EF vs EF-S interchangeability

[privateaddressf]

I know this has been discussed before, but I have a fairly specific case and I'm still not sure how the discussions apply.  My wife has agreed to photograph a relative's wedding.  She has done some semi-pro photography before but her Sony alpha DSLR has been acting up and she is buying an m50 as a backup.  She needs to buy lenses quickly.  

If she buys an EF 50mm and an ef-s 50mm and takes a picture from the m50 (aps-c) with each lens, in the same place, will the two pictures produced by the camera subtend the same visual angle or will one of them portray a larger apparent visual angle?

We don't have time to experiment with lots of things and do three or four rounds of shipping to get the fovs she needs covered. It would also be nice not to waste money on redundant lenses if EF and EF-S focal ranges behave differently when used on her camera.

[MikeSowsun · Accepted solution]

No, You still have it wrong…..

An EF 50mm and an EF-S/EF-M 85mm will NOT produce similar field of view. Not even close.
Neither will an EF 85mm and an EF-S/EF-M 50mm.  If she buys an EF 50mm and an ef-s 50mm, they will both look the same when used on the same camera.

[johnrmoyer · Accepted solution]

https://www.cambridgeincolour.com/tutorials/digital-camera-sensor-size.htm

This article aims to address the question: how does your digital camera's sensor size influence different types of photography? Your choice of sensor size is analogous to choosing between 35 mm, medium format and large format film cameras — with a few notable differences unique to digital technology. Much confusion often arises on this topic because there are both so many different size options, and so many trade-offs relating to depth of field, image noise, diffraction, cost and size/weight.

Background reading on this topic can be found in the tutorial on digital camera sensors.

[deebatman316]

Buy the Canon EF to EF-M adapter. 3rd Party Mount adapters cause all kinds of problems. The product description says speed booster. Its best not to use Amazon or eBay for camera gear purchases. Unless it says sold and shipped by Amazon. Stick with Canon Authorized Dealers such as B&H Photo or Adorama. Also 3rd Party links WILL BE REMOVED by forum Moderators.

[privateaddressf]

My bad, didn't realize this was a no links forum.  Link removed.  My wife is certainly not purchasing that adapter.  She's getting the one that is a spacer with electrical passthroughs.  She can figure out which lens to use without adding extra cheap glass to the system.  I hear you about the 3rd party adapters, but at the same time, there's a reason 5,000+ people have given great reviews to a product that does the same thing for 1/4 of the price.  Going to the Canon adapter costs as much as another prime lens.  My wife's not a pro.  It's a hobby.

[krahe]

I've had no problems with my Viltrox adapter (not speed booster).

[deebatman316]

Almost all of Canon's prime lenses are full frame (EF) not EF-S. Except for the EF-S 24mm lens. So a 50mm on crop sensor camera would have an equivalent angle of view of 80mm when compared to full frame. Then an 85mm lens would have an equivalent angle of view of 136mm when compared to full frame. It's the image sensor that causes the crop NOT the lens. An EF 24mm lens & EF-S 24mm lens would yield the same result. Crop factor applies to all lenses wether Full Frame or APS-C. This is due to the image sensor NOT the lens. You can easily see this while looking through the viewfinder on an APS-C camera. Try with a 50mm lens 85mm lens. They will look drastically different.

[krahe]

The short answer is that on a crop sensor camera like the M50, a longer focal length will yield a narrower FOV than a shorter focal length, regardless of whether the lens was designed for a full frame camera or what the FOV would be on such a camera with the same lens.

[Tronhard]

That is true as far as it goes.  Certainly a 50mm EF lens has the same focal length as an EF-S lens.  However, on a crop-sensor camera, while the lens has the same Angle of View that is what it projects towards the sensor, the sensor captures a smaller area of that (Field of View), which is equivalent to using a lens of a longer focal length on a FF body - hence the term Equivalence.  To go back to the original post, given a Sony Alpha has approximately the same size as a Canon APS-C camera, so the Fields of View, assuming the same or similar lenses, should be about the same.

[Tronhard · Accepted solution]

Read this: 
As has been said, a 50mm lens is a 50mm lens, no matter the mount: EF or EF-S.  What makes the difference is what the sensor can capture from what the lens projects into the camera.  For a full explanation see:
Equivalence.pdf

[johnrmoyer · Accepted solution]

https://www.cambridgeincolour.com/tutorials/digital-camera-sensor-size.htm

This article aims to address the question: how does your digital camera's sensor size influence different types of photography? Your choice of sensor size is analogous to choosing between 35 mm, medium format and large format film cameras — with a few notable differences unique to digital technology. Much confusion often arises on this topic because there are both so many different size options, and so many trade-offs relating to depth of field, image noise, diffraction, cost and size/weight.

Background reading on this topic can be found in the tutorial on digital camera sensors.

[privateaddressf]

Ok, let's see if I've got this now after trying to digest all that.

The fov is a function of two things.  Sensor size, and lens focal length.  Swapping lenses of equal focal length on the same camera always produces the same fov.

Changing sensor sizes with a set focal length (e.g. 50mm on a full frame vs 50mm on an aps-c) changes the captured fov.

The "crop factor" then is really an effect of moving to a different sensor size.  A photographer used to using a 50mm lens for a particular setting with a full frame camera will have to adjust which lens/focal length they use in that setting if they switch to a smaller sensor?

[johnrmoyer]

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@privateaddressf wrote:

Ok, let's see if I've got this now after trying to digest all that.

The fov is a function of two things.  Sensor size, and lens focal length.  Swapping lenses of equal focal length on the same camera always produces the same fov.

Changing sensor sizes with a set focal length (e.g. 50mm on a full frame vs 50mm on an aps-c) changes the captured fov.

The "crop factor" then is really an effect of moving to a different sensor size.  A photographer used to using a 50mm lens for a particular setting with a full frame camera will have to adjust which lens/focal length they use in that setting if they switch to a smaller sensor?

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Yes