Reviews |What Sony lens should I buy: full-frame vs APS-C and camera mounts explained

What Sony lens should I buy: full-frame vs APS-C and camera mounts explained Review

What Sony lens should I buy: full-frame vs APS-C and camera mounts explained

Due to two different image sensor sizes and two different camera mounts, coupled with a brand name change in 2013, there is some reasonable confusion about what Sony lenses are compatible with which cameras.

Don’t fret, we have compiled everything you need to know about Sony lens compatibility, along with a quick explanation of Sony camera types.

Two Sony camera types

Sony provides two kinds of interchangeable lens cameras; single lens translucent (SLT) cameras and compact system or mirrorless cameras. Prior to the end of 2013 Sony used the Alpha brand for its SLT cameras, while its compact system camera (CSC) line used the NEX brand.

However, at the end of 2013, Sony no longer used the NEX name and now its CSCs and SLTs are both branded Alpha.

Sony’s single lens translucent (SLT) cameras have a mirror, similar to the more familiar single lens reflex (SLR) cameras from Canon, Nikon, and Pentax. In SLT cameras, however, the mirror is set in place rather than moving out of the way to let light in and it’s translucent so that light can always reach the sensor.

Compact system cameras don’t have a mirror at all, meaning they can be smaller in size.
Sony makes both APS-C format and full-frame SLT and compact system cameras.

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Two Sony lens mounts

Two Sony lens mounts

Sony’s SLT cameras have the A-mount. First introduced by Minolta in 1985, the A-mount was adopted by Sony when it bought the Konica Minolta camera business in 2006.

Sony’s compact system cameras have the E-mount, first introduced in 2010 in the APS-C format Sony NEX 3 and NEX 5 models.

The E-mount lenses that are designed to be used on compact system cameras are not compatible with Sony A-mount camera models such as the A99 (full-frame) or A77 II (APS-C format).

There are adaptors, however, that allow you to use Sony A-mount lenses on E-mount cameras – they cannot be attached directly.

Sony’s full-frames cameras can accept APS-C format lenses as long as they have the appropriate mount, however images will be restricted to an area that’s equal to an APS-C sized sensor.

You need to use a lens that’s designed for a full-frame sensor if you plan on using the full benefits of a full-frame camera.

Full-frame E-mount Sony lenses are badged FE, while the APS-C format lenses are labelled E. The letters ‘DT’ denote Digital Technology, which means that an A-mount lens is intended for APS-C format.

Some literature on Sony packaging employs the abbreviations SAL and SEL; denoting Sony Alpha Lens and Sony E-mount Lens, respectively.

Sony full-frame vs APS-C format

The sensor on full-frame cameras is the same size as a 35mm film frame, while APS-C format cameras have a sensor that’s smaller, measuring around 23.5×15.6mm. APS-C format lenses have to cover only the smaller area of an APS-C format sensor, while full-frame lenses produce an image circle that can cover a full-frame sensor.

The implication is that if a full-frame lens is used on a camera with an APS-C sized sensor, only the middle portion of the image circle is used and the image will appear as if it has been made by a lens with a focal length that is 1.5x longer than the actual marked length.

If an APS-C format lens is used on a full-frame camera it is incapable of producing an image that will cover the whole area of the sensor.

Sony full-frame cameras, however, have a crop mode whereby the size of the image is reduced to complement that produced by an APS-C format lens.

SEE MORE: Sony A99 II vs A99: key differences explained

Sony lens format abbreviations

The following provides a brief summary of what the most important letters are on Sony lenses and cameras.

A – A or Alpha mount, used on Sony Alpha SLT cameras and compatible lenses
E – E mount, used on Sony NEX and Alpha compact system cameras and compatible lenses
FE – Full-frame E-mount
SAL –  Sony Alpha Lens
SEL – Sony E-mount Lens
DT – A-mount lens for APS-C format


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5 years ago

Actually, the NEX cameras were part of the Alpha brand from day one: the very first NEX-3 and NEX-5 models already had the Alpha logo on the front and showed the Alpha logo briefly on bootup.
The article name was the thing that was changed: here NEX was dropped, and instead everything now has the Alpha sign in the product name.