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Occasional Contributor
Posts: 6
Registered: ‎04-06-2019

Re: M5 or M6 or M50

[ Edited ]

To me it seems the confusion is being powered by marketing and labeling policies of the company.
The Powershot G series, included the good G3X I used, for example had only 24-600mm printed on the barrell, which was the equivalent of the optic on a full frame.
On Aps-C based sensor series instead, either EF-S and EF-M lenses are reporting the effective length.

The ideal should be to have either the physical length and the equivalent, like I remember it was on some legacy compact zoom film camera with fix lens built around 90's, eventually at least among the same brand , Canon, it would be great to have the same labeling criteria for optics.

Esteemed Contributor
Posts: 4,982
Registered: ‎06-25-2014

Re: M5 or M6 or M50


@ebiggs1 wrote:

"Similarly the EF-S15-85 will deliver a FoV equivalent to a FF 24-136mm."

 

Here is how I see crop factor.  Only older guys seem to think it has a meaning or need.  Yes, these older guys seem to keep it going passing it to a lot of younger photographers who never knew it existed.  In reality it is a meaningless term invented when 35mm film was king.  The conversion to digital and the newer, small sensor caused people to notice the lenses they commonly used  were giving a different picture. Most new and younger photographers never used and will never use 35mm film. Even today a lot, maybe most new and amateur and even enthusiasts photographers will never use a FF DSLR. Some will of course but at that point I would hope they were knowledgeable and accomplished enough to know FOV is the true factor.

Evidence of this is medium format photographers. They don't rely on a 'crop factor' to know what lens to use.  They have one so they could use it but they don't.  The 35mm crop factor, or a better term “equivalent focal length”, for medium format lenses is around .62x.  A 50mm lens can be a wide angle and a 90mm lens is considered normal.

 

It is something we fret over way too much.  Just learn what your lens does and how it performs on your camera and don't try to think, geez how would this lens look if I had a FF.


Er ... come down off your high horse, Ernie. As (probably) the oldest person in this forum, I can't let your demeaning of "these older guys" pass. Surely you'll recall that I've always regarded the "crop factor" as largely BS. My position has been that one should simply learn how lenses behave on the camera one is using (a 50mm lens is a mild telephoto on an APS-C camera, etc., etc.) and ignore how they behave on a camera of some other form factor - thus avoiding the confusing "equivalency" calculation. (And that despite the fact that I was a math major in college, BTW.)

 

The one case where you do need to consider equivalency is if you commonly use two cameras, one of which is APS-C and the other FF (as I did for three or four years). You do the calculation once per shoot, just to ensure that you aren't leaving an unacceptable gap between the zoom ranges of the two cameras.

 

Are there still any medium format photographers around? I thought they'd pretty much faded away as the resolution of FF cameras continued to increase. Come to think of it, what is "out there" these days? Is there such a thing as a large format digital camera? A digital view camera, maybe?

Bob
Philadelphia, Pennsylvania USA
Valued Contributor
Posts: 456
Registered: ‎10-18-2016

Re: M5 or M6 or M50


@ebiggs1 wrote:

"Similarly the EF-S15-85 will deliver a FoV equivalent to a FF 24-136mm."

 

Only older guys seem to think it has a meaning or need.  Yes, these older guys seem to keep it going passing it to a lot of younger photographers who never knew it existed.  In reality it is a meaningless term invented when 35mm film was king.  The conversion to digital and the newer, small sensor caused people to notice the lenses they commonly used  were giving a different picture. Most new and younger photographers never used and will never use 35mm film. Even today a lot, maybe most new and amateur and even enthusiasts photographers will never use a FF DSLR. Some will of course but at that point I would hope they were knowledgeable and accomplished enough to know FOV is the true factor.

Evidence of this is medium format photographers. They don't rely on a 'crop factor' to know what lens to use.  They have one so they could use it but they don't.  The 35mm crop factor, or a better term “equivalent focal length”, for medium format lenses is around .62x.  A 50mm lens can be a wide angle and a 90mm lens is considered normal.

 

It is something we fret over way too much.  Just learn what your lens does and how it performs on your camera and don't try to think, geez how would this lens look if I had a FF.

 


EB You know I have great respect for you as a photographer and contributer but I am disappointed that you make such a sweeping statement connecting age to the issue of equivalence, and I just don't accept your premise that it is really a leftover from the days of film and has no relevence to the digital era.

 

This issue really only came more to the surface for me with digital.  In my film days I had shot 35mm exclusively so the number on the lens was the focal range I expected to use.  The fact that 35mm is no longer "king" but co-exists with the APS-C format, and sharing lenses between the two is the issue.   I don't know how many times I have had people in my classes say that they bought (for example) a 10-22mm lens and it didn't give them the field of view they were expecting on their APS-C body, especially if a similar lens was observed on a FF body and that is what they expected to get.

 

So the issue certainly IS a hangover from the film days when the convention to specify lenses for 35mm was established, and although (I will say it YET again) the physical characteristics of the lens don't change, what is delivered as the end product IS.   And frankly I firmly believe that is what is most important.    I think the concept of focal length in this situation is counter-productive, hence my preference for something that describes magnification and/or Field of View. As I said before a photo isn't taken by a lens alone, it is the combination of a lens with a sensor to capture what the lens delivers.

