Crop Sensor Shows no Difference between Full Frame and EP-S Lens

[paulsiegenthal]

Hi,

I made two photos on a Canon 80D using a

a. Canon EP 100 Macro lens and

b. Canon EP-S 55-250 lens

Both times I focused on 100mm. I don´t see any difference. One should be cropped?

Any explanation? 
Thanks

[Waddizzle · Accepted solution]

Your results are correct. Focal length describes a physical characteristic of the lens. When you use a EF. 100mm prime, or an EF-S 55-250nn set at 100mm, the image circle projected onto the image sensor will be almost identical. 

The primary diffference between EF and EF-S lenses is the size of the image circle projected by the lens. An EF lens projects an image that is wide enough to cover a full frame sensor, and more than cover an APS-C sensor.

An EF-S lens projects and image circle that is just large enough to cover an APS-C sensor, but not fully cover a full frame sensor.

[ScottyP · Accepted solution]

The camera crops the lenses. Not the other way around. A 100mm lens on an 80d is a 100mm lens on an 80d no matter what mount the lens has. 

A 100 mm lens on a FF body will have a wider field of view than a 100mm lens on a crop body. 

A FF lens on a crop sensor projects an image circle bigger than a crop sensor, so some of the image laps over the edges of the sensor and that excess outside edge of the image is therefore lost. The small sensor basically cropped it off by not being large enough to take it all.   An EF-s lens is made for crop cameras and it projects a smaller image circle that is matched to the smaller sensor so less of that cropping occurs. 

Full frame EF lenses can mount on either add Or crop bodies. EF-s lenses are made so they physically won’t mount on FF bodies because their rear elements may protrude back into a FF body too far and would perhaps hit the mirror in a FF body.  In any event if you do manage to jam an EF-s lens onto a FF body the image circle the lens projects onto the sensor will be too small and your picture will be a circle in the middle of a black rectangle. 

[Waddizzle · Accepted solution]

Here is another image that might help clear it up.

The image projected by an EF-S lens is a subset of the image projected of an EF lens.  Your EF lens projects an image the size of the full frame image above.  Similarly, the EF-S projects and image the size of the APS-C image above.  Its’ image would not include the much wider view projected by the EF lens.

An APS-C sensor would not see any difference between the image circles projected by the two lenses

[ebiggs1]

"A crop sensor camera does crop "

A "crop sensor" crops nothing.  It can't it only records what it sees.  It has no idea you want to compare it to a 35mm camera or a movie projector.  Geez, movies now?  That is a human interpretation that doesn't exist in the real world.  It is made up!

"It is a "crop sensor" because it is "as if" someone took a full frame sensor and physical cropped it down to a smaller size ... dividing it's dimensions by 1.6x."

Again extremely confusing.   Let's use a more realistic example.  A person buys a Rebel and that is their only camera.  They do not for one second think about comparing it to any other camera.  They look through the view finder and the photo looks exactly like that. Then along comes Tim Campbell and says, "Oh you can't do that you must compare what you got to what you could have gotten with the 35mm film."

There are no crop sensors there are just sensors. 

[wq9nsc]

The "crop sensor" identification made a lot of sense close to two decades ago when many people were transitioning from film to digital and the crop sensor label provided for an easy understanding of how the image coverage of their older lens would be impacted by a smaller than 35mm size sensor.  To me it is still useful even though I have never used a APS-C size sensor but I have noticed the coverage difference transition from my APS-H/1.3X 1D Mark II sensor.  If you have experience with a particular lens or set of lenses on a different sensor size body then having a label to organize the differences around is useful.

I think it is fortunate (and somewhat unusual for the electronics industry) to have largely standardized largely on two different sensor sizes that makes it far easier for the public at large to gain some grasp of the differences between the two.  I would not have been at all surprised had the industry developed a dozen or more sensor size and aspect ratio variations as the digital camera matured.

In general given a choice between an APS-C sensor with a larger number of "megapixels" versus a full frame sensor with a lesser number I would take the full frame choice because using the SAME generation of technology the larger area of individual sensors on the full size sensor will have a noise advantage.

Rodger

[ebiggs1]

You know since you brought up the APS- H sensor, but nobody typically calls it a crop sensor but that is exactly what it is.

"...would take the full frame choice because using the SAME generation of technology the larger area of individual sensors on the full size sensor will have a noise advantage."

Than why stop at a so-called FF sensor.  Why not go medium format?

"...the crop sensor label provided for an easy understanding of how the image coverage of their older lens would be impacted..."

That I can almost understand that usage and kudos to you for bringing it up.  In the beginning of digital there were no FF sensors.  Times change and things advance, however. 

[wq9nsc]

"Than why stop at a so-called FF sensor.  Why not go medium format?"

That would be fine except the majority of my images are captured either at soccer games or on long hikes and even the 1 series with a good lens is approaching practical weight/size limits.  And I suspect the maxium frame rate of the medium format is still pretty limited for sports given the large amount of data that has to be shuffled from the buffer to storage.  If I was a studio or landscape type I would definitely consider medium format but I am very happy with the range of performance of the 1DX M2.

Of course the pain from dealing with a larger camera is relative.  When my daughter was not quite three I took her, my 1DM2, 24-70 F2.8 and 70-200 F2.8 on a short two mile hike which means I carried Anna and a lot of camera equipment most of the way on this short but very steep hike.  I was feeling pretty tired near the end until we met a young couple who were just coming off part of their honeymoon trip hiking the AT.  The woman had broken her arm the day before on the trail and had self-splinted it and continued the hike-that made my "suffering" from carrying heavy camera equipment seem like not so much anymore.

