Full-Frame crop vs. Anamorphic s35

[Bryce O]

Not sure if this has been covered anywhere... I've done some searching but nothing yet.

If you shoot FF35 (5D, Epic FF, ect...) and then crop in post to 2.35, wouldn't you end up with a similar FOV to the same shot as if it were captured with an anamorphic lens on s35? If not, how do the FOV's differ? I saw some forums discussing the use of anamorphic lenses on a 5D... and it seemed kind of redundant as the size of FF imagers almost double the FOV of s35 already.

 

[David Mullen ASC]

Well, it's not exactly the same if you are talking about standard 2X anamorphics, which doubles the horizontal view. A FF35 sensor is 1.5X wider than a S35 sensor (36mm instead of 24mm), it's not 2X wider.

But the reason one uses anamorphic lenses (other than for unique optical artifacts) is to maximize resolution for a widescreen image on a squarer film format or sensor. So if you are using anamorphic lenses for that reason, to retain as much pixel resolution as possible, it all depends on what you are comparing it to.

Remember the 5D only records 1080P in video mode (and that doesn't even measure out to 1080 lines...) for a 16x9 image (1.78) so if you want a 2.40 image, it may make sense to use something like a Hawk 1.3X anamorphic lens to be able to avoid cropping the 1080P recording.

But most anamorphic lenses have a 2X squeeze and thus only use a 1.20 : 1 area of any sensor for usable picture information to end up with a 2.40 image. So they make the most sense for squarer 4x3 sensors, unless for some reason, you are only using anamorphic lenses because you like the optical look.

But let's say you are shooting the 5D in RAW still mode, like for time lapse. That's a 5616 x 3744 pixel frame (1.5 : 1 aspect ratio.) So cropped to 2.40 : 1, that's a 5616 x 2340 pixel frame (13.14 megapixels). If you used a 2X anamorphic lens on the camera, you can only use 3744 pixels max height-wise, so that would mean the usable horizontal pixels for a 1.20 : 1 sensor area (with a 2X optical squeeze, remember) is 4493 pixels. So 4493 x 3744 pixels is 16.82 megapixels, a bit more resolution than cropping a spherical image to 2.40 and getting 13.14 megapixels.

But that's for a 1.5 : 1 sensor; the amount of wasted horizontal resolution when using a 2X anamorphic gets worse as the sensor gets more widescreen, like for a 1.78 : 1 sensor or a 2:1 sensor (for a 2:1 sensor, it's a lot simpler to just crop the little amount to get a 2.40 : 1 image.)

All of this is ignoring whether most anamorphic lenses even cover the full 24mm height of a FF35 sensor since the lenses were designed to cover a 22mm x 18.5mm 4-perf 35mm aperture originally.

 

[David Mullen ASC]

A further complication in the field of view question is that on a Red One camera, your picture/sensor height is only 12.44mm, not 18.5mm as on a 4-perf 35mm camera.

I think the general answer to what I think you are asking is that as sensors get higher in resolution, there is less and less reason to worry about resolution loss from cropping a spherical image to get a 2.40 image.

But to get into specifics about field of view requires that we are specific about the sensor areas we are talking about and whether we are talking about 2X anamorphics or the rarer 1.3X Hawk anamorphics.

 

[Charles Angus]

The short answer is that your field of view on FF35 cropped to 2.40:1 is 75% of S35 anamorphic, as David said.

 

[David Mullen ASC]

The short answer is that your field of view on FF35 cropped to 2.40:1 is 75% of S35 anamorphic, as David said.

As long as we are talking about 4-perf 35mm anamorphic (22mm x 18.5mm), not a 2X anamorphic lens on the Red One camera (which uses about a 15mm x 12.5mm area).

 

[Bryce O]

Yea... I didn't think they would be exactly the same. But still, I thought it was worth asking since once there are high enough resolution FF sensors (i.e. Epic FF), it seems like it would be a better option to just crop, as anamorphic lens are expensive and less available... and the apparent loss of quality and distortion.

Anyways, thanks for the replies and the info... :thumbsup: