Pixiq

Water droplets as lenses

So, how do you begin to get droplet images easily and consistently?  Forgive what used to be a bit of high school science first but it might help your own experiments. I know in the dumbing-down process of education in the USA and UK such things have been thrown out…makes you think so get rid of it. Cynical you bet.

If you take the time to examine raindrops closely you’ll see tiny images of flowers or leaves behind them…. The reason is that the droplet acts as a near spherical lens with a very short focal length. You can get two sorts of images:

1. The magnifying glass image (called a virtual image) – it is upright and seems to be behind the lens. You get this when the subject lies between the focus and the droplet surface. It is the image you get with optical instruments you look through such as a microscope and telescope.
2. A ‘real’ image: this is the one we’ll use. It is an image created in space that you can project onto something – a screen, sensor or film. This is the sort you use with camera lenses, projectors. It is inverted and formed by the hanging droplets     which act like fisheye lenses and pull in all manner of extraneous detail at the edges. This is evident in some of the shots included to show what goes right and wrong…
3. Moving the flower behind the drop changes the size of the inverted image and the two pictures below show this. The further away the flower is the more background gets included…
4. Move close and you get the flower appear as a blurred, coloured background that fills the field of view with the flower sharply focused, seemingly within the drop. If you are photographing a daisy then because of its symmetry it looks the same whichever way up it is. Flowers like orchids need to be mounted upside down…the droplet images then appear erect not inverted.
5. Several drops close together will produce a series of images of the same flower.

A bit of a challenge…

You might have picked up on the words "seemingly within the drop". When you get close-up you find that the image in the drop, the grass blade and the drop are not quite in the same plane. This does not matter if you want a clear image and slightly-blurred drop for ‘mood’.

However, if you are going for both drop and flower sharp then experiment. Set the lens on manual focus just beyond the image of the flower – this gives you some depth behind and in front. Check with the depth of field preview to see if you can get the image sharp and the drop…stop down or shift focus (or move the camera on a focus slide) to get a result you like. 

Getting Those Larger Images – coupled lenses

Several raindrops can be photographed in a row using a macro lens that will give you 1:1 reproduction. But water droplets are small and if you want one of them to dominate you have to enter the macro realm with images of up to 3x magnification and more. A 1:1 macro on DX with a x1.4 converter fills the frame to the same extent as x2 on FX and is a useful combination.

The easiest practical way to get this kind of magnification is by coupling or stacking lenses (reversing a 50mm standard lens on to a 150mm lens, for example). For this you need a ‘male to male’ thread adapter that couples the lenses via their filter threads.

NB: The details will be in one of a series of posts I’ll make soon on practical ways of getting larger than life images using old lenses from microscopes and cine camera that don't break the bank

In brief, the 50mm lens used wide open acts as an ultra high quality supplementary lens whilst the automatic diaphragms and all lens connections belong to the 150mm lens. NB The magnification achieved is found by dividing the focal length of the prime lens fitted to the camera by the focal length of the additional lens:

eg 150mm (prime)  ÷ 50mm (stacked) = 3 x magnification

NB. In the studio shots (greenhouse shots) I used an old Olympus 80mm f/4 bellows macro (a much prized lens) on a bellows with home made adapters to fit to a Nikon system.

THE PRACTICALITIES

Forming drops and trying your patience

You can go out on a rainy day looking for droplets that have collected on a twig or at leaf tips, but they will seldom be in the right place and the slightest disturbance will dislodge them.  It seems easier to take control and construct your own imaging system by placing a twig just a few centimetres in front of a flower, for example.  I used one of those small stands with crocodile clips to hold the twig for the droplets and the subject is held behind as the image of a set-up shows.

In theory, if you spray or ‘wet’ the twig, then droplets will form. In practice it is easier to hold a dropper against the twig and gently squeeze: control is tricky and persistence is essential. You first have to ‘wet’ the twig – as the surface soaks up some water the droplets hold better. It is all down to surface tension: you get a feel for how large you can let a drop grow before it drops…patience! 

Beware: if you experiment in a greenhouse then be careful the view angle of the drop will include the greenhouse spars as well: I know.

In film making, plants are often sprayed with a mixture of one part by volume of glycerine (glycerol) to one of water. The mix does not evaporate as easily as water and is better under bright film lights. It's also a useful mix for creating your own ‘raindrops’, the slightly higher viscosity and increased surface tension compared with pure water create slightly larger, more stable droplets…or so they say.  I use water.

Lighting

Any form of artificial lighting is tricky at first because you have to light both the background and avoid creating create distracting reflections on the drop surface. If you are using tungsten lamps, LEDs or sunlight where you can see what is happening, then you could theoretically fit a polarizing filter to the lens front and largely eliminate the reflections.

When you photograph a water droplet using flash, it can create tiny, but perfect images of the flash tube that you do not see until the image is on screen and the twin bars of a macro flash appear unnatural. The solution is to use a single flash, preferably diffused, or a touch of “Ye Olde Photoshoppe” later. In general, light the subject rather than the drop: it makes the drop edges look darker and more dramatic.

Diffused daylight, either in the field or with a camera set-up in a conservatory or similar place,  provides better lighting quality plus some protection against air currents. The drops act as ‘vibration detectors’ quivering with the slightest breeze or movement of a support. For outside work very still days are best: an icicle slowly melting allows water droplets to grow at the tip so, pre-focus and await your chance. Early morning dew when insects are waking is another source of striking images in drops.

I was delighted a few years ago when I gave a first exhibition locally in Italy – Lois, my better half was listening to a conversation where the basic thread was that this guy is pretty good with Photoshop…look how he curves the edges of the image. She politely waded in and explained – the person was a local artist who makes giant classical figures out of motorbike parts and a good friendship began!

Good luck: as usual, this is offered as starting point for YOUR ingenuity and creativity. Please let me know how it goes, maybe how you improve the method or if you have problems that I can help with. If you take some shots of your own then send me a link.

Confession...

Usually, I think of shots I would like to take and then work out how to create them and then try it out. I thought this one out, described this technique and wrote it up as copy for a book (Nature Photography Close-up: Amphoto) before I tried it. Sod’s law – I should have tried it first. Showing a little too much confidence I worked out in theory where the images should be from a half-remembered optics formula…in practice the image and drop were spatially separated more than I had thought. Things eventually worked out...it was a warning!

The motto, as Lois keeps reminding me should be: “RTFM Davies, RTFM !” ie  Read The ‘eFFing Manual

If you missed the first part of this with more on water drops check it out