[Day by day]SONY α NEX-C3 +LEICA SUMMILUX 50mm E60 +SpeedBooster Ultra-0.71x

Last updated on 2026-03-17

A short report on using the LEICA SUMMILUX 50mm E60 with the Metabones SpeedBooster Ultra-0.71x on a SONY α NEX-C3.

• Please see the disclaimer regarding advertising here.
• Italicized links in the text are advertisement links that take you to other sites.
• If you find any images used on this site problematic, please contact us via the comments or inquiry form, either as the rights holder or their representative. We will review the matter and take appropriate action.

The information about the camera and mount adapter is the same as it was on February 25th, so it has been moved to the introduction below.

This time, I added a Canon-EF to Leica-R mount adapter to a mount adapter that converts a Canon EF mount to a Sony E mount, using a LEICA R mount lens.

Stacking mount adapters in this way is not recommended by the manufacturer, so please do so at your own risk. Focal reducer mount adapters in particular contain a lens to widen the angle of view, so if you attach a lens whose rear lens element recesses into the mount, it may come into contact with the lens on the mount adapter, damaging both the lens and the mount adapter, so you need to be extremely careful when attaching them.
In particular, many wide-angle lenses for the LEICA R mount are designed so that the rear lens element recesses into the mount, so there are many lenses that you will likely be viewing.

In particular, wide-angle lenses for the LEICA R mount often have a design where the rear element extends into the mount, so they are likely to be used for viewing.

The change in focal length when using a reduction optics system can be calculated using the following formula:

• When using the Metabones SpeedBooster Ultra-0.71x
  • 50mm (lens focal length) x 1.5 (sensor size conversion factor) x 0.71 (adapter reduction factor) = focal length 53.25mm

As you can see from the calculation results, using a mount adapter with a reduction optics system allows you to achieve nearly the same focal length as the original lens. The camera looks like this:

One added benefit of the focal reducer is that it increases the lens’s maximum aperture by one stop, transforming the LEICA SUMMILUX R 50mm F1.4 lens used in this experiment into a super high-speed LEICA SUMMILUX R 53mm F1 lens.

The focal reducer mount adapter does not only have benefits; it also uses a reduction optical system to bend light so that the peripheral areas of the lens are captured on a smaller sensor, resulting in worse image quality at the edges compared to the original lens. In particular, if the original lens’s peripheral image quality is poor, these poor areas will be amplified, making the poor lens performance more apparent. With a lens that delivers sharp image quality all the way to the edges, these imperfections are less noticeable.

This combination weighs 754g, consisting of the 500g lens, 224g SpeedBooster Ultra-x071 adapter, and 30g EF-R adapter. The lens is quite heavy and unbalanced during shooting, so care should be taken to prevent it from falling, such as by wrapping a strap around your arm.

The results of the wide-open aperture shot were taken on a sunny, light-filled day, with the camera’s maximum shutter speed of 1/4000. While highlights are mostly blown out, the core of the focal point remains, and out-of-focus areas are intensely blurred with F1-equivalent bokeh.

Since the camera does not have an electronic viewfinder, I was shooting while looking at the rear LCD screen, but I was able to adjust the focus by enlarging the image on the monitor.

The left image in the example below has been reduced in size, causing the focus to appear distorted and out of focus, so a 1:1 crop of the center of the frame is included on the right. The enlarged photo in the center has been compressed using Webp compression, but it’s clear that the core of the focal point remains. Furthermore, the example below was taken from F5.6 to F4 equivalent; stopping down three stops results in a more refined image, making this a lens that’s easy to use. There’s also no noise in the peripheral areas, and the negative effects of the focal reducer are barely noticeable. Although no sample images are included, when photographing a subject with a linear focus, distortion can be seen in the peripheral areas compared to when the focal reducer mount adapter is not attached.

Introduction

The SONY α NEX-C3 is a mirrorless camera released in 2011 with a 16-megapixel APS-C sensor.

When using lenses compatible with 35mm film, the smaller sensor size results in clipping of the peripheral areas. This is because lens focal lengths are based on 35mm film, meaning that APS-C sensors cannot be used at the focal length indicated on the lens.

While it’s true that mirrorless and digital SLR cameras capture what you see exactly, eliminating the need to worry about focal length, personally, I rely on the focal length of 35mm film for my photography, so it’s a concept I find hard to discard.

One item that can resolve focal length discrepancies with APS-C sensor cameras is a focal reducer mount adapter, which incorporates a reduction optical system into the mount adapter used to connect the lens to the camera. These are available from various companies, and one such example is the Metabones SpeedBooster Ultra-0.71x, which I used here.

This mount adapter has a large mount area for attaching the lens, and unlike a regular bayonet mount where you attach a lens by twisting it, it uses a spigot mount where the lens is connected in an unlocked state and then secured in place by the locking mechanism on the mount adapter.
It uses the same lens locking method used to secure lenses on professional equipment.

This mount adapter allows you to attach a Canon EF mount lens to a Sony-E mount camera, enabling autofocus and includes a lens to widen the angle of view, allowing you to use the Canon EF mount lens at a focal length close to that of 35mm film.

Reference links

• SONY α NEX-C3・Shige’s hobby
• [Day by day] α NEX-C3 +FUJIFILM TIARA 28mm M-mount modified・Shige’s hobby
• [Day by day]SONY α NEX-C3 +CANON EF40mm +SpeedBooster Ultra-0.71x・Shige’s hobby
• LEICA SUMMILUX R 50mm E60・Shige’s hobby

寄付のお願い・Request for donations

Affiliate links

• SONY NEX・Ads by Amazon
• SONY E・Ads by Amazon
• CANON EF・Ads by Amazon
• LEICA R・Ads by Amazon