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New Contributor
Posts: 3
Registered: ‎03-08-2019

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

I drew it out and finally understand.  I wish Canon explained this differently for their lenses.  All this time I was miscalculating/misjudging my lenses.  I uploaded a (slightly) cleaned up version of what I sketched in the hopes that it'll help someone else.  Canon crop image.jpg

 

I wish Canon would just describe it as "angle of view" or something - agree as others have noted that "crop factor" is WAY too confusing.  In the beginning I guess it made sense to refer to 35mm to serious photographers.  But it really wasn't clear to me (or others, it seems like) that the EF-S lenses did not adjust - I always thought the focal lengths on them referred to how it would look on a full frame camera and was doing all this calculating for my EF lenses.  Now I understand why my pictures didn't always come out the way I thought they would on my EF ones.  Anyway, hope this helps someone else visualize it.

VIP
Posts: 11,650
Registered: ‎12-07-2012

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

"In the beginning I guess it made sense to refer to 35mm to serious photographers."

 

I was there!  It never made sense.  No other camera format group, I.E. medium or large etc. format are this involved and so infatuated with the crop factor or lack there of.  A medium format guy typically doesn't go around thinking, lets see how does this lens 'factor' on my 35mm FF camera compared to my 120 film size camera.

I guess it must have something to do with being smaller. Because you see the P&S guys doing it, too.

EOS 1DX and 1D Mk IV and several lenses!
Esteemed Contributor
Posts: 3,493
Registered: ‎02-17-2016

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

It came about because none of the original DSLR's were FF. The mfg's needed some way to inform the public that the field of view for a Non-full frame camera DSLR was not the same as the 35mm film cameras they were replacing, even though the form factor - and the lenses! - were the same. Other formats used different lens mounts, so there was no reason to make a direct comparison.

 

Canon complicated things even further by having both APS-C and APS-H size cameras.

 

So crop-factor was born. Field of View does not help, since to make it apply to every lens you would need a "Field of View factor" which would be just a different name for the crop factor.

VIP
Posts: 11,650
Registered: ‎12-07-2012

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

""I was there!  It never made sense.""  Smiley Indifferent

 

"Canon complicated things even further by having both APS-C and APS-H size cameras."

 

Exactly and the H sensor never fell into the crop factor concept like the C sensor did. 

 

"Other formats used different lens mounts, so there was no reason to make a direct comparison."

 

They use equivalent to 35mm FF, crop factor, on P&S's even if they don't have a removable lens. It is totally unnecessary.

 

 

EOS 1DX and 1D Mk IV and several lenses!
Esteemed Contributor
Posts: 3,493
Registered: ‎02-17-2016

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

APS-H had a 1.3 crop factor:

https://www.dpreview.com/forums/thread/4216745

 

Esteemed Contributor
Posts: 3,493
Registered: ‎02-17-2016

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

"They use equivalent to 35mm FF, crop factor, on P&S's even if they don't have a removable lens. It is totally unnecessary."

 

How else do you get a handle on a "4.5 to 18mm" lens on a '1/2.3"' sensor other than with a 35mm equivalent?

 

VIP
Posts: 11,650
Registered: ‎12-07-2012

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

"APS-H had a 1.3 crop factor:"

 

So..........?

EOS 1DX and 1D Mk IV and several lenses!
VIP
Posts: 11,650
Registered: ‎12-07-2012

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

"How else do you get a handle on a "4.5 to 18mm" lens on a '1/2.3"' sensor other than with a 35mm equivalent?'

 

I don't!  Most people that use a P&S don't care either.   They don't even know what a 35mm FF camera is. They never had one and never intend on getting one.  They don't care. Just another confusing number that is meaningless to them.

EOS 1DX and 1D Mk IV and several lenses!
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New Contributor
Posts: 3
Registered: ‎03-08-2019

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

Yeah for people like me who started off in the digital world (yes I knew what 35mm film was but I only ever used it with point-and-shoot, never tried to actually "compose" pictures as the wanna-be amateur I am now), none of that ever made sense.  And yeah I'm glad kvbarkley pointed about the APS-C vs -H.  WHY????  Anyway,  I hope Canon reads some of these and works on a simplification.

Esteemed Contributor
Posts: 3,493
Registered: ‎02-17-2016

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

APS-C vs APS-H:

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

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