OPTIMO lens specifications

Mathew Collins · May 27, 2017

Hi,

I was just going thru some lens specifications in the following links and confused.

OPTIMO SPHERICAL LENS 15‑40mm says,

https://www.angenieux.com/optimo-compact-lens-zoom-15-40/

Lens specification gives,

IMAGE COVERAGE: S35+: 31.4 mm diagonal

Image coverage: S35+ (Ø 31.4 mm), expanded to Ø 35 mm when used with Optimo extenders (more info in DOWNLOAD section)

OPTIMO SPHERICAL LENS 28‑76mm

https://www.angenieux.com/optimo-compact-lens-zoom-28-76/

IMAGE COVERAGE: S35+ 31.4 mm diagonal

Image coverage: S35+ (Ø 31.4 mm), expands to Ø 35 mm when used with Optimo extenders (more info in DOWNLOAD section)

OPTIMO SPHERICAL LENS 45‑120mm

https://www.angenieux.com/optimo-compact-lens-zoom-45-120/

IMAGE COVERAGE: S35+: 31.4mm diagonal

Image coverage: S35+ (Ø 33.34 mm), expands to Ø 35 mm when used with Optimo extenders (more info in DOWNLOAD section)

OPTIMO SPHERICAL LENS 24‑290mm

https://www.angenieux.com/optimo-long-lens-zoom-24-290/

IMAGE COVERAGE: 35 mm academy – 30 mm diagonal

With extenders, image coverage becomes S35+ - 31.4 mm diagonal

Image coverage up to S35-3 perf. (Ø 30 mm), expands to Ø 35 mm when used with Optimo extenders (more info in DOWNLOAD section)

1. Does the corresponding focal length increases while adding an extender?

2. Does the image coverage decreases by adding and extender?

3. What is the difference between S35 an S35+ ?

4. Is S35+ bigger than 35mm academy?

5. Why the image coverage of 45‑120mm on S35 is 33.34 mm and others 31.4 mm?

6. By adding extender to some lenses 35mm academy changes into s35+ and vice-versa? How?

7. By adding an extender on 15‑40mm or 28‑76mm or 45‑120mm, S35+ changes to 35mm academy

but for 24‑290mm 35mm academy to S35+?

Please share your thoughts.

-Mathew Collins.

Dom Jaeger · May 27, 2017

An extender increases the focal length and also increases the image circle diameter.

Academy is the old 35mm format standard, Super 35 Is a little wider.

Probably as some sort of arse-covering exercise Angenieux are labelling their 24-290 as an Academy zoom because at the wide end the image circle gets down to 30mm in diameter, but in practice all those Angenieux zooms cover S35, since the full camera aperture is always cropped in a bit, and most digital sensors that are labelled S35 will be covered by a 30mm diameter image circle. All Alexa formats except Open Gate are under 30mm diagonal for example. 24-290 zooms have been used on countless S35 film and digital productions.

Optimo extenders will increase the image circles of those zooms to at least a 35mm diameter, which is enough to cover Alexa Open Gate and the larger Red sensor formats.

Mathew Collins · June 2, 2017

Thank you D

An extender increases the focal length and also increases the image circle diameter.

Academy is the old 35mm format standard, Super 35 Is a little wider.

Probably as some sort of arse-covering exercise Angenieux are labelling their 24-290 as an Academy zoom because at the wide end the image circle gets down to 30mm in diameter, but in practice all those Angenieux zooms cover S35, since the full camera aperture is always cropped in a bit, and most digital sensors that are labelled S35 will be covered by a 30mm diameter image circle. All Alexa formats except Open Gate are under 30mm diagonal for example. 24-290 zooms have been used on countless S35 film and digital productions.

Optimo extenders will increase the image circles of those zooms to at least a 35mm diameter, which is enough to cover Alexa Open Gate and the larger Red sensor formats.

Thank you Dom.

>Optimo extenders will increase the image circles of those zooms to at least a 35mm diameter.

In this case is 35mm is bigger than Super-35?

For all the lenses by adding an extender Super-35+ expands to Ø 35 mm.

Edited June 2, 2017 by Mathew Collins

Michael Rodin · June 2, 2017

Don't confuse the aperture size (Super-35/Academy/Silent) with the image circle diameter (Ø 30 or 35 mm). Different apertures have different diagonals which have to fit (and be correctly centered) inside the lens' image circle.

