Sony Alpha Blog

Sirui 50mm T1.8 Astra Anamorphic AF

Published by

Marc Alhadeff

on

A Sony mirrorless camera with a Sirui 50mm T1.8 anamorphic lens attached, showcasing the lens's focusing and aperture rings.

in Blue English / en noir en Français

Table of Contents / Table des matières hide
1 Presentation
1.1 Introduction
1.2 Specifications
1.3 Assessment of the 50mm / Evaluation du 50mm
2 Optical performances / Performances optiques
2.1 Sharpness / Piqué
2.2 Vignetting / chromatic aberrations / distortion / flare
2.2 Vignettage / aberrations chromatiques / distorsion / flare
2.3 Bokeh / Color Rendition – Bokeh / Rendu des Couleurs
3 Video
3.1 Anamorphic Desqueeze / Etirement anamorphique
3.2 Samples video / vidéo d’exemple
4 Samples images / Exemples d’images
5 Conclusion (English)
5 Conclusion (Français)
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All the tests were made on A1. You can find some photos samples here : Sirui Astra 50mm T1.8

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Tous les tests ont été faits avec un A1 . Vous pouvez trouvez les photos d’exemples ici : Sirui Astra 50mm T1.8

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1 Presentation

1.1 Introduction

The Sirui 50mm T1.9 Full frame Anamorphic AF is part of a set of 3 full frame Anamorphic with AF with a 1,33x factor. Those are among the first AF full frame anamorphic lenses

Le Sirui 50mm T1.9 Anamorphique plein format AF fait partie d’une série de 3 optiques avec un facteur 1,33x. Ce sont les parmi les premieres optique anamorphiques avec AF

  • Sirui 50mm T1.9 Astra anamorphic AF (849$/999euros)
  • Sirui 75mm T1.9 Astra anamorphic AF (849$/999euros)
  • Sirui 100mm T1.9 Astra anamorphic AF (849/999euros$)
Trois objectifs anamorphiques de la série Sirui, montrant les focales 50mm, 75mm et 100mm avec des marqueurs d'ouverture et de mise au point.

Other non AF series exists / D’autre series non AF existent

If you work on APSC there are series of APSC Anamorphic with a 1,33x factor that are cheaper and lighter I have tested here

Si vous travailler en APSC , la série d’optiques Sirui anamorphique APSC avec un facteur de 1,33x

With AF / Avec AF

Without AF / sans AF

1.2 Specifications

All lenses share the same filter diameter, positions of focus ring, aperture rings, same focusing throw, so you don’t need to adjust your follow focus system when chaining lenses

The build quality is excellent and the lenses are quite light for anamorphic lenses

The min focusing distance is quite small for anamorphic lenses

All lenses are delivered with a lens pouch

Tous les objectifs de la série partagent le même diamètre de filtre, de position des bagues d’ouverture et de mise au point, même course pour la bague de mise au point, donc il ne faudra pas ajuster la position d’un follow focus au changement d’objectif

La qualité de construction est excellente et elles sont assez légères

La distance min de mise au point est courte pour des optiques anamorphiques, spécialement

Toutes les optiques sont livrées avec un sac de transport

SIRUI 50 mm T1.8 1.33x anamorphic full frame AF lensSIRUI 75mm T1.8 1.33x anamorphic full frame AF lensSIRUI 100mm T.18 1.33x anamorphic full frame AF lens
Fixed focal length35 mm75mm100mm
Max. ApertureT1.8T1.8T1.8
Min. apertureT22T22T22
Lens design18 elements in 14 groups18 elements in 13 groups18 elements in 13 groups
Aperture blades111313
Sensor sizeFull formatFull formatFull format
Close focus distance0,5 m0,6m0,7m
Focus ModeAFAFAF
Filter ThreadM67×0.75M67×0.75M67×0.75
Focus ring rotation angle136°136°136°
Max. Diameter80 mm80 mm80 mm
Focus ring diameter80 mm80 mm80 mm
Weight620g650g700g
Length131mm131mm135mm
A close-up shot of a decorative lantern on a wooden table, with a blurred glass of cocktail and soft bokeh lights in the background.
100mm
A dimly lit table setting featuring a lantern and a cocktail glass with a slice of lemon, with a blurred background of warm lights and a rustic ambiance.
75mm
A blurred restaurant interior with a focus on a wooden table featuring a lantern and a glass of beverage garnished with a lemon slice.
50mm

