Art and Photography

DIY motorized rail for macrophotography - any ideas how?

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  • Dec 15th, 2014 9:24 pm
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[OP]
Deal Addict
Aug 30, 2007
1666 posts
698 upvotes

DIY motorized rail for macrophotography - any ideas how?

Occasionally I do extreme macro photography (magnification 5-10:1), using a stacked reversed lens setup (reversed manual focus lens, like 50mm f1.8, on top of an AF telephoto lens, like my 135mm f2.0), Magic Lantern firmware on my Canon camera to run a sequence of shots automatically with focal plane continuosly moving through the subject, and free focus stacking software. For lighting I use a flash with a DIY modifier (1$ semi-transparent semi-sphere lunch box from dollar store), plus a reflector (a piece of paper). This of course can only work with still (dead) subjects, and results in photos like these:

ImageTEST: DIY macro lens by syamastro, on Flickr

ImagePortrait of my neighbour by syamastro, on Flickr

But here is an issue here. Relying only on AF of my primary lens to move the focal plane results in a fairly small composite (or synthetic) DoF of the photo after the focus stacking is done, which is in most cases is not sufficient. Say, if the frame width is 4mm, the synthetic DoF will be 1mm or so. It is not possible to put the whole object in sharp focus, which would make the photo much more spectacular and out-of-this-world.

I tried to circumvent this problem, by purchasing a cheap manual macro rail from ebay, and doing two sets of shots for focus stacking. Within each set, I still rely on AF of my lens to move the focal length, but I move the camera manually between the two sets, to cover wider range in DoF. This procedure is very cumbersome and time consuming. When moving the camera, everything (angle of view, angular size of the object, position and orientation of the object, brightness) changes in a step-wise fashion between two sets, which makes it imposssible to simply put the two sets together and stitch them together with a focus stacking software. I end up doing lots of measurements on both sets, and manually modifying one set (change scale, angle, brightness) to make the transition to the second set as seemless as possible. Here is one attempt of this kind:

ImageMacro fly by syamastro, on Flickr

So DoF did double, but it was a very laborous exercise. Plus, I'd like to have even wider DoF, and doing three sets would make it even more time consuming.

One can always solve this problem by spending ~500$ or more - buying a professional motorized macro rail. There the idea is that you move the camera itself for each shot by step motor, then pause and make the shot, and so on.

But I was trying to come up wit a DIY setup to achieve the same result but for free or very cheaply. Specifically, I am almost sure that one can greatly simplify the problem by avoiding the step motor + syncing with the camera, and simply moving very slowly the target (or the camera) while continuously taking shots using Magic Lantern intervalometer script - say every second or so. This will work because the duration of flash light is dramatically shorter than 1s interval between the shots, so the shots should be perfectly sharp despite the fact that the target is slowly moving.

Say, I want my target to move 5x the distance I can currently cover witrh the AF technique - that is , around 10mm. That will require ~200 shots, or 200s for the target to travel the 10mm, resulting in 0.05mm/s required speed. My flash (Canon 580EX) has a flush duration ~1ms for full output, and ~10x less when used for macro (I use 1/8-1/16 manual power). So during the flush the target will travel 0.05mm/s / 10,000 = 5 microns between the two shots (a millionth fraction of the frame width), which should result in a totally undetectable motion blur. In fact, continuous moving of the target should be smoother (meaning less chance for the target to shift during the shot sequence) compared to using a step motor.

So my question is: can anyone come up with a bright idea what cheap or easily accessible parts or components can be used to make a small (say, 4x4cm) platform which would move extremely slowly (0.05mm/s) away from the camera for a distance up to 20mm or so? Ideally, the speed would be adjustable (not principal - one can simply change the time between shots), and it would be easy to disengage the platform from the motor for quick initial positioning of the target. Something one can buy on ebay, or find in IT dumps (old printers, scanners etc.). No need to sync the platform with the camera, it is perfectly fine to start the platform and then start the intervalometer scripts in Magic Lantern on the camera. Just a simple horizontal super-slow continuous motion in one fixed direction.

