolet with Hoya U340 + BG40
[f/11 for 1/8" @ ISO-800]
Well, this BG40 pair is unusual.
Added Later: In
, there is a follow up to this combo.

crocus_u340bg40Sun_f111-8iso800_20150411wf_150219pn.jpg

 
7. Ultraviolet with Hoya U340 + BG40
[f/11 for 1/2.5" @ ISO-800]

crocus_u340bg40Sun_f111-2.5iso800_20150411wf_144250pn2.jpg

 
8. Ultraviolet with Hoya U340 + BG39
[f/11 for 1/2.5" @ ISO-800]

crocus_u340bg39Sun_f111-2.5iso800_20150411wf_150316pn.jpg

 
9. Ultraviolet with Hoya U340 + BG39
[f/11 for 1" @ ISO-800]

crocus_u340bg39Sun_f111iso800_20150411wf_144345pn.jpg

 
10. Ultraviolet with Hoya U340 + B+W 470
[f/11 for 3" @ ISO-800]
I'm not sure what this blue-green 470 filter is because I couldn't find any current reference for it in B+W literature. There is a touch of green in the false colour.

crocus_u340bg470Sun_f111-3iso800_20150411wf_150506pn.jpg

 
 
And finally, the Color Checker Passport and Labsphere White Standards using the Hoya U340 with IR blockers.
 
11. Ultraviolet with Hoya U340 + S8612
[f/11 for 1/15" @ ISO-400]

stdsCCcard_u340+s8612_f111-15iso400_20150411wf_145124pnDemExpWB.jpg

 
12. High saturation version.

stdsCCcard_u340+s8612_f111-15iso400_20150411wf_145124pnDemExpWBsat.jpg

 
13. Ultraviolet with Hoya U340 + BG40
[f/11 for 1/10" @ ISO-400]
Lots of colours. Very interesting!

stdsCCcard_u340+bg40_f111-10iso400_20150411wf_145249pnDemExpWB.jpg

 
14. High saturation version.

stdsCCcard_u340+bg40_f111-10iso400_20150411wf_145249pnDemExpWBsat.jpg

 
15. Ultraviolet with Hoya U340 + BG39
[f/11 for 1/3" @ ISO-400]

stdsCCcard_u340+bg39_f111-3iso400_20150411wf_145338pnDemExpWB.jpg

 
16. High saturation version.

stdsCCcard_u340+bg39_f111-3iso400_20150411wf_145338pnDemExpWBsat.jpg

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So, what in the world is going on with that U340 + BG40 stack? Very anomalous colours, but pretty.

 

Added Later: Well shoot-me-for-dumb for forgetting to put a smiley on that comment. Too many people now think I actually had no idea that my particular stack was leaky. Really? :P :P :P :lol: ;) :lol:

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So, what in the world is going on with that U340 + BG40 stack?

 

Is the BG40 passing significantly more >650nm?

 

added later:

 

Without filter thicknesses this may be speculative but, might we be seeing the difference between suppressing the secondary VIS/NIR transmission band to ≤10^-3 -vs- ≥10^-4 a transmittance of ≥3x10-4 -vs- ≤10-4 ?

 

added later:

Sorry, I said that backwards, less suppression is more transmittance. (Dyslexics Untie!)

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My impression of these 'anormalous false colours' (sic) is they arise from contamination in the 650-700+ nm band. Thus they can mask the UV response to a substantial extent, because they might overlay the very same dark areas of the subject caused by low UV reflectivity. The final outcome is pretty, but less useful, as it were.

 

I'm with JCDowdy. Suppression of the VIR/NIR range is inefficient for the U340/BG40 stack.. With low UV content of the incident sunlight, and factoring in the native response of the camera's sensor, filter response around 10-3 isn't sufficient to keep the image clean of Vis/NIR leakage. A few narrow spikes of this magnitude may not be manifested in an overall change of false colours, but a wider range over which filter response reaches 10-3 obviously results in the "golden" issue.

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Thanks for the insightful comments. I'm busy with other things this week, but when I'm able to get back to experiments my plan is to test for visible and/IR leakage with my particular U340 + BG40 stack.

 

Note that filter thickness and chart references are in Post #1.

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Note that filter thickness and chart references are in Post #1.

 

Thanks, I somehow missed that.... :lol:

 

I see in your earlier plot of the U340/BG40 stack you modeled a thicker 2mm U340 and showed transmittance higher than ~3x10-4 in the secondary pass band. As you know, if you recalculate that stack with 1mm U340 that will increase.

