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UltravioletPhotography

Simple Conversion of Raw UV File


Andrea B.

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Here's the photo as shot.

It has been cropped so we don't have to stare at large boring areas. "-)

I was using an almost uniform white balance setting in the D600 along with the Neutral picture control.

Nikon D600-mod + UV-Nikkor 105/4.5 + Hoya U-340 (4mm) + SB14-mod

f/5.6 for 15" @ ISO-100 with two flashes.

santaUS_u340-4_sb14_20171209wf_848001.jpg

 

This is the raw composite (from Raw Digger).

In the Raw Digger data (not shown) there is some slight underexposure in the blue channel which occurs in the shadows under the gloves. There is also a bit of blowout in the red channel on the stocking cord hanging on the glove. Knowing where problem areas are can help with the conversion and tonal adjustments.

santaUS_u340-4_sb14_20171209wf_8480rawComp01.jpg

 

This is the raw histogram (from Raw Digger).

Again, this confirms blue channel underexposure via the left-hand blue "comb" and confirms red blowout via a tiny right-hand wall hit in the red channel.

santaUS_u340-4_sb14_20171209wf_8480rawHisto01.jpg

 

 


Conversion and Basic Adjustments

At the beginning of every conversion we do the same few things (but only as needed). Here's the list along with a reference to the sliders in Photo Ninja, my chosen converter. Your chosen converter will have tools to enable these same steps.

  • Set the white balance (and colour profile if you have one).
  • Optional: Temporarily convert to black & white.
  • Make tonal adjustments.
    • adjust the white point
      (PN exposure slider moves histogram from right side.)
    • adjust the black point
      (PN black slider moves histogram from left side.)
    • retrieve blown highlights
      (PN highlights slider moves right end of histo.)
    • lift shadows
      (PN shadows slider moves left end of histo.)
    • adjust the midtone curve
      (PN illumination slider moves middle of histogram.)
    • adjust the contrast
      (PN contrast slider stretchs/shrinks the histo.)

    [*]And finally, adjust the colour.

    (PN color enhancement tool for overall saturation and individual color tweaks.)

These are basic well-accepted digital conversion steps. No one would ever accuse you of "shopping" after a judicious application of those edits.

 

Here is a trick I use: After I have set the white balance, I convert the file to Black & White. This makes it much easier to perform the 5 tonal adjustments because the false colour does not distract me. It also makes it easier to determine whether you have a real 3-channel blowout (not retrievable) or just a single channel blowout (usually retrievable). I'll show these steps as done in Photo Ninja.


 

Open photo in Photo Ninja.

This is PN's version of the demosaiced raw file made by clicking the demosaic setting (Conservative) and the Exposure & Detail setting (As Shot only). PN applies a stronger default saturation and default midtone curve than you see in the Raw Digger raw composite version above.

PN_demosaic.jpg

 

Apply white balance and D-600 color profile.

I dragged the Photo Ninja white balance dropper over the white standard. The resulting photo is rather flat looking and kinda dark. It does need some tonal adjustments because I have used very neutral settings while shooting. (Nikon Neutral Picture Control [0].)

PN_demosaic_wb.jpg

 

Turn off the false colour.

PN performs a simple desaturation. The B&W tool does permit you to set color filters to enhance tonality. I don't do that with UV or IR photos because I don't want to disturb the tonal relationships. (ymmv).

PN_demosaic_wb_bw.jpg

 

Make tonal adjustments.

  • Increase Exposure slider to set white point. I pushed it until the white standard was just beginning to show clipping (small red area). That standard is 99% reflective, so I would want it to be about 95% bright, or slightly more.

  • No black point adjustment was needed so I did not touch the Black slider. Sometimes I need to drag the Black slider up a bit to slightly lift dark UV files to better show details.

  • There was one tiny blown patch on the stocking cord draped over the glove. I could have retrieved that by a tiny negative adjustment on PN's Highlights slider. But when I tried that it dulled the white standard, so I decided just to call the blowout spectral and leave it alone.

  • I lifted the Shadows just a smidge but didn't see any improvement, so reset this to 0.

