vertical image, rotating camera changing aspect

[pailhead]

I am a bit confused, and i'm not sure what im doing wrong.

 

I want to have an image aspect ratio of 1.5, so lets say i have a 500x333 px image. I set up a camera with 28mm lens and i get a certain perspective. Now i want to change the frame so it looks like i rolled the camera by 90deg.

 

I would normally change the aspect ratio to 1/1.5 ending up with a 333x500 px image, but that always seemed weird. It seems like the lens is no longer 28mm but actually shorter as i get a much wider angle.

 

This is the rotated image at 500x333 (camera roll - 90, then photoshoped nd turned back).

 

 

 

And the changed aspect, 333x500.

 

 

 

Both are 28mm.

[Nils Norgren]

There is a small pull down button in the camera modifier box(top left) a little button with a side to side arrow on it, this is the way the FOV is calculated. If you changed it to vertical in the top image they would match (and made sure the FOV was the same in both cases).

 

The FOV # is the important number as the lens is a artificial construct that doesn't always make sense, as you did if you were using an actual 28mm lens, you would turn it on its side to take a portrait photo, when the rendering dialog is set to a tall aspect ratio, the lens is no longer a reliable measure of the field of view (as it by default is calculated sideways).

 

Hope this helps,

 

-Nils

[pailhead]

It helps a lot, i tried to figure out if the FOV number changes when i change aspect ratio but i didnt notice. It doesnt seem to be refreshing in real-time or something, now when i wrote down the numbers i notice that there is a difference.

 

 

Huh... how can i tell which value to use as a constant. Set it to 4:3 or 3:2 and write down diagonal FOV (or horizontal then use it for vertical) at a certain Xmm preset, and then use it for the changed aspect?