Full frame, about 4.5 mm wide:
This was a 29 frame stack, shot at 5X on sensor, using just what you see above: a Canon T1i camera and a Canon 18-55 mm kit lens reversed on a short extension. Continuous illumination, no macro rail, not even a cable release.
Here's a crop from the image:
Now, this certainly isn't as sharp as I'm used to getting from a microscope objective or an MP-E 65 on a high precision rail. On the other hand, it's a lot cheaper. Beyond normal kit components, what's used here is equivalent to a reversing adapter (like HERE) plus one ring from a set of no-frills extension tubes. The tubes and reversing adapter combined can be purchased new for less than $15 with free shipping.
There are a few aspects of this setup that are not obvious, so let me step through them.
Aperture. The aperture on this lens is controlled electronically by signals from the camera. There is no ring or lever like is often found on older lenses with mechanical controls.
When mounted normally on the camera, the lens stays wide open except for two conditions:
1) when a picture is being taken, and
2) when the depth-of-field (DOF) preview button is pressed.
However, the lens can be made to stay stopped down for use on non-automatic tubes by the following procedure:
1) Mount the lens on the camera.
2) Set the camera in Av mode, turn it on, and dial in the desired f-number.
3) Press the DOF preview button. Looking into the front of the lens, it's easy to see the aperture close down.
4) Press the lens release button and remove the lens from the camera, while keeping the camera turned on and continuing to press the DOF preview button.
This procedure removes power from the lens while it is stopped down, and as a result it will stay stopped down until it is mounted again on the camera as usual. The procedure is physically awkward and feels dangerous because it involves interrupting a connection with power applied. Nonetheless it is frequently advised. I've never heard of any ill effects, and I've certainly not experienced any. (My legal advisor makes me add: "Your mileage may vary, and the advice comes with no guarantees.")
As usual with high-magnification work, it's important to select an appropriate f-number: wide enough to avoid excessive diffraction blur, but stopped down enough to avoid excessive aberrations. The above stack was shot at a lens setting of f/5.0, which produces an effective f-number around f/30 at 5X. The image is certainly not sharp at actual pixels, but as shown by comparing the crop and the full frame, there's more detail than will fit in a single web-sized image. I determined the f/5.0 by a fairly crude experiment -- it was a lot sharper at f/5.0 than wide open at f/3.5 or closed more at f/8. There may be an even better value that I didn't check.
Focus. Surprisingly simple. It turns out that with this lens used in this way, turning the focus ring shifts focus by a pleasantly small amount. Even at 5X and f/5.0, I had no trouble stepping focus by small enough increments to avoid focus banding. This was a surprise. I had expected from just looking at how the lens moves that the focus shift would be much more. So, coarse focus by moving the subject, and fine focus by turning the ring.
Vibration. I shot here in Live View mode without flash, which means that I was using Electronic First Shutter Curtain (EFSC), no vibration caused by the camera. Then I set the camera's self-timer to give 10 seconds delay between pressing the expose button and actually taking the picture. That gave plenty of time for vibrations from my hand movements to die down.
An alternative would be to shoot with flash, and we'll see an example of that a little later. I just used continuous illumination and Live View in this case because I could and it was convenient.
Magnification. A pleasantly wide range. Here is a mm scale, photographed by just turning the zoom control between 18 mm and 55 mm. The sensor size on this camera is about 22 mm, so magnifications here range from about 5X to 1.5X.
Here's another subject, shot at minimum magnification, about 15 mm field width. I believe the aperture was set at f/8.
Full frame:
Crop:
This was a 22-frame stack. Here's an illustration of why I stacked it:
One last example... This is the Anthers and stigma of a Christmas Cactus flower that I posted over in the Technical and Studio gallery.
This was a 5-frame stack. Here's how it was shot. The Kleenex is not for show, it's mandatory for decent illumination using on-board flash with this setup. Without the Kleenex serving to block direct illumination and provide lots of indirect, the lens shadows most of the frame and all that comes out is a narrow band of overexposed subject at top of frame. With the Kleenex, I think it's OK.
I hope you find this interesting and possibly useful. I've seen other people using various setups along these lines, but I had never pursued it myself due to lack of need. It actually worked better than I expected it to.
--Rik
