EF lenses on an EOS D

Apologies if this question's been done to death, it's pretty obvious but I

can't find a straight answer. I have 2 Canon EF lenses (from an EOS 300) and

I'm looking to get an EOS 400D. I've been told that the EF lenses will fit the

EF-S mount, but that some sort of calculation will have to be applied to offset

the shutter speeds or aperture settings. I don't understand this and was

wondering if it was just something my local camera shop told me to get me to

cough up more money for EF-S lenses. Can anyone enlighten me?

the EF-S will not work o nthe bigger canons (5D, 1Ds, 1D series or 25mm film cameras. All EF lenses will work on all Canon EOS cameras.

Thanks for responding, Ellis. I was fairly sure the lenses would fit, but was slightly worried by this supposed "recalculation" issue. Do you know about this?

 

(Typically, I didn't notice the separate Canon EOS forum here until I'd already posted this here!)

That "some sort of calculation" is multiplying the focal lengths by 1.6. For example a 28-105mm lens becomes a 45-168mm. The reson for Efs lenses is to compensate for the loss of wide angle, which is why all but one EF-S lens start at 17-18mm. Whoever told you that something will have to be done to shutter and aperture settings is wrong, those will (for the most part) be the same. Your current lenses will be fine.

Thanks, Leopold. I think the thing about shutter speeds and apertures was just my foggy misunderstanding of what I was being told. So, if an EF lens in an EF-S fitting results in a longer focal length, does this mean that there's a discrepancy between the perceived width of the view in the viewfinder and the actual width of the picture taken? Do I need to mentally "crop" what I'm seeing when I'm composing a shot?

The crop factor/equivalent field of view calculation has nothing to do with the lens mount. It's a function of the size of the image sensor.

 

It's of very little importance except in determining what focal length range you want to choose for your lenses.

 

What you see through the viewfinder is what you will get.

Nope, its actually an apparent focal change, so what you see in the viewfinder is what you get. For instance, a 50 f1.8 will be like an 80mm f1.8, and it will apear as an 80mm lens through the viewfinder, and the image will look like one taken with an 80mm lens.

"What you see through the viewfinder is what you will get."

 

That's really what I needed to know, I guess. The thing that worried me most was the idea that I might have to try and use my camera and do some mental maths at the same time :)

I think it is much preferable if people talk about Angle of view.

 

Putting an EF lens on an APS DSLR doesn't turn the lens from a 50mm into at 80mm but changes the Angle of View from 50mm to 80mm due to the small sensor compared with the regular 35mm film frame.

 

Or is this even more confusing :-)

Except the "angle of view" doesn't change from 50mm to 80mm (since it's not measured in mm), it changes from ~40 degrees to ~25 degrees (courtesy of Bob Atkin's FOV calculator).

A E

 

You don't have to recalculate exposure in terms of apertures and shutter speeds with either EF or EF-S lenses. And the field of view of either lens will be the same on the same digital camera body, so you don't have to recalculate that either. A 30mm EF lens will give you the same field of view as a 30mm EF-S lens, provided they are on the same camera body.

 

One difference between EF and EF-S lenses is mechanical. EF-S lenses will not fit on some EOS digital bodies (like the D30, D60, 10D, and 1D series cameras). Don't confuse the D30 with the 30D. (What was Canon thinking with such similar names?) EF-S lenses don't fit on EOS film bodies either. EF-S lenses throw a smaller image circle than EF lenses, but that won't matter at all on any Canon body it is designed (mechanically) to fit.

 

EF lenses fit on all EOS film and digital bodies. Even though the image circle of EF-S lenses is smaller than EF lenses of the same focal length, the equivalent focal lengths are the same. In other words, a 50mm EF lens and a 50mm EF-S lens have the same focal length (despite the difference in the size of the image circle - more info at the link below).

 

Based on your comment, I am suspicious of the advice you were given at the camera store.

 

The focal length of a lens does not change whether you put the same lens on a film camera, a "full frame" digital camera, a digital camera with a smaller image sensor, or even a medium or large format camera. A 50mm focal length lens is always a 50mm focal length lens no matter what camera you put it on. Field of view is another matter.

 

A smaller sensor digital camera (like the 400D) will not show as much of the image circle as a 35mm film camera (or a full frame digital camera) so the field of view is cropped, or smaller. A 50mm lens on a 400D has the same field of view as an 80mm lens on a 35mm film camera, so it just LOOKS like the focal length changed, but the focal length of the lens didn't change at all. Just the cropping of the image. This is usually called the field of view (FOV) crop.

 

More information and examples are here:

 

http://jimdoty.com/Digital/fov_crop/fov_crop.html

 

Jim

Angle of view can be expressed in degrees or 'equivalent to full frame 35mm camera' the latter is probably more easilly understood ... by me anyway :-)