I ventured into my garden Saturday evening after some severe thunderstorms
had passed to the north. To my surprise, I discovered that a Guayacan
(Guaiacum coulteri syn. G. planchoni) shrub I planted more than twelve years
ago had flowered for the very first time:
http://www.flickr.com/photos/64004640@N03/7582795920/in/photostream
To many native plant purists this plant is considered to be an outsider
since it is not native to Arizona. However, it can be found in the southern
portions of the Sonoran Desert near Carbo and Ures in the state of Sonora, and
for that reason it can be considered a native Sonoran Desert plant in the broad
sense, in the same way that we accept plants from Baja California and the
northern portions of the Chihuahuan Desert that extends into the southeastern
portion of the state. Although there is some general disagreement at the
northern extreme, the crest of the Sierra Madre Occidental establishes the
separation between the Sonoran and Chihuahaun deserts.
My garden is manicured to provide a variety of environments for plants
outside of the Lower Sonoran vegetation zone. This is done mostly with
afternoon shade, which is contrary to the environment of many desert plants,
especially native grasses. The Guayacan is located in the middle of the
highest elevation area, and the dense shade combined with the low level evening
light plus the dense cloud cover provided a great opportunity to determine how
to best take photos in this situation without resorting to fill flash.
I tried a variety of combinations of lenses and macro accessories,
beginning with the Tokina RMC II 28-85/4.0 combined with a 12mm extension tube.
I could get a good image size, but even stopped down to f/16 did not provide
sufficient DOF to include all of the flower let alone the nearby foliage, plus
the shutter speed was an excruciating 1/2 second. I moved on to the Tamron
28-80/2.8-3.8 that stops down to f/32 but matters did not improve even when the
extension tube was replaced with the Vivitar 2X macro-focusing teleconverter
(tele-macro).
Next step was to try backing away and use a telephoto zoom, the first
choice being a Soligor 80-200/3.5 that I've been wanting to take out for a
field trial. Things improved right away, but the vibration from pressing the
shutter release prompted using the IR remote. Adding the tele-macro improved
things even further, but the combination put the centre of gravity well away
from the tripod mount, which added to the vibration problem, so the Manfrotto
lens support frame was added to get a better balance.
This worked fine, with the tele-macro set at 1:4 to get the desired
image size from a distance of about 1 meter with the lens FL set at 200mm, then
using the lens focusing for fine adjustment. With an aperture of f/8 the
shutter speed was bracketed from 1/60 to 1/100, and the photo take at 1/60 came
out best.
This combination of telephoto zoom and tele-macro performs exactly as a
3-touch lens, the largest of which I know of is the Soligor 75-205/3.5.
However, that lens lacks a tripod mount and the Manfrotto lens support frame is
a bit inconvenient to be carrying around in the field. I have three telephoto
zoom lenses with tripod mountss: Sun Optical 80-240/4.0, Vivitar 75-260/5.6 TX,
and Vivitar 90-230/4.5 TX. Of these, I'm very partial to the Vivitar
75-260/5.6, so I'm going to set aside some time and practice this technique
with that lens and become familiar with any limitations.
At the same time, is anyone aware of other film/manual/mongrel lenses in
this range that have tripod mounts? I've looked around for third-party tripod
rings as well but all that seem to be available are for larger diameter Canon
lenses, though I'm tempted to try modifying one to fit the Soligor 85-300/5.0
which has plenty of room to add one.
Chris
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