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IR, UV, UV+IR, UV+Vis, UV+Vis+IR, Vis: Which Is Which?

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#1 Andrea B.

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Posted 09 July 2017 - 19:13

Can you figure out what kind of filter was used to make each photo?

Added: This is just for fun. I had absolutely no idea what these photos would show before I made them. Well, not exactly "no idea", but more like "only a vague idea".

All photos were made using a D610-conversion + 105/4.5 UV-Nikkor + Filter.
Exposures were made at f/5.6 and ISO-100 for an exposure time long enough to push the brightness histogram to the right without hitting the wall.

The filter choices are:
  • IR only
  • UV only
  • UV + IR
  • UV + Vis
  • UV + Vis + IR -- Actually, this is an unfiltered shot. No lens filter was used, only the clear filter inside the D610 conversion.
  • Vis only
These photos are shown in monochrome.
I'll post the false color raw composites in the next post.

The standards are displayed in a pressed cardboard box.
Thus, the more experienced viewers may be able to use this background to figure out some of the filters.

In an expanded browser, these 300 pixel wide photo should appear in two rows of 3 each.
From left to right the filenames consist of letters only, which you will see if you hover your cursor over each photo.
A B C
D E F


Attached Image: A.jpgAttached Image: B.jpgAttached Image: C.jpg
Attached Image: D.jpgAttached Image: E.jpgAttached Image: F.jpg
Andrea G. Blum
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#2 Andrea B.

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Posted 09 July 2017 - 19:14

<saving this post for later display of corresponding raw composites>

The raw composite colours will definitely give major clues (for some of you) to the identities of the filters. :D

These raw composites were made in Raw Digger. A raw composite has been demosaiced but has had no white balance applied to the raw data. However, in the process of conversion to JPGs, an sRGB colour space is assigned so that the monitor and browser know how to display the photos.

In an expanded browser, these 300 pixel wide photo should appear in two rows of 3 each.
From left to right the files are named with double letters, which you will see if you hover your cursor over each photo.
AA BB CC
DD EE FF

Attached Image: AA.jpgAttached Image: BB.jpgAttached Image: CC.jpg
Attached Image: DD.jpgAttached Image: EE.jpgAttached Image: FF.jpg
Andrea G. Blum
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#3 Hornblende

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Posted 09 July 2017 - 21:19

Lets try:

A: UV + VIS + IR
B: VIS
C: UV + VIS
D: IR + UV
E: IR
F: UV

Edited by Hornblende, 09 July 2017 - 21:24.


#4 OlDoinyo

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Posted 10 July 2017 - 03:05

I will agree that E is probably IR and F is most likely UV. C contains UV and the box is dark in color, so UV+VIS might be a good guess. The black and dark grey standards give no diagnostic information at all; the three pale standards contain some info but not a great deal. B and D have the next darkest renditions of the box, with two of the pale standards slightly darker in B; thus I guess that D might be UV+IR and B might be straight VIS. That leaves A as the blank shot.

#5 Andrea B.

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Posted 10 July 2017 - 15:32

Doesn't anyone else want to hazard a guess? It's just for fun.

I'm prepping the raw composites now and should have them posted later today.
Andrea G. Blum
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#6 Andrea B.

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Posted 10 July 2017 - 18:50

So far we have:

A. unfiltered, unfiltered, ir
B. vis, vis, vis
C. uv+vis, uv+vis, uv+vis
D. uv+ir, uv+ir, unfiltered
E. ir, ir, uv+ir
F. uv, uv, uv

(One person sent me a guess not posted here.)

Now that the raw composites are up, would you revise your guess?
Andrea G. Blum
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#7 Andrea B.

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Posted 10 July 2017 - 19:15

A and E have the brighest backgrounds and are most nearly alike.
Here are A, E and the Difference between the two frames.
Attached Image: A.jpgAttached Image: E.jpgAttached Image: A_E_Diff.jpg

C and F have the darkest backgrounds and are most nearly alike.
Here are C, F and the Difference between the two frames.
Attached Image: C.jpgAttached Image: F.jpgAttached Image: C_F_Diff.jpg

B and D have the (remaining) matching backgrounds and are most nearly alike.
Here are B, D and the Difference between the two frames.
Attached Image: B.jpgAttached Image: D.jpgAttached Image: B_D_Diff.jpg
Andrea G. Blum
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#8 Andrea B.

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Posted 10 July 2017 - 20:06

A = Infrared Only = Schott RG850

Top Left: Monochrome Top Right: Raw Composite
Bottom: White-balanced Final Version

One person got this correct.

Attached Image: A.jpgAttached Image: AA.jpg
Attached Image:  std_irRG850_sun_f56_iso100_20170709shoreCottageSwhMaine_2806pn.jpg
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#9 Andrea B.

