2010-10-11

DIY Macro Photography IV: On-Board Flash Diffuser

As I get more into macro photography it has become clear that lighting is absolutely critical for good results   The best way to achieve good lighting appears to be one or two external flashes mounted on a bracket.  This allows you to have loads of control over the light sources.

However, in the truest bodging spirit I decided to see what I could do with just a few bits of rubbish I had lying around.  Obviously this rules out using external flashes and brackets.  Despite this I thought I could probably do a bit better than just using the on-board flash on my camera.  The plan was to build a snoot / diffuser to direct and soften the built-in flash in a way that fitted my macro set up.


Ingredients
  • Cardboard tube
  • Aluminium foil
  • Duct tape
  • Kitchen roll


Construction
The first step is to cut down the tube to size.  I wanted the tube to reach the end of my macro lens, but also to have a bit of a an angle at the end.  I used my mitre saw to chop the tube down to the angle I wanted:



I also decided to cut a small notch in the opposite end of the tube to make it fit slightly better against the built-in flash on my camera:





Once this was done I did a quick test fit to ensure all the dimensions were as I wanted:


I decided that lining the tube with aluminium foil would be a good idea.  I imagine this will help minimise light loss.  As the flash on the 7D is a bit weedy I need all the light output I can manage.  I cut some foil to size allowing enough for double thickness when rolled up and also a good edge for securing the foil to the tube:



Fitting the foil to the inside of the tube proved tricky until I realised that the fuel bottle for my camping stove was a perfect fit inside the cardboard tube.  This allowed me to use it as a blank around which I could wrap the foil and insert it into the cardboard tube:







Once the foil was inside the cardboard tube I cut tabs into the ends to allow it to be folded back and secured to the tube:



To make the diffuser a bit more robust I decided to wrap the whole thing in duct tape (bodge tool #1).  I paid particular attention to the ends of the tube where the foil was folded back.  The foil is not very robust, so some protection here is a good idea:


Once the foil lining was in good shape I fitted a diffusing element to the business end.  I used some kitchen roll, but any translucent material would be suitable:


One final feature I decided to add was a foil-covered cap for the camera end of the tube.  This simply hinges on a piece of duct tape and sits behind the flash head.  Again the idea is to try to direct as much flash energy forwards as possible.  I'm not sure if this makes any difference, but it does reduce the bounce-back you get when using the camera.




Once construction is complete it's a simple matter to fit the tube to your camera with some strategically placed rubber bands:


Results
Overall this modification works very well.  The snoot directs the flash quite nicely and really pours light on the subject.  I still have a few issues in my macro setup with vignetting, but that's a lens issue that I will address some time in the future.  Here's a few test shots:
SD card contacts

Zippo flint

Dead fly

2010-10-09

DIY Macro Photography III: Extra Stuff

Macro photography can be a tricky and frustrating experience. By investing some time (and some money) in a few bits of extra equipment you can make life a lot easier. There are plenty of other websites around which offer comprehensive tutorials on building a macro setup, this page just details the bits and bobs that I use.

Lighting
Macro photography is almost always easier when you have plenty of light available. I currently use a single 50W halogen desk lamp as my light source. Ideally, a second lamp would also be used to throw even more light onto the subject. To compensate for the colour cast from the lamp, I always shoot a grey/white card before starting to take real pictures.

Light diffusing box
If you simply douse your subject with light directly from a desk lamp you will end up with very bright highlights and very deep shadows. Sometimes this is what you want. I find that slightly softer lighting works well for macro pictures, so I built a light box to diffuse my light sources.


The basic construction is very simple: take a cardboard box, line it with white paper, cut holes in the side and cover the holes with tracing paper. The tracing paper on the sides of the box diffuses the light evenly inside the light box. There's a good tutorial on how to build this box somewhere on t'Internet - just use The Goggle to find it. My lightbox is very rough and ready as it's only designed for macro subjects. If you are photographing larger objects, take more care with lining the inside of the box to avoid ugly seams.

Tripod setup / focus rails
When using very high magnifications it is almost essential to have a good stable tripod. I use a Benro tripod with a fairly sturdy ball-head. Cheap tripods may seem tempting, but they are usually a false economy - you'll get annoyed like I did and end up buying something decent in the end.

With macro photography, focussing is both critical and very difficult. The optical properties of a macro setup leave you with a very shallow depth of field. It is almost always better to control the focussing in a macro setup manually. Autofocus usually doesn't work very well (of course, you may have better luck than me).

After a bit of experimentation and research, I found that the easiest way to focus is to use a set of adjustable rails in between your camera and the tripod. These are typically geared racks which allow very precise control of the fore/aft position of the camera.

