Water Drop Equipment

 

Solenoid Valves

There are various valves suitable for water drop photography and if you search online you can see people using many different models. Currently my main two types are Shako PU220ARs and SLGPC PU220ARs. I have several other makes which come out occasionally. Like most people doing drop photography I have standardised on valves with a 1/4″ NPT thread. This means the same nozzles can be used on all the valves I have.

Valves with different sized threads are available and sometimes within the same range, for example the Shako PU220AR which has different models:

Over the years I have tried many different makes and models. Some good, some not so good. My favourite is a noname Chinese clone of the PU220AR. Unfortunately I can no longer buy these but the SLGPC version comes a close second.

 
The Shako PU220AR-02. This has become the gold standard for water drop valves. Repeatable performance, reliable, and can produce relatively small drops.

SLGPC PU220AR-02. Similar but not identical to the Shako (smaller valve block but same size orifice), and my current favourite valve. I cannot prove this and my experiments to show it have failed but I feel I get better drops from this valve.

AirTak 2V025-08. Good performance and fairly cheap. The AirTaks have an aluminium block that needs more TCL than the brass ones and means more frequent and careful cleaning.

An AirTak that wasn’t cleaned properly the last time it was used.

This is still my favourite type of valve, noname Chinese brand that was sold as a Shako clone but it is more like a SLGPC clone (same size). This is an old photo and I now use these valves with 24v coils.

I tried several all in one valves. One was kind of OK but in general I found then too slow.
There are people using all-in-one valves successfully online but after trying a few I didn’t pursue them.

 

Honorable Mention

Chuka 2V025-08, this used to be mentioned online far more than it is now. I haven’t used this valve so cannot comment on the performance but it does appear to be very similar to the AirTak.

2P025-08, available branded (STC) and unbranded. I believe this is the valve provided with the StopShot system.

 

12v or 24v Valves?

The quick answer is it doesn’t really matter. Although 24v valves are technically faster, the difference is so small you will not notice.

I started with 12v valves, then added some 24v valves and for quite a while I used both (not at the same time). I then settled on 24v to simplify things and upgraded some of the 12v coils to 24v ones.

Either 12v or 24v valves will work with the dropController just match the voltage of the valve(s) with the voltage of the power supply; 12v valves with a 12v power supply and 24v valves with a 24v power supply. It is not recommended to mix different voltage valves on the same circuit.

If you built your own controller and you want to switch from 12v to 24v you need to check the specs for the mosfets or TIPs you are using to switch the valves. 12v and 24v should be within spec of most mosfets and all TIPs but you never know. Also check the device you are using to drop the voltage to 8/9v to power the Arduino. A DC-DC step down buck converter should have no problems handling 24v but a LM7808 will get hot when used with 24v (and the reason I use buck converters).

 

Cleaning the valves

The below video shows how to dismantle and clean the Shako valve

and this one shows a slightly neglected Airtac 2V025-08 (not as neglected as the one above though).

The Airtacs are pretty good valves but they need more maintenance than the brass valves.

 
 

Nozzles

I have tried brass nozzles and plastic nozzles. I find the brass ones give better results with more consistent drops. The plastic nozzles tend to be unreliable, sometimes the drops are good, sometimes they are not. I feel that plastic is too “slippy” and the water drips from the nozzle when it is not active.

The smallest 1/4″ NPT brass nozzles I have found are 6mm. These gives good results but can sometimes be too large. When creating small drops they often will not drop from the nozzle. A smaller opening helps.

To help get smaller drops I add small pieces of tube and a short length of drinking straw. Inside the straw there is another small piece of PVC tube. I still experiment with different tubes and pipes. Adding additional tubes also helps when aligning drops.

And here is an experiment that never really worked. The opening is too small.

 
 

Stands

When I first started I used what ever was on hand, chair backs, stools, lengths of wood taped together. I used a couple of tripods for a while before making my way to lab stands.

 

Lab Stands

Lab stands (retort stands) are easy set up and adjust and make it fairly simple to get started with water driop photography.

I live in a very small apartment and generally use the dinning table as my work bench and the lab stands were easy to pack away at dinner time. I used lab stands for quite a while and developed some fairly complex and not so stable contraptions out of them.

Here is a simple one valve set up.

One of the nice things about using these stands is the large range of accessories that are available. Here are some of the parts and accessories I have.

And here the valve and bottle are connected directly together.

This is an easy way to get started with a single valve.

When using a lab stand a convenient method is to attach the valve to the bottle using a double sided connector.


Here is a two valve set up. Two valves on a lab stand is possible but not the best solution.

Lab stands make getting started fairly easy but they can become limited when you start using more than one valve. I now normally use an aluminium frame and use the lab stands to support the backdrop.

