Saturday 24 August 2013

Assembling a focus stacking rig

Okay, you've accumulated all the equipment mentioned in the previous post. How do you put it all together and shoot a low magnification* stack?

(* low magnification here means up to 4:1)
  1. A Digital SLR (Here an Olympus E330)
  2. Ideally a wired or wireless remote shutter release.
  3. A Manual-focus, manual-aperture lens (Here an Olympus OM 50/1.8)
  4. Extension tubes or bellows (Here OM Auto bellows)
  5. Focusing rail (built into OM auto bellows)
  6. Solid mount for camera/bellows/lens assembly (A tripod or copy-stand)
  7. An adapter from the camera mount to the bellows (Here an Olympus MF1)
  8. If necessary an adapter from the bellows to the lens (not needed here)
  9. Some light: a bright window, a desk lamp or a flashgun with off camera cable
  10. To process the stacks you will need a computer and some stacking software.
First, mount the camera/bellows adapter to the camera and then mount to the bellows. Mount the lens on the front of the bellows. We're going to reverse the lens by reversing the whole front stand/lens assembly. (As at higher magnification, this standard lens will work better in this orientation).

Carefully unscrew the bellows retaining screw (circled in red in the next photo). You do not need to remove this screw - just undo until the bellows comes away from the front stand.

Unscrew and remove the end-stop screw from the lens end of the focus rail.

Now wind the lens assembly off the end of the focus rail, reverse it and push it back on a little before winding it back into place.

Tighten the bellows retaining screw to hold the bellows to the front of the (now reversed) lens, and replace the end-stop screw in the end of the focus rail. (This just stops you extending the lens off of the rail, I say 'just', this is quite important!).

You should now have something like this:

Note: From the left: Reversed front stand, reversed OM 50mm/f1.8, Bellows, Rear stand, 4/3 to OM adapter, E330 DSLR.

Now mount this whole assembly onto the tripod/copy stand. Make sure all the mounting screws and the screws that hold each end of the bellows in place are done up tightly. The whole camera/bellows/lens assembly is quite heavy, so I use pliers to tighten the screw that holds all that onto the copy stand as I really don't want that coming undone.

Note the lens aperture control switch on the bellows. When set as in the following picture, pointing down the length of the bellows, the lens will remain wide open.

When set as in the following picture, almost perpendicular to the bellows, the aperture of the (OM) lens will stop down to the setting on the aperture ring.

Notes: The aperture control switch still operates the lens aperture when reverse mounted in the way described above. If you are using a non OM lens via an adapter then this switch will have no effect, in that case you will have to rig some way to stop the lens down manually.

Set your camera up as follows:
  • Manual exposure mode. (or if your camera does not have fully manual mode then use shutter priority mode)
  • Check exposure bracketing is turned off. (in fact make sure all bracketing modes are disabled)
  • Set White-balance to flash (5600k)
  • Set ISO to lowest available setting.
  • If using flash, set manual flash power, and set fastest available sync shutter speed (If using E330 and compatible flash then 1/160th second is the fastest setting available).
  • Set Mirror-lock-up to 5 seconds.
  • Ensure you have fresh camera battery in camera (and fresh batteries in flash if using flash).

My version of this particular lens works best at around f5.6, so set that on the lens aperture control ring. For now, leave the bellows aperture switch to hold the aperture wide open, if you stop down the lens at this point then you will need to put a lot more light on the subject to be able to see what's going on...

Now you're all setup to shoot and focus stack at up to around 4:1. The next article will describe the basic process of shooting the stack and combining the slices in Zerene Stacker.

1 comment:

  1. Wish you were my friend so that I see your work from close distance that how you make a MAGIC WORK.