# EF Lens vs EFS Lens on Crop Sensors Question



## Samerr9 (May 12, 2011)

Hi all.. 

I have been reading about Canon lenses lately and I couldn't find an answer to this question. EFS lenses are made for crop sensors cameras and EF for full frame cameras. If we mount the EF lens on a crop sensor camera we will have the multiplication of 1.6 factor. My question is: Is it the same case with EFS lenses? (which are made for crop sensor cameras) 

In other words, it is confirmed that 100mm EF on 60D is 160mm(compared to that if on 5D II). Is 100mm EFS on 60D is only 100mm or 160mm?

Thank you.


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## analog.universe (May 12, 2011)

The focal length is related to the geometry of the lens of itself.. so whatever is printed on the lens is how the glass actually measures.  A crop camera doesn't change the focal length, only the effective field of view.  100mm doesn't become 160mm it just looks like 160mm.


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## Bitter Jeweler (May 12, 2011)

Yeah, the misconception is that the crop body gives you more reach, but it doesn't.


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## Big Mike (May 12, 2011)

This is a very common misconception.  

The 'crop factor' is a comparison and really only applies to the field of view...not the focal length.

So if you have a 100mm lens, it will give you a certain field of view on a 35mm film SLR (or full frame digital).  If you use that same lens on a 'crop body', the focal length is still 100mm....but the outsides of the image circle (projected by the lens into the camera) will not be recorded by the camera's sensor (because it's smaller).  So you end up with an image that covers a smaller field of view.  

It doesn't matter if the lens is EF or EF-S....50mm will give you the same FOV (on the same camera).  

The only reason why the crop factor exists, is because the 'standard' for so long was 35mm film.  So when they came out with cameras of the same size & format, but with smaller sensors...they wanted to let people know that the FOV would be different that what they were used to with 35mm film.
Fast forward 10 years and many of the people buying these cameras have never used a 35mm SLR...so the crop factor *should be* meaningless to them.


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## o hey tyler (May 12, 2011)

Bitter Jeweler said:


> Yeah, the misconception is that the crop body gives you more reach, but it doesn't.


 
Well, they do give you more "reach" in terms of resolution of the image captured, right? For example, if I took the same photo with a 5D1, and an XSi (both 12 MP) from the same camera location, and the same lens (lets say 50mm), I'd have an ~85mm FoV with the XSi, but it would be a 12.2 MP FoV of the center of the 5D's photo of the same subject. Whereas if I were to crop the 5D's photo to mimic the image of the XSi, it would be smaller in terms or resolution, no? 

We could be defining "reach" as different things though.


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## subscuck (May 12, 2011)

Samerr9 said:


> Hi all..
> 
> I have been reading about Canon lenses lately and I couldn't find an answer to this question. EFS lenses are made for crop sensors cameras and EF for full frame cameras. If we mount the EF lens on a crop sensor camera we will have the multiplication of 1.6 factor. My question is: Is it the same case with EFS lenses? (which are made for crop sensor cameras)
> 
> ...


 
The short answer is crop factor still applies with an ef-s lens.


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## Bitter Jeweler (May 12, 2011)

o hey tyler said:


> Bitter Jeweler said:
> 
> 
> > Yeah, the misconception is that the crop body gives you more reach, but it doesn't.
> ...




Yeah, I compare it to a 5dmkii at 21megapickles. I also shoot wider, to give me cropability&#8482;.


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## Samerr9 (May 12, 2011)

Thank you all for the clarification


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## Robin Usagani (May 12, 2011)

basically EF-S is just made specifically for cropped sensor so it will be cheaper to make (i.e. smaller front element size).

If theoretically speaking we are able to mount an EFS 18-55mm lens on a full frame camera, at around 30mm or wider you will start seeing your lens barrel and heavy vignetting.


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## Derrel (May 12, 2011)

o hey tyler said:


> Bitter Jeweler said:
> 
> 
> > Yeah, the misconception is that the crop body gives you more reach, but it doesn't.
> ...



A better way to describe what o hey typer is talking about above is to say that a crop-sensor body gives "greater pixel density", or "puts more pixels on the subject", than cropping away the outer parts of an image shot with a comparable pixel count FF or FX sensor. So, for example  if one has a 12.8 megapixel Canon 5D mark I FF camera and a 12 megapixel CANON XSI, and wishes to take a tight, frame-filling close-up of say a distant bird in flight, using a 400mm lens, the FF Canon 5D Mark I will have the same-size image of the bird in the middle of the frame as does the XSi. Both lenses are 400mm and a 400mm lens projects an image that is ALWAYS (and I mean ALWAYS!!!!) the same size, no matter what piece of film or sensor is behind it to catch the image. So, with the 1.6x Field of View Crop factor of the XSi sensor, the image of the bird will be the SAME size as it is on the FX, full-frame body BUT the bird will be placed into a smaller, more-restricted size of sensor area, and so the picture of the bird will be framed more tightly than the same-sized projected bird's image captured on a larger sensor.

So--each particular lens focal length projects the SAME size of image, no matter what the format of the sensor behind the lens. The sensor "catches" the aerial image, and captures it. The circular image coming out of the back of a lens is captured more or less in its entirety by a FF or FX or "full-frame" d-slr; the 1.5x and 1.6x Nikon and Pentax and Canon cameras simply do not capture the outer edges of the image circle that each focal length projects. So, the image captured on the different sizes of sensors is the same actual height. The Canon EF-S lenses have the same focal length as a Canon EF lens, but the S refers to a short mount distance, which means they come into the camera body much closer than the EF lenses, and are at risk of being hit by the larger mirrors needed for FX framed Canon bodies. Therefore, Canon EF-S lenses will not mount onto Canon FX bodies. Nikon's DX series lenses work differently, and they WILL MOUNT and work on all Nikon bodies, but they do not project a large enough image circle to cover the entire area of a FX-sized (24x36mm) Nikon sensor.

Because each focal length has its own image size, the physical height and width of the image captured always stays the same when camera-to-subject distance is the same between the two capture format sizes. Soooooo, for taking pictures of distant subjects, many bird and nature and sports shooters prefer to put "all the pixels" into recording the subject. To get the same desired, tight, FRAMING of say a bird in flight, the full-frame guy has to crop down his larger image and throw away the outer areas that the sensor recorded, and so, using a crop-body camera means that no cropping-away of the outer areas is needed. In that way, the crop-body camera "puts more pixels on the subject", or can be described as giving the photographer "greater pixel density".


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## Samerr9 (May 12, 2011)

Derrel said:


> o hey tyler said:
> 
> 
> > Bitter Jeweler said:
> ...


 
That made it really clear to me, Thanks Derrel


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