 

Aluminium Extrusion

As you become more serious you will probably start thinking about a more permanent frame. There are a few options; wood and aluminium extrusion are popular. I don’t have the space or tools to work with wood but I do have a local supplier of aluminium extrusion.

Almost any size is suitable, 2020, 2040, 4040. 4080 is good you want something really solid. I use 2020 in 50cm lengths. This allows me to build different stands depending on what I am doing. A major benefit of aluminium extrusion is that you can completely tailor it to your needs and make it as big as you like. For the most part I keep it simple.


This is a fairly basic frame built to fit either side of my large acrylic trays. All that is required to build a similar frame is:

2020 50cm length x 9

corner x 10

M5 nut and bolt x 20 each

2020 straight joiner x 4
M5 grub screw for the joiner x 16

End cap x 6

There are many variations of the above parts and you do not need to have exactly the ones shown above. If you are not familiar with aluminium extrusion it may be worthwhile browsing an online shop to see what is available.

 
You then need something to hold the bottles and the valves.

To hold the bottles I use regular bottle clips secured with cable ties.
You can also attach the clip directly to the frame if you have a suitable nut and bolt.

To hold the valves I had some brackets milled.

2 valves and 4 flashes.
This is set up for milk which is opaque and I have all 4 flash guns at the front. I haven’t started shooting yet and I will need to add blinds/flags to block light hitting the background.

 
 

Bottles/Reservoirs

For a long time I used drink bottles, especially bottles from sport drinks that had a nipple style top. I then moved to lab squirty bottles which I bought from the same place I got the retort stands. Later, when I upgraded the stand to 2020 extrusion I started using the T33 filter holders.

The lab squirty bottle has a tube that runs through the lid and this makes it easy to turn them in to a Mariotte syphon. A Mariotte syphon delivers a constant rate of flow regardless of the liquid level inside the bottle.

I remove the top tube and then make a small hole at the bottom and hot glue a piece of stiff tube in the hole. This then allows me to connect PVC tube.

For the aluminium frame I generally use T33 filter holders. A benefit of these is they have threaded connections so nozzles can be easily attached. It is slightly harder to create a Mariotte syphon though.

Because the bottles have threaded caps they can be connected directly to the solenoid valve using a double sided connecter.

 
 

Tray/Splash Pool

Just about anything that can hold water can be used for the splash pool but different shapes have different properties. For eye level shots; CD container lids, salad bowels, large glasses, cups, soy sauce saucers, all work. For angled shots with a reflection; backing trays and large flat trays work well.

My wife doesn’t like me using our regular bowls so I bought a set of my own. Sizes range from 9cm to 20cm.

The different sizes have very different properties. The smaller bowls are good for simple Worthington Jets using smaller drops and the larger bowls are good for taller jets using larger drops.

Here is a shot using the 14cm bowl. The the second largest in the photo above. This bowl is 6cm deep and good for jets produced from large drops. It is not so good when using small drops.
For small drops I get much better results with the smaller bowls or the trays.

This is a 2 drop collision using larger drop sizes. The first drop size was around 60ms, the second drop was around 55ms.

If you want to know why 60ms is good see the First Drops guide. The picture has been cleaned up slightly (I cloned out some stray drops).

The cover from a stack of DC/DVDs works quite well.

Here is a largish (10cm) soy sauce dish. I broke my favourite smaller one which worked surprisingly well and gave really nice jets from small drops.

I had a couple of trays made from 4mm clear acrylic. One is 80x40cm and the other is 60x30cm. I also bought black and white acrylic sheets to use as inserts. I use these trays as the splash pools and also as spill trays when using smaller bowls.

 
 

Backgrounds

There are two main types of background, opaque and translucent/transparent. You normally shoot light through a transparent background and bounce light off an opaque one. There are of course exceptions, like when using a black background. Backgrounds is one of the areas you need to experiment with and when I am looking for a new background effect I will shoot just the background without the drops. After I am happy with the background I then start working on the drops.

I use both types of backdrop. For a solid background, when using lighter colours I will normally have one or two flashes directed at the background. When using a dark background, like black, I will try to to keep the light away from it.

Here are some of the backgrounds I currently have. With the printed ones I tend to move the background as far back as possible to get it as blurry as possible

Some of the best results can be obtained from using a translucent/transparent background with flash fired through it. For colour effects add gels to the flash guns.

The background does not need to be that transparent to work. The one in the photo is almost opaque and I also use it as a base when photographing small objects.

Different flash settings can have a big impact on the final effect. Both these were shot with the same flash position but with different power settings.

The gels on the flash guns are from the Selens filter packs. I have a couple of the sets.
There is no need to buy this brand and any type of gel will work.

 
 

Flash Guns

For water drop photography you really need flash and ideally off camera flash. You can get by with a single flash but if you want nice looking backgrounds then you need 2 or more.

