As of January 2011, for nearly
three years I have been imaging with "Version III" of
my whole camera peltier cooler as detailed HERE.
The cooling system has been working very well and astro images
taken with the cooled camera can be seen HERE.
The cooler has been providing a temperature drop of up to 44 degrees
Fahrenheit. For the peltier/heatsink/fan assembly, I used a unit
from a Thermo-Electric Travel Cooler branded "RubberMaid". The cooler
was made by Vector, Inc. and is branded under other names as well.
It operates on 12 volts DC and Vector also makes a 6-Amp AC/DC
converter to operate the cooler using 120 volts AC.
no longer marketting the cooler but these type of low cost coolers
have become widely available for vehicle use and are available
from many manufacturers. In order to locate a peltier device that
would perform as well as the peltier used from the RubberMaid
cooler, I purchased two other brand coolers and tested the cooling
performance of all three coolers as detailed below.
The three coolers
were all purchased from online sources. The specifications of
each as provided by the manufacturer are below:
Cooler - Model #VEC222RB
Cooler - Model #RPAT-788
3. Wagan Tech
- Model #2260
The three coolers
tested outside of their boxes:
For the testing
I used the same Canon T2i (550D) camera body with body cap and
its viewfinder taped over with electrical tape. The temperature
probe was taped to the top of the camera body in front of the
flash shoe. A timer remote control was used to take 24 exposures
over a 2 hour period, each 5 minutes in length, with a 15 second
interval between exposures at ISO 1600. A Vector 12V DC 6-Amp
AC/DC converter was used for powering all three coolers. An AC
power adapter was used to power the 550D for all tests.
The camera settings
of the 550D for all tests were as shown below:
The photo below
shows how the camera was placed inside each cooler for testing:
Keep in mind
that these cooling results were with the camera body just resting
on the bottom of each cooler. The testing was done solely as a
comparison of the cooling power of the coolers. The level of cooling
and noise reduction obtained is less than that if a whole camera
peltier cooler is made with the same peltier devices, since the
cooling chamber would be sized for cooling the camera and would
be directly and firmly connected to the camera body. The level
of actual cooling using the peltier from the RubberMaid cooler
for a whole camera peltier cooler can be seen HERE.
The graph below
compares the temperature readings from the camera body temperature
probe over the two hour period. The upper line shows the temperature
increase of an uncooled camera. The RubberMaid and RoadPro coolers
dropped the camera body temperature at nearly the same rate and
to the same degree. The Wagan cooler lagged the other two coolers
by about 3 degrees Fahrenheit. Since the RoadPro cooler (7 Liters)
is larger than the RubberMaid cooler (5 Liters), the slightly
slower rate of cooling with the RoadPro cooler is understandable
and at the end of the two hour period the RoadPro cooled the camera
a little lower than the RubberMaid.
On the graph below the temperature readings from the EXIF data
of the captured 5-minute RAW files were plotted along with the
camera body temperature probe readings in the above graph. The
EXIF temperature plots show how quickly the camera's electronics
heat up during the first half-hour of taking exposures before
the cooling effect begins to lower the temperature. There are
a few obvious out-of-expected-value EXIF readings and I think
they point to the inaccuaracy of the method used by Canon to measure
and record temperature in the EXIF data. The EXIF data shows the
same general cooling effect for all three coolers.
The graph below
shows for an uncooled 550D how the temperature readings using
a camera body temperature probe compare to the EXIF temperature
readings as recorded in the RAW frames:
frame noise test results:
For the graph below, I converted
the ISO 1600 Canon five-minute dark frame raws to TIFs using Images
Plus and then recorded the luminosity standard deviation of the
whole color image for each dark frame. All three coolers appear
to have reduced dark frame noise in a similar fashion.
The graph below is the same as
above without the "uncooled" plot in order to better
display the cooler plots.
Next, I plan
to compare how well each of four Canon DSLR models respond to
a whole camera peltier cooling system.
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Digital Rebel 350 - Canon Digital Rebel 350XT
with Canon Digital Rebel XT Camera