1.3 Assessment of the 50mm / Evaluation du 50mm

  • The lens has AF , a Fn button
  • The aperture ring is click less as expected for a video lens
  • When set to MF The focusing ring is turning smoothly and adequately dampened with hard stops
  • Gear Mods allow to easily install follow focus unit as you can see from below photos

The main characteristic of this lens is its anamorphic design, meaning the image is squeezed at capture time and is expected to be desqueezed in post processing

So any footage captured on a 16/9 ratio on a Sony A7, will give after desqueeze a 16/9 x 1,33X = 2.36 / 1 ratio with give a wide cinematic look

The lens is not to be used at all for photos

Sirui 50mm T1.8 anamorphic lens with autofocus, featuring a black body and markings indicating focus distances and aperture settings.
Sirui 50mm T1.8 anamorphic lens with focus settings and aperture markings.
A close-up view of the Sirui 50mm T1.8 1.33x anamorphic full-frame AF lens, showcasing its design and features such as the focus and aperture rings, and an autofocus switch.
Close-up of the Sirui 50mm T1.8 anamorphic lens showing focus and aperture rings, buttons for autofocus/manual focus, and iris lock.
Sirui 50mm T1.8 anamorphic lens with focus and aperture rings, featuring a sleek black design.
  • L’optique dispose d’un commutateur AF/MF, un verrou iris, un bouton de fonction
  • La bague d’ouverture est sans clics comme sur toutes les optiques vidéos
  • La bague de mise au point est bien amortie et a des arrets
  • Les bagues crantées permettent l’utilisation d’unités de follow focus (voir photos ci dessous)

La principale caractéristique de cet objectif est d’être anamorphique, ce qui veut dire que l’image capturée est compressée en largeur sur un champ 16/9 , le but étant de l’étirer en post production pour avoir un ratio cinéma

Sur un plan 16/9 pris avec un Sony A7, l’image après post traitement sera de 16/9 x 1,33 = 2.36 / 1 qui donnera ce rendu cinéma avec une image très étirée

L’optique n’est pas du tout conçue pour la photo mais uniquement pour de la vidéo

Image of the Sirui 50mm T1.8 anamorphic lens mounted on a Sony camera body, showcasing the lens design and focus controls.

2 Optical performances / Performances optiques

2.1 Sharpness / Piqué

Table detailing the optical performance of a lens at various apertures (T1.8, T2.8, T4, T5.6, T8, T11, T16) for center and corner sharpness.
  • The tests were made on a Sony A7RIV, with its 61MPix sensor
  • For 8K you need 7640 pixels and for 4K you only need 3840 pixels out of the 8192 pixels , so anything good in photo will be very good  in video
  • For the 50mm
    • In the centre the lens is average at AT1.8 and reach very good level as of T5.6 ,
    • For 4K resolution (8Mpix) , it will be good wide open and Excellent at T4
    • Corners are not good wide open but become vert good at T8
  • Les tests on été effectués sur un 7RIV, avec ses 61Mpix
  • Pour filmer en 8K on a besoin de 7640 pixels et en 4K on a besoin de 3840 pixels sur les 8192 donc un piqué “bon” pour de la photo sera très bon en vidéo
  • Pour le 50mm
    • Au centre les performances sont moyenne à pleine ouverture et deviennent très bonnes à T5.6
    • Pour de la 4K (8Mpix) on sera toutefois bon à T1.8 et Excellent dès T4
    • La performance dans les coins est assez faible , il faut fermer à T8 pour avoir de très bons coins

Centre

A shelf filled with books and decorative items, including a gnome and a golden spoon, set against a textured wall.
  • T1.8
  • T2.8
  • T4
  • T5.6
  • T8
  • T11
  • T16

