lens question

[Laydewlf]

Photocamel tells me I haven't posted in a while, so thought I would ask something I have been wondering.

I've been looking at additional lenses for my rebel xt and I am learning what the information on the lens means. I think I have it all figured out except for "EF". as in 50/2.8 AF EF or however it goes. I know that the 50 is the mm. 2.8 is the minimum apeture and AF is auto focus. But what about the EF?

I'll probably have to buy used lenses and want to make sure I am buying for digital and not film cameras. Is there anything else I should be on the look out for?

Thanks!!

[stevedunster]

EF refers to the lens mount type, but there is an important difference between EF and EF-S lenses.

EF lenses can be used cameras with full-frame sensors as well as the cheaper cropped sensor cameras which can also take the EF-S (I remember the S as "short" because the mirror is smaller, they can push the barrel of the lens futher into the body of the camera making the external dimensions smaller.

BUT if you fit a EF-S lens into a camera with full-frame sensor (like 5D or 1D), it will fit onto the EF mount okay, but when you take your first shot the bigger mirror will smash against the bit of the lens which goes too far into the camera.

All you need to remember is: EF lenses work with any camera with EF mount, but EF-S (cheaper) lenses must only be used on the cheaper cropped sensor cameras or you may do damage to your expensive camera.

I hope this helps

Steve

[Killjoy]

There is nothing "cheap" about Canon's cameras with a cropped sensor.

Yes, the "EF" is the mount type. You would not be able to put an FD lens (older non-auto focus lenses) on a body that takes the EF style lenses.
And as for the EF-S lenses, you will not be able to mount them on a body with a full frame sensor.
All of the EF lenses have a red dot telling you where to line up the lens to the body before twisting it to lock.
The EF-S lenses have a little white square. There is also a white square on the body to line this up to.

[stevedunster]

Originally Posted by Killjoy

There is nothing "cheap" about Canon's cameras with a cropped sensor.

To be precise, I didn't say "cheap", I said "cheapER" - which in terms of RRP I think they all are. It seemed the best way to try to explain what "EF" is to somebody who may not be aware they have a cropped sensor or not.

Apologies if it has cause some confusion

Steve

[swampler]

And just to clarify, at the risk of confusing, but 2.8 is the MAXIMUM aperture, not the minimum. A smaller number is a larger aperture because it is actually a fraction (1/2.8 ).

I think the EF has been covered...

[stevedunster]

Originally Posted by swampler

I think the EF has been covered...

LOL

[Laydewlf]

Originally Posted by Killjoy

All of the EF lenses have a red dot telling you where to line up the lens to the body before twisting it to lock.
The EF-S lenses have a little white square. There is also a white square on the body to line this up to.

I just looked over my camera. The body has the red dot, but the lens that came with it is an EFS with a white dot. I bought a canon 75-300mm not long after I got the camera and it has the red dot, but no where on it does it say EF. Should I be concerned that the lens that came with the camera is an EFS?

Thanks for the responses. I appreciate all that I am learning here.

[stevedunster]

No - you're fine!

You have a rebel xt (which I believe is the same as the 350D) which has a cropped sensor (multiply all your focal lengths by 1.6 to be equivalent to a film camera or full frame sensor camera).

So your camera can take EF-S and EF lenses. If you buy any additional lenses, it might be worth buying EF lenses, so if ever you upgrade (or hire) a full-frame camera, your lenses will be compatible.

Steve

[swampler]

Originally Posted by Laydewlf

I just looked over my camera. The body has the red dot, but the lens that came with it is an EFS with a white dot. I bought a canon 75-300mm not long after I got the camera and it has the red dot, but no where on it does it say EF. Should I be concerned that the lens that came with the camera is an EFS?

Thanks for the responses. I appreciate all that I am learning here.

Your body should have a red dot and a white dot, especially since it came with a white dot lens. You can use either EF or EF-S in this case.

I wouldn't worry about buying only EF lenses on the chance of going full frame later, you should buy for the system you have now. I would hate to miss out on a shot because I was afraid to buy the correct lens for my body. You can always sell an EF-S lens if you upgrade bodies.

