Anamorphic lenses

[Ben johns]

Can someone explain to me (in simple terms) how these lenses work and why their used?
As far as I know their used to get that letterbox or x pan look. But why don’t we just use a wider lens and crop in? Is the loss of resolution the only reason or is there something I’m missing?

 

[woof woof]

AFAIK...

They distort the image to fit on the sensor, the image is then stretched to its intended ratio... we get that and that's easy enough to follow but I think there's more to it. I think it's also to do with distortions, bokeh and even lens flare that all combine to give a distinctive look that can''t be achieved with a wide normal lens, AFAIK

Maybe googling will answer all questions.

 

[Kei]

Anamorphic lenses use cylindrical elements rather than spherical. They also create a non circular image projection that, as woof woof said, is squished to fit the recording medium that stretched out later. Much like old SD anamorphic 16:9 television which was 720x576 natively with a display resolution of 1024x576 which stretched the squished image back. Early HD was similar (HDV) which was shot at 1440x1080 and stretched out to 1920 pixels wide when displayed.

This is the best overview that I could find on the subject.

 

[Canon Bob]

Another 'feature' of anamorphic lenses is the reduction of DoF. Simplified somewhat but a 2x anamorphic generates similar DoF to a lens of twice it's focal length if all other parameters remain the same (aperture and magnification). This means one can achieve reduced depth of field by employing a lens of double the focal length but maintaining the same horizontal field of view. This is/was used for subject isolation in wide scenes in motion pictures.

I have a 2x anamorphic that is a supplimentary attachment to a regular spherical, rectilinear lens. It operates infront of a lens of 80-120mm and gives the reduced DoF (of the chosen FL) whilst having the wider field of view of a 40-60mm lens.

Bob

 

[Ben johns]

Oh right. I thought it was purely the aspect ratio, seem to be a few more factors.
I saw a short video on them on YouTube. Didn’t go into a lot of why they use them but it seemed like a high cost for not a lot

 

[Deleted member 21335]

Another 'feature' of anamorphic lenses is the reduction of DoF. Simplified somewhat but a 2x anamorphic generates similar DoF to a lens of twice it's focal length if all other parameters remain the same (aperture and magnification). This means one can achieve reduced depth of field by employing a lens of double the focal length but maintaining the same horizontal field of view. This is/was used for subject isolation in wide scenes in motion pictures.

I have a 2x anamorphic that is a supplimentary attachment to a regular spherical, rectilinear lens. It operates infront of a lens of 80-120mm and gives the reduced DoF (of the chosen FL) whilst having the wider field of view of a 40-60mm lens.

Bob

Wow. I knew that they projected an oval image as opposed to a circular one (that's the over simplified version), but wasn't aware of the DoF. Great info, Bob. Thank you.

Oh right. I thought it was purely the aspect ratio, seem to be a few more factors.
I saw a short video on them on YouTube. Didn’t go into a lot of why they use them but it seemed like a high cost for not a lot

The lens doesn't really do anything to the aspect ratio. As above, it just provides a different shaped image onto the film/sensor which can then be stretched to correct.

The XPan (seeing you used it as an example) projects a 'normal; round image but on a larger piece of film than usual. 65x24 instead of 35x24. Anamorphic lenses would be shot on normal 35mm or 70mm film.