  • When I shoot UV, I use a neutral low-contrast setting so that over-saturated, over bright false colour does not obscure results. Thus I almost always add a few points of Contrast slider back to the raw file -- making sure not to re-darken shadows two much or blow highlights again.

  • Sometimes you do have to re-adjust this or that.

This now looks almpost like a real photograph. (Well, to me anyway.....lol.)

PN_demosaic_wb_bw_tones.jpg

 

Turn on the false colour and adjust it.

I didn't quite like the violet cast so I nudged it towards blue. Totally subjective.

PN_demosaic_wb_bw_tones_colour.jpg

 

Finish

To finish this file, I took it into NX2 and removed the danged dust bunnies. I also decided to slightly erase the double shadow thing. (Bad placement of flash, bad Andrea.) This erasure needs to be slightly cleaned up in PS Elements perhaps.

PN_NX2_bunnies_shadowRemoval.jpg

 

Final

This took literally 5 minutes to do. And an hour to write up. B) It would have only taken about 2 minutes to convert if I hadn't decided to fool around with that shadow in the background. This final result is a pretty good UV documentary photo. You could stop now or..... you could go and make wild and crazy art out of it.

santaUS_u340-4_sb14_20171209wf_8480pn.jpg

 

 

 

well fudge this is about a degree off rotation. oh well.

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Bob, what is a scene referred WB? Do you mean moving the individual channel histograms so they are lined up?

 

scene referred WB is simply taking a preset WB measure of the scene itself... usually it is difficult to get the channels perfectly lined up but pretty close.. i use this technique with all my IR, UV and the monochrome conversion..

 

also, folks have been having trouble doing this sort of WB.. but if you take an exposure measurement in live view, turn live view off, set the exposure measurement you just took in manual, hit preset WB... you should get a "good", has been working for me in the IR and recently with UV using the BG-38 monochrome conversion with a Baader.

 

 

the following is an example. with the monochrome sensor conversion..

post-16-0-63670900-1514651066.jpg

post-16-0-90920000-1514651101.jpg

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an example in the UV - Baader U with BG-38 Monochrome D800.. same technique but kind of a crummy shot.. i am having some trouble getting UV esthetically pleasing shots in this weather.

post-16-0-71942700-1514651523.jpg

post-16-0-53445200-1514651532.jpg

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Ok, now I’m REALLY confused! Haha. How can you do a white balance with a monochrome sensor?

 

that's unfortunate.. since the camera's software still thinks they are there

 

which is why they have to be leveled to get the best results in my opinion.... now with a cam that was designed specifically for this purpose this wouldn't be necessary but we are re-purposing these cameras and do not have the ability to modify the s/w, f/w to align with the modifications.

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Oh, I shoot RAW and white balance in PN like Andrea above. The camera’s setting is irrelevant.

 

oh i shoot RAW myself.. the technique i employ gets the most out of each channel when it is recorded. i have been doing it for years.. since my first UV shots back 2008/9 timeframe... i had to convince Vivek it worked which was not easy..

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The white balance in camera does not affect the RAW data. It doesn’t change what is recorded, only how it is rendered in a JPG.
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That can be shown in Raw Digger. Shoot a scene with any kind of white balance and you have the same underlying raw (i.e., raw composite in Raw Digger). So I'm not sure where Bob is going with his suggestion.

 

I will say that using a white balance preset of some kind (scene wb or uni-wb) along with a low-saturation, low-contrast setting does enable you to determine more easily whether you have an optimal UV exposure in the sense of gathering as much light as possible. (Remembering of course that headroom varies on each camera model. The Nikon D810 for example can overshoot between 2-3 stops and still recover highlights. ) So if that is what we are talking about here, then I agree.

 

For example, if you shoot UV with an Incandescent, Auto or Daylight white balance, the file will be awash in red channel overload and often turns out to be underexposed when converted because it is so difficult to "see through" all the red blowout to determine whether you can increase the exposure time. So you don't ever want to do that. Try instead to make some kind of wb preset. Even the wb preset made through an IR filter works better for optimizing a UV shot than does Incan, Auto or Daylight.

