New year – projects? Rotating macro stage…to become a goniometer?

It’s  New Year and I am starting to think about what I will be making in the next 12 months. Certainly, I will be wanting to improve on existing designs. Currently, I have functioning versions of the following set-ups:

High speed shutter

Cross-beam sensor

Laser rangefinder sensor

Motor driven focus rail and Arduino-based controller

I am sure the high speed shutter can be significantly improved. I don’t think it can be made to go much faster (5mS to open, a little longer to close). However, I would like to make a light-trapped version in which the shutter blade runs inside a housing. I have a preliminary design for this and will be trying it out in the near future.

The cross-beam sensor works well, and I don’t think I can improve on it much, though I might try building a frequency modulated system like that used in the rangefinder sensor. The main thing that needs doing with this system is to reduce the weight  – I find it too heavy and, though I plan to use it with a harness, I think a lot can be done to cut down the mass. More on this below.

On the rangefinder front, though the current system is very precise, I think I can improve the optics of the rangefinder. I plan to take an old 50mm standard lens and use this as the optic for the rangefinder. This will allow focusing at different distances and make the system quicker to set up. I also think the diaphragm in this lens could be useful in reducing the light falling on the sensor. The sensor itself works fine but some other and potentially better, IR photodiodes exist and could perhaps provide improved results. Once again, the main issue is weight. I intend to deal with this as described below, but also by creating a single printed circuit board to replace the four little boards and arranging the power supply so that the system can run off a single battery. I may also, as Maurice Ribble (of Camera Axe fame) suggested, get the Camera Axe trigger to do more of the work. I will abandon the current very robust, but somewhat heavy 3mm aluminium chassis for something lighter. I also want to incorporate some better targeting lasers to make it easy to target small insects. The Yongnuo strobes aren’t light, but I think they are here to stay….

The focus rail works well and I am pleased with its precision and also with the Arduino controller. I have just finished a dedicated version of the controller using an Arduino Nano and an EasyDriver. The whole thing fits in a die-cast box (see below) and is a bit more robust than the original LCD/button shield version. The only change/improvement I envision is the incorporation of a button on a free digital input to allow the software to swap to menus that enable control of the optoisolator switches so they can be used to control lighting, and motors to for example, rotate the specimen (see the paragraph below on the goniometer stage) when acquiring stereo images. The point-to-point wiring inside the die-cast box was a nightmare to do… I guess I might also practice my new found PCB drafting skills on it as well.

Recently finished Arduino Nano-based focus stacking controller.

Recently finished Arduino Nano-based focus stacking controller.

OK, so weight is a problem with both the cross-beam and rangefinder setups. Size and weight often go together where cameras are concerned. My Nikon D7000 isn’t a particularly hefty camera but with the Nikon 105 macro lens coupled to it, it definitely isn’t light. I recently purchased an Olympus OM-D EM10 and three micro 4/3rds lenses (two zooms and a macro – see picture below). I have only had the camera a few days,  but my initial impressions are that it is truly excellent. The Olympus Zuiko 60mm macro lens seems very sharp and it performs well both as a macro, and a portrait lens. The camera is a lovely example of miniaturization. If you lever the back off (don’t do this!!), you find exactly what you come to expect from using this outstanding little camera, all that is inside is a small wax doll and some finger nail clippings…….it’s all done by voodoo! The sensor may be small but it’s extraordinarily noise free. The electronic view finder works brilliantly, the touch screen/live view screen is great and you can configure the two main control dials to do whatever you want. It is very intuitive to set up so if you have, like me, an aversion to reading manuals, it’s very easy to work things out as you go along. You can read the reviews for the camera so really I don’t need to say much except….it’s small, light and cute, and it has everything I need to put in place of the Nikon in any of the applications in which I am interested. It is controllable via wi-fi and both my iPad and iPhone can be used as controllers with live view display to their screens. There is scope to do some interesting things with this in terms of remote control. Pictures can be immediately uploaded to the controlling device. This camera, together with a frame made of thinner aluminium, should solve most of the weight problems of the cross-beam and rangefinder set ups. I wonder how long DSLRs will go on selling – mirror free has so much going for it.

Light and fast, I think it could be good for macro work of the kind I am interested in. The Olympus Zuiko 60mm macro lens is very good. It too, is very light.

Light and fast, I think it could be good for macro work of the kind I am interested in. The Olympus Zuiko 60mm macro lens is very good. It too, is very light.

New projects for 2015? The only one I have started is a goniometer stage – a macro stage that allows one to change the angle of an object in three dimensions and yet have it remain central in the camera’s viewfinder. So far, all I have made is the ‘turntable’ on which the object sits. This is made from aluminium parts coupled to a small stepping motor with a built in 64:1 reduction drive. This Motor has a gear ratio of 64 , and Stride Angle 5.625°  so it makes a 4096 steps to turn 360 degrees .This means one step will drive the turntable through 0.088 degrees! Slop makes that figure pretty meaningless but I would be upset not to be able to position the turntable with a repeatability of better than 0.2 degrees….we shall see.

The stage is driven by a BYJ48 stepping motor coupled to an Arduino controller.

The stage is driven by a BYJ48 stepping motor coupled to an Arduino controller.

Arduino controller for the rotating table. Allows movement to any position and at any speed.

Arduino controller for the rotating table. Allows movement to any position and at any speed.

I am sure other projects will occur to me but I think I am mostly bound on a route of continual improvement of what already exists.

PS the turntable is now functioning well (it is accurate to better than 0.2 degrees if you dial out the backlash) and generating some interesting shots – more to follow.


About petermobbs

Inveterate meddler.
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