Lenses for full frame vs aps-c cameras.

[filmalaska]

101 question here- how does one differentiate the lenses between the full frame sensor cameras and the others? I come from the cinematography side, picked up a 6D for starters and am trying to figure out what the lens options are. Thanks

[filmalaska]

...sorry my question isn't real clear. Will lenses from non-full frame camera work on 5D/6D cameras? Thx

[ScottyP]

In a word, no.

Full frame lenses work on both full frame and crop sensor cameras. Crop camera lenses, however, only work on crop bodies. Don't try mounting a crop lens on a full frame body because it can damage the camera's mirror and/or the mounts on both..

Canon full frame lenses are designated "EF" and its crop lenses are called "EF-s". Third party lens companies also make the two different mounts but they all have different naming conventions.

[filmalaska]

Scott,
Thanks very much. That exactly what I needed to know.

Morgan
Anchorage

[TCampbell]

There are two sensor sizes in Canon digital cameras sold today (there was a  third, but that's no longer offered.)  

A "full frame" camera (like a 1D X, 5D III, or 6D) are so named because the physical size of the sensor is roughly the same size as a single frame of 35mm film.  That's about 36mm wide by about 24mm tall.

An "APS-C" camera (all Rebel series, midrange bodies like 60D, and 70D, as well as the 7D) are so named because the physical size of the sensor is roughly the same size as a single frame of APS-C film (APS-C = Advanced Photo System - Classic size).  This film was a little smaller than 35mm... the frame measures roughly 22mm wide by about 15mm tall.  It has a 60% (1.6x) crop factor.

The EF-S lenses project an image circle into the camera body which is large enough to fill the size of an APS-C sensor, but will not quite fill the frame of a "full frame" sensor.  You'd get vignetting and the image quality would degrade substantially near the edges and corners.   But possibly even more important that that... a "full frame" mirror is physically larger and requires more clearance to swing clear of the light path when taking an exposure.  The EF-S lenses have a shorter back-focus distance and the rear-most lens element is so close that the mirror would strike the rear-element.  As such, Canon designed the mount of the full-frame bodies such that the EF-S lenses wont even mount flush to the body.  

In short, Canon "EF-S" lenses will only work with Canon cameras that have APS-C size sensors (well.. with the single exception of the old EOS 10D which hasn't been made in ages.)

Canon "EF" lenses will work on every Canon EOS camera... film or digital... regardless of sensor size.

[filmalaska]

Thanks Tim, for the all the good background information. I find it very useful.
Best,
Morgan Evans

[mdougc]

I have the Canon EF 50mm f/1.4 USM lens, and use it with my Canon 70D.

I have several other lenses, but this is reserved for portraits and miscellaneous detail work.
After many years of amateur photography, I am trying to understand lens specifications at a deeper level.

In reading about the "1.6 crop factor", it implies that this full-frame lens presents a 80mm field-of-view on an APS-C camera.
But I don't experience that.  It appears to act like a 50mm lens on my Canon 70D.

Here is my confusion.
I put my camera on a tripod and aimed at a test subject with a well-defined area - a book cover.
1. First picture was shot with a Canon EF-S 18-55mm lens, set at 50mm.
2. Second picture with the Canon EF 50mm.

I get the same picture - same FOV, identical crop.
The way I interpret your comments, I should zoom the first picture to 80mm in order to match the shots.

Optically, this would indicate the sensor is closer to the lens for the EF 50mm, in order to match the crop.

The reason I want to understand is that I am considering buying a Canon EF 17-40mm F/4L.

If this is going to produce shots on my 70D that look like 27-64mm, then it won't provide the wide angles that I need sometimes.

If you help me understand, thank you.

[kvbarkley]

First: focal length is focal length is focal length and is camera independent and therefore EF vs EF-S independent.

Now the field of view of that lens depends on the size of the sensor.

For a FF lens the FOV is 47 degrees diagonal for a 50mm lens. For an APS-C 1.6 Crop factor lens, it is 30 degrees for the same 50 mm, (Note that it scales exactly with crop factor.)

Now, if you had a FF and APS-C camera a 80mm lens on the FF would have the same image as the 50mm on the APS-C.

http://www.bobatkins.com/photography/technical/field_of_view.html

ETA: screwed up FF vs APS-C!

[ebiggs1]

"Here is my confusion.

I put my camera on a tripod and aimed at a test subject with a well-defined area - a book cover.
1. First picture was shot with a Canon EF-S 18-55mm lens, set at 50mm.
2. Second picture with the Canon EF 50mm."

You actually need to stop think in millimeters if you want to compare lenses on different camera formats.  Crop values was an attempt to put a name on something that really didn't need it.  It has caused a lot of confusion. A chart like the one below is the most accurate way to see what a lens will do.

You were wanting something in the 17mm focal length which has an AOV of a little over 100 degrees.  On your crop body you will need a 12mm lens to see the same AOV.  Perhaps the Canon EF-S 10-22mm f/3.5-4.5 USM Lens will fill the bill.  I used that lens for years and can recommend it.  There is a newer model the Canon EF-S 10-18mm f/4.5-5.6 IS STM Lens.  I have not bought into it as I was never impressed with it.  Not nearly as well built, IMHO, of course.

If you are confirmed on buying an "L" lens, I like the Canon EF 16-35mm f/2.8L II USM Lens over the 17-40mil.  There is a version III out now but I have not tried it yet.

[mdougc]

But why, in my described test of the EF and EFS lenses with a APS-C sensor, did I get the identical picture???

There was NO CROPPING to be seen.

Something is missing in this stream of logic.