[stevedunster]

Originally Posted by swampler

...You can always sell an EF-S lens if you upgrade bodies.

Fair point

[aam1234]

Welcome to the forum, Steve (Dunster).

[stevedunster]

Hey thanks Aam

This place is an amazing resource. Photography, its study and practice can sometimes feel pretty lonely - but no more. There are so many posts, about so much stuff here. I'm jazzed.

Thanks for the welcome

Steve

[Laydewlf]

OK.... new question about lenses since y'all are so great about answering... My mother in law has a Canon film (not sure of the make). Can I use her lenses interchangeably? Or is there a difference for digital cameras?

[stevedunster]

mmm, it depends I think. I use a lot of lenses that were apparently design for use with film and all is fine. But I do have a very old film canon, that pre-dates the EF mount. You need to find out precisely what camera she's got.

Perhaps somebody else can give you a more precise answer, but should think they'd need to know what her camera is - unless somebody out there knows which ranges are and are not compatible off pat.

Steve

[Songman45]

Originally Posted by swampler

And just to clarify, at the risk of confusing, but 2.8 is the MAXIMUM aperture, not the minimum. A smaller number is a larger aperture because it is actually a fraction (1/2.8 ).

I think the EF has been covered...

I want to play! First, PFFFFT on a DX or 1.6 crop camera being cheap. But that's not what I want go in to. Since we are all being so technicolor about things. 2.8 is not a fraction, its a ratio 1:2.8 (one-to-two point eight)

[Killjoy]

Any of the EF lenses will fit and work with your Digital Camera.

The older style of FD lenses will not work with your camera without purchasing an adapter.
So, if your Mother-in-laws camera is something along the lines of an EOS camera, you are good to go.
If it's something like an AE-1, then no. It won't work. But then again, you should be able to tell it it will mount just by looking at the bayonet mount.

Give me a little bit, and I'll take some photos of three types of Canon mounts (EF, EF-S, FD) and post them here.

[stevedunster]

...and again - lol:

Originally Posted by stevedunster

To be precise, I didn't say "cheap", I said "cheapER" - which in terms of RRP I think they all are.

Whenever I've taught /f numbers I've found the following helps people get operational quicker, and then we do the sums later:

"big /f numbers - big depth of field, small numbers - small depth of field"

[Rain Lily]

Originally Posted by swampler

Your body should have a red dot and a white dot, especially since it came with a white dot lens. You can use either EF or EF-S in this case.

I wouldn't worry about buying only EF lenses on the chance of going full frame later, you should buy for the system you have now. I would hate to miss out on a shot because I was afraid to buy the correct lens for my body. You can always sell an EF-S lens if you upgrade bodies.

Originally Posted by stevedunster

Fair point

It is a good point, but as an owner of both the 300D and the 5D, I'm really glad that my husband bought an EF zoom lens back when I just had the digital rebel...

If you KNOW you're going to upgrade in the future, I'd go EF now, if it was me.

[Killjoy]

Pardon the quick shots. Taken with my G2 on top of my desk blotter.

Here is an old FD lens. If you look, you can see that for the bayonet mount, the camera tabs fit into the lens.


Here is an FD mount Camera. If you look closely, you can see the tabs on the camera body that fit into the lens.



Here is an EF Lens. You can see that the tabs are now on the lens instead of the camera body.



Here is a Film camera that takes all EF style lenses. You can see that the bayonet mount is styled to accept the blades that are now on the lens.




Here is a DSLR that will accept both EF and EF-S lenses. You can see both the Red Dot and the White Square for the different lenses.




Here is a different angle, so you can better see the two dots.





And here we have an EF-S lens. The S is for Short Back Focus. You can see that not only does it have a White Square instead of a Red Dot, but the rear of the lens extends beyond the bayonet mount.



So if your Mother-in-law has a camera that has EF style lenses, they will fit, and they will work on your Digital SLR.

An additional note, all of the FD lenses are going to be manual focus.

[Laydewlf]

Thanks for the helpful information. I have asked her to check her camera to find out exactly what camera and lenses she has.