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UltravioletPhotography

Bird vision (again)


Jim Lloyd

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I use PTFE for UV-only-pass shots, but I don't use PTFE for UG5/U-330 stacks.

I use Photo Ninja white balance using RAW file for almost everything, NX-D works also, but I prefer Photo Ninja these days.

For UG5/U-330 stacks I usually sample the whole screen, sometimes I sample a smaller area, say a gray area, etc..

Ulf is right, different cameras may work differently, even when WB'ing for RAW, I don't use any other cameras except the Nikons.

NX2 (CNX2) works even better than NX-D for me, if the camera is old enough, NX2 does not support newer Nikons. NX2 and NX-D work about the same, but NX-D will not do a full frame sample, it can only do a small sample,

but it works if you find a gray spot. Like I said, I have slowly moved away from using either of those, because Ninja seems to work best for me.

If you are using a Nikon, then I would think you will get similar results as me.

The example I show with the red flower was done using NX2, before I have NX-D or Ninja.

If you like, I can resample the red flower using Ninja...?

 

I think the three best stacks for UV+Blue+Green+Red (aka bird vision) are these, and the first of which I have tested and shown here.

UG5 (or U-330) 1mm + S8612 2mm

UG5 (or U-330) 1mm + S8612 1.5mm

UG5 (or U-330) 0.75mm + S8612 2mm

(however, I can't find any UG5 0.75mm or any S8612 1.5mm at the moment)

 

Here are the three best bird vision stacks I can think of.

I will retest the 1 + 2 stack tomorrow if I can, but unless I can find the other thicknesses I can't compare the difference, but they should have stronger red.

post-87-0-63242500-1606323373.jpg

 

Here is the difference between UG5 and U-330, which I don't detect in actual photos.

There is a big difference in price, UG5 being more expensive. U-330 having the data drop out, which is common for some of Hoya's data sheets.

post-87-0-78887700-1606171804.jpg

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Took me a while, but I found the original NEF (RAW) file.

This time I used Photo Ninja to white balance. It was a little over exposed, so I adjusted that as well in Photo Ninja.

Looks about the same as the previous old version.

This is UG5 1mm + S8612 2mm.

 

post-87-0-94697600-1606197913.jpg

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Thanks for all the information Steve

 

My theoretical concern was that added the red might be at the expense of seeing contrasts with the UV, but your image above appears to dispel that concern.

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These didn't work out exactly like I had anticipated.

Conditions were not good, overcast skies, no sunshine.

With the very red plastic drill pit case I expected less red with the first stack and more red with the last stack, more like the older example I have posted.

I did find an S8612 1.5mm thick to include in the comparisons.

 

post-87-0-62151900-1606270227.jpg

 

post-87-0-34160900-1606270250.jpg

 

post-87-0-55357300-1606270275.jpg

 

post-87-0-92687400-1606270295.jpg

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  • 2 weeks later...

post-175-0-35214000-1607206027.jpg

 

Now received U-330 1mm and S8612 1mm. [EDIT - correction these are with S8612 1.5 mm]

These on D3200 full spectrum camera Nikon E 50 mm

Afternoon sun, but low UV this time of year.

Hand held iso 1600, f/5.6 around 1/30 sec.

White balance View NX2.

Channel swap Ps

Adjustment in Lr

 

Sunny periods are infrequent and short lived at the moment. Will do proper tests later.

 

post-175-0-77908300-1607205886.jpg

 

post-175-0-81030400-1607205916.jpg

 

post-175-0-20630400-1607205943.jpg

 

post-175-0-33273400-1607205961.jpg

 

post-175-0-89859400-1607205977.jpg

 

post-175-0-72923000-1607205992.jpg

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Steve, it was a triple swap - I need to go back to check but it was one of

 

R to G, G to B, B to R

or

R to B, G to R, B to G

 

The second one is a rotation which (sort of) makes sense for the bug vision - assuming that the R channel is responding to UV, then it can be thought of as shifting from the bug view to human

 

Not sure if there is any logic for the other version

 

Not sure if it makes sense in this case where there is visible red present

 

Of course colour vision is a lot more complex than just response in three channels in humans - so trying to think of what it is like for birds with 4 channels is nigh on impossible

 

So I am thinking of producing images using a little science and a lot of intuition

 

A fairly modest aim of (hopefully) producing images that defamiliarise our view of the world

 

Thinking of these printed very large in a gallery

 

Or maybe projected in a slide show ?

 

Early morning here - waking thoughts ....

 

 

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Well, OK. :smile:

Personally, at least as a starting point for myself, I would like to see some nu-swapped images using the new filters stacks, just to see how they look, just optimally white balanced, say a full frame NX2 'marquee', say,

so I can get my footing.

You have U-330 1mm, right? and S8612 1mm? 1.5mm? 2mm?

I would like to see, again, just my personal interest, 1mm + 2mm, 1mm + any other

, basically all combinations compared, white balanced the same way optimally, making sure you have something red in the frame to judge the red by...

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Hi Steve

 

Sorry I made an error above (correction added) - the new images are with U-330 1 mm plus S8612 1.5 mm (not 1 mm as I originally stated). I also have U-330 1.5 mm and S8612 2 mm.

