Where do I go on a t3i to set the ratio?

[miata2u]

I used the setting that is on my camera and cropped on picmonkey.  When I tried to enlarge at walmart, it cut off part of my photo.  Please help me with this.  I am a novice with photos and my t3i.  So please explain simply so I can understand.  Thanks.

[TCampbell]

The camera records a 2x3 aspect ratio.  That's the native ratio of the sensor (using all the pixels.)

Print sizes, however, have LOTS of aspect ratios... a 4x6" print would fit perfectly because that's a multiple of 2x3.  But a 5x7, 8x10 etc. are all different aspect ratios.  

Don't try to set an aspect ratio in-camera... that's pointless.  Just let it use all the pixels.

When you prepare an image for printing, you'll crop it on the computer to fit the print size you intend to use.  How you do this depends on what software you are using on your computer to handle your images.

[ebiggs1]

The camera's Live View function has Canon's Aspect Ratio feature. The Live View screen can display cropping lines for 1:1, 16:9 or 4:3 aspect ratios in addition to the standard 3:2 ratio. These cropping lines make it easier to compose images in Live View, and they can help to expedite printing when using Canon's supplied DPP software. 

The default ratio is 3:2.  You can also shoot at 4:3, 16:9, or 1:1, if you desire, but only in live view mode.

[ebiggs1]

Oh, BTW, look in the Live View menu screen.  

[PhillRoath]

Owner's manual page 129 shows HOW to set aspect ratio.  The other posts here give some thought as to why you might decide to do so...  My T3i is left at 3:2 and works great for me.

Phill

[RobertTheFat]

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@PhillRoath wrote:

Owner's manual page 129 shows HOW to set aspect ratio.  The other posts here give some thought as to why you might decide to do so...  My T3i is left at 3:2 and works great for me.

Phill

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In any camera, the principal effect of changing the aspect ratio is to disable some of the pixels on the sensor. The camera has no way of rearranging them so as to use them all. Unless you intend to do your printing directly from the camera (an unusual requirement for a serious photographer), you're probably better off doing your cropping with a photo editor.

OTOH, grid lines that show different aspect ratios in the viewfinder are another matter. They can be very useful if you're pretty sure you're going to crop to a non-native ratio. They provide guidance without locking you in.

[PhillRoath]

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@RobertTheFat wrote:

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In any camera, the principal effect of changing the aspect ratio is to disable some of the pixels on the sensor. The camera has no way of rearranging them so as to use them all. Unless you intend to do your printing directly from the camera (an unusual requirement for a serious photographer), you're probably better off doing your cropping with a photo editor.

OTOH, grid lines that show different aspect ratios in the viewfinder are another matter. They can be very useful if you're pretty sure you're going to crop to a non-native ratio. They provide guidance without locking you in.

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Totally agree.  That's why I said I leave mine at default 3:2 so as to get all the pixles. 

Spoiler

Phill

[ebiggs1]

Most DSLR images require some cropping to make popular sized prints.  Knowing this a wise photographer leaves plenty of space around his subject.  This allows for more successful cropping and printing.