 

I think it is perfectly valid to call the APS-C sensor a "crop sensor" because if you affirm that the lens has unchanged physical properties of aperture and focal length, what is delivered to the sensor plane at a given distance would be the same, but the sensor "crops" that because it is so small.   That is particularly valid for an EF lens on an APS-C body.  The lens is unchanged but the resultant image IS: it IS cropped by the limitations of the physical size of the sensor - this can easily be demonstrated by taking an image, using the same lens with the same settings on a FF and an APS-C camera.  If the print from the FF unit is cropped to 0.625 of its dimensions (the inverse of 1.6) you will get the an image same FoV as the crop sensor captured.

 

For reference see this Article on Crop Factor and FF Sensors

"All the beauty of life is made up of light and shadow", Leo Tolstoy;
"Skill in photography is acquired by practice and not by purchase" Percy W. Harris
VIP
Posts: 11,200
Registered: ‎12-07-2012

Re: M5 or M6 or M50

"As (probably) the oldest person in this forum, I can't let your demeaning of "these older guys" pass."

 

You are not one of the "older" guys I was referring to, so rest easy, there Robert. Smiley Wink

EOS 1DX and 1D Mk IV, even less and less other stuff.
VIP
Posts: 11,200
Registered: ‎12-07-2012

Re: M5 or M6 or M50

Trevor, my friend, we all are different and all of us have different points of view. Let me try to clarify mine so you won't think so poorly of me. When I did my DSLR 101 classes for Park and Rec, the single most confusing thing was crop factor. As long as no one told or mentioned the term crop factor all was well. Younger folks don't know.  Eventually it gets out. They read about it or somebody tells them about it but they find out. New people know two things, a cell phone and they just bought a new Rebel or D3200. They know nothing about 35mm film and as far as they are concerned their cropper camera is FF. It produces exactly what they see in the VF or LCD panel. They have no need of or to understand crop factor. As far as newbies are concerned the 18-55mm is a pretty normal acting lens that is right for what they require. Then some wise guy says you know that lens is really acting like a 28 to 88 lens not like an 18-55 like it says. It's just not something that is needed to further complicate photography.

 

" In my film days I had shot 35mm exclusively ..."

 

So see, you know that lenses didn't act like what you were used to so in order for you to understand what is happening you invent a term for it and crop factor is born. Some people never shot 35mm film and couldn't care less.  It is a generation thing, nothing more.  Crop factor exists to translate equivalent FL so that old, right I said older,  Smiley Happy 35mm photographers can figure out the FOV of a lens based on the equivalent focal length when using lenses on sensors smaller than 35mm film.  Not all photographer are in that class.

 

"The lens is unchanged but the resultant image IS:..."

 

 Nothing is actually cropped. A round lens produces a circular image circle. It does not produce a rectangular image. The sensor, or 35 film for my older friends, in the camera captures a rectangular portion of that image circle. You can certainly crop an image after it is made by the camera but nothing is cropped by the camera.  In that  sense all cameras are FF.

 

Not quite as disappointed, I hope.

EOS 1DX and 1D Mk IV, even less and less other stuff.
Valued Contributor
Posts: 456
Registered: ‎10-18-2016

Re: M5 or M6 or M50

A healthy debate is a good thing, it makes us clarify our thoughts! Smiley Very Happy  So all good!

 

I think this about semantics rather than physics. I am used to the convention that an APS-C sensor is a crop sensor because lens specs are aligned to the size of a FF one. I completely agree that a rectanglular sensor is going to be a crop of a circle, but I am aware of only one camera design that attempted to use a circular recording medium.


So RELATIVELY speaking an APS-C sensor is a reduced sized version of a FF one, and that is what is referred to in publications under that heading from which I take my reference. My point is that APS-C sensors with FF lenses attached were not an issue in the days of film (to my knowledge), but they are in the digital world.

 

Anyway, it is what it is and life will go on and we will still enjoy the process of taking photos and debating the merits of technology, terminology and technique!  What else can one do when we aren't out there taking pictures.

"All the beauty of life is made up of light and shadow", Leo Tolstoy;
"Skill in photography is acquired by practice and not by purchase" Percy W. Harris
VIP
Posts: 8,168
Registered: ‎08-13-2015

Re: M5 or M6 or M50

Crop Factor, or Angle of View?  I think associating crop factor with a camera body is the lesser of all evils.  I say keep defining it the way we have done it for years.

 

Lenses have neither a crop factor or an angle of view.  Lenses only have a magnification factor..  Crop factor and angle of view are two sides of the same coin.  Crop factor is commonly associated with the camera body, while AOV is commonly associated with the lens.  

 

Both descriptions are attempts to describe the same thing, and neither of which actually applies to a lens or an image sensor.. It is not until we pair a lens with a camera body that these descriptions begin make sense.  So, which description is better to use, CF or AOV?

 

I say CF is better to use, even with all of the confusion that it may create.  If we assign an AOV to a lens, then a lens can have at least two AOV specifications, which would be FAR more confusing than assigning a CF to camera body.

 

 

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