Shooting at night, under exposed problems.

I just got my T3i which I am using with a 17-85mm and 50mm

I took the video out tonight to some indoor parking garage, also outside parking lot which was lit up a bit... just testing it on my car.

I was using my 17-85mm. My exposure is set to Auto which goes up to 3200 ISO I think. At 17mm this lens is at least f/4


My problem is that its a bit under exposed. Is it my lens or most likely the shooting locations, and just simply too dark?

I know that the indoor garage had plenty of lighting. I even took some videos inside my home and the video came out great.

I watched some of the "low light" T3i videos on youtube and seems like people are shooting at night no problems.

Sure, you can shoot at night with no problems... at f/2 tops, maybe. f/4 is just too slow for shooting video in all but good light.

The problem is that current still cameras skip lines to generate a 1080p image, and so use maybe a third of the sensor area for gathering light. As the new C300 has shown us, if Canon had the tech to use the full sensor area and down-sample from the get-go, you could be shooting f/5.6 at ISO20000 and have a relatively clean image, but as it is, you have to use primes and keep them fairly open.

I am looking to get a Sigma 17-70 OS f/2.8-4

hope it will help out with that.

f/2.8 is alright, I guess, but you really want to have some primes on hand for the purpose of video, even if they're inexpensive.

Many people buy up old manual-focus lenses that can be anywhere from $30 on up to $200 and they perform just fine, since you're basically fulfilling the resolution requirements of a 2 megapixel image.
Once you think of it that way, the most important factors become secondary things like distortion and flare/CA resistance, which are more important factors for motion as they are difficult/impractical to get rid of in post.

mlech wrote in post #13583364
I just got my T3i which I am using with a 17-85mm and 50mm

I was using my 17-85mm. My exposure is set to Auto which goes up to 3200 ISO I think. At 17mm this lens is at least f/4

Part of your problem is likely having exposure set to Auto. The metering system probably read light sources and caused the underexposure.

Go into the menu and select manual exposure, then set shutter to 1/60th if in NTSC region, 1/50th in PAL countries.

Set aperture for Depth Of Field effect desired or in low light to maximum (wide open).

Set ISO to AUTO only temporarily. press shutter button lightly to cause settings to read out at bottom of LCD (display must be set for this) to see what ISO the camera will select. Manually dial in this setting.

If image on LCD is too dark, press the ISO button and increase ISO until you see what you want on the LCD. Exposure is now "locked" and will not change as you pan.

If you are using a viewfinder loupe your eyes may adapt to the darker lighting and the image on the LCD may be too bright. I find I have to set LCD brightness down a notch or two (don't forget to return it to normal or midscale when done).

Without a loupe you'll just have to run some test video and see how it looks on the computer, then you may have some idea how to set the LCD brightness. Canon has provided a tool to help here. Take a still photo then when you go to the LCD brightness menu that still image appears with a gray scale on the right edge of it. Adjust brightness until you can see every step on that scale from pure black to pure white and at the same time see adequate detail in the still image.

Good luck.