Wednesday, 3 April 2013

Improvised macro lens for a point & shoot camera.

Flower of an unnamed native buttercup, photographed with my old Spotmatic. The flower is probably about 15 mm diameter.
Years ago (about 1970) I was given an Asahi Pentax Spotmatic 35mm camera with a 50mm macro lens.  I used that camera for field and family photography for about 30 years.  It was tough and I never had it serviced, and sometimes the photos were great.  In the last 12 years I've had three different digital cameras, all cheap(ish) point-and-shoot models.  While they get pretty close, they don't match the best performance of the Spotmatic for plant close-ups, although they have some real advantages.  On the whole I'm pretty happy with the latest one, a Sony Cybershot 14.1 megapixel camera.  It's small and light and has a macro function that does a reasonable job with all but the smallest flowers.
Digital cameras are evolving rapidly and so I seem to need a replacement every few years. Fortunately they're also getting cheaper as they get better.  I'm reluctant to shell out a lot of money for a digital SLR, knowing in a few years it'll be obsolete, or at least surpassed by newer models.  However, I would like to get closer to small flowers, so I've been playing with cheap alternatives.

The latest is a $10 home-made macro lens.  It's inspired by the idea of the Ōlloclip lenses for iPhone (I've just bought a set of these and they're pretty good and very portable).  You can get reasonable results by simply holding a botanist's field lens in front of the camera lens, but I was lucky enough to have a cheap jeweler's loop that fits quite snugly over the lens of my camera.  Unfortunately though, it's a bit tricky to hold it aligned in place while you take the photo.  I wanted something a bit more stable.

I hit on the idea of using cheap plastic plumbing attachments to hold the lenses together.  Here's the camera with the parts of the new system.  The loop fits snugly in one end, and the other end fits snugly over the camera lens when it's extended.  You have to zoom a bit to fill the field of view.
My point & shoot camera with components of the clip-on macro lens: a $2.50 plastic pipe attachment and a $10 jeweler's loop.
And here's my camera with its new macro lens fitted.  I still have to hold it while I take the photo, but the pipe fits snugly so I don't have to position it as well.  I could superglue a threaded plastic ring onto the camera, then screw the pipe attachment into it (it's threaded on both ends), but I don't want to do that to my camera, at least until it's out of warranty (in a few weeks).  If I did that, I could put the camera on a tripod for greater stability and better focusing, so I might do it quite soon.
The macro lens clip-on in place.
The real test is in the results.  Here are three shots for comparison: using the standard camera as close as it can get (left), then using the new clip-on lens with the zoom half-extended (centre) and fully extended (although not quite focused, right).  Printed at 300 dpi, the 1 cm wide key in the right hand picture would be about 33 cm across:

The new system has quite a good working distance and is easy to use.  There is a little distortion of parallel lines (see above), and there might be other effects like chromatic aberration that I haven't looked for.  But at $12.50, it's a bargain.  I'm playing with other improvised systems too, and might report on them later.

I used it in the field this week too:
Veronica scutellata, Foxton Beach.  In the original photo, the flower was 1240 pixels across; in life it's about 6mm.
Veronica catenata, Himitangi Beach.  In the original photo, the flower was 800 pixels across; in life it's about 4 mm.

To finish, here's what the Ōlloclip macro lens can do with an iPhone 4S:
Veronica serpyllifolia capsule.  It's 4 mm across, and spans about 600 pixels in the original.

It focuses at 13mm, so I guess I need some kind of adjustable stand to hold the phone at that distance from the subject.  I've started building one.

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