Focussing racks can be purchased for around £30 on eBay, or about £50-£70 in a camera shop. I decided to spend a bit extra and purchased a Novoflex Castel-Q rack. This rack is very well built and has absolutely no play in the mechanism. Another nice feature is the Arca-Swiss compatible mounts which allows it to work with other bits of equipment (such as my Benro tripod).

DIY Macro Photography II: Reversed Lenses

Ingredients
  • Canon FD manual lenses (28mm f2.8 and 50mm f1.8).
  • 77mm-77mm reversing ring.
  • 77mm-55mm and 77mm-52mm step-up rings.
  • Canon FD rear lens cap.
Construction
Most of this approach is very simple to put together. All you need to do is reverse mount one of the manual lenses onto the front filter thread of one of your digital camera lenses. This is done using two adapters in my case. I have some L-series Canon lenses, so chose a 77mm reversing ring for maximum flexibility. In order to use this ring on the manual lenses, a step-up adapter is needed (55mm thread for the 50mm lens, 52mm thread for the 28mm lens).


The one stumbling block I found was stopping down the FD lenses. The FD design has a number of catches and levers on the rear face of the lens. Unless particular pins are pressed in, the lens will not stop down. You can work around this by poking the pins and levers with a screwdriver, then gluing them in place.

Instead of fiddling around with a screwdriver I decided to modify an FD rear lens cap to fool the lens into thinking it was mounted on a camera body. This hack is easy to do:

  • First, cut the central section of the lens cap away. I cut the cap right back to the edge so that there would not be any bits poking into the image frame.

    • Next remove the stop tab on the edge of the cap. Normally this prevents the lens cap from rotating all the way round. This normally allows the lens to distinguish between and lens cap and a camera body. By removing the tab we can rotate the cap all the way around and fool the lens.

    • Mount the cap and depress the stop-down lever on the lens. The lens is now stopped down, the lens cap also doubles as a handy lens hood.



    Once this is done, simply use the appropriate reversing and step-up rings to mount the manual lens onto the front of one of your digital lenses. The picture below shows my complete setup with the 50mm lens mounted onto my 100-400L.



    Use
    I found the following method worked best for me:
    • Set both lenses to manual focus, set focus to infinity.
    • Leave the manual lens aperture wide open (f1.8 on the 50mm lens).
    • Frame the image and set focus using focus rails.
    • Set the main lens to stop all the way down (f40 on the 400mm lens).
    • Take the image.

    Results and conclusions
    As expected, the 28mm lens gives greatest magnification, but results in a large amount of vignetting. Combining the 28mm lens with the 400mm lens gives about 7-8x magnification. I found that the 50mm lens combined with 300mm on the main lens gives the most useful magnification (somewhere around 5x).

    Image quality is reasonably good. The main issues are a lot of cyan/red chromatic aberration which can be partially corrected during raw processing. The other difficulty is the extreme limited depth of field, however this is just an aspect of macro photography

    Some example images below:









    2010-10-08

    DIY Macro Photography I: The Enlarger Lens Bodge

    A simple way to make a DIY macro lens is to build one from an old enlarger lens and a set of extension tubes.

    Ingredients

    • M42 to EOS adapter.
    • Two sets of M42 extension tubes.
    • 50mm enlarger lens (a Durst Neonon f/2.8 in this case).
    • Hot glue gun.

    Construction
    I picked up most of my ingredients from eBay, I think in total I paid about £20 for the whole lot.

    The first thing to do is to mount the enlarger lens to one of the extension tubes. The lens can be mounted either way around, but reverse mounting gives higher magnification.

    This bit can be a bit tricky - you should try to get the lens mounted as straight as possible with no gaps between it and the extension tube. I held the enlarger lens against the tube and put a small blob of hot glue on the joint to hold it in place. Once the glue had cooled it was easy to finish the job by running a line of hot glue all the way around the seam.

    Don't worry if you don't get this right first time, just let the glue cool, then peel it off and start again.
    That's the fiddly bit done, now you just need to assemble the extension tubes, screw on the M42-EOS adapter and mount it on the camera.


    Use
    Once you have the lens mounted up it's time to take some piccies. Enlarger lenses are completely manual which means you will need to set the aperture manually and also devise a way to set the focus. My process was as follows:

    • Set the lens aperture wide open (f/2.8).
    • Frame the image.
    • Set the focus. I used my focus rails to do this. If you don't have access to rails, you can move the subject a bit or maybe take advantage of any play in your tripod head. Note: at f/2.8 the depth-of-field with be wafer thin (mint), this will improve once the lens is stopped down.
    • Stop down the lens to f/16 to achieve reasonable depth-of-field.
    • With the camera on full manual, take pictures of varying exposure durations until the exposure looks good on the histogram.