Corners / Coin

A cozy interior scene featuring a wooden cabinet filled with books and decorative items, alongside a wall-mounted mask and a plant.
  • T1.8
  • T2.8
  • T4
  • T5.6
  • T8
  • T11
  • T16
A busy square during the holiday season in Brussels, featuring a large Christmas tree and festive decorations, with crowds of people admiring the beautifully ornate buildings.
Close-up view of a historic building facade featuring ornate decorations, large windows, and intricate architectural details.
Portrait of a young woman with light hair wearing a brown jacket, standing in a busy street scene. The background is blurred, emphasizing the subject.
T1.8
Close-up of a human eye, showcasing the iris with subtle green and brown tones, well-defined eyelashes, and a natural skin texture.
Portrait of a young woman with blonde hair, wearing a brown jacket and a plaid scarf, standing in a bustling indoor shopping gallery decorated with lights.
T2.8
Close-up of a human eye, showcasing detailed eyelashes and a green iris.
A portrait of a young woman with blonde hair, standing in a busy shopping arcade decorated with festive lights. She is wearing a brown jacket and a checkered scarf, with people and shops visible in the background.
T4
Close-up of a human eye showing detailed texture of the skin and eyelashes, with a focus on the iris and pupil.
Portrait of a woman with long dark hair, smiling lightly in a busy square with historic buildings in the background and blurred figures of people walking.
T1.8
Close-up of a human eye highlighting eyelashes and subtle skin texture.
A young woman with long hair smiles in the foreground of a bustling square adorned with a Christmas tree and historic buildings in the background.
T2.8
Close-up of an eye with a natural makeup look, showing detailed eyelashes and a reflection in the iris.
A young woman with long dark hair smiling in the foreground of a bustling square decorated for the holidays, with a large Christmas tree and historical buildings in the background.
T4
Close-up of a human eye highlighting the iris and eyelashes.

2.2 Vignetting / chromatic aberrations / distortion / flare

  • Vignetting is very visible wide open and decrease progressively but it still present at T16
  • Distortion is quite visible
  • Flare resistance is average with a lot of flare effects which is nice for a cinema lens
  • You get the typical Anamorphic flare = blue straight horizontal line when pointing directly to a light source
  • You get nice sunstars when when aperture is closed down to F16
  • Chromatic aberrations are average

2.2 Vignettage / aberrations chromatiques / distorsion / flare

  • Le vignettage est présent à pleine ouverture diminue fortement à T4 mais reste présente
  • La distorsion est assez visible après desqueeze
  • La résistance au flare est moyenne avec pas mal de halos ce qui est bien pour une optique cinéma
  • On obtient le flare anamorphique typique tant recherché en cinéma = ligne bleu horizontale quand on pointe vers une source de lumière
  • On note de beaux effets d’étoiles à F16
  • Les aberrations chromatiques sont moyennes
Bookshelf with a mix of books and decorative items, including a gnome and a glass display cabinet.
A wooden bookshelf filled with various books and decorative items, featuring a gnome and a golden egg under glass doors.
Bright sunlight shining through leaves, creating a lens flare effect with a blue streak.
A bright sunlight peeking through green foliage, creating lens flare effects with rainbow colors and starburst patterns.
A nighttime street scene with cars parked along the curb and streetlights casting a warm glow. People are seen walking in the distance along a dimly lit sidewalk.
Nighttime city street scene with illuminated lampposts, people walking, and parked cars.
A snowy urban landscape featuring historical buildings bathed in sunlight, with a lens flare effect and trees in the foreground.
Sunlight shining through trees near snow-covered buildings, with lens flare effects in the foreground.