 

I agree with you that in the right conditions my inclination is to make the tests you suggest. My quick informal test did indicate to me that I am seeing more red as expected. I think it very unlikely to learn much as a surprise with more thorough tests as you have already nicely demonstrated this and the charts would strongly suggest the red coming through more with the thinner filters. I guess what is of particular interest is whether the additional red transmission is at the expense of any UV specific features. So yes I will do them some time.

 

My particular issues doing this as an arts practice based project is how to present images to people who know very little about the scientific theory behind the images. Of course one approach is to try to explain that to them in advance (or along side the images in a gallery). The real problem I face is around the "truthfulness" of the images for people who don't know the background to how they are produced. It seems to me there has to be some clues in the images themselves - but I don't know how. Anyway these are the sort of questions I grapple with as part of my research ...

 

Somehow I think I need to frame the images as "images produced by a system that responds to a wider range of wavelengths than the human eye can detect - a range that is accessible to various animals including birds" - rather than "what a bird sees" - but obviously I need to have a much snappier way of saying that!

 

One could maybe say the ambition is downgraded from "reproducing bird vision" to "using what we know of bird vision to produce images that make us see the familiar world anew".

 

PS

 

Steve, how do you do "full frame marquee" for WB in NX2 - I seem to remember having this same issue before - I can only seen how to do a point correction (or up to 5x5 square)

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Jim, Yes the U-330 1.5mm + S8612 2mm is the standard UV+Blue+Green stack, so called 'bee vision'.

U-330 1mm + S9612 2mm is the 'bird vision', UV+Blue+Green+Red stack that I have used.

I have not tried U-330 1mm + S8612 1.5mm or S8612 1mm stacks before the fast tests in overcast skies I tried above, and because the weather was dark and I had no rudbeckia to shoot... I don't consider those test to be very conclusive.

 

OK, in NX2, load RAW file (NEF).

right hand menu: Camera Settings > White Balance > Get Gray Point > Marquee > Start, then click/hold mouse butting wile dragging mouse from top left to right bottom corner, then release mouse button, that will select the full frame and use the full frame sample for the white balance, same can be done for any smaller area of the photo, to sample a smaller area.

See photo below for example. Works for UV or IR or any shots suing RAW.

 

post-87-0-62589600-1607496844.jpg

 

Furthermore, I load the resulting tiff from the NX2 into Photoshop, and I often do Auto-Levels, or Auto Contrast, I try those to see how they look, and one or the other usually 'cleans them up' to me eye,

but if they don't look better then I leave the photo alone. Sometimes auto levels doesn't look better but bakes it look worse, so then I try just auto contrast, which can be better...

Usually one of those two clean up the photo, improve the contrast slightly...

Then I might sharpen the image, depending.

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Thanks Steve

 

Looks like you caused the system to crash (only joking!)

 

Or maybe I did - I was just posting this reply when it went down ...

 

 

-----------------------

Thanks Steve

 

 

 

aah - I'm using View NX2 - (not Capture NX2) - the free version and this only has point correction.

 

 

 

But I do wonder if my context how important WB is? - if I am trying to express something of an alien sensorium?

 

 

 

I guess one could surmise that birds have a concept of white which is what they experience when all cones are equally stimulated? But even if that is true, does doing that and making it look "right" to our eyes help to communicate the issue - namely one of trying to understand something beyond our comprehension. The problem then is well if not WB what else? I can't think of another "anchor" - other than just being purely intuitive - which is what I did above ...

 

 

 

Just thinking aloud

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Hmm, my marquee illustration photo? Yeah, weird, it was gone, I just cleaned it out and reposed it.

So I am finally famous then, right? :wink:

Well, I hope it wasn't my pic that did it. :unsure:

 

Well, white balance is very important. It makes a huge difference. Otherwise results have a color cast and often have poor contrast also.

If you want to use some kind of white balance target, then that can be done, but from my experience with UV+Blue+Green+... images, the full frame WB can often times be the best.

Also white balancing on a smaller gray area can work nicely also. But no white balance is not usually ever very nice, and I would say never as good as an optimized white balance from RAW.

The only time I have experience otherwise is an in camera white balance from WhiBal gray card with the 729+KG3 stack. But that is very rare from my experience and my equipment.

Since you are using Nikon, I would imagine you will have very similar results as I do...

So white balancing from RAW using Photo Ninja seems to be the best for me.

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Thanks Steve

 

All the images I showed above are WB in ViewNX2

 

My question about WB is more of a philosophical one in the particular context of an art project that seeks to explore how we might imagine how birds see -

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Bird philosophy :smile: I don't know how they see things. You can white balance something however you want, however it looks best to you.

Removing any color cast looks best to me, no matter what area is selected and sampled for the WB.

I am unfamiliar with white balance using ViewNX2, does it do white balance from RAW?

When I say "NX2" I am referring to Capture NX2 (CNX2 more specifically).

NX-D is another option, much the same as CNX2, except the 'Marquee' is different, not really an option, but the single point can be click dragged to a very small square, for more than one pixel sample,

but not the full frame. But it can work. I think it is a free download, still?

.

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