FILTERS
& OTHER EQUIPMENT
I have used a lot of filters over the past year and a half. I started
with 58mm, as mentioned
above, and migrated to entirely 77mm now based on the lenses I use. The
filters that get
the most use have been a circular polarizer, UV haze, and an infrared
filter.
The polarizer is essential for daytime landscapes and in the rare occasions when I shoot water.
I really only use the UV haze filter for protecting the lenses and generally
ends up stacked
on the inside of my polarizer, which means it isn't really doing anything.
I have never noticed
a difference in photo quality from the UV have filter.
For infrared my solution has migrated somewhat. I have used two
different
types of infrared filters; when I used to have 58mm lenses I used a Cokin holder
and a
gelatinous filter. This was a constant pain to put together and, since my
lenses moved when
focusing, attaching the filter system after focusing often changed the
focus. Remember, the
Canon DSLRs have IR filters over their CMOS sensors, so the sensitivity to IR
frequencies
is so small that you have to manually focus before putting on the filter.
The net effect of the
image sensor's filter screening out IR frequencies, with the attached filter
screening all but
IR frequencies, is a very narrow band of frequencies that actually get
through. This also
leads to a very long exposure time, typically 30 seconds, in order to get enough
light. I
addressed the problems above by; first, getting 'L' series lenses that don't
rotate or extend
when focusing, so attaching a filter doesn't disturb the manually set focus;
second, I
switched to a circular glass filter that attaches to the 77mm lens front.
This makes
switching between visible and IR spectrum shots much easier. The only IR
picture in
the gallery was taken with the old setup, and you can see if you look closely, a
little
bit of distortion in the image that resulted from deformation of the filter in
warm
environments.
In order to reduce vibrations when shooting long-exposures, typically for
night cityscapes, I use Canon's RS-80N3 remote switch. This doesn't allow you
to program the duration of the exposure, however it does have a lock switch that
will manually keep the shutter open until you choose to close it. This is helpful
for 30 second-plus exposures, assuming you have a stopwatch.
I have also played around with graduated neutral density and color warming
filters, but not enough to know what I am doing.
Still adding more to this part...[August 21st, 2006]
© 2009 Peter W. Carpi.
All rights reserved.