2.3 Bokeh  / Color Rendition – Bokeh / Rendu des Couleurs

  • Considering the focal length of 50mm, the aperture of T1.8 and min focusing distance of 50cm , bokeh balls are of quite good , the background blur is quite soft
  • The color rendition is very good , natural and consistent across all SIRUI lenses of the series
  • Considérant la focale de 50mm , l’ouverture de T1.8 et la distance min de mise au point de 50cm, les ronds de bokeh sont de taille moyennes et le flou d’arrière plan est assez doux
  • Le rendu des couleurs est très bon, assez naturel et très consistant entre les différentes optiques de la série
A Playmobil figurine stands on top of a lens with out-of-focus bokeh lights in the background, creating a dreamy effect.
T1.8
A Playmobil figurine stands on a camera lens with a bokeh effect created by background lights.
T2.8
A Playmobil figure stands on a black lens cap, with blurred Christmas lights in the background.
T4
A Playmobil figure stands on top of a camera lens with blurred lights in the background, creating a soft bokeh effect.
T5.6

  • T1.8
  • T2.8
  • T4
  • T5.6
  • T1.8
  • T2.8
  • T4
  • T1.8
  • T2.8
  • T4
  • T1.8
  • T2.8
  • T4
  • T5.6
Close-up of green ivy leaves with a dusting of snow, creating a soft-focused background.
A display of various colored stainless steel water bottles arranged in a row on a wooden shelf, with a blurred background.
Photo of postcards featuring a view of Brussels, Belgium, with notable buildings illuminated at dusk and blurred background.
Colorful display of bath products arranged on wooden tables, featuring various shapes and sizes of soaps in vibrant hues of pink, purple, and blue.
Colorful display of pink raspberry-shaped soaps on sticks, with a vibrant assortment of other bath products in the background.
Close-up of delicious waffle desserts featuring various toppings, including cookie crumbles, whipped cream, strawberries, and chocolate drizzles, displayed neatly in serving trays.
A close-up image of a padlock attached to a chain securing a wooden gate, with ivy growing around the post and some snow on the ground.

3 Video

3.1 Anamorphic Desqueeze / Etirement anamorphique

To treat footages taken with an anamorphic lens you need to define a project with the correct ratio : the Sirui is a 1,6 anamorphic lenses so instead of having a 16/9 you need to define a 25.6/9 ratio = 2.88 ratio which is a bit too large to my taste

For a 4 K project you have 3840 * 1,6 = 6144 Pixels wide (and 2160 pixels of height)

When you add your footage to the project you need to apply a transformation on the X axis x 1,6

Pour traiter les rushs d’une optique anamorphique, il faut définir un project correspondant au ratio anamorphique de l’optique , le Sirui étant un 1,6x , au lieu d’avoir un projet 16/9 il faudra définir un format 26,6/9 = 2,88 ce qui est extrêmement large

Donc pour un projet 4K on aura : 3840 pixels X 1,6 = 6144 pixels de large (sur 2160 de haut)

Une fois les rushs ajoutés à votre timeline il faut appliquer un ratio de 160% sur l’axe horizontal

Project settings interface showing 'Sirui 35mm T2.9' as the project name, with a start timecode, custom video format option, and resolution set to 6144 x 2160 at 25 frames per second.

Image showing editing settings for an audiovisual project, featuring parameters for position, rotation, and scaling adjustments.

A bookshelf with glass doors displaying a variety of books and decorative items, including a gnome and a golden object, against a white wall with floral designs.
standard
A wooden bookshelf with glass doors displaying a variety of books and decorative items including a gnome figurine, a clock, and other knick-knacks, set against a plain wall with decorative foliage.
desqueezed

Field of view

The field of view you get is also to be divided by the anamorphic ratio, so the Sirui 50mm is behaving like 50/1,33 = 37mm

Angle de vue

L’angle de vue obtenu avec une optique anamorphique doit être adapté au ratio de l’optique donc pour le Sirui 50mm APSC il sera equivalent à 50mm / 1,33x = 37mm

3.2 Samples video / vidéo d’exemple

After desqueeze the results are good globally

  • Good to very good sharpness
  • Cinematic field of view
  • Color rendition is very good
  • Anamorphic flare (horizontal blue line)
  • Focus breathing is average
  • But Moderate distortion

Après étirement en post production les résultats sont bons globalement

  • Bon à très bon piqué
  • Rendu large cinématique
  • Très Bon rendu des couleurs
  • Flare anamorphique (ligne bleue horizontale)
  • Focus breathing moyen
  • Mais distorsion modérée

Focus breathing

A Playmobil figure standing on top of a red object with a blurred bookshelf in the background, showcasing a shallow depth of field.
A blurred image of a bookshelf with several books, a figure in the foreground, and a decorative wall design.

