aspect ratio

Hey, Im having some trouble with aspect ratios in blender. I know I have the correct aspect ratio (16:9 with 720 by 480 dimensions) entered in blender because the camera view conforms to the right shape and size. If i render a scene in the camera view instead of the render window it displays it at the right size. However if I render it in the window it appears to be stretched out to fit blenders default size render size. Either way I render the final file comes out the same stretched out, I can squash the image in premiere manually but I dont really care to do this. Is there some button I have switch ed on or off thats causing this?

Not quite right.

720 x 480 is the render size for Standard Depth Video, or 4:3. Still, most video editors prefer 720 x 486 for overscanning.

16:9, or hi-def, is rendered at 1920 x 1080. Those renders will take a long time just because of the size. If you want the 16:9 ratio, but don’t want HD, then you can scale that size down.

Yeah, and you really don’t want Premiere squashing stuff. That I can understand.

Premier doesn’t need to squash, it can crop.


thanks for the correction,

heres what I mean

this is rendered with blenders default settings
this is rendered with 720 x 480, with 4:3 aspect ratio

it stretches it, instead of giving it in it’s true dimensions

That’s in Blender, what does it look like in an NTSC or PAL (or whatever you’re showing it in) app?


thats what it looks like in windows picture and fax viewer, quicktime, and any other program. The same thing happens when I render using the preset 16:9 button.

Sorry, I thought you were doing video.


The problem lies between aspect ratio and pixel aspect ratio. Aspect ratio is the ratio between pixels across the screen and pixels down the screen. Pixel aspect ratio is the dimensions of the pixels themselves. Both PAL and NTSC pixels are non-square (rectangular) versus the square pixels on your computer. NTSC pixels are wider than they are tall and PAL pixels are taller than they are wide. If you only intend to view your video on a computer monitor then make sure that the Asp X and Asp Y buttons have the same number in them. These are located directly under the size X and Size Y buttons on the format tab where you set your codec (F10 Key).

Click on the Pal button: you will notice that the Asp X (54) and Asp Y (51) numbers are not the same. Try this: raise Asp X to 75 and lower Asp Y to 25, then render. Think your renders were stretched or squished B4? How about now? Now set Asp X to 50 and Asp Y to 50, then render. I bet you get a perfect sphere. That’s because you’re looking at the image on a square pixel monitor. But, if you look at the same image on a PAL monitor it will seem slightly squished. Clicking the button again will reset the pixel aspect ratio correctly for video output.

So, when you set your frame size with the PAL or NTSC buttons, just remember that these will give you the correct aspect ratio and pixel aspect ratio for VIDEO output to their respective television screens. In order to view the images correctly on a computer monitor, you need to reset the pixel aspect ratio back to a 1:1 ratio via the Asp X and Asp Y buttons. Sorry, but if you want accuracy across these different viewing platforms you’ll either have to render more than once or get to know your non-linear video editing software a bit more intimately.

thanks man that helps alot!