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Flowers in UV 3D/Stereo

Conical Cells Processing
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#1 Bernard Foot

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Posted 29 April 2019 - 13:42

One of the things I have been trying for some time is to get interesting UV photos of flowers in Stereo (i.e. 3D), especially in close-up and macro. In this post I'll outline the technique (happy to provide more detail if you need it), and provide some samples: you will need red/cyan anaglyph glasses (a couple of $ on ebay or Amazon) to view them. Also because of the 800 pixel-width that UVP impose, you will not get the full effect, and won't be able to do what I love - zooming in and "wandering around" the flower and looking at the detailed internal structure. If you've got some red/cyan glasses and want to look at some full-resolution files then drop me a line. And if you haven't got the glasses but would like to see any of the detailed images in 2D, let me know - but you really lose a lot in 2D.

I've now got to a point where I get a reasonable percentage of successes, although some flowers make life difficult because of the amount they move during the process: some move in their entirety (wilting, esp. under the bombardment from flashguns), and some just waggle their stamens about. Dandelions are particularly irritating in this respect. This movement is a problem because it can easily take 30-45 minutes to complete one stereo shot. This is because I use focus stacking to get the image quality and depth of field, and that can mean 100 shots for each of the stereo pair of images.

The traditional way to make stereo pairs is to move the camera sideways between the two images. For image distances of 1-10 metres, the sideways separation would be the inter-ocular distance of 6 or 7 cms; for greater image distances you would use greater separations (I have used 100 metres for a subject 12 miles away), and for shorter distances a smaller separation. However, for macro this does not work - with even a small separation the image disappears from the field of view. So you need to use a toe-in approach - swing the camera through about 5 degrees between the two stereo images, and then move it sideways until the image comes back into the field of view. There is nothing magical about 5 degrees - it is the angle between the line of sight of the 2 eyes for a subject at 0.5 metres. Other people use 3.7 degrees, or some other number. If you read materials about stereo photography, they often say that toe-in is a definite non-no, but modern 3D software can handle it perfectly. (I use the excellent and free Stereo Photo Maker to create the stereo image from my stereo pairs.)

One of the difficulties with any kind of macro work is the shallow depth of field that you experience. To overcome this I use focus stacking - taking a number of mages focused on different planes in the subject, and combining them in software to get a single sharp image. I use Zerene software for this. This also overcomes the problem of how to focus accurately in UV, because all you need to find out is where the image starts to come into focus and where it starts to go out of focus.

Another difficulty with UV+macro is getting enough light on the subject. I use 3 cheap-from-China but powerful WS-560 flashguns (with UV-absorbing "lens" removed) a few centimetres away from the subject. The repeated shooting for focus-stacking overheats the flashguns, and already three have failed for this reason. But they're so cheap (I just bought a couple new for $20 each) that they're effectively a consumable rather than a capital purchase.

Let's look at some examples. They're all taken on a full-spectrum Canon EOS M, U340+S8612 filters, flash, white-balanced on PTFE. Lenses were either a Steinheil Cassar S 2.8/50mm and El-Nikkor 5.6/105mm, always stopped down to f/8.

First, one that didn't work so well. This is a type of Geranium AFAIK. The body of the flower is OK, but the central area is not so good to look at. This is because of stamen movement.
Attached Image: Stereo Geranium UV Nikkor 800.jpg

I mentioned above that Dandelions cause movement problems. This shot isn't too bad, but I had to crop it a lot to get rid of moving petals.
Attached Image: Stereo Dandelion UV 800.jpg

Fruit blossom seems to work well - here is Quince, Pear, Alpine Strawberry.
Attached Image: Stereo Quince UV 1 800.jpg

Attached Image: Stereo Quince UV 10 Deg 800.jpg

Attached Image: Stereo Pear UV 800.jpg

Attached Image: Stereo AlpineStrawberry UV Nikkor Despidered 800.jpg

On the strawberry, you'll see a couple of tiny spiders in cyan. This is an irritant that comes from focus stacking - insects that wander around the flower while you are taking the images. In fact on this shot there were about a dozen out-of-focus spiders in cyan (i.e. on the right image) and a few in red (i.e. on the left image) which I had to post-process out of the image.

