EF vs. EF-S and crop factor

[naveenmedia]

OK, so I get that the APS-C sensor is not full frame, and therefore there is a crop factor of 1.6.

And so a 50mm EF lens is really giving you an 80mm shot.

However, since the EF-S lenses are designed for the APS-C sensors, does that conversion still apply? Is a 50mm EF-S lens going to give us 50mm or 80mm?

 

[dcloud]

50mm efs would give you 80

 

[Barry_Green]

The lens doesn't change.

It's the sensor that's cropping the shot off, not the lens.

A 50mm EF lens, and a 50mm EF-S lens, will give you *identical* images, when both are mounted on an APS-C camera.

 

[bwwd]

I guess perspective would change a bit if you would be close to subject cause glass is smaller on ef-s lenses since they cover smaller area.But its also depends on the shape of front glass.

 

[Ben_B]

OK, so I get that the APS-C sensor is not full frame, and therefore there is a crop factor of 1.6.

And so a 50mm EF lens is really giving you an 80mm shot.

However, since the EF-S lenses are designed for the APS-C sensors, does that conversion still apply? Is a 50mm EF-S lens going to give us 50mm or 80mm?

http://www.dvxuser.com/V6/showthrea...-wide-primes&p=1973210&viewfull=1#post1973210

There is no such thing as an APS-C "optimized" lens in the sense you've described. The DX lenses from Nikon have the exact same FOV as full frame lenses when both used at the same mm value of focal length on a crop camera. What DX means is that the image circle of the lens is not large enough to fill the full frame.

Lets put it another way. If you put your 20mm full frame lens and your 20mm DX lens on a crop camera they would both look exactly the same.

If you put your 20mm full frame lens and your 20mm DX lens on a full frame camera the DX lens would not fill the frame and would sort of be like looking at a circle in the middle of the frame, with black edges (think super vignetting.) If you were then to cut a circle exactly the same size out of the photo from the 20mm full frame lens and compare the two shots, they would look exactly the same.

Here is an example of what a DX lens looks like on a full frame body:

If you had a FF lens of the same focal length on their, the dog and the man and everything else that you see would all look the same, the edges would just be filled in with new imagery that we can not see in this photo as well. Therefore, when you put both lenses on a crop body the images will look exactly the same.

Did this explain it? Feel free to link this post whenever someone gets confused by this.

For this replace DX with EF-S and FF with EF.

 

[Mo.licious]

So by this logic, (and here comes the newbie question), is my Tamron 17-50 really 27-80mm fov?


EDIT: Nevermind, it seems that the Tammy 17-50mm 2.8 is designed for the crop sensor.

 

[steventimothy]

So by this logic, (and here comes the newbie question), is my Tamron 17-50 really 27-80mm fov?

EDIT: Nevermind, it seems that the Tammy 17-50mm 2.8 is designed for the crop sensor.

You might be confused. Effectively, yes. If you were using a 35mm film camera or a FF digital like the 5D, it would be LIKE using a 27-80 mm lens.

Here's the quote again by Ben_B:
"There is no such thing as an APS-C "optimized" lens in the sense you've described. The DX lenses from Nikon have the exact same FOV as full frame lenses when both used at the same mm value of focal length on a crop camera. What DX means is that the image circle of the lens is not large enough to fill the full frame. So your lens may not be as wide as you think it is!

Lets put it another way. If you put your 20mm full frame lens and your 20mm DX lens on a crop camera they would both look exactly the same.

If you put your 20mm full frame lens and your 20mm DX lens on a full frame camera the DX lens would not fill the frame and would sort of be like looking at a circle in the middle of the frame, with black edges (think super vignetting.) If you were then to cut a circle exactly the same size out of the photo from the 20mm full frame lens and compare the two shots, they would look exactly the same. "

If the Tamron 17-50 were designed for a FF camera, the image would be IDENTICAL, as Barry said.

 

[steventimothy]

I guess perspective would change a bit if you would be close to subject cause glass is smaller on ef-s lenses since they cover smaller area.But its also depends on the shape of front glass.

Yes, because with a FF designed lens, on an APS-C camera, the optics at the edges of the lens are not used, so theoretically less distortion. Also, theoretically less falloff as well. But other than that, identical image.

Edit: That's another good reason to use vintage lenses, designed for full-frame cameras on APS-C or DX cameras - less distortion and fall-off, especially at low F numbers. And, if you ever upgrade your camera to FF, you're good to go.

 

[steventimothy]

On another note, it's a shame that EF-S lenses for APS-C cameras with Canon can't be mounted on FF cameras like the 5D, in the same way that Nikon allows its DX lenses to be mounted on FX cameras (with only a DX-sized portion of the sensor used).

 

[nosys70]

"

On another note, it's a shame that EF-S lenses for APS-C cameras with Canon can't be mounted on FF cameras like the 5D, in the same way that Nikon allows its DX lenses to be mounted on FX cameras (with only a DX-sized portion of the sensor used). "

but this is exactly the case, you can mount an EF-S lens on a FF camera and crop the part you need to remove the black borders. And you will get a zoomed picture from about 1.6.... (well only if you resize it to a video standard frame, if you are just leaving as is, you just get a smaller picture)
​

 

[Barry_Green]

Not with the Canons on certain cameras. The 5D, for example, cannot take canon EF-S lenses. It can take the Tokina, but not the Canon brand. They made the mount ever so slightly different to prevent it.

 

[Chris Johnston]

Not to hi jack but....... I have a 60d with a 17-55 canon 2.8 and several old nikkor lens' (28 2.8 and a 50 1.8) Can I assume the nikkors will work on a 5D? (both, will they mount without damaging the mirror and will they give a full frame, without the viginetting? (if I'm using the nikon/eos mount adapter that I'm currently using for my 60D)

 

[steventimothy]

Not to hi jack but....... I have a 60d with a 17-55 canon 2.8 and several old nikkor lens' (28 2.8 and a 50 1.8) Can I assume the nikkors will work on a 5D? (both, will they mount without damaging the mirror and will they give a full frame, without the viginetting? (if I'm using the nikon/eos mount adapter that I'm currently using for my 60D)

Yup - with adapter (like Fotodiox) it's no problem. You don't need the spendy version of the Fotodiox. You'll have full frame, no vignette. You'll love them on that cam. I did a day's worth of shooting with a Nikkor 50 mm f1.4 on a 5D. The adapter is the same for either the 60D or the 5D.