Nature photos at night?
James Copley
night. I'm thinking of using my canon f1.8 50mm MkII. I know that this
sounds stupid, but I also have a f.4-5.6 28-200mm, I know that the 50mm is
better for lower light levels, but would it still be worth taking the zoom
lens to get up close and personal with the creatures, or will it be a waste
of time with that aperture range for what I am wanting to take pics of.
My apologies for the annoying question
James
Al Denelsbeck
news:BC6BC32E.F24%cop...@myrealbox.com:
Not annoying at all. Sounds like a good challenge...
The light levels you're working with are exceptionally dim, very hard
to get to register on film. Even with f1.8 and fast film, you're probably
talking about exposures along the lines of 30 seconds and much longer. So
there's two issues you're going to be dealing with: subject movement, and
whether you capture anything but the glowing portion of the critters. I.e.,
will the photos contain anything like the head, legs, surroundings, and so
on? Or just a glowing abdomen?
The lower apertures would necessarily require much longer exposure
times, greatly increasing the risk of the critter moving, and also the
potential (almost certain) introduction of reciprocity failure from your
film, where the emulsion becomes unevenly sensitive to long exposure times
and produces color shifts and hard-to-predict results. Decreasing the
aperture by four stops may not equate with increasing the exposure time by
four stops - you might have to go much longer, and potentially even filter
to correct the color (and increasing the exposure even more because the
filter reduces light, woo hoo!). It differs from film to film, and the
manufacturer's recommendations rarely extend to exposure times as long as
you'd need. So experimentation would be in order.
I would look into achieving macro magnification, however you can -
any 'standard' lens magnification is going to make your tiny subjects too
insignificant in the frame. This has its own problems, mainly that depth-
of-field becomes terribly short with macro, necessitating smaller apertures
anyway. It's too easy to have an insect's head in focus and the abdomen
completely blurred at high mags.
My suggestion would be to look at doing your work in a 'studio'
setting, such as a small aquarium (preferably transportable), where you can
control the conditions as much as possible. You would be able to experiment
with light levels and exposures much easier. But one hangup is, the
bioluminesence you're after is a reproduction display, and takes place only
in certain conditions, primarily temperature, but also influenced by
whether there's any pheromonal stimulation - hard to induce within your
house. You can take a look at my tips pages at http://wading-
in.net/Easiermacro.html and http://wading-in.net/Tank/Macrotank.html to see
if they give you any usable ideas.
I would also consider some kind of light that can give "fill". In
other words, a long exposure time to capture the bio-glow, then an
additional pop of very low-level flash to illuminate details and
surroundings. Full moonlight is actually way too bright - you're going to
need a light carefully balanced to the amount of glow you capture over
time. Experiments galore!
Commercial photographers usually photograph glow-in-the-dark toys and
such under UV ("black") lighting, which gives them a lighting level to work
with but also stimulates the phosphorescense. Since fireflies and glowworms
are not producing the same effect, it's very hard to say if this would be
any assistance at all, but I'm throwing it out there.
Good luck with it! I have a goal to capture the bioluminescense in
the river nearby that occurs in the summer - very dim water glow that
appears only momentarily with turbulence. Even more fun - have to induce
repeated turbulence somewhere that the camera can sit for two minutes or
longer. A home aquarium didn't work, so I'm still trying. Hope yours goes a
bit faster ;-)
- Al.
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