Differance between EF and EF-S Lens?

[kuanyu]

Hello,
I know the EF-S lens are for digital only but my question is do they take into acount the 'crop' factor of 1.6 ( ie would a 50mm EF-S lens really be 50mm on my XTi) or do I still need to do the math? Also what other differances are there?
Thanks,
KuanYu

[crn3371]

50mm is 50mm is 50mm, regardless of crop or full frame, ef or ef-s.

[pup]

efs lenses are less expensive (in general) and lighter

[E-K]

As crn3371 said, 50mm is 50mm. The image circle on the EF-S lens does not have to be as big as an EF one. I also thought the rear lens element could pertrude further into the camera body in the case of the EF-S because the mirror on an APS-C is smaller -- I could be wrong on that one though. In theory this means that smaller more cost effective lenses can be designed for APS-C - at least in theory ;)

e-k

[BradT0517]

A 50mm EF and 50mm EF-s are both still physically 50mm lenses whether on a crop or FF camera. Both lenses would end up being the equilent of an 80mm lens if put on a XTi.

[Mark_Cohran]

So, if it hasn't become clear yet, an EF-S lens at 50mm on your crop camera will still give you the equivalent field of view as an 80mm lens on a full frame digital or 35mm film camera. This is no different from a 50mm EF lens.

Mark

[ed rader]

So, if it hasn't become clear yet, an EF-S lens at 50mm on your crop camera will still give you the equivalent field of view as an 80mm lens on a full frame digital or 35mm film camera. This is no different from a 50mm EF lens.

Mark

but an EF-S lens will only fit a 1.6 crop camera (excluding 10d) so we have no way of proving this :D .

ed rader

[SkipD]

but an EF-S lens will only fit a 1.6 crop camera (excluding 10d) so we have no way of proving this :D .Sure you do. Take a shot with an EF-S set to 50mm and another with an EF 50mm (or an EF zoom set to 50mm) and you will see the same framing of the subject if the two shots are from the same position.

The only difference would be due to the errors of calibration of the focal length indications on the lens.

[SkipD]

Hello,
I know the EF-S lens are for digital only but my question is do they take into acount the 'crop' factor of 1.6 ( ie would a 50mm EF-S lens really be 50mm on my XTi) or do I still need to do the math? Also what other differances are there?
Thanks,
KuanYuIt seems you need to bone up a little on the "crop factor" stuff. This link (http://photography-on-the.net/forum/showthread.php?t=45388) is a good place to start.

The bottom line is that a 50mm lens is always "really" a 50mm lens. Read the link to learn about field of view, etc. There's even a picture or two in there to help.

[chakalakasp]

Hello,
I know the EF-S lens are for digital only but my question is do they take into acount the 'crop' factor of 1.6 ( ie would a 50mm EF-S lens really be 50mm on my XTi) or do I still need to do the math? Also what other differances are there?
Thanks,
KuanYu

BTW, it's not just for digital only, it's for 1.6x crop only. If you try to put an EF-S lens on a full frame body, the mirror will slap the back of the lens.

[Rhilton4u]

I've been meaning to ask this question -

What exactly is the purpose of making lenses that are constructed for 1.6 digital sensors (EF-S)? You can still use regular EF lenses on 1.6 sensor bodies without vignetting right? So why do they bother? Thanks.

[Medic85]

As crn3371 said, 50mm is 50mm. The image circle on the EF-S lens does not have to be as big as an EF one. I also thought the rear lens element could pertrude further into the camera body in the case of the EF-S because the mirror on an APS-C is smaller -- I could be wrong on that one though. In theory this means that smaller more cost effective lenses can be designed for APS-C - at least in theory ;)

e-k


You're right about the rear lens element protrouding into the camera body further.

[kfong]

Cost.
Say the lens has a focal length of 24mm. It is a lot easier and cheaper to design a lens so that the distance between the rear element and the sensor is say 30mm than 40mm.
Ken
I've been meaning to ask this question -

What exactly is the purpose of making lenses that are constructed for 1.6 digital sensors (EF-S)? You can still use regular EF lenses on 1.6 sensor bodies without vignetting right? So why do they bother? Thanks.

