hello. i am doing a small project that consists of rendering an animation in AE into anamorphic 1:240 and am not sure how to do this as I am confused about the pixel size and aspect ratio. The animation is a png sequence 1920 x 1080. I am pretty sure I will have to downsize to 1280 x 720, though if the anamorphic factor plays in I'm not sure how to set my ratios. Can someone please tell me what I should set my render at to get anamorphic 1:2.40?
When you say anamorphic do you mean a 2.40:1 image aspect ratio or do you mean a rendered 16:9 image that will be projected at 2.40:1?
If the former then you'll want to just work and render at the correct resolution in square pixels, 2592 x 1080 for example (a 2.40:1 ratio).
If the latter then you'll still want to work at 2592 x 1080 (or another 2.40:1 ratio) but you'll pre-compose your working comp into a 1920 x 1080 render comp and render from there. This will add the 'anamorphic squeeze' necessary for anamorphic projection (assuming that the projector or display device will be expecting a 16:9 source).
If the source sequence is anamorphic I don't think there's a pixel aspect ratio that will get you to exactly 2.40:1 from 16:9, so you can simply put the source footage in your 2592 x 1080 comp and use Layer > Transform > Fit To Comp.
If you do the above then pixel aspect ratio shouldn't enter into it (work in square pixels).