First of all, the ISO on a modern digital camera is not like the ISO of old. I use ISO 400 by default, you're only going to see an improvement to ISO 200 or ISO 100 on exceptional surfaces or plain blue sky.

Sorry for stating the obvious, but if you're taking 30fps, your shutter speed has to be 1/30 or faster.

If the other user had a lens with an aperture going to F/2.8 then that's one of the "L" series pro quality lenses, although I wouldn't have thought that would make so much difference to noise, since it doesn't originate in the lens.

I did my own 'low light' tests, mainly to compare with my quality "point and shoot" - a Sony HX5. I posted the results on youtube; can you watch (skip to the second half if you like, where the T2i shots are) and tell me how it compares to what you're getting?

Low light video tests, Sony HX5 & Canon T2i

 

First off are you sure you are in manual video mode?

Go to video mode and press the menu button, one of the first two menus will have your two choices:  Exposure AUTO or MANUAL.  Select MANUAL.

Then select resolution and frame rate.

Back in video mode, set shutter to 1/60th (1/50th if in PAL region).

Set aperture for desired "Depth Of Field" (Zone Of Acceptable Sharpness) effect.  Wide aperture for shallow zone, small for deep zone, or medium aperture for something in between.  But night scenes may dictate wide for enough exposure.

ISO should still be at AUTO for the moment, press the shutter button lightly to cause settings to all display on the bottom of the LCD (you need to have the display set for this), take note of the ISO the camera will select and "dial this value in" manually.  Exposure is now "locked" until you change it, the camera will not be changing it on you as you pan around. 

You can, at this point, adjust ISO up or down for specific exposure effect desired.

NOISE:  Check your monitor settings (from the controls on the monitor).  Especially sharpening, even the very slightest degree of oversharpening on the monitor will create the effect of noise where there may be NONE.  I was "plagued" with bad noise on one workstation to the point almost every video showed noise.  Until I thought to check monitor configuration and found sharpening, contrast, and brightness all way too high.  Sharpening and contrast were almost to MAX and brightness was up to 75%.

Pulling everything down to midpoint and then "tweaking" to taste solved the problem.

On my 7D, night tests I ran at f4 showed ISO 1600 to be totally clean, 3200 maybe a bit of noise but still looked very good, 6400 some noise showing but quite usable, 12,800 fair amount of noise except where I was able to get proper exposure in the scene (sidewalk scenes where store windows "bathed" most of the area with enough light to get good exposure on most surfaces).  I would use 12,800 if necessary to get the scene and not obsess about it.

I don't think Bif meant to set the shutter to 1/60th, he must have been thinking that you were shooting at 60fps. Obviously you want to have the sensor capturing all the time, which means matching your shutter speed to your frame rate. Again obviously, you can't ask for a slower shutter speed than the time for a frame, because capturing for the next frame would have to start before the last one finished... 

Would you like to set up an experiment where we compare results? It would mean choosing a set of manual settings, then finding a plain wall that exposed to the centre of the scale (that should ensure that we're both working with the same amount of light), and taking a picture of it, and posting it, along with a 1:1 detail to see the noise. If you'd like to do that, suggest manual photo settings that manifest the problem you think you have.

Lenses I have are the two kit lenses 18-55 / 55-250 and the 50mm 1.8 prime.

Have you got your "long-exposure noise reduction" set to off, auto or on? (Custom II-4). What about your "high iso speed noise reduction" (Custom II-5)?

Hello Danj,

What lens are you using. I have been having noise issues since day one but mine usually happen indoors with the kit lens which I hear is to be expected? I don't think I've shot one video yet that compares with many of the clean t2i shots I've seen online.

Do you have any online examples you've shot? I'm curious if mine is in the same boat

Actually Bif is correct, 1/60th is a 180 degree shutter when shooting at 30fps.  That would be the "standard" setting to use.  You can effect the amount of motion blur you'll get by changing the shutter speed, but if you are going for a film look you should only be using 1/60th and adjusting aperture to control DoF and then using ND to control light levels.

In the final analysis, beauty is in the eye of the beholder, so whether Bif is "correct" is a matter of opinion.  I should explain that I did not grow up in the United States, so this concept of "film look" is not something I aspire to - rather, I want my videos to look pleasant and realistic. I understand that many people, and possibly work contracts too, require that videos be 'broken' in exactly the same way as old films were, to create the right effect in the (American) viewing audience. In the same way, incidentally, as my favourite "Mario Kart Wii" fakes gobs of lens flare in its rendering engine. However, the original poster did not do anything to imply that he wanted his video broken in this way, so I still maintain that my advice to "fill real time with sensor capture" (i.e. to choose the longest available shutter time) is more "correct" [sic] than Bif's advice.

P.S. it may be me. I've recently done a bit of night driving, and I hate pulse-modulated (i.e. flashing) LED rear (tail) lights because of the dotted trails they leave across my retina when I look around. My family can't even tell. (sigh)

The 180 degree "rule" is what resulted from a mechanical rotating shutter with half (or 180 degrees) "cut out".  The cut out portion made the exposure, the other half "masked" the film gate as the next frame was pulled into place. 

24 frames per second was the best compromise between economy of film consumption and the slowest frame rate at which persistence of vision could be counted on to work for most people.  The resulting shutter speed at 24fps from the 180 degree rotating shutter was 1/48th second.

That no longer really applies much to what we do.  We have electronic scanning of the sensor for shutter.  Setting the shutter speed to 1/50th second almost exactly duplicates the motion blur at 1/48th we got used to seeing in movie theatres but in regions where the power line frequency is 60Hz that 1/50th can result in flickering and/or "banding" if artificial lighting is in the scene.  So in the US and other regions that have a power line frequency of 60Hz, 1/60th of a second is a better choice (still enough motion blur to come close to that of 1/48th second)  1/50th is the best choice in regions where the power line freq is 50Hz.

So that's where I recommended 1/60th.  In extreme low light 1/30th can be used, there may be more motion blur in each frame but it can still be usable.  But that's as slow as the shutter will go in video mode (NTSC).

Back to the OP's problem.  Noise.   In a darker scene noise will result in any underexposed area of the scene.  There is likely nothing wrong with the camera.  Avoiding noise means trying to insure that what the camera sees can be given proper exposure.  When I shoot a night sidewalk scene I choose an area where the store window lighting pretty much "bathes" the area in light and I rarely see objectionable noise (I shoot at 1/60th and f2.8 to f1.8  ). 

HDR states trying to shoot low light at night with ISO 100, that's pretty much going to insure plenty of underexposure in most of the scene and literally "tons" of noise.  Typically on night street/sidewalk locations I start at 1600 and jump right to 3200 if I'm not getting good exposure.  At 6400 I'm willing to put up with some noise if I have to in order to "get the shot".

Noise comes from underexposure, yes higher ISO's will tend to result in more noise but it really comes from not getting enough exposure in the darker parts of the scene.

If the scene is mostly light sources themselves then "crushing" the blacks a bit in post processing can help a lot.

The "kit" lens is not the best to attempt low light work with unless the scene is pretty well lit.  I've seen some good stuff shot with it at the wide end (f3.5 can be close enough to f2.8 to work if you have enough street and storefront lighting) but the best night work is done with fast prime lenses.  I use the EF 24 mm f2.8, EF 28mm f1.8 (just about my favorite), and the EF 50mm f1.8 (old style with focusing ring on the barrel) for much of the video I shoot.