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VIP
Posts: 11,100
Registered: ‎12-07-2012

Re: Does an EF-S lens' focal length have the 1.6 crop factor calculated?

It was too expensive to jump right to full frame sensors, so Canon took the intermediate step of APS-H."

 

Makes you wonder how the 1Ds (first FF) ever got built?  Released less than a year after the 1D with its H sensor. As I recall the 1D was $6999 and the 1Ds was $7999 so it did cost more but not so much as a percentage of the total coat.

EOS 1DX and 1D Mk IV, even less and less other stuff.
Esteemed Contributor
Posts: 3,308
Registered: ‎02-17-2016

Re: Does an EF-S lens' focal length have the 1.6 crop factor calculated?

They might have learned how to improve the yield with the APS-H so much that it was only a $1000 adder for the Full frame.

 

The area increased 67% from APS-C to APS-H and another 58% from APS-H to FF- so not quite as big a jump. They might also have caught a lucky break with an increase of wafer size. Silicon wafers have increased in size from about 4" to 12". With each step, you have to change all the tools in the fab to handle the new size. With a larger wafer, even if the yield (defects/mm^2) stays the same, you get a lot more sensors so you are likely to get more per wafer.

Occasional Contributor
Posts: 8
Registered: ‎05-28-2019

Re: Does an EF-S lens' focal length have the 1.6 crop factor calculated?

I've read this entire, years-long thread, and I don't see a clear answer to the OP's question. Let's say I own two lenses: an EF 24-70 and an EF 70-200. Yes, a lens is a lens; a focal length is a focal length. But, these two lenses will both be cropped on an APS-C, and they will, as a result, have an "effective focal length" greater than stated on the barrels, because the sensors capture only a portion of their image circles and the smaller sensor's image is enlarged to output dimensions equivalent to that of a FF sensor.
 
However you want to describe it, the coverage of these two lenses will be seemless, as follows:
EF lenses with 24-70 and 70-200 will yield effective 38.5mm - 112mm and 112mm - 320mm
 
But, if you substitute an EF-S 24-70, the question now becomes, does the effective focal length of the shorter lens change from what you got with the EF version? Does it yield an effective 38.5mm - 112mm, or does it yield an effective length of 24mm - 70mm?
 
The question matters if you want seemless coverage of focal lengths across two zoom lenses on the same camera body, i.e., no gap in zoom range for your captured images.
Esteemed Contributor
Posts: 3,308
Registered: ‎02-17-2016

Re: Does an EF-S lens' focal length have the 1.6 crop factor calculated?

[ Edited ]

A 24-70 will have the same field of view no matter whether it is EF or EF-S. The visible field of view will be narrower on an APS-C sensored camera.

Esteemed Contributor
Posts: 3,308
Registered: ‎02-17-2016

Re: Does an EF-S lens' focal length have the 1.6 crop factor calculated?

Clear answer to the OP: NO.

Occasional Contributor
Posts: 8
Registered: ‎05-28-2019

Re: Does an EF-S lens' focal length have the 1.6 crop factor calculated?

So, I take your response to mean that the images, taken at the stated length of 70mm, for both the EF and EF-S lenses, will be indistinguishable. That the EF-S, despite not throwing away any image circle, will have its image "cropped" as much as the EF. Makes no sense to me.

Esteemed Contributor
Posts: 3,308
Registered: ‎02-17-2016

Re: Does an EF-S lens' focal length have the 1.6 crop factor calculated?

On an optical bench they are indistinguishable. In a real camera, there is a difference.

The FF camera will have a field of view of 35 degrees

The APS-C camera will have a fov of 22 degrees.

 

A 70 mm EF-S lens does indeed "throw away" image circle. What makes you think it doesn't?

 

Esteemed Contributor
Posts: 3,308
Registered: ‎02-17-2016

Re: Does an EF-S lens' focal length have the 1.6 crop factor calculated?

Just to add to my own reply:

The new Fuji MF camera would have a 46 degree FOV with a 70 mm lens. So if you compared this camera with an EF FF camera you could also say that the 70 mm lens on a FF camera "throws away" image circle compared to MF.

Occasional Contributor
Posts: 8
Registered: ‎05-28-2019

Re: Does an EF-S lens' focal length have the 1.6 crop factor calculated?

"Canon EF-S lenses have a smaller image circle that is only big enough to cover the smaller sensor found on Canon APS-C cameras."

 

If this is true, then there is nothing being thrown away, in the sense that a smaller sensor would throw away a portion of the EF lens's image circle.

Occasional Contributor
Posts: 8
Registered: ‎05-28-2019

Re: Does an EF-S lens' focal length have the 1.6 crop factor calculated?

[ Edited ]

The question I asked did not relate to differences between APS-C vs FF cameras. It was about EF-S vs EF lenses with the same focal length dialed in and on the same APS-C camera, identically placed, seeing the exact same subject. Are the resulting images different?

 

Sorry if I appear to be obtuse. This entire discussion has gone off into the technical weeds on bunny trails several times, where the essential question is simple.

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