Go Back   Steve's Digicams Forums > Digital SLR and Interchangeable Lens Cameras > Canon Lenses

Reply
 
Thread Tools Search this Thread
Old Jun 8, 2007, 10:05 AM   #1
Senior Member
 
Join Date: Feb 2006
Posts: 172
Default

Curious if someone could point me in the right direction for a better understanding of lens interchangeability between full frame cameras and cropped. (Correct terminology?) If not clear, pro line of cameras versus 30d and Rebels.

Personally nowhere near a need for a full frame camera. Just curious what exactly limits one lens to one camera or the other, which lens families are interchangeable, how one knows which is which and what is what, etc.

Assume there is plenty of info on this and any links appreciated.
leeraff is offline   Reply With Quote
Sponsored Links
Old Jun 8, 2007, 10:17 AM   #2
Administrator
 
Join Date: Jun 2003
Location: Savannah, GA (USA)
Posts: 22,378
Default

Different sensor sizes are used in some cameras. For example, most of the entry level Canon DSLR models use an APS-C size sensor.

Because of the smaller sensor size compared to 35mm film, you'll have a narrower angle of view (more apparent magnification) for a given focal length lens. Basically, to see how the angle of view would compare to the same lens on a 35mm camera, just multiply it by 1.6x. IOW, a 50mm lens on a camera with an APS-C size sensor would give you the same angle of view that you'd have using an 80mm lens on a 35mm camera, or a DSLR with the same size sensor (50mm x 1.6 = 80mm). IOW, your lenses would appear to be longer on a model with an APS-C size sensor.

This would apply, regardless if a lens was "made for digital" or not.

Some Canon models fall somewhere in between for sensor size.

What manufacturers starting doing, was making lenses that project a smaller image circle to help make a lens smaller and lighter for use on cameras with sensors smaller than 35mm film.

With Canon, these lenses are designated as EF-S. Because they project a smaller image circle, they are not designed to work on models that have larger sensors. So, if you are planning to upgrade to a model using a larger sensor (or want to use the same lenses with a Canon EOS film camera), you would want to take that into consideration. Some of the third party manufacturers have similar lens designs (they would cause issues like vignetting if you tried to use them on a camera that has a sensor or film size larger than APS-C).

You can use Canon EF mount lenses on Canon 35mm camera, as well as a Canon DSLR model with a larger or smaller sensor. But, you can't use EF-S lenses on a camera model with a sensor smaller than 35mm film (since these lenses are projecting a smaller image circle). There are also some mounting restrictions with EF-S lenses (some of the older, discontinued Canon DSLR models won't work with them, even if they use an APS-C size sensor).

JimC is offline   Reply With Quote
Old Jun 8, 2007, 10:30 AM   #3
Senior Member
 
Join Date: Feb 2006
Posts: 172
Default

Thanks JimC. Great reply. I've certainly picked up, by now, on some of those topics/terms such as the narrower angle of view, 1.6 crop factor, etc. Your explanation helps beat it further into the skull.

That simple "S" designation is what had not yet registered. Other than the angle of view (more or less narrow) is there any other factor one considers? Do these lenses work EQUALLY well on cropped and full-frame cameras?


leeraff is offline   Reply With Quote
Old Jun 8, 2007, 10:42 AM   #4
Administrator
 
Join Date: Jun 2003
Location: Savannah, GA (USA)
Posts: 22,378
Default

You can't use EF-S lenses with a camera that has a sensor larger than APS-C.

IOW, no they won't work equally well on both.

You'd need to stick with EF (not EF-S) lenses if you want to use them on Canon EOS series cameras with both larger and smaller sensors or film.

As far as how well a given lens works, you really need to take them on a case by case basis, regardless if they're designed strictly for cameras with sensors smaller than 35mm film or not.

JimC is offline   Reply With Quote
Old Jun 8, 2007, 11:18 AM   #5
Senior Member
 
Join Date: Feb 2006
Posts: 172
Default

Thanks. Got that. That's what I meant by the "S" designation from your reply and how that hadn't "yet registered" at least prior to your reply. Thanks. So...

EF-S = for cropped cameras (only)
EF = for both types of sensors (and film)

And, case by case on how each works with each type of camera. Those owning both types of sensors may use same the EF lens on different the bodies and get totally different angle of views by interchanging the same lens to different bodies (sensors).

Simple issue but helps a newbie further decipher that crazy code such as
EF-S 70-200mm f/2.8. Now have the "S" part figured out a little better. Getting the f/x.x down well enough. Now need first hand experience looking through these different ranges to see what one can achieve between, say, 17mm and 300mm.


leeraff is offline   Reply With Quote
Old Jun 8, 2007, 12:05 PM   #6
Administrator
 
Join Date: Jun 2003
Location: Savannah, GA (USA)
Posts: 22,378
Default

If you're looking at third party lenses (Tamron, Sigma, Tokina), some of those are designed specifically for use with APS-C size sensors. Those will have different designations.

For example, Tamron's Di II lenses and Sigma's DC lenses will only work without vignetting on cameras with APS-C or smaller sensors.

JimC is offline   Reply With Quote
Old Jun 8, 2007, 1:58 PM   #7
Super Moderator
 
peripatetic's Avatar
 
Join Date: Nov 2004
Posts: 3,599
Default

Because a reduced image circle lens has to cover less area it can be made smaller, and often to a higher optical quality for a given price. This isn't necessarily the case, but the engineering challenges are reduced for a given price or image quality. One reason for this is that they can move the rear of the lens closer to the sensor - this makes things easier from an optical/engineering perspective, particularly with wide-angle lenses.

This point does not apply to telephoto lenses however; generally there are few telephoto lenses that are designed for the smaller sensors. i.e. They will normally have an image circle that covers a full 35mm frame.

Another factor to remember is that recently designed lenses (say 1995 onwards, and advances are still being made) started to get the full effect of computer modelling and are often of much better design than older lenses. All the digital-only lenses are new, so they often compare very favourably with older designs. Not specifically because they cover a smaller image circle, but just because they are modern designs.

Scroll down this link to see an indication of the relative difference in sensor sizes of the 3 Canon DSLR formats. The 5D sensor covers about 2.5 times the surface area of the 30D for example.

http://www.sphoto.com/techinfo/dslrs...slrsensors.htm
peripatetic is offline   Reply With Quote
Old Jun 8, 2007, 11:01 PM   #8
NHL
Senior Member
 
NHL's Avatar
 
Join Date: Jun 2002
Location: 39.18776, -77.311353333333
Posts: 11,547
Default

To add to peripatetic excellent write up, selecting smaller and lighter 'digital' lenses only can bring many benefits especially at the shorter focal lenght because the light rays produced by theses lens tend to strike the 'cropped' sensor more straight on than a full-frame lens - The benefit are increase contrast (which brings better MTF) and less light fall-off at the corners.
-> Digital sensors are not like film where it is flat - Image sensors have pits in them and most of the time they have micro-lenses in front to top it off. Oly has some excellent pictorials on this:





Longer teles do not benefit much from going 'digital' since the light rays are already striking almost straight because of the very narrow FOV characteristic that theses type of lenses already offered
-> Don't buy a full-frame unless going to a full-frame camera is in your plan because one can end up carrying a lot of more heavy (as well as expensive) lenses for not much benefit
NHL is offline   Reply With Quote
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 9:21 PM.