Canon Digital Rebel T3 (1100D)

Review for Astro Imaging

March 2011

by Gary Honis

On March 21, 2011, I purchased a Canon T3 (1100D) from my local Walmart for $599. The kit included 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 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."

Canon is marketing the T3 (1100D) as a replacement for the XS (1000D), that had been the lowest priced DSLR in its lineup since 2008. The chart below has some key specifications for the T3 that can be compared to four Canon models popular for astro imaging at this time:

Notice that the 1100D has the same number of effective pixels (12.2 million) and same pixel size (5.2µm) as the 450D. This would point to Canon using the same sensor as for the 450D but according to Canon, the 1100D has a 12.6 megapixel sensor and the 450D has a 12.4 megapixel sensor. Hopefully Canon has retained the good characteristics of the 450D imaging sensor that has performed so well for astro imaging. Some other differences between the models are as follows:

Sensor cleaning: The 1100D has no automatic sensor cleaning function as the other camera models. This is not a disadvantage for astro imaging. This was most likely deleted to keep the price down. There is no piezoelectric element to generate ultrasonic vibrations that attempt to knock dust off the front most filter. For astro imaging, most users keep that feature's auto mode disabled anyway since it might change the flat fields used for calibration. Having cleaned many Canon cameras, I find the auto cleaning function very ineffective anyway since it works only on the loosest of debris. The piezoelectric system is set up to capture the dust under a sticky black gasket around the front most filter and the dust can become dislodged or even smeared onto the filter if a wet cleaning is done. That is why I do not re-use the sticky gasket when I do Full Spectrum modifications with clear glass and prefer to clean cameras using a simple blower bulb cleaning instead.

The 1100D does have a menu function that allows manual cleaning of the front filter, by which the flip mirror goes up for cleaning, as in other models. It also has the "Dust Delete Data" function as other models.

Size and weight: The 1100D is a tad heavier than the 1000D, 450D and 500D but lighter than the 550D. The 1100D is also a little larger than the 1000D by 4mm in width, 2 mm in height and 16mm in thickness:

 BODY SIZE  Width  Height  Depth
 1100D  130mm  100mm  78mm
 1000D  126mm  98mm  62mm

I found that even though the 1100D is larger than the other models, it still fits well inside Version III of my Whole Camera Peltier Cooler.

Processor: The 1100D uses the new DIGIC 4 processor, while the 450D and 1000D use the DIGIC 3 processor. The ADC of the 1100D, like the 450D is 14-bit as opposed to 12-bit of the 1000D. Some astro imagers prefer the 14-bit processing but it is difficult to discern differences in astro images taken with 12-bit versus 14-bit cameras. Although the 450D and 1000D's highest ISO setting is 1600, the 1100D has ISO ranges up to ISO 6400.

Liveview and Movie Mode: The 1100D has in-camera video capture that is absent on both the 450D and 1000D models, even though all three have the liveview function. Some software developers have created video capture software that allows video to be recorded from the 450D and 1000D, if a computer is used with a USB 2.0 connection. I would expect as the new Canon SDK gets in the hands of software developers that they will upgrade their software to provide a similar feature for the 1100D. The 1100D however, can do video capture to SD card or computer "out-of-the-box" using the latest version of Canon's "EOS Utility" that comes with the camera. "EOS Utility" is really all one needs for remote control of the 1100D for astro imaging. Using it, all camera parameters can be adjusted, liveview can be used for framing and focusing and multiple exposures can be sequenced. I noticed that the camera ISO can be changed when in liveview mode but not when in movie mode. Being able to set the ISO while in liveview mode is a good feature for brightening stars used for focusing. The 1100D camera white balance settings can be adjusted for movie mode. That is a welcome feature because it is useful for color correcting videos captured with modified cameras, since the Custom White Balance (CWB) feature can be used for video. The 1100D lacks the movie crop mode of the Canon T2i model. The movie mode of the 1100D allows recording 1280 x 720 HD video, at either 25 or 30 frames per second. Movies are captured as .MOV files using the MPEG-4 format. Movie mode should be useful for planetary, lunar and solar imaging.