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Posted 10 July 2017 - 20:10

B = Unfiltered = UV+Vis+IR
Although mostly IR is recorded, then some Vis. UV?? Hard to say, depends on the subject.

Top Left: Monochrome Top Right: Raw Composite
Bottom: White-balanced Final Version

Nobody got this one correct.

Attached Image: B.jpgAttached Image: BB.jpg
Attached Image:  std_unfiltered_sun_f56_iso100_20170709shoreCottageSwhMaine_2743pn.jpg
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#10 Andrea B.

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Posted 10 July 2017 - 20:12

C = UV + Vis = BugU3
Some visible blue and green are passed.

Top Left: Monochrome Top Right: Raw Composite
Bottom: White-balanced Final Version

And some traveling fibers make an appearance.

Everyone got this correct based only on the monochrome.
Beats me how it looks different in monochrome than the UV shot F. They look alike to me.

Attached Image: C.jpgAttached Image: CC.jpg
Attached Image:  std_bugU3_sun_f56_iso100_20170709shoreCottageSwhMaine_2896pn.jpg
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#11 Andrea B.

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Posted 10 July 2017 - 20:15

D = Visible = Baader UV/IR-Cut

Top Left: Monochrome Top Right: Raw Composite
Bottom: White-balanced Final Version

Nobody got this one correct.

Attached Image: D.jpgAttached Image: DD.jpg
Attached Image:  std_visBaaderUVIRcut_sun_f56_iso100_20170709shoreCottageSwhMaine_2778pn.jpg
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#12 Andrea B.

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Posted 10 July 2017 - 20:16

E = UV+IR = Schott UG-11

Top Left: Monochrome Top Right: Raw Composite
Bottom: White-balanced Final Version

One person got this correct.

Attached Image: E.jpgAttached Image: EE.jpg
Attached Image:  std_UG11-75_sun_f56_iso100_20170709shoreCottageSwhMaine_2765pn.jpg
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#13 Andrea B.

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Posted 10 July 2017 - 20:19

F = UV = KolariU

Top Left: Monochrome Top Right: Raw Composite
Bottom: White-balanced Final Version

Same remark: Everyone got this correct based only on the monochrome.
Beats me how it looks different in monochrome than the UV+Vis shot C. They look alike to me.


Attached Image: F.jpgAttached Image: FF.jpg
Attached Image:  std_uvKolari_sun_f56_iso100_20170709shoreCottageSwhMaine_2784pn.jpg
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#14 Hornblende

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Posted 10 July 2017 - 23:39

UV + VIS is slightly lighter.

#15 Andrea B.

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Posted 11 July 2017 - 16:28

I was thinking that I should repeat this kind of thing for landscapes. That would probably be more interesting and relevant.
Thanks to my 3 participants!
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#16 Alaun

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Posted 11 July 2017 - 16:49

I had 2 correct (A and D). That raised the question, how big is the probability to get 2 correct by chance?

With 6 to place there are 720 combinations. If you fix 2, there are 15x24 combinations left. Which makes a 15x24/720 chance (that is 50%).
Is that correct?
Werner

#17 Andrea B.

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Posted 12 July 2017 - 03:48

A little bit too high, Werner. If you fix 2, then there are not 15*4! combinations remaining. There are rather 15*3! combinations remaining. We have to omit the combinations which have "matches" in the remaining 4 placements. So 15x6/720 = 1/8 = 12.5%.

Combinatorics is maddening stuff!!!! I hated it in school!!!!
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#18 Alaun

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Posted 12 July 2017 - 17:01

Yes, maddening stuff. Hated and liked it in school at the same time! I was to fast yesterday, did the calculation in a hurry. The remaining combinations are (4!/3!+3!/2!+2!/1!) =9 :) and this times 15. so 135/720 so 18.75%

Edited by Alaun, 12 July 2017 - 17:04.

Werner

#19 Andrea B.

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Posted 12 July 2017 - 17:13

This is too funny! OK, I will try again. We both agree on the 15 and the 720. :lol: :lol: :lol: :lol: :lol:
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#20 Andrea B.

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Posted 12 July 2017 - 23:05

(arghhhhhh!!!!) I left out the 3 arrangements (...or, derangements as they are properly called...) where two of the photos "exchange labels". So should have written: 15*(6+3)/720 = 18.75%.

Those 3 derangements I omitted are:
6587 (1st & 2nd) or (3rd & 4th)
7856 (1st & 3rd) or (2nd & 4th)
8765 (1st & 4th) or (2nd & 3rd)

Finally !!! Hurray !!!
(Now *I* am deranged. Smile.)
Andrea G. Blum
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