Read about the camera ISO noise tests in the help section to learn more about the tests and how they are conducted. A key take-away from that page is that all noise reduction is turned off unless otherwise specified.
There are many MB of files required to be downloaded to make all of the mouseclicks on this page function properly - please be patient while they load.
Like the EOS M and EOS Rebel T4i, the EOS Rebel SL1 has its sharpness turned up relative to the prior 18mp APS-C models including the T3i, 60D and 7D. Increasing sharpness makes noise more visible. The choice is really yours - you can adjust the sharpness and resulting noise to your preference on all of these cameras.
Just because it has the setting available doesn't mean you should use it. I'm talking about ISO 12800 and 25600. You will probably also want to avoid ISO 6400 and use ISO 3200 only when necessary. The noise is quite apparent even at these settings.
As shown by the 5D Mark III image samples, larger sensor EOS bodies are currently showing significantly less high ISO noise. Likewise, the Rebel SL1 and other APS-C DSLR cameras show far less noise than point and shoot models (as the above graphic showing the relative size of available sensor formats suggests).
In-camera noise reduction is standardly available in EOS DSLRs, and noise reduction is of course also available during post processing. The bottom row of results in the comparison above (and below) show examples of SL1 noise reduction. Noise reduction effectively reduces visible noise in images, but it is also destructive to fine details and image sharpness. I prefer to apply only light NR to my noisier images.
The SL1, like other recent Rebel DSLR models, features Multi-Shot Noise Reduction. MSNR utilizes information taken from 4 exposures captured in a full-frame-rate burst (with one shutter release press) to create a noise-reduced single JPG image file. The amount of noise reduction is noticeable – perhaps a stop or more.
Some of the downsides to Multi-Shot Noise Reduction include: MSNR is currently available only with JPG output - I want to see this feature to be added to DPP for RAW capture - perhaps as another HDR preset? Multi-Shot Noise Reduction will not be so useful with moving subjects. Long exposure NR must be off ("Auto" is not off) to enable MSNR. The SL1 reverts to Standard NR in Basic zone modes, during video recording, in Bulb mode and when the camera is powered off. Flash is not supported in MSNR mode. And the camera remains "busy" for a brief period of time after the 4 shot burst - while processing the merged image.
Here is another noise comparison that includes fine details in a piece of fabric.
The fine details in the fabric better-hide high ISO noise.
Again, the Canon EOS Rebel SL1 / 100D has great image quality, but ... I don't see purchase differentiation from Canon's other 18mp models in this regard.
Back to the Canon EOS Rebel SL1 / 100D Review.
Bringing you this site is my full time job (typically 60-80 hours per week). Thus, I depend solely on the commissions received from you using the links on this site to make any purchase. I am grateful for your support! - Bryan