Camera Back LCD Display: The camera back LCD display of the 1100D is a 2.7 inch TFT color monitor and sized in-between the 450D and 1000D displays. The displays of all three models are 230,000 pixel:

 1000D  2.5 inches
 1100D  2.7 inches
 450D  3.0 inches

Power: The 1100D takes yet another different type battery than earlier models. It uses a new LP-E10 battery that is a 6.4Wh unit providing about 700 shots per charge. That is 200 shots more than the 1000D with a full charge. One thing I don't like about the new LP-E10 battery is that all its contacts are exposed instead of recessed as for the batteries of other models. A new power supply (battery eliminator) is therefore needed and the battery charger provided with the camera is also different than that of other models.

Functionality: The grip of the 1100D is very smooth and has no area of textured rubber layering as in other models. I would prefer a less slippery grip to avoid camera falls.The SD card slot has now been repositioned to the bottom of the camera, inside the battery compartment. For other models the card slot is on the side. I prefer a side mounted card slot because it is easier to remove the card when the camera is being used on a tripod.

Some camera-back buttons have been repositioned from earlier models.

There are three ports on the 1100D. The remote timer connector is the same as other recent models....hurray! The mini-USB connector is the 11-pin connector of the newer models with in-camera video so that one connector can share both USB 2.0 and Audio/Video functions. The 1100D has a built-in mic but no external microphone jack.

Dark Frame Noise Testing:

My first testing with this camera model was to take a 5 minute dark frame at ISO 1600 as was done in previous testing I have done for the 450D, 500D, 550D and 1000D. Camera settings were adjusted to be similar to those used for testing those other models and the settings info from Canon's DPP for the 1100D dark frame test image 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 5 Canon models for comparison.

The image below compares the initial 5 minute ISO 1600 dark frames of all 5 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 200 X 700 pixels:

For the above cropped TIF dark frame images, image pixel standard deviation values for luminosity were recorded using Images Plus for all 5 Canon models and are displayed in the graph below:

The true test of dark frame noise is how the camera performs over time while capturing long exposures and as the camera heats up. I do plan to test the 1100D (T3) camera in the same manner as was done for the other four Canon models over a period of two hours. (see update below).

Summary: Based on my initial time with the new 1100D camera model for only a few days, these are the key features I found most applicable for astro imaging:

Features that I did not like:

I'll be updating this page with more dark frame noise and sensitivity test results, and hopefully initial deep sky images soon.

Update April 4, 2011: Comparison of 450D (XSi) and 1100D (T3) over two hour period with peltier cooling.

Based on the dark frame tests above, the low noise performance of the Canon 1100D (T3) tested very close to that of the 450D (XSi) when single dark frame exposures were compared. This time, I tested both cameras in a Version III Whole Camera Peltier Cooler that I recently finished building. 5-minute dark frames were taken continuously over a two hour period. A 15 second delay was used between the exposures at ISO 1600. I measured the camera temperature using the cooling chamber probe and also recorded the EXIF temperature readings from the RAW dark frame files over the two hour period and plotted both below:

The above plot shows that the cooling chamber cooled the camera body at the same rate and degree for both camera models. A 43 degree Fahrenheit temperature drop was achieved for the 1100D (T3) and 42 degrees for the 450D. The plots for the EXIF recorded camera temperature show the 1100D heating up more during the first 15 minutes, most likely because of its additional in-camera video/audio circuitry. After the initial 15 minutes, both cameras cool at nearly the same rate with the 1100D staying about 5 degrees warmer than the 450D.

Cooled Standard Deviation:

Using the Canon software "Digital Photo Professional", all Full Frame RAW files were converted to TIF files and the histogram luminosity value using "Images Plus" for image pixel standard deviation was plotted in the graph below. The standard deviation values for the 1000D trend higher for the first few minutes in line with the increasing internal temperature of the 1100D, but after 30 minutes of continuous exposures, there is a crossover in the plots. At 30 minutes the image pixel standard deviation for the 1100D goes lower than that of the 450D and stays lower for the remainder of the two hour period.

Dark Frame Comparison:

Images Plus was used to crop the dark frames at two hours of cooling to 400 X 400 pixels at center. The cropped images were both adjusted in Photoshop levels and curves using the same action and then converted to grayscale:

The 1100D dark frame crop does appear to have less noise than the 450D crop.

Additional test results for comparisons of the Canon Digital Rebel T2i (550D), T1i (500D), XSi (450D) and XS (1000D) 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 camera CLICK HERE.

Removal of IR Cut Filter for Astrophotography

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