Rodger

[ebiggs1]

"...-that made my "suffering" from carrying heavy camera equipment seem like not so much anymore."

Ain't that always the way?  Just when you are feeling the most pity for yourself................

When I was working I really never gave much concern to weight or the gear.  That wasn't an option.  You were told what was needed and you are expected to provide it.  Whatever you had to do was just not important.  The results were!   Even now I still carry two 1 series with L lenses almost every time I go out shooting.

[TCampbell]

---

@ebiggs1wrote:

"A crop sensor camera does crop "

A "crop sensor" crops nothing.  It can't it only records what it sees.  It has no idea you want to compare it to a 35mm camera or a movie projector.  Geez, movies now?  That is a human interpretation that doesn't exist in the real world.  It is made up!

"It is a "crop sensor" because it is "as if" someone took a full frame sensor and physical cropped it down to a smaller size ... dividing it's dimensions by 1.6x."

Again extremely confusing.   Let's use a more realistic example.  A person buys a Rebel and that is their only camera.  They do not for one second think about comparing it to any other camera.  They look through the view finder and the photo looks exactly like that. Then along comes Tim Campbell and says, "Oh you can't do that you must compare what you got to what you could have gotten with the 35mm film."

There are no crop sensors there are just sensors. 

---

I'm sorry this is so confusing for you Ernie.  If you don't get it... fine.  But you don't get to tell other people that there's no such thing as a crop-sensor concept when the entire photographic industry disagrees with you (and for good reason).

You are firmly holding to your belief... despite all facts to the contrary.  (You might want to grab a dictionary and look up the word "delusion".)

These aren't my facts.  I didn't invent the concept.  I learned about crop-sensors like everyone else and I understand why it's called a "crop sensor".

Here's a Wikipedia page dedicated to it:  https://en.wikipedia.org/wiki/Crop_factor

There are a few formulas in photography that involve knowing the "crop factor" of a camera.  If you don't know the crop-factor (or don't believe such a thing exists) then the formulas dont work.  

And here's a helpful video that demonstrates why it's called a crop-factor and why knowing such things is useful.   

The numeric value of the crop-factor isn't made up... it's based on a multiplication from a baseline.  The baseline the industry uses is the 35mm film and, as a side note, the reason it's called "35mm" film isn't because the images are 35mm... but that' was the width of the film strip ... including the part with the sprocket holes used to advance the film.  The image size on the film was 24mm tall by 36mm wide.  

A digital sensor that is 24mm tall and 36mm wide is called a "full frame" sensor because that's the standard that the camera industry chose... and it stuck (with few exceptions, everyone accepts the definition.  There are loads of examples of such standards.   If we go to the store to buy a "gallon" of milk, there's a standard for how much milk should be in the gallon.  You don't get to sell milk in a considerably smaller container and tell customers that it's a "gallon" ... when it clearly is not what the world accepts as the standard for volume based measurements.)

When a sensor has a different size, then the "crop-factor" is the value that would be used to either multiply or divide that size by in order to arrive at the full-frame baseline.

If a "full frame" camera has dimensions of 24x36mm and a Canon APS-C size sensor has a crop-factor of 1.6x then it means if you divide the 24 and the 36 both by 1.6, you'll get the dimensions:

36 ÷ 1.6 = 22.5

24 ÷ 1.6 = 15

If I visit the specs page for the Canon 80D (I picked that particular camera since it's the model that the OP asked about.  It's located here:  https://www.usa.canon.com/internet/portal/us/home/products/details/cameras/dslr/eos-80d

And it lists the "Image Format" as being:    "Approx. 22.5mm x 15.0mm (APS-C)"

So the math works!   BTW, the math works everywhere.  The diagonal measure works.  The math that determines what the focal length of a normal "1x" magnification is also works.  The math involving changes to depth of field work.  And many other examples of math work.

So the whole industry (not just me) uses the term and the "crop factor" value and the math because it works.

If you, personally, don't get it... fine.  The rest of us aren't going to hover over you and make you do homework until you can pass a test.  But please don't post information which is patently false (and you know it) when someone is asking for help on a message board.  You're not being helpful.  That's the opposite of help.  

[ebiggs1]

Tim maybe you should re-read your own statement.

""It is a "crop sensor" because it is "as if" someone took a full frame sensor and physical cropped it down to a smaller size ... dividing it's dimensions by 1.6x.""

It is "as if" someone did it.  But in reality, my friend, no one does. It is a made up term that may of had a place in the beginning to let photographers of the day know their 35mm lenses will look differently on the new smaller digital sensors but it has little to no value now.

You can write all the long posts with tons of figures you want and it simply proves the fact it is confusing.  Things that are not confusing are the opposite of that.  I do not deny the fact that "crop factor" exists. The whole inner web is full of guys like you that try to explain it.  I simply say it isn't needed.  Crop sensors crop nothing.  They never did and they never will.

"If you, personally, don't get it... fine.  The rest of us aren't going to hover over you and make you do homework until you can pass a test"

Apparently you are!  Here's a tip, all you need is an Angle of View chart.  It is no different than when we started with 35mm film way back there. Once you know the AOV you are done. with it.  You can d/l one from the net.

"... don't post information which is patently false (and you know it) when someone is asking for help on a message board."

This is beneath you, Tim.  I expected more from a person of your intelligence. Perhaps, I am wrong there too.