Making a Helicon Macroscope - By Julian Brooks

The Basics

Most people will be familiar with a microscope. It has three common features, an objective, a stage and an eyepiece. Photomicrography is already a well-established field but conceptually too specialized for most amateur and professional photographers and not many ever bother to buy them. What we are talking about here though is something everyone can do for a very limited budget and get results they only ever dreamed of.

So what’s a macroscope? It shares pretty much all the components of a microscope. It has an objective (camera lens) it has a stage (board) and it has an eyepiece (camera). You can think of it as a copying stand for copying very small things. The main difference is that it follows principles that all photographers understand.

Everyone who has ever tried macro photography has come across the same problem, limited depth of field. Most people who buy a set of bellows try connecting a lens to it and find out just how hard it is to take decent photos. They then either sell it or put it away, never to use it again.

Helicon focus has provided a simple and enormously effective way of addressing this problem using image or focus stacks. The principal is this: If you photograph the very front sharp part of the image and gradually take a series of photographs through the image until the back point is focussed, the software will analyze the sharpest parts in all the images and produce a final photograph which is sharp throughout. Impossible? It actually works, though some tweaking is normally necessary to get the best results.

What do I need?

What we need are the following: An old copying stand, a digital SLR with a remote, a set of bellows (any sort) and a macro or micro lens, some lights and a flashgun. That’s it. If you have a way of engineering components then so much the better, but most can be sourced from somewhere like ebay.

My aim is to produce a flat field system which is flexible enough for both incident and transmitted light systems. We’ll talk about lighting later but let’s build the machine first. My goal with this first set-up was to photograph the scales on a butterfly wing.

I found an old Meopta enlarger in my shed with a copying stand attachment, but for this system any copying stand will do. The more solidly built the better. If it’s too flimsy there will be lots of trouble when it comes to lining up the images afterwards.

My lens cupboard produced the following but everything is sort of interchangeable. A Micro-Nikkor 105mmF/4, a 55mm Micro-Nikkor (elderly but sharp as anything), and a recently acquired Zeiss Luminar 25mm (the best and sharpest micro lens there is, in my opinion). I also have a large collection of adaptor rings to connect anything to anything else, but this is not a mandatory requirement.
First I connected the camera, bellows and 55mm lens to the copying stand as shown. Two problems became immediately apparent. Firstly, when you touch the system everything wobbles. This is no good. It needs to be firm in order to produce your stack accurately. The second problem was the working distance between the lens and the subject. With a big lens like this, it’s difficult to get light underneath it at an angle to light the subject effectively. As you can see, the lighting angle would be nearly impossible.
The first problem is solved by not being tempted to use the maximum magnification. I cranked the column of the copy stand down so the end of the bellows was braced on the copy board. Now the whole system was stable. By shortening the bellows I was able to focus on the wood of the board and now there was a much better angle for light to get to the subject. However, my subject, the scales of a butterfly wing were not really visible at the magnification this system now had, about a 1cm field of view.

I can’t see a thing!

Now I come to the next problem. Light. Everything is very dark down the eyepiece of the camera. I solved this by using two tungsten table lamps to light the subject. At least this way I could now see it! You won’t be able to photograph using these lights, but you can focus, and focussing is the difficult part…

To light at these magnifications, flash is essential. I use a Nikon SB800 with the D300 simply because I can use it wirelessly and it has a manual mode to set the light very accurately.

The longer your bellows are, the closer your subject is to the lens. This is a fundamental principal and can’t be changed. In order to get closer I needed either a lens with a longer focal length and more bellows length, or a shorter focal length lens.

Over the years there have been very few lenses made that bridge the gap between macro photography and microscopy. One such lens is the Zeiss Luminar. They were originally made for photomicrography in the Zeiss Ultraphot system. These are still available, and it is possible to get RMS (Royal Microscope Society) thread adaptors to Leica, and T mount. For this next part I went to my trusty lathe and made a BPM to RMS adaptor (I don’t know if anyone else ever made these). One of the reasons I bought the BPM bellows was the ease with which I could attach other objectives to it.

This shows the Luminar attached to the bellows. I once again braced the system using the bellows and was delighted to find that all my problems were now solved. These lenses are very well worth acquiring and they are still available on ebay if you can get one. The 25mm one is the best for photography, since you can use it quite effectively in the field. The 16mm is sharper they say, but your subject is right up against the lens front.