 

Ultraviolet landscapes to my eye are never particularly esthetically pleasing. They are always so danged dark. That might be a heretical statement to make, but it is just an opinion so may be ignored should anyone not particularly agree with it. :lol: That is NOT to say that I don't find UV landscapes interesting. I find UV landscapes very interesting.

 

ADDED a moment later: I meant to mention that (some) converted cameras do not always set an accurate on-scene white balance through some filters. I found that my GH1 conversion has this problem with certain filters. I had always thought that the GH1 was one of those cameras which could always set a wb thru a UV or IR filter, but not true. Sometimes it screws up and the wb preset it records is not really white-balanced. There's a post here somewhere about that.

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For what it’s worth, my NEX-7 hasn’t had any trouble setting the WB in camera, through every filter I’ve tried so far. (This note provided for anyone camera shopping who is reading this.)
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(maybe clean the sensor as well).

 

It's a Nikon. The danged sensor stays clean for about 5 shots. Then blammo - oil, dust, lint. I clean the sensor before EVERY shoot. SIGH.

 

*****

 

Andy, I should run my Sony A7R through a few filters. I think it might be able to handle all the wb. So it has been reported anyway.

Usually I get wb failures in the GH1 and in my Pentax K5 mod only with certain dual bandpass filters or certain strong colour filters. An example: U-340 in 4mm thickness. Perhaps not surprising as it's so thick?

 

 

*****

 

No comments from anyone on the tutorial? I was hoping it might be helpful in some way.

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I am waiting for Bob to explain his in camera white balance technique that he spoke about above:

"oh i shoot RAW myself.. the technique i employ gets the most out of each channel when it is recorded. i have been doing it for years.. since my first UV shots back 2008/9 timeframe..."

 

Bob may be talking about some other technique above, but he taught me this technique below, which works with some filters, not all filters, but more filters than I was ever able to white balance in camera with before.

My experience is limited to a handful of Nikon models, but Bob uses this technique with his Nikon models.

http://www.ultravioletphotography.com/content/index.php/topic/2360-in-camera-white-balance-with-newer-nikons/page__hl__%2Bwhite+%2Bbalance__fromsearch__1

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This was initially a tutorial about raw UV file conversions.

Does anybody have any comments about that?

We've covered white balance many times.

 

 

 

I'm going to give up writing these things.

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I was interested in what Bob said above in this topic:

http://www.ultraviol...dpost__p__18544

 

Actually, looking further back in this topic, I think Bob answers my question in his previous post, which I think is the same method he taught me before:

http://www.ultraviol...dpost__p__18539

 

Andrea, Very well done tutorial.

White balance and questions pertaining to that are naturally part of this discussion, and pertinent to the tutorial.

The reason I felt a need to post above was because I wondered what technique Bob was referring to.

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This was initially a tutorial about raw UV file conversions.

Does anybody have any comments about that?

We've covered white balance many times.

 

I'm going to give up writing these things.

 

Andrea, the tutorial will be really helpful for all the new people but you’ve told us in the past what you do before, so I already knew your general procedure. On top of that it’s not really any different than what I do myself. So while I don’t think it was wasted effort because there are plenty of people don’t know, for the people currently in the conversation there just is not much to comment on. You explained it well!

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Thank you for the comments, Andy and Steve. Much appreciated. You see, I have no idea how other folks handle their UV conversions because nobody ever writes about it. So I have no way to know whether what I do during conversions is optimal or whether I'm missing some "trick". :D

 

If anyone is using Adobe CS or PS to convert and "edit" their raw UV files, it would be really cool to see a brief tutorial about how they do that.

 

Well, onward everyone........

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there is also AccuRaw Monochrome which has a switch for UV/IR..... also has switch for scene referred WB and no CFA
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Bur you said you didn't think that program was worth the price?

 

i mentioned it for completeness... i prefer DarkTable.. i am not sure PhotoNinja is worth the price either. of course, they are not really expensive by many standards.

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I'm going to try Dark Table again !! I had it a long time ago on the old laptop. But it looks like it's been totally reworked so it's time to try it again. And it's always good to find an open source, free program.
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i would get the latest.. i am using darktable-2.4.0.rc2 until i can get the build for the mac which should be soon.
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