Thanks for any feedback.
9 replies
Deal Addict
Sep 12, 2007
1982 posts
527 upvotes
Well, you lost me after the first paragraph but these are some awesome shots, I'd love to be able to pull one of these off at some point. I will have to reread your post several time to get what you're currently doing. Cool pictures!
[OP]
Deal Addict
Aug 30, 2007
1666 posts
698 upvotes
I am rethinking my strategy here. Moving the target is not the best thing for macro photography because

- any non-smooth motion and the target (say, a fly) can shift or even fall;
- moving target will result in changing lighting on the target;
- most importantly (just occurred to me), when you move the target you have to collimate well the vector of the target motion and the direction of the camera, otherwise the motion will be sideways, which will result in obvious distortions of the target shape. And this is something not easy to achieve - when camera and the target are totally decoupled.

So I am going back to the idea of moving the camera itself, again just a smooth continuos motion (no step motors, just a gear motor - so no need to synchronize camera shutter with the motor). So perhaps I will try to connect this manual macro rail which I already have (16$ US with free shipping),

[IMG]http://img.dxcdn.com/productimages/sku_136305_1.jpg[/IMG]

with this super-slow (0.5RPM under load) gear motor (17$ US with free shipping):

[IMG]http://www.tsinymotor.com/uploads/allim ... 6070-L.jpg[/IMG]

The specs for the gear motor are: 12V DC voltage, 0.5RPM under load (0.6RPM no load), 25 kg*cm torque under normal load (53 kg*cm torque to stall the motor).

In my macro rail, one full rotation of the knob moves the camera by 20mm. Then 0.5 RPM will result in the camera motion of 10mm/minute (0.17mm/s). This is 3x faster than my goal (0.05mm/s), but perhaps my camera+flash will handle the required higher framerate (3fps) - I will test that. Or perhaps I should look for even slower gear motor (~0.2rpm).

The uncertainties are whether the motor's torque of 25 kg cm will be good enough to move my camera on the rail (~2kg with the lens). I have to figure out how to attach the motor to the rail's knob in a way when it can be easily disengaged, for camera repositioning.
[OP]
Deal Addict
Aug 30, 2007
1666 posts
698 upvotes
I assembled my DIY motorized macro rail using the parts mentioned in my previous post (gear motor + macro rail). I'll post a detailed description later, and for now here is the first test shot made using the gadget (120 shots):

ImageFIrst shot with a DIY motorized macro rail by syamastro, on Flickr
[OP]
Deal Addict
Aug 30, 2007
1666 posts
698 upvotes
The colors were a bit off, I fixed that.
Deal Addict
Sep 12, 2007
1982 posts
527 upvotes
Could you please share.

-What is the focus stacking software that you use, you mentioned that it's free.
-How do you you sync your flashlight to blink at the same time as the pictures are taken?

Thanks!
Deal Guru
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May 6, 2005
10305 posts
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Vancouver
Missed this when it was originally posted! Would love to see an updated DIY guide for what you actually used - and some more pictures!
[OP]
Deal Addict
Aug 30, 2007
1666 posts
698 upvotes
vodka wrote:
Dec 15th, 2014 8:46 am
Could you please share.

-What is the focus stacking software that you use, you mentioned that it's free.
-How do you you sync your flashlight to blink at the same time as the pictures are taken?

Thanks!
I used enfuse + align_image_stack command line utilities (the latter is a part of the Hugin package). All open source. I followed these instructions:

http://blog.patdavid.net/2013/01/focus- ... nfuse.html

I believe there are GUI for enfuse, but I prefer to use command line tools (more flexibility). I did everything using 16-bit TIFF images (all these programs support that), this ensures the best possible quality. My workflow is to
- Use ACR to convert all RAW files to 16-bit TIFF (no processing; I set the sharpness to zero, but this might not be very important)
- Run align_image_stack - produces another set of 16-bit TIFFs (aligned)
- Run enfuse - produces a single 16-bit TIFF
- Load the TIFF file in ACR, and then do all the PP: color balance, sharpness, clarity, saturation, exposure etc. Then save it as a jpeg.

I tried other software (e.g. yesterday I tried a trial version of Zerene Stacker), and the quality I get is comparable to enfuse or worse - and these are commercial packages.

Regarding flash synching: currently the flash is off-camera, but connected to the camera with a cable (from ebay). In the future I will try to make a macro flash ring for my macro rail, which will use the on-camera flash.
[OP]
Deal Addict
Aug 30, 2007
1666 posts
698 upvotes
Kaitlyn wrote:
Dec 15th, 2014 2:24 pm
Missed this when it was originally posted! Would love to see an updated DIY guide for what you actually used - and some more pictures!
Sure, will do.

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