Now we have a Daffodil. This works really well in a full-resolution image, with the a great wander-about capability.
Attached Image: Stereo Daffodil UV_800.jpg

Here are a few shots of an Orchid - full flower and then a macro shot of the interior. I have provided a visible light shot (taken on a Canon EOS 6D Mk 2, Sigma 105mm macro lens, ring flash) of the interior for comparison. The UV interior shot is another great one to wander around.
Attached Image: Stereo Orchid UV Nikkor 800.jpg

Attached Image: Stereo Orchid UV Nikkor 2 800.jpg

Attached Image: Stereo Orchid Sigma 800.jpg

Now a Bluebell:
Attached Image: Stereo Bluebell UV 800.jpg

A chrysanthemum:
Attached Image: Stereo Chrysanthemum Pink UV Nikkor 800.jpg

A daisy:
Attached Image: Stereo Daisy UV 1 Crop 800.jpg

A Grape Hyacinth:
Attached Image: Stereo Grape Hyacinth - Christmas Pearl UV 800.jpg

An "ordinary" Hyacinth:
Attached Image: Stereo Hyacinth UV 800.jpg

Magnolia (this is another flower that can move significantly when young - I could actually observe it twitching):
Attached Image: Stereo Magnolia UV 800.jpg

Snowdrop (also good for wandering around inside):
Attached Image: Stereo Snowdrop UV 800.jpg

Forsythia:
Attached Image: Stereo Forsythia Upper Garden UV 800.jpg

And finally a Sunflower:
Attached Image: Stereo Sunflower UV 800.jpg

Edited by Bernard Foot, 29 April 2019 - 13:58.

Bernard Foot

#2 GaryR

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Posted 29 April 2019 - 15:45

Hi Bernard,
I'm glad that I still have a pair of red/cyan 3D glasses in the drawer.
These are amazing in 3D!

#3 Bernard Foot

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Posted 29 April 2019 - 18:09

Thanks, Gary.

Glad you hung on to your 3D glasses.

You really need to see the full-res files to get the real value. As I mentioned, one of the things I love is zooming into the image and then scrolling around to see the flower's detail.When you zoom in you can only go so far before the eyes get strained, but if you move back from your screen you can zoom in further before your eyes scream at you.

Anyway, I've made some of my Stereo UV images available at the following link. Hopefully you can access them there and download - and go wandering around inside the flower!

https://btcloud.bt.c...vite/jnd89DA7ZX
Bernard Foot

#4 Bernard Foot

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Posted 29 April 2019 - 18:44

P.S. - download the images you like to your desktop, rather than viewing them online. The online view is much lower image quality.
Bernard Foot

#5 Andy Perrin

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Posted 29 April 2019 - 22:44

Cool! Wish I had the glasses to view them with.
--
BTW, I think the image size cutoff for the site is 1200px, not 800px.

#6 GaryR

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Posted 29 April 2019 - 23:27

Wow, the downloaded full screen versions are even better!
It took a few seconds to get my eyes adjusted, but when you do, the depth is detail is memorizing.
Welcome to UVP, and thanks for posting !

#7 Bernard Foot

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Posted 30 April 2019 - 06:09

Re Andy's comment on max. image size, the rule is a bit ambiguous:

Review of Photo Pixel Dimensions
To avoid resizing and degradation by the forum software, please note these suggested pixel dimensions.
Maximum page display dimensions = 800 pixels.
Maximum upload dimensions = 1200 pixels, but 1000 pixels is better for most viewers on smaller monitors. And choosing 1000 pixels also reduces file size.


I got the impression from this that you could upload to 1200 pixels but it would be resized to 800.
Bernard Foot

#8 WiSi-Testpilot

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Posted 30 April 2019 - 06:21

Very interesting pictures, Bernard. Some flowers are visible in front of the screen. I’m using red/blue glasses, which I used in the past to investigate molecular structures from quantum chemical software.
Best regards,
Wilhelm


#9 Andy Perrin

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Posted 30 April 2019 - 06:42

Bernard, I don’t think that is the case. 1200 is 1200 in my experience. Also, I think Andrea should revise that text...all our monitors and even smartphone resolutions have expanded in recent years. It’s dated.

I do still try to keep my file sizes smallish (jpeg 8 seems to work well for me).

Edited by Andy Perrin, 30 April 2019 - 06:45.


#10 Bernard Foot

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Posted 30 April 2019 - 07:30

Thanks, Andy - I'll go for 1200 in the future.