    Results and Conclusions
    Here's a picture from this setup:


    What a disappointment. It is fairly clear what has happened. As the Durst lens elements aren't coated this leads to an internal reflection causing a huge amount of flare. This is a particular problem on digital cameras as the digital sensor is shinier than film. The original enlarger-bodge macro I used had a Nikon enlarger lens with coated elements - this reduced flare a great deal and resulted in some nice images.

    The problem of flare can be reduced a bit by placing your subject onto a dark background and by under exposing the image slightly. This reduces flare, but also brings up more noise in the image when the exposure is corrected. Below is the best image I managed to produce using this setup:


    So, lesson learnt: if you are going to take this route, make sure you buy an enlarger lens with some sort of anti-reflective coating on the elements. I decided to move on and try something different... stay tuned for a different approach to DIY macro...

    Example Geocoding Program

    Download - geocode.py

    This is a very simple piece of software which will geocode images. It is not intended to be used as an end-user piece of software, but is instead an example of how to write this code in Python.

    The code will read a GPS tracklog data file in GPX format using the minidom XML parser which is part of the Python standard library. The position information in the tracklog is interpolated using the Numpy mathematics library. The positions are then matched and written to the image files using exiftool.

    2010-10-07

    Scolty Woods

    Distance: 24.9km TRL GPX
    Physical:  Technical:  Fun:


    Scolty Wood is a popular location for walkers, so bear this in mind when cycling here - look out for the red socks! This tracklog is based upon another of the Neep's routes. It's a fairly gentle ride that takes in some of the nice bits of singletrack in the area.

    At the start of the ride the route climbs to the monument on Scolty Hill. There are a number of routes up and down the hill, but I have chosen the easiest climb and a descent which is fairly rocky and fun. Having taken in the hill, the route branches off into the forest to take in a few bits of singletrack around Goauch Wood (don't ask me how to pronounce that).

    Once the singletrack fun is over, the ride finishes with a very pleasant quick spin alongside the River Dee. Take it easy along here, enjoy the scenery and look out for the Herons on the river.

    Pitfichie Forest

    Distance: 17.4km TRL GPX
    Physical: Technical:  Fun:



    This Pitfichie Forest route takes in the three main hills in the forest. A climb from the car park to the main forest road acts as a short, sharp warm-up. Once on the main forest road you duck left into the forest to begin the climb up to Green Hill. This climb starts off on some decent singletrack which is steep, but reasonably easy. Once the climb leaves the tree line the technical, loose and steep climb to the top of Green Hill starts - see if you can do it in one go!

    Having taken in Green Hill there is a nice rocky descent down the other side and a winding piece of singletrack which links up to Cairn William. The Cairn William climb has recently been resurfaced and is now a fun technical climbs with some pretty cool trail features to play on. From the summit of Cairn William is a really fun twisty, bermed descent.

    Once at the bottom of Cairn William you have a choice of either taking a shortcut off to the left which leads back to the main forest road and back to the car park. Alternatively, you can climb to the top of Pitfichie Hill to have a go on the downhill course. The DH course starts off fairly open and fast with a few small rock drops. Once you enter the forested area the course becomes rocky and technical.

    2010-10-06

    Mount Tampie

    Distance: 35.7km TRL GPX
    Physical: Technical: Fun:



    This route takes in some of the nicest bits of Glen Tanar and the Fungle Road. The route is based on one found on the Ecurie Neep website. To start with, there is a little bit of road riding from Aboyne to the Glen Tanar estate - nothing too strenuous.

    Once in the Glen Tanar estate, the climbs quickly start to ramp up. First up is Craigmahandle (574m) and Hill of St Colm (700m) followed by the climb to Mount Tampie (723m). Keep an eye on the weather at this point as it can change very quickly on the top of the hills. From the top of Tampie you are faced with a fun (if a bit smooth) descent down to the Fungle Road.

    When you reach the Fungle Road you can enjoy several kilometres of fun singletrack - lots of roots and stream crossings to keep you awake. After tackling the Fungle you arrive back at the Glen Tanar road and a short spin back to Aboyne.

    Ordiequish / Fochabers Loop

    Distance: 35.2km TRL GPX
    Physical: Technical: Fun:

    The Ordiequish trails are one of the Moray Monster trails. The routes are well marked and easy to navigate. This tracklog shows my usual route which samples the best bits of both the Ordiequish area and also the Fochabers side of the forest. Trail highlights include the infamous Gully Monster and the endlessly fun blasts through the forests of the Fochabers Ring trail.