In June 2011, I took a series of test images using a new Canon
T3i (600D) for comparing to test images of other Canon DSLR models
popular for astro imaging. Some info on the T3i along with comparison
What camera features are new?
The T3i camera kit includes a newer version (II) of the 18-55mm
IS zoom lens that Canon has been providing with earlier models.
Other than minor cosmetic changes on the lens, the new Version
II of the lens seems very similar to the old version. According
to Canon: "The major changes are the shape of the zoom ring
rubber grip and the tapered area at the front of the lens."
This is the same kit lens that comes with the T3 (1100D) model.
The main difference between the earlier T2i (550D) model and
the T3i (600D) is the articulating (swivel) screen added to the
T3i. This feature can be a very useful one for those using the
camera back display, as opposed to a computer screen for astro
imaging. No more bending into awkward positions to see the camera
back display or cricking your neck. If the camera is mounted in
a telescope focuser, piggybacked on a telescope, or tripod mounted;
the display screen can be easily flipped out to the side and pivoted
up or down 270 degrees. The display screen can be positioned outward
in its normal position on the back of the camera, as with previous
models or completely turned facing inward, so the LCD display
is not seen. This is a good feature to avoid errant light emitted
from the display at dark sky sites and also to protect the LCD
display glass from scratches. Both camera model screens are 3"
in size and have the same resolution, 1.04 million dots. Because
of adding the articulated screen, the camera weight and body dimensions
have increased over that of the T2i. The T3i will not fit inside
the Whole Camera Peltier Cooler
if built to the dimensions on my web site.
T2i and T3i compared side by side:
In the above photos, notice that the T3i (on right) has two
port flaps as opposed to one on the T2i. The extra rubber grippy
material of the T3i gives it a better feel when handheld and it
provides a more secure grip on that side. The larger size of the
T3i is very noticeable in the above photos.
The chart below has some key specifications for the T3i that
can be compared to five other Canon models popular for astro imaging
at this time. Notice that the T3i has the same number of effective
pixels (18.7 million) and same pixel size (4.3µm) as the
T2i, pointing to the same sensor used in both cameras. Both cameras
have the same Digic 4 processor and use the LP-E8 battery. Both
have a sensitivity range of ISO 100 to 12,800.
For planetary, lunar and solar imaging, the Canon camera model
that has stood out because of its special "movie crop mode"
is the T2i (550D). In movie crop mode, only the center 640 X 480
pixel area of the CMOS imaging sensor is captured at a speedy
frame rate of 60 frames per second. The movie crop mode provides
a 7X fixed zoom without video interpolation. This feature is not
available on the T3i. Instead, a similar feature "Video Digital
Zoom" is a function of the T3i that captures the center of
the imaging chip, in a cropped zoom mode that is adjustable from
3X to 10X magnification. A drawback of the Video Digital Zoom
feature for astro imaging is that the capture rate is limited
to 30 frames per second, half the capture rate of the T2i. As
an example, if imaging Jupiter with a 2 minute video, the T2i
at 60 fps can capture 7200 frames from which to select the most
detailed frames for stacking. Using a T3i at 30 fps would capture
3600 frames. I have an example of Jupiter taken with the T2i movie
crop mode here.
Dark Frame Noise Testing:
My first testing
with this camera model was to take a series of 5-minute dark frame
exposures at room temperature and ISO 1600 over a two hour period
as was done in previous
that I have done for the 450D, 500D, 550D, 1000D and 1100D. A
15-second delay was used between each exposure. Camera settings
were adjusted to be similar to those used for other models and
found to be most conducive for astro imaging. The settings information
from Canon's DPP for the 550D, 600D and 1100D camera dark frame
test images is below:
Below are the
histogram displays using Canon's Digital Photo Professional software
for the initial 5-minute ISO 1600 dark frame exposure of all six
Canon models for comparison.
As seen in the
above graphic, the 450D continues to have the lowest initial 5-minute
dark frame noise with the 1000D having the highest level based
on DPP histogram displays. The initial 5-minute dark frame noise
of the 550D and 600D are similar. For the purpose of these tests,
please be aware that the dark frame noise levels for cameras of
the same model type that I have tested over time can vary from
unit to unit as discussed HERE.
The image below compares the initial 5-minute ISO 1600 dark
frames of all six Canon models. RAW dark frame files were converted
to 16-bit TIF files using Canon's DPP software and the TIFs were
then cropped at center to 300 X 300 pixels using Photoshop CS5.
The 600D image appears to have the lowest noise.
For the Full Frame TIF dark frame images, image pixel standard
deviation values for luminosity of the initial dark frames were
recorded using Images Plus for all six Canon models and are displayed
in the graph below:
for three camera models are shown below, for both the initial
5-minute dark frame and the last 5-minute dark frame of the two-hour
imaging sessions. The 1100D model with its minimal video circuitry
maintains the lowest dark frame noise level at the end of the
two-hour period based on the histogram display. Between the three
cameras, the 600D has the highest noise level at the end of the
imaging session based on the histogram display.
The image below compares the final 5-minute (after two hours)
ISO 1600 dark frames of three Canon models. RAW dark frame files
were converted to 16-bit TIF files using Canon's DPP software
and the TIFs were then cropped at center to 300 X 300 pixels using
For the final Full Frame TIF 5-minute dark frame images (end
of 2-hour period), image pixel standard deviation values for luminosity
were recorded using Images Plus for all three Canon models and
are displayed in the graph below:
For the 5-minute dark frames taken continuously over a two
hour period, I recorded
the EXIF temperature readings from the RAW dark frame files over
the two hour period for all six camera models and plotted them
Based on my review
and testing of the T3i (600D) camera model , these are the key
features I found most applicable for astro imaging:
What I didn't like:
Check back for test results of the T3i (600D) compared to other
camera models with peltier cooling.
Additional test results for comparisons
of the Canon Digital
Rebel T2i (550D), T1i (500D), XSi (450D), XS (1000D) and T3 (1100D)
can be seen HERE.
For discussions on DSLR modifications
and cooling for astro imaging, please consider joining the DSLRmodifications
Yahoo Discussion Group HERE.
For my low cost astro & infrared
modification service for your Canon DSLR cameraCLICK
DSLR Astro Imaging Guides on CD-ROM by Jerry Lodriguss HERE......