That's an excellent reference, Dave.DaveW wrote:I know many have Lester Lefkowitz's book "The Manual of Close-Up Photography", so see his combination of three sets of standard bellows plus extension tubes on p.86.
Note he also makes his own ultra long extension tubes from lengths of plastic drain pipe on p.88. As he claims his centre drainpipe extension tube illustration is 27" long, that makes the longest one in the same illustration over 4ft long!
For those who don't have a copy of the book, let me quote the introduction of Lefkowitz's discussion (page 85):
It's important to note that the previous page is titled "WARNING: DIFFRACTION!" (in caps and boldface, just like this).SUPER EXTENSION
There are special cases when extremely long extensions are necessary. Examples include: (1) a need for unusually long working distances and high magnifications, such as when photographing dangerous or remote industrial or medial procedures, or when recording behavior of misanthropic or skittish animals and other biological species; (2) a desire for high-resolution photography (scientific, forensic, medical, or professional) at magnifications greater than 10X (10:1) without buying the expensive true macro lenses.
The example on page 85 shows an 8X image that is already quite soft even at its published size of 3 x 4.5 inches. The example on page 86 shows a chain of 3 bellows, with a 105mm lens on the front of it. The caption also describes the picture next to it, which was shot with a 200 mm lens. That picture is of the "Star of India -- world's largest blue star sapphire", shot in situ at the American Museum of Natural History, sitting "6 inches behind a very thick slab of impenetrable glass", and requiring a working distance of 28 inches even at 0.5X magnification. The example on page 88 shows a 22X shot of a dollar bill. That image is reproduced at 2-1/4" square and is barely sharp even at that small size.
What Lefkowitz is demonstrating is the use of long bellows to produce images that are large enough to fill a 35mm frame, regardless of how fuzzy those images might be.
With film, there are compelling reasons to do this. Projecting a cropped slide doesn't work very well, and with any film, using the whole film area produces significantly better gradation than using only a part of it.
With digital, the advantage is quite a bit less because resizing is easy and the images are not so noisy to start with. Given that the underlying image is fuzzy, it's hard to tell the difference between 2000x1500 pixels rescaled from a full-sensor image of 4000x3000, and 2000x1500 pixels simply cropped from an image at half as much magnification.
Finally, Lefkowitz's book deals primarily with 35mm film -- a 36 x 24 mm sensor. But elf asked about the Olympus e330, which has a sensor barely half that big, only 18 x 13.5 mm. The acceptable size of the Airy disk, and the corresponding bellows length, simply scale to match -- half as big, half as long.
The bottom line, in the context of elf's question, is that long bellows could be very useful if he wanted to make high magnification fuzzy pictures with really excellent gradation. Barring that, shorter bellows will work just fine.