Friday, August 15, 2008

Mustard Seeds

Mustard seeds were what I photographed two days ago. The photograph above is of a pile of mustard seeds taken with a macro lens at 1:1 magnification. The photograph from the previous day was taken with a macro lens at 5:1 magnification. Just for fun, I wanted to see if I could take an image with even great magnification by putting 72mm of extension tubes on the MP-E 65mm lens. Below is the result.

With the Canon MP-E 65mm lens, at 5x magnification, the working distance between the front element and the subject is less than an inch. At that distance, the lens and camera body also block so much light that the subject becomes unlit. This means that a flash like the MT-24EX or the MT-14 ring lite are essential. Here is an image I took at approximately 3x magnification:

Apart from the lighting, the other big challenge in extreme macro photography is focus. Focus is tricky because of two reasons:
  1. The relatively low light because the camera body and lens blocks so much of it
  2. The extremely thin depth of field at these magnifications means that even a slight focus error can ruin an image
You can see in the image above that even at f/13 the depth of field isn't large enough to allow all the seeds to be in perfect focus. The (~6-7x) magnification image (2nd down from top) was taken at f/16 and even there the bottoms of the seeds are out of focus, though the tops of the seeds are all in focus.

The top most image was also taken at f/16, however the seeds were piled in a slightly pyramidal fashion so there were many seeds out of focus. That image is a composite of three images that were taken at three different focal depths and then put together in Photoshop.

Though I took the image from 2 days ago with the 1D3 and used Live View (which really helps getting critical focus), this time I decided to use the 5D with the Ee-S focus screen. I actually didn't have that difficult of a time getting things in focus for the 1x and 3x images. This was mainly due to the fact that I could use the modeling lamps on the MT-24ex to light up the subject perfectly. However the image at 5x with extension tubes posed a real challenge since the modeling lamps couldn't be oriented properly, so I had to 'pulse' the flash several times to get things in focus along with taking a few test shots along the way. Overall I'd say LiveView isn't essential for super macro photography but it does help, especially in knowing when all the vibrations have been suppressed so that you can release the shutter.

So what the rig to do all this look like?

My office is still 'under construction' as is about 1/3 of the rest of the house so I had to use the dining table. The tripod is a Gitzo G2257 (has now been replaced by the GT2530) carbon fiber tripod. It has a unique feature which you can see which makes it very useful for macro, garden, insect and flower photography; its center column can be rotated to be perpendicular to the base of the tripod and the legs can be locked independently and at any position. All my macro photographs from the last 4 months have been taken with these legs and I've found it very useful and easy to use.

The ballhead is a Markins M10L with a Really Right Stuff B2LR II base. Though the entire kit only weighs a few pounds, I've found it to be incredibly sturdy and wouldn't hesitate to put my 300 f/2.8 with a 1-series body on these legs and ballhead (though I probably wouldn't tilt the center column too much with that much weight).

Attached to the ballhead is the RRS B150-B macro focusing rail. Since the MP-E has a collar and foot, the RRS LMT is needed to mount the set up in the correct direction. The Really Right Stuff gear is horribly expensive but its extremely well built and there really is nothing better out there.

Finally, attached to the 5D, is a set of Kenko Extension Tubes (36, 24, & 12mm) which in turn is attached to the Canon MP-E 65mm lens. And then we have the light source, the MT-24ex whose flash heads attach to the front of the lens.

Also note the seeds on the plate and how small they are in comparison to the images of them above. When I took the first picture of the seeds I was amazed by the amount of detail on the surface of the seeds. I've always thought of mustard seeds as being round and completely smooth and it was neat to see the variations in shape and to see that the surface texture wasn't smooth.

These seeds were kind enough to sit still for me, but I think I may have a bigger challenge when I try to get out and photograph living creatures. Still it should be fun!

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