My normal setup is 4 Yongnuo wireless flash guns. I have a Canon camera and so also have the Yongnuo Canon remote trigger. The trigger is connected to the dropController not the Camera and it is the dropController that triggers the flash.

While it is possible to take splash photos without flash the results are not going to be that good; you need a fast shutter with a small aperture which normally required lots of light.

The normal way to shoot high speed photos is to use an open shutter in a dark environment and fire the flash at the right moment.
– turn the lights off
– open the shutter
– fire the flash
– close the shutter
In this way it is the flash taking the photo not the shutter.

 

Aperture and Ambient light

A common technique used in high speed photography is to shoot in a dark room with a long shutter speed with flash, and the same technique is well suited to drop photography. I have found that as long as the environment is not bright I do not need to be in pitch darkness and I can use the aperture to control the ambient light (another standard flash photography technique).

Using a longish exposure (half a second to a second), a small aperture, and flash, it is the flash that produces the photo and the aperture can be used to control the amount of ambient light allowed in to the shot (as well as the depth of field). Reducing the aperture can only go so far though and it is still better to reduce the ambient light as much as you can.

To test your own environment, take a photo without the flash. Use manual mode with a shutter speed of half a second or a second. If the image is black you are OK. If it is bright or has too much detail either lower the ambient light or decrease the aperture size. You are looking for a dark photo at around a half to 1 second exposure.

The first photo was taken at F11 and you can still see the edge of the bowl. The second photo was at F16 and is (almost) totally black. Both photos were taken in daylight, inside with the lights off, not in total darkness.

As long as you are not in bright light you can remove ambient light by reducing the size of the aperture. This also has the benefit of increasing the depth of field. Caveat: the smaller the aperture the more light you need to take a photo. At F16 four flash guns is fine. Two flashes would probably not be enough though.

 
 

Flash Leads

The trigger ports on the dropController are standard 3.5mm sockets. Speedlite/light flashes generally use PC sync ports so to connect the flash to the dropController you need 3.5mm to PC sync leads. These are very common.

Hot Shoe Adapters

If you have flash guns that do not have PC sync terminals there are hot shoe adapters available. These attach to the flash trigger plate and add either a socket or a small lead.

 
 

Shutter Trigger Leads

Depending on the camera you are using, a shutter lead may or may not be easy to create. Of course you can simply buy one.

The dropController uses the following shutter release connections.
he 3.5mm plug has the following connections:

I have a Canon 40D which uses a proprietary N3 connector and it is hard to source just the plugs. It is far easier to buy a lead or adapt a cheap shutter release. The shutter release I bought was under US $10.00.
dropController - Shutter Release Cable

Canon N3 Pins

Shutter Release

The shutter release is basically a couple of contact switches. Connect the focus pin to ground and the camera focuses. Connect the shutter pin to ground and a shot is taken. For this particular cable; white is ground, red is +3V shutter release and blue is +3v focus. Other makes will have different colours.

Other cameras will have different styles plugs. For example newer Canon cameras use a regular 2.5mm stereo plug and creating a lead is fairly straight forward.

For more information about different cameras and shutter release connections see the excellent Camera remote release pinout page at http://www.doc-diy.net.

 
 

Additives

When it comes to adding things to the liquids there are no rules, just trial and error.

Bottle Reservoir: Thickener

Plain water is OK when you are first starting but if you want to achieve complex shapes you need to use something a little thicker. For beginners I suggest milk; full cream and chilled. From there most people start experimenting with adding thickening agents to water. The most popular additives are Guar Gum (my usual choice) and Xanthan gum. Glycerin as well as food & drink thickeners (such as Thick & Easy® and THICKENUP®) get mentioned online but I have never tried them.

I mix a level teaspoon of Guan Gum powder to 1 litre of warm water. I blend this is an electric blender and then strain with muslin cloth to remove any bits. This gives me a slightly cloudy thick liquid which I dilute with cold water and add colour as I use it.
A large bag like this will last a long time.

Here is my stash of Guar Gum and Xanthan Gum. I bought these before I knew how much I needed and over did it. I ended up throwing away about half of what I bought.

 

Bottle Reservoir: Colouring

To the Guar Gum mix I add regular food colourings. The ones in the photo are from a very cheap Chinese brand I buy locally.

 

Splash Tray: Surfactants

You can get by with using just water in the splash tray/pool but adding a little bit of detergent can have a big influence. The detergent will reduce the surface tension of the water and the Worthington Jet can become much taller and thinner. I add various detergents or cleaning fluids (I have tried lots of different ones). You only need to add a drop or two. Too much and you just create a mess, albeit a clean mess.

One that works well is natureclean’s All Purpose Cleaning Lotion. This works very well and was recommended by Corrie White sometime ago.