As you can see from the picture right, the system is now quite friendly. There’s a good angle to get light in,huge magnification, and a stability which means photographing the samescene repeatedly is now possible.

Some Technical stuff

Before we start with the photography let’s talk about resolution and optics. Everyone who is reading this probably knows that stopping down a lens increases the depth of field. This seems to indicate that the larger the F-stop number, the better the end result will be. This is sadly not the case. A macro lens, such as the superb Micro-Nikkors and Canon’s equivalents (also the Tamron 90mm Macro) are corrected for close focus, which means they are theoretically sharp at higher magnifications. However ALL lenses suffer from diffraction if stopped down too far. This means that the optimum F-stop for most lenses is about F/8-F/11. Once you get below this something peculiar happens.

The resolution actually falls off at greater F-stops. The reasons are too technical to go into in great depth here, but essentially the lens tends towards a pinhole camera and the optics play a less important part in the photograph. But when you look down a camera with the lens stopped down to F/11 at these magnifications, the depth of field is TINY, much less than 1mm. By using Helicon, however, it’s possible to keep the optimum resolution of the lens and still get that elusive depth of field. The better Macro lenses seem to resolve pretty well down to F/16, and the Zeiss, though still not immune from diffraction, stops down nearly all the way without too much loss of detail.
Everything has to be manual. Set the camera to it’s highest possible synch speed (to avoid orange casts from the focussing lights). Now play with the flash to get the desired exposure. I found that with the diffuser on the flash and the lens set to about F/11 (not easy to determine with a luminar, since they aren’t marked the normal way) about ¼ of full flash gave the desired result. If it’s too bright, but not much too bright, you can adjust the light very effectively by simply moving the flash further away. Bear in mind that every time you double the flash to subject distance you lose a stop of light.
With a Micro or Macro lens, I’d always set the focus to infinity and use the bellows to focus. This is because most Macro lenses just move the whole block of glass up and down the lens barrel anyway, and also because twisting the system to focus the lens might just skew the images and make them difficult to stack (though Helicon does have a control to allow some skewing to be corrected). At this point it’s worth mentioning remote releases. I had a radio release which I used but any remote is fine. This avoids moving the camera too much when pressing the button. Try it without a remote and see just how much your field of view moves, even with the final stabilized system, you’ll be amazed!

Lighting

For this set up, as with all photographic lighting, it’s best to keep it simple. Finally though, we get an advantage when using a very small subject. That advantage is as follows: Even the smallest flash gun is huge compared to your subject, which means using a flash such as an SB-800 you effectively have a giant soft-box for incident light pictures. You can of course make the source of light smaller by sticking a piece of card to it with a hole in it, but for most work, a single unadulterated flash will be enough.

Taking Pictures and Making the Stack

Finally, the fun part. To make a successful image stack you will need to determine your range of focus. Using the focus control of the bellows move the lens up and down until you see the very nearest part of the image come into focus. Take a picture. Check the image on the camera’s screen and wait for the flash to warm up again. Rack the bellows down until you feel that your next “slice” is sharp. Repeat as many times as you like until you reach the furthest part of your subject. You will now have a stack of images, all of which contain a sharp area. Here’s mine

Using Helicon Focus

This is where the software really takes over. Download your pictures to the computer and import them all into Helicon Focus. You’ll see them all on the right of the work screen. To try out the default settings, just go straight to render and wait. You might find it’s not perfect first time, but there are lots of variables to play with. The clone brush tool in the Pro version is a great extra investment.

Here is the finished result of my first image stack using the Macroscope. As you can see all the wing scales are sharp, and the lighting has been more than adequate.

Without too much fuss Helicon focus has created an image more than a little impossible a few years ago. I have been a professional film-maker and photographer for more than twenty years and I have never been more impressed by a software.

I’m not going to pretend that everything is this straightforward. I have only just scratched the surface here, but hopefully you can now reproduce some of my results, and produce your own. Everyone has their own interests but the micro world has now become more accessible to everyone. Most of all, if you don’t do it for a living (and even if you do!) have fun, and play with all the settings and all the variables.

I’d love to hear from more people who are interested in this field. Please feel free to contact me on jules@wildwater.tv or visit my site www.wildwater.tv to see what we do. I might also be able to make you an adaptor of some kind if you need one.

Julian Brooks 2009