[Rhilton4u]

Cost.
Say the lens has a focal length of 24mm. It is a lot easier and cheaper to design a lens so that the distance between the rear element and the sensor is say 30mm than 40mm.
KenCool. Thanks for the explanation.

[Hermeto]

Try 200/2.8 and 300/2.8 to see the di$$erence..

[Rhilton4u]

Try 200/2.8 and 300/2.8 to see the di$$erence..I don't see any EF-S lenses at that focal length. ???

[SkipD]

The simple reason for the EF-S lenses is to provide lower cost wide-angle lenses to the users of APS-C format cameras (the Rebel series, 20D, 30D, etc.). The two basic differences in the design criteria, relative to the EF specs, are the smaller image circle needed to cover only the APS-C sized sensors and the deeper penetration of the lens itself into the mirror box.

If you modified EF-S lenses to fit on a 35mm film camera, you would likely find the mirror crashing into the rear element of the lens under certain circumstances. Also, if you managed to get an EF-S lens to work on the 35mm camera, you would find very significant vignetting of the image in the 35mm film frame.

[kitacanon]

I just converted the EF-S 18-55 kit lens from EF-S to EF by slicing off the rear protective mount cylinder to fit my 10D...it's the only way to get a wide angle lens for the 10D for under $100.

[ScottE]

If you put an EF 50 mm lens and then an EF-S 50 mm lens on your XTi you will get exactly the same image. However the EF-S lens takes the crop factor into account because the available image circle is only large enough to cover the sensor. The EF lens has a larger image circle so that it can cover a larger sensor and your XTi only uses the centre portion of the sensor.

If you could manage to fit the EF 50 mm and EF-S 50 mm on a full frame camera like the 5D, the EF lens would provide an image that covers the whole frame. The EF-S lens would provide the same image, but the corners would be blacked out.

The advantage of the EF-S lens for your XTi is that the optical engineers who designed it were able to concentrate on image quality over a smaller area. They do not have to compromise image quality in the centre of the image in order to preserve image quality in corners that your camera cannot use. Generally this means that for a similar cost lens the EF-S lens should give better image quality.

[Rhilton4u]

If you put an EF 50 mm lens and then an EF-S 50 mm lens on your XTi you will get exactly the same image. However the EF-S lens takes the crop factor into account because the available image circle is only large enough to cover the sensor. The EF lens has a larger image circle so that it can cover a larger sensor and your XTi only uses the centre portion of the sensor.

If you could manage to fit the EF 50 mm and EF-S 50 mm on a full frame camera like the 5D, the EF lens would provide an image that covers the whole frame. The EF-S lens would provide the same image, but the corners would be blacked out.

The advantage of the EF-S lens for your XTi is that the optical engineers who designed it were able to concentrate on image quality over a smaller area. They do not have to compromise image quality in the centre of the image in order to preserve image quality in corners that your camera cannot use. Generally this means that for a similar cost lens the EF-S lens should give better image quality.Got it...that clears it up completely.

[canonphotog]

I just converted the EF-S 18-55 kit lens from EF-S to EF by slicing off the rear protective mount cylinder to fit my 10D...it's the only way to get a wide angle lens for the 10D for under $100.

Here's another method of achieving your goal. Perhaps a bit less risky also.

http://forums.dpreview.com/forums/read.asp?forum=1029&message=15346329.


This is works on the 17-55 f/2.8 IS also; although I haven't been able to find any info on a replacement bushing to make it an EF vice EF-S.

Here's the link regarding the 17-55 conversion.

http://www.photography-on-the.net/forum/showthread.php?t=282467&highlight=17-55

[kitacanon]

I checked out the other posting on the conversion and it's for the 17-85mm lens...which IS easier I've read....but really, once the rear mount is removed (with the barrel/baffle) it's not so difficult to slice that barrel off...just a bit of care...
http://img88.imageshack.us/img88/5968/1855v3xj7.jpg

[Chandler.]

Couldn't you use an EF-S on a FF body with an extension tube?