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.

[AtticusLake]

They're both 50mm lenses, so they should give you the same exact picture.  (In practice, 50mm is kind of approximate, so the pictures may vary slightly.)

The difference between those lenses is the size of the image they produce; i.e. the size of sensor they cover.  But they will both cover the APS-C sensor in that camera.  You will need an adapter, of couse, since the camera's lens mount is EF-M.

If you later used these lenses on a full-frame RF camera, like the R5, then the EF-S lens would put the camera into crop mode, giving you a narrower view.  You can not use the EF-S lens on an EF camera.

If you want more info on lens mounts and compatibility, here's an article I wrote: https://moonblink.info/MudLake/gear/lenses

[privateaddressf]

So to confirm, buying a 50mm EF lens and an 85mm EF-S lens will produce significantly different images?  Not the difference between an 80mm and an 85mm both from EF-s lenses that the crop factor camp would suggest?  Remember, someone's wedding photos are on the line here.

[rs-eos]

A 50mm focal length is a 50mm focal length.  So any of the characteristics, distortions, etc. of that lens would still mainly be there no matter the camera it's used on.

e.g. a 50mm focal length on full-frame for headshots will lead to facial distortions (typically the person's nose and any feature closest to the camera will be exaggerated).  On a crop-sensor body, while the field-of-view of the 50mm will be as an 80mm lens on a full-frame camera, those distortions will still be there.  Though due to framing of the headshot, you'd be physically further back, so the distortions may be lessened.

If you're comparing 50mm vs 85mm on a crop-sensor (or on full-frame), they would indeed be different.  Though I wouldn't say drastically different.   The 85mm would render portraits betters (less facial distortions with headshots) and give you a narrower field-of-view vs the 50mm.

[AtticusLake]

If you're asking me to take responsibility for someone's wedding photos, then no, you have to pay for that kind of support.  Please try to remember how much you're paying for this information.  I'm just giving you the best of my understanding on a best-guess basis.

If you're shooting something that has a major impact, like a wedding, and particularly for money, it's your resposibility to know your gear, and know how to use it.  Please dont try to fob that off onto online forums.  That's a sure road to disaster.  If your wife isn't confident enough to kow how to figure this out, then she shouldn't take the job.

But based on my best-guess, top-of-the-head, just-what-I-think-I-remember wild-assed guess, yes.  The focal lengths are different, so the angles of view will be different, as different as the numbers imply.  There's no reason an APS-C camera would do anything different with those 2 lenses.  At least no reason I can think of offhand.

Not the difference between an 80mm and an 85mm both from EF-s lenses that the crop factor camp would suggest?

---

No idea what that means.

[privateaddressf]

The wedding shoot is being done as a favor, free of charge, but it's still someone's wedding.  All I'm saying is there is definitely conflicting information around and this isn't a hypothetical or I'm thinking of buying something someday, so if you're not sure, just say you're not sure.  I'll see if I can find technical drawings/specifications to confirm this, but if this forum is confident the fov presented in the picture when using the two lenses will be the same, then we can shop that way and I'll let you know if you were right later.

This is the same problem we had when my wife was moving from a Minolta to a Sony alpha.  The lenses were compatible in terms of mounts, but a 50mm Minolta lens used on the alpha yielded the same fov as an 80mm Sony lens used on the same camera.  Because the alpha had an aps-c sensor, the sensor only picked up some of the resolved image from the lens, meaning the picture subtended a smaller visual angle.  If Canon has somehow fixed this problem when moving between EF and EF-S, (or in the adapter from EF/EF-S to EF-M) then that's awesome.

[deebatman316]

What you're describing is not a problem. It's the image sensor that makes the image more narrow. Since the image sensor is smaller than full frame (36x24). It only can record the center of a full frame lens. A 50mm lens used on a Sony camera would yield an angle of view of 75mm instead of 80mm. Since Sony's and everyone else's APS-C crop factor is 1.5x opposed to 1.6x that Canon uses. 

[privateaddressf]

Ok, thanks to everyone for the help.  Sorry for the panic.  To be clear, the narrowed field of view isn't a problem per say.  I just need to make sure she doesn't do something like buy an EF 50mm and an EF-S/EF-M 85mm since those would end up being basically the same field of view and leave her unable to take shots closer up.  She just needs to make sure she can cover her distance bases since she won't always be able to move wherever she needs to to get "the right shot". 

Again, thanks for everyone's help

[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.

[privateaddressf]

Ha!  Quick update.  I figured out where some of this confusion is coming from.  Viltrox sells an EF-M mount to EF lens adapter that includes a glass element that changes the apparent focal length of the lens.  If you use that adapter, the field of view on a cropped camera comes out approximately the same as when used on a full frame camera natively.

Lens Mount Adapter EF-EOS M2 Auto-Focus 0.71x Speed-Booster Control Ring for Canon EF Lens to Canon EOS-M (EF-M Mount) Mirrorless Cameras M M2 M3 M5 M6 M10 M50 M100 <search on Amazon if you want>