"S35+" is not a format or some special term, it just means the image cirlce is more than 31,4 mm in diameter.

5. Why the image coverage of 45‑120mm on S35 is 33.34 mm and others 31.4 mm?

If they could design all their zooms to cover a Ø 33-35 mm circle, they'd likely do it. But it's harder to do with other zooms as they're wider, thus a more radical retrofocus design, must be more difficult to correct.

David Mullen ASC · June 2, 2017

Yes, you're getting confused by the repeat of the number 35 in one case to describe the format (35mm Academy versus Super-35) and in the other to describe the size of the image circle.

Since most of the time you are shooting the Super-35 width cropped in height to some widescreen shape from 16x9 to 2.40 : 1, the vignetting that happens at the wide-angle end of the 24-290mm zoom usually falls outside the corners of the cropped area being used. Or at worst you have to zoom in a few millimeters to lose the vignetting in the corners.

But it becomes more of a problem when using cameras that use an even larger area than Super-35 like an Alexa in Open Gate mode or many of the Red cameras.

David Mullen ASC · June 2, 2017

Even though Super-35 describes a recorded area about 24mm wide, as opposed to Academy which is more like 22mm wide, the aspect ratio determines the length of the diagonal and the more you crop the height, the shorter the diagonal gets which is why a lens like the 24-290mm, even though technically it doesn't cover Super-35, covers it most of the time because you are cropping to a widescreen ratio.

For example, on the Alexa in 2K 16x9 (1.78 : 1 aspect ratio) mode, it uses a 23.66mm x 13.30mm sensor area, so this counts as Super-35, but your image diagonal is only 27.142mm so the Optimo's 24-290mm 30mm image circle of Academy covers it.

But in Open Gate mode (1.55 : 1 aspect ratio), which is 28.25mm x 18.17mm -- wider than Super-35 -- you have an image diagonal of 33.59mm so even some of the other Optimos designed for Super-35 will vignette at the wide-angle end. However, most people shooting Open Gate are cropping from 1.55 to 1.78, 1.85, or to 2.40 and you start to see less of the vignetting the more you crop.

David Mullen ASC · June 2, 2017

Here's a crude drawing I did to show how some format that is roughly 4x3 might vignette with a certain image circle of a lens but once cropped to widescreen, it would fit inside the image circle. So let's say that the circle is the "Academy" image circle of the 24-290mm and the large rectangle is 4-perf Super-35 -- so the lens would be vignetting -- but the smaller dashed line represents Super-35 cropped to 16x9 where the vignetting problem falls outside the picture area:

Mathew Collins · June 2, 2017

Thank you David, Michael.

As David pointed out, I was confused with 35mm format and Ø 35 mm.

Again that opened bunch of new knowledge.

Thanks much.

Mathew Collins · June 3, 2017

Hi,

Would that vignetting will be visible in the Camera LCD screen or while looking thru view finder?

Now I remember one issue came up while assisting a DP in the last movie. We were using Red Epic MX and

Arri Ultraprime lenses.

DP asked camera assistant to change the lens into 16mm and he encountered some issues with the lens. But not sure the issue is about vignetting. I think after that he did not use that lens. We were shooting in 2.4:1.

The following link says, "S35 Mysterium-X sensor is 30mm x 15mm. So to cover the entire sensor, you would need an image circle of 33.54mm or call it 34mm.".

I am not able to find out the diameter of the image circle formed by Arri Ultraprime 16mm.

http://www.reduser.net/forum/showthread.php?41080-Definite-Image-Circle-Size-for-Epic-5K-Sensor

Would the image circle of Arri Ultraprime 16mm cover Red Epic MX?

Edited June 3, 2017 by Mathew Collins

David Mullen ASC · June 3, 2017

http://cameramarket.eu/data/pdf/cameramarket_image-circle-database.pdf

Vignetting would be visible on any camera viewfinder or monitor but how much you notice it depends on the brightness of the edges for the scene and what f-stop you are shooting at. On a ground glass, like in a lens finder, it can be harder to see because of the fuzziness of the ground glass and its tendency to be brighter in the center.