WiSi-TestPilot - I guess red/blue will work in terms of seeing in stereo, but the colours will be even more disturbed than with red/cyan. But in most of these UV shots the colour is not so impressive anyway.

When creating a stereo image you can choose at what depth of plane in the image you make the left/right images line up. This plane in the image is then perceived as being at the level of the surrounding frame. Typically you arrange it such that the nearest point is at the level of the frame, and everything else is behind it - like looking through a window. But you can choose a more distant plane for alignment such that things in front of that appear to come in through the viewing frame. You have to make sure that you do not violate the rule that anything touching the edges of the picture must not appear to be this side of the frame - for example the ground in a landscape, or leaves at the side of a flower: that confuses the eye/brain system and leads to uncomfortable viewing. I like to have all or some of the flower appearing to come through the frame - for dramatic effect.
Bernard Foot

#11 dabateman

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Posted 30 April 2019 - 14:53

Absolutely Amazing work!

I am fortunate to have many pairs of glass to view these images. Got ten for $1 from Amazon years ago to play with my own stereo creations, that never really panned out. Thank you for the software information I will have to check that out.

Silly question. When you say you use 5 degree separation, are you lining up the center of the object, then rotating 2.5 degrees to the left, then back and 2.5 degrees to the right. Or are you just taking a stack and shifting 5 degree from your initial position to get the stereo view? I have never even tried that before. I was previously trying to calculate the distance separation using horizontal linear track, simple to do on a x/y macro rail. But never really processed anything. I was also trying to get things using a crossed eyed approach, but that is too hard for some people. I liked that method for stereo maps of topography.

Something that may work better or different or not at all. Maybe instead of using flash is to use a constant 365nm LED E26/E27 light bulb. I like these as they are cold, and not very stressful for flowers for long imaging times. But you may need longer exposure times.

#12 Bernard Foot

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Posted 30 April 2019 - 15:36

Hi, Da.

Thanks for the comments.

Re. the 5 degrees thing, I guess you can do it either way. Lining up on the "centre" first makes sense if there is a definite centre, but generally there isn't - I try to take the shots off-centre to get a an angled view so you can see the shape of the bowl formed by the petals, but centred enough so you can see down into the depths of the flower. So I normally do the right image first and then swing through 5 degrees to do the left. To manage the swing I bought a gadget that fits on your normal tripod head and lets you pan without any risk of changing the tilt, and is graduated in units of 2.5 degrees. I think it's really designed for making panoramas. Before that I was just trying to use the pan-and-tilt head on the camera, but that's too coarse. I also got a Benro geared tripod head to make fine movement easier, but that has a drawback which means that for any non-horizontal shot you need to mount it on top of the pan-and-tilt head, which is getting a bit stupid.

I too use an x/y macro rail - one axis for forward movement while I'm taking the focus stack, and one for the lateral movement between the left/right stereo pair. An approximation for the lateral movement needed is RxD/60, where R is the degrees of rotation (5 in my case) and D is the distance from the subject to the sensor (i.e. the focal plane). I sometimes use this as a guide to position the camera for the second stereo shot, and then take some test shots to find the exact position by trial and error - this avoids having to revert to visible so I can do the alignment visually.

I don't have any UV LEDs, but I have tried using a bank of 8 UV Compact Fluorescent lights. Problem is they are too weak, leading to long exposure times - esp. for macro. This results in camera shake when you are doing macro, and the extra time becomes a significant factor if you're doing a stack of 100 images. Maybe I'll have a go with some UV LEDs.

I agree that the cross-eyed approach is too difficult. Pity there's no other glasses-free method.
Bernard Foot

#13 Andrea B.

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Posted 07 May 2019 - 17:30

This is the first time I have seen stereo UV. Can't wait to view it thru the right colors.

Somewhere amongst the UV gear I have a little packet of cello filters from which I can cobble together a stereo viewer. Going to look for that stuff now.




The forum software has a page which will display up to 800 pixels width. However, if you click the displayed photo, then you can view it in a larger size. The suggestion for 1200 pixels is just a suggestion.

In theory you can upload any size you want. But we do like to keep massive file sizes down. And usually you get better results if you perform your own resizing and resharpening.

Repeat: The maximum page display width of 800 pixels is not something I can change. It is a limitation of our forum software. I suppose this is why the photo click is supplied so you can see the photos larger if desired.
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Often found hanging out with flowers & bees.