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