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Camera slider/Macrophotography slider

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Achilles:
Hey Folks,
I have an idea for a while.....
I take some macrophotos and have done some timelapse shots before, what I would like to do again.
So it came to my mind to build an automated slide for high magnification photos and focus stacking. I can go up to 1:1 with my macro, but a bit more would be nice. Even with 1:1 it can get hard focus all (even with a veeeery small aperture)

The Idea is to build a slide that controls a spindle drive with a stepper motor. I use an old Nikon DSLR with 12Megapixel and DX sensor, so I calculated a Depth of Filed of about 0.3mm at f8 and 1:1 magnification.
If I go up to 3:1 Mag this shrinks to 0.071mm (crazy.....). So I want to try if I can get 0.05mm steps accurate, otherwise I choose 0.1mm what should be manageable.

The Slide will be made of a spindle drive on ball bearing, like on a cnc-router, with a belt drive with  reducing gear. So that is the first use ;)

Hardware will be a Micrprocessor (thinking of Pic32Mx440), TFT Touchscreen for inputs and fine adjustments (softkeys) and a rotary encoder for course/fast drive, powered by a Lipo (I may take 13,7V Lipo like for RC Toys) and four stepper motor controls.

For the Macro slide I just need one, but I also want to use that controller for a longer track (less accurate of course ;)) for a Stop Motion slide with Pan/Tilt, Focus control. Or use it as Slide with Focus and Zoom Control (I think I may just take some rubber wheels which press on the Zoom and Focus ring connected to a stepper motor) because I always wanted to try out the Hitchcock Zoom ;).

I will be in the green in a few weeks so I may take some work for after work with me ;)

DrGeoff:
Not sure what you are trying to achieve here.
Why not just use extension tubes or a bellows?
Or another trick for really close shots is to reverse your 50mm lens (you can get reversing rings for standard lenses). You lose all the auto stuff, so you need to manually focus and calculate your exposure, but you can get some really close shots.

DrGeoff:

--- Quote from: Achilles on October 27, 2011, 08:27:40 am ---
The Idea is to build a slide that controls a spindle drive with a stepper motor. I use an old Nikon DSLR with 12Megapixel and DX sensor, so I calculated a Depth of Filed of about 0.3mm at f8 and 1:1 magnification.
If I go up to 3:1 Mag this shrinks to 0.071mm (crazy.....). So I want to try if I can get 0.05mm steps accurate, otherwise I choose 0.1mm what should be manageable.

--- End quote ---

Don't use f8 then, I use f42 for most close up macro shots. Never had a problem with focus (manual) or dof at this aperature.

Achilles:
Nope it isn't the Magnification I am working on, it is focussing. 1:1 Magnification is achieved at special object-sensor distance and objects have some issues. Number one, at these Magnifications you have a very small depth of field, which you can overcome by shutting the aperture. This means you loose sharpness (at least when you shoot digital) due to diffraction.

So you have about 0.3mm DOF. which means focussed at 300mm, everything between 299.75 and 300.15 is sharp, the rest blurs more and more.... A bellow doesn't help here, because you alter the magnification. So you have slides where you can slide your camera forward and backward to bring this small sharp area over your desired object. If you need a higher DOF you could, as I said, close the aperture down or just take a picture, slide the camera back 0.3mm, Take a picture, slide, picture until the whole object is covered and then take the sharp areas of these pictures and stitch them together in Photoshop. As I said, that is called focus stacking.

I currently use a 150mm Macro, that allows me to go up to 1:1. With a reversed 50mm attached to that I can go up to about 3:1.
http://en.wikipedia.org/wiki/Focus_stacking

Achilles:

--- Quote from: DrGeoff on October 27, 2011, 09:37:53 am ---Not sure what you are trying to achieve here.
Why not just use extension tubes or a bellows?
Or another trick for really close shots is to reverse your 50mm lens (you can get reversing rings for standard lenses). You lose all the auto stuff, so you need to manually focus and calculate your exposure, but you can get some really close shots.

--- End quote ---

Yeah, that's what I usually do, but if you increase the Magnification you loose more and more of the depth. You could also use microscope lenses and a bellow for macro. At 1:1.f52 the calculator tells me about 5.2 mm DOF, which isn't very much either. And at least in my setup I see a clear difference between f12 and f42. So for real sharpness I try to avoid really high apertures. My camera has a quite high packed sensor which doesn't help at high apertures, too.

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