Stacking It In the Studio - And not at the Motorcycle Races

on February 22, 2017

I mentioned earlier in the week the unending quest for depth of field with studio tabletop illustration. In most cases of products or packs, we can shoot from such a distance that we avoid running out of depth of field. We select medium focal length lenses and stop down enough to get the thing sharp from the front of the product to the back.

I do not know if anyone uses the facilities of the older monorail large format cameras to gain this sharpness - perhaps they would if there were an affordable digital sensor that you could slot into the back of the camera. But there isn't - no great new discovery of a 4 x 5 digital back has appeared.
The pack shots take care of themselves - people also have the option for tilting and shifting if they use the larger full-frame cameras. For an amazing amount of money they can get tilt and shift lenses for their DSLR. Few give way to the need for amazement and many save their money...

Well today I tried the Olympus solution to this problem - the focus stacking program inside the new OM-D E-M1 mk II camera. Thanks to YouTube I found out the difference between focus bracketing and focus stacking and watched the camera do both things.

Focus bracketing is the automatic process of shooting slices of an image with different focus points and then having them ready to present to a suitable external processor - Zerene or Helicon or Photoshop - for combination. You get to specify how many slices and how deep they are, and once you press the go button the thing is automatic. You can apparently use it to fire flashes as it works, though I did not achieve this. In any case you can watch the back LCD screen as it shoots and see the focus travel back from the start point.

Focus stacking is similar, but you don't get to choose how many slices - just the depth. Compensation is provided by the fact that this Olympus program does the processing in-camera after the final shot and presents you with a final result.

Here's an illustration of the basic problems - this Soviet motor bus is 1:43 scale, and ends up being about the length of your hand. A conventional shot with a macro lens leaves soft edges at the front and back bumper.

You don't have this sort of problem with a shorter model such as this taxi.

I was unable to get the 25mm f:1.2 lens to work with the focus stacking, but the 300mm f:4 lens did go very well. It meant retreating to the back of the studio to get the thing in frame...not a practical way to shoot... but look how well it stacked in front and back.

Perspective is different as it is a tele lens. But the fact that it has a much shallower intrinsic depth of field due to the focal length - but still renders the thing sharp - means that with one of the smaller Pro zoom lenses you could get even better backdrop. The smaller sensor size, allowing a shorter focal length for the same angle of view, scores here. The Focus stacking is the sweet icing on the cake.

Can it pass the Pontiac Test? The 60's Pontiacs were some of the longest American cars available to the general public and the 1:18th scale models of them are nearly impossible to adequately illustrate with a standard lens - they run out of focus front and back. But look what happens with the 300mm Zuiko and the focus stacking....

I see a few shiny blob artifacts where the lights bounce off the chrome but the overall rendition is sharp. You see the same compression of perspective in the heading image round the studio Muzz Buzz bar.

The process of the stack is very fast, but you need to have the camera on a tripod, as well as constant lighting. I selected Incandescent WB for the strobe modelling lights and it all worked well.