4 Samples images / Exemples d’images

Just to illustrate the quality of the lens , I took a few photos with and desqueezed them.

Ci dessous quelques photos d’exemples , étirées pour leur donner une proportion normale

Three individuals posing together in a covered shopping arcade, surrounded by festive decorations and other people in the background.
A group of three young adults posing for a photo in a bustling urban setting, with decorative lights and greenery in the background.
A young man with glasses standing in a busy alley, smiling at the camera with blurred background elements.
A woman with long hair wearing a gray coat stands in a cobbled square, with a Christmas tree in the background and people walking around.
A serene winter scene featuring a partially frozen pond surrounded by snow-covered ground and trees, with modern buildings in the background reflecting the light.
A busy street scene with pedestrians walking past shops, decorated buildings, and festive lights in a city center.
Interior of a colorful toy store with bright displays, featuring a 'Pick & Build' section and various shoppers browsing.
A bustling indoor shopping gallery decorated with Christmas ornaments, where people are walking and shopping. There are trees adorned with festive greenery and lights, along with storefronts visible on both sides.
Winter scene featuring a frozen pond with snow-covered banks and patches of greenery, skyscrapers in the background.
A woman standing on a busy street, holding shopping bags and looking at her phone, surrounded by pedestrians and storefronts.

5 Conclusion (English)

The Sirui 50mm T1.8 Astra Full frame AF 1,33x anamorphic (849$/999euros) is part of a full cine set of 50, 75, 100mm T1.8 lenses which all shares same position for the gear mods rings, same color rendition

It is the first series of Anamorphic lenses with AF. The AF is quite efficient and the relatively small min focusing distance allow for nice background blur

Sharpness is may be not the strongest point but it is more than good enough for 4K resolution

Recommended

Pros

  • First AF full frame anamorphic lens
  • Efficient AF
  • Cinematic look
  • Size and weight
  • Very good build quality
  • Gear mods rings compatible with Follow focus units
  • Small min focusing distance for a anamorphic lens
  • Typical anamorphic flare
  • Reasonable price (849$)
  • Consistency with other Sirui lenses
  • Very good color rendition
  • Soft background blur
  • Sizeable Bokeh balls

Average

  • Sharpness
  • Moderate focus breathing
  • Flare resistance
  • CA

Cons

  • Distortion
  • Vignetting
A Sony camera with a Sirui 50mm T1.8 anamorphic lens attached, showcasing the lens's features and settings.

5 Conclusion (Français)

Le Sirui 50mm T1.8 Astra Full frame AF 1,33x anamorphic (849$/999euros) fait partie d’une série de 3 optiques 50, 75, 100mm T1.8 qui partagent la même ergonomie (position des bagues crantées) et le même rendu des couleurs.

C’est la première série d’optiques anamorphiques avec AF. L’AF est assez efficace et la distance min de mise au point relativement courte pour une optique anamorphique permet d’avoir des beaux ronds de bokeh et un flou d’arrière plan agréable

Le piqué n’est peut être pas son point fort mais elle est plus que suffisante pour de la 4K

Recommandé

Pour

  • Premiere optique plein format anamorphique avec AF
  • AF efficace
  • Rendu cinématique
  • Flare anamorphique
  • Prix raisonnable (849$)
  • Poids et taille
  • Distance min de mise au point assez courte pour une optique anamorphique
  • Quantité de flou d’arrière plan et taille des ronds de bokeh
  • Très bon rendu des couleurs
  • Excellente qualité de construction
  • Bague crantées compatibles avec une unité de follow focus
  • Homogénéité avec les autres optiques de Sirui (gamme complète)

Moyen

  • Piqué
  • Focus breathing modéré
  • Resistance au flare
  • AC

Contre

  • Vignettage
  • Distorsion

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