 

One thing to also consider is that out of band transmittance, or leakage, should be considered relative to the transmittance of the UV pass band. Normalizing the curve to a transmittance of 1, or transmission of 100, will show the true relative out of band rejection, or leakage if one prefers that term.

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I didn't make those charts, JD. They are just collected from Ebay Uviroptics or from other folks. :lol:

But, yes, obviously my U340 at 1mm thick is going to transmit more.

 

I will get an investigation done later this week. I have various colour filters, IR-pass filters and also got in one of those GG filters you recommended in another conversation. (BTW, be careful with that thing - it can fluoresce as was pointed out to me by SS.)

 

Meanwhile.......that "anomalous" look with my particular U340+BG40 is rather fetching in its weirdly-coloured way. I think that might make for an interesting art filter combo. I always hope to try something non-documentary whenever I get some of that elusive thing called "time".

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The ever optimist. Time is a most precious commodity.

 

As for normalising the charts, using the peak UV transmittance is of course natural. However, what is even better is relating the filter response to the levels of incoming illumination. A filter might suppress Vis with a factor of 10-4, but if Vis is 50-100 times stronger than UV (a realistic scenario in my country), we're looking at an actual manifested suppression of 10-2 instead of the nominal value.

 

The conclusion must be a true UV bandpass filter should suppress everything above UV-A as much as possible. 10-4 is good, 10-5 is better, and 10-6 would be even better.

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Woo!! 10-6 would be some strong filtration indeed, Bjørn.

Do we know supression factor for either the BaadU or the PrecU?

 

****

 

As it turns out I'm not going to have all my time taken up this week with other duties, so I was able to get out this afternoon and investigate my U340 (1mm) + BG40 (2mm) stack a bit more to see what is getting through. I'll get that all converted and posted this evening.

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..... I have various colour filters, IR-pass filters and also got in one of those GG filters you recommended in another conversation. (BTW, be careful with that thing - it can fluoresce as was pointed out to me by SS.)

 

Yes, I keel forgetting some GG do fluoresce and I do not recall if the GG-400 or GG-420 do or not. I tend to use the Schott names as a generic term, I would think a nice Hoya Y(K2) should do nicely and you might find a used one much less expensive.

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As a former sufferer from the "golden" issue (shudder!) I can safely say that killing it was a great delight. However, that said, eliminating all undesired wavelengths is a will-of-the-wisp -- you can follow the bobbing light (now it's visible, now NIR, now visible again...) but it leads only into a morass.

 

Ultimately, one must decide how long to play Whac'a'mole. Personally, I like maximum UV transmission both in depth and peak. Driving the entire NIR 700-1100nm range below OD5 would require the loss of too much UV, IMO. However, I am not averse to letting customers customize their filters. One man's meat...

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eliminating all undesired wavelengths is a will-of-the-wisp -- you can follow the bobbing light (now it's visible, now NIR, now visible again...) but it leads only into a morass.

 

I can certainly see how that could happen. :lol:

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This is a follow-up to the Hoya U340 + BG40 combination above in Post #1.

 

I have a thin 1mm U340 and my 2mm BG40 was not quite thick enough to suppress all leakage. (Really this is not a surprise. I would say it is immediately obvious!) So I attempted to discover where the leakage was happening.

I didn't think I'd be able to get to it this week, but expected duties were postponed and I went out to shoot.

Hurrah !!

 

On a side note, the March winds were fierce. It is sometimes tough to shoot in Sunlight. Kindly forgive the less-than-acceptable soft focus. "-)

 

Equipment: Nikon D600-broadband + Nikon 105/4.5 UV-Nikkor + Sunlight

 

1. Visible Reference with Baader UV/IR-Cut [f/11 for 1/320" @ ISO-100]

chionodoxa_visSun_20150413wf_30621pn.jpg

 

2. Ultraviolet Reference with BaaderU [f/11 for 1" @ ISO-400]

chionodoxa_uvBaadSun_20150413wf_30631pn.jpg

 

 

Now for the U340 + BG40 combo, under investigation for needing a slightly stronger IR block or Vis block.

This photo shows the yellowish cast which was also seen in the crocus in Post #1.

Scroll to the photo #6 and #7 in that series.

See also photo #13.

 

3. Hoya U340 + BG40 [f/11 for 1" @ ISO-400]

chionodoxa_u340bg40Sun_20150413wf_30637pn.jpg

 

 

The next 3 photos show that some IR is being passed. And perhaps some visible light as well. Let's see what we can see.

 

4a. Hoya U340 + BG40 + BW092 IR/Red-Pass [f/11 for 1.6" @ ISO-800]

The B+W 092 is ~2mm thick and it passes some visible red starting around 660nm, reaching 50% transmission around 690nm.

chionodoxa_u340bg40ir092Sun_20150413wf_30645pn.jpg

 

4b. Hoya U340 + BG40 + BW092 IR/Red-Pass [Raw Composite from Raw Digger]

This is an RGB raw composite with gamma 2.2 applied.

chionodoxa_u340bg40ir092Sun_20150413wf_30645_rawComp.jpg

 

4c. Hoya U340 + BG40 + BW092 IR/Red-Pass [Raw Histogram from Raw Digger]

The amount of blue recorded is negligible and it is way down there at EV-4 in the shadows.

chionodoxa_u340bg40ir092Sun_20150413wf_rawHisto.jpg

 

4d. Hoya U340 + BG40 + BW092 IR/Red-Pass [R, G, B]

chionodoxa_u340bg40ir092Sun_20150413wf_30645_rawR.jpgchionodoxa_u340bg40ir092Sun_20150413wf_30645_rawG.jpgchionodoxa_u340bg40ir092Sun_20150413wf_30645_rawB.jpg

 

 

5a. Hoya U340 + BG40 + GG420 [f/11 for 1/1.3" @ ISO-1600]

The Schott GG420 blocks UV starting at about 420nm. So this photo shows Visible + IR with the IR no doubt predominating.

chionodoxa_u340bg40gg420Sun_20150413wf_30675pn.jpg

 

5b. Hoya U340 + BG40 + GG420 [Raw Composite from Raw Digger]

This is an RGB raw composite with gamma 2.2 applied.

chionodoxa_u340bg40gg420Sun_20150413wf_30675_rawComp.jpg

 

5c. Hoya U340 + BG40 + GG420 [Raw Histogram from Raw Digger]

chionodoxa_u340bg40gg420Sun_20150413wf_30675_rawHisto.jpg

 

5d. Hoya U340 + BG40 + GG420 [R, G, B]

chionodoxa_u340bg40gg420Sun_20150413wf_30675_rawR.jpgchionodoxa_u340bg40gg420Sun_20150413wf_30675_rawG.jpgchionodoxa_u340bg40gg420Sun_20150413wf_30675_rawB.jpg

 

 

6a. Hoya U340 + BG40 + Baader UV/IR-Cut [f/11 for 1.6" @ ISO-1600]

This looks very IR-ish but should be mostly Visible light.

chionodoxa_u340bg40baadUvirCutSun_20150413wf_30671pn.jpg

 

6b. Hoya U340 + BG40 + Baader UV/IR-Cut [Raw Composite from Raw Digger]

This is an RGB raw composite with gamma 2.2 applied.

chionodoxa_u340bg40baadUvirCutSun_20150413wf_30671_rawComp.jpg

 

6c. Hoya U340 + BG40 + Baader UV/IR-Cut [Raw Histogram from Raw Digger]

Blue is negligible, again in the shadows.

chionodoxa_u340bg40baadUvirCutSun_20150413wf_30671_rawHisto.jpg

 

6d. Hoya U340 + BG40 + Baader UV/IR-Cut [R, G, B]

chionodoxa_u340bg40baadUvirCutSun_20150413wf_30671_rawR.jpgchionodoxa_u340bg40baadUvirCutSun_20150413wf_30671_rawG.jpgchionodoxa_u340bg40baadUvirCutSun_20150413wf_30671_rawB.jpg

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BTW.

No, I don't have a chart for every combo I might use. Not yet anyway. Whenever I receive charts or have time to create them, I will add them. I'm more into photographic results than I am into charts. A minor failure surely. :lol: ;) :lol:

 

However.

I do now have Raw Digger (Research Edition) and can provide very interesting raw composities which I find very illuminating for ultraviolet photography, no pun intended. The whole white balance and false colour thing has gotten away from us and we really do need to check where that UV light is landing in those RGB channels before we make any claims about what false colour indicates.

 

[steve is working overtime to shuffle lovely charts our way. THANK YOU !!!!]

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Whew, done finally with Post #14 !!

*****

 

Now I need to study up on these raw histograms and figure out what they are telling us. :lol:

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Comments and corrections and suggestions for improvement always welcomed. Post 'em here.

I'm just hoping such presentations are useful or interesting to the members of the community.

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