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Watch Crop Factor Myth: Your Lenses are NOT 1.5/1.6/1.3x Longer on YouTube

In last week's video on why 50mm Prime Lenses are NOT Portrait Lenses I had a ton of questions about the crop factor of smaller sensor DSLRs. This video will show you what is actually happening with your camera and dispel the myth that your lenses are magically longer with a crop sensor. Keep shooting!

Nikon D3s on DX Mode

Nikon D3s on FX Mode

Nikon D3s on FX Mode, Cropped

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0 # Don P. 2012-12-18 11:12
Great video Greg. Is there any need to buy a 50-150 zoom for a DX camera vs. a 70-200 zoom?
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0 # Gregory Cazillo 2012-12-18 16:18
I don't see the advantage personally.
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0 # Joe 2012-12-18 12:34
Thanks Greg. What's your opinion on extender tubes for the lower budget enthusiast like myself?
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0 # Gregory Cazillo 2012-12-18 16:18
They can be great for macro work.
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0 # Joe D 2013-01-02 00:15
I agree this was a great video. I just had to mention, I think Joe meant the Teleconverter like the 1.4, or 2.0. Not sure but thinking that's what he meant to make his lens a longer focal length.

Greg I would like to thank you for your great videos. I enjoy them very much, thanks.
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0 # Ron 2012-12-18 13:11
It would be a wonder to have any mathematical equation make a lens longer...

I sure would hate it if it happened anyway, considering everything fits in my bag nicely now...
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+1 # Eiti Kimura 2012-12-18 13:17
Interesting, the image is pretty much like just a crop, but indeed gives you the feelling of a longer focal lenght in DX body.

Have you tried the same experiment with a real DX body instead of simulating it on a FX body? I'm wondering if the body construction differences could interfeere over the final result.

Thanks for the video, it is great!
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0 # Gregory Cazillo 2012-12-18 16:19
I'm sure there will be slight differences and framing will be difficult to reproduce 100% but the primary idea is the same.
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0 # Steven 2012-12-18 18:01
Great video, and demonstrates the 'crop factor' really well. However, while you show that the DX image is simply a crop of the FX image, some may say that this simply reinforces the fact that with a DX camera you effectively have a longer lens.

Maybe an alternative, or additional, way of showing the difference would be to take a photo on a FX camera with a 300mm lens, and one in DX mode at 200mm. The difference in DoF should show that the two are NOT that same.
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0 # Gregory Cazillo 2012-12-23 11:21
Thats correct, the lens does not get longer as stated, it only crops the image. Not everyone understands that difference.
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0 # Jim 2012-12-18 23:32
Thanks Greg,
a lot of people don't get that you are only seeing a smaller part of the same image on a crop, and when you look at it on the screen it looks larger because you are not seeing all of the available image just the inner part. It's a good illusion of extra reach with a lens.
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0 # Gregory Cazillo 2012-12-23 11:22
Illusion is a good word for it!
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-1 # Flo 2012-12-19 02:52
I do get his point, but could have been made better. 'Till the very end of the video.
He says that the size of the chip does not make the lens longer. That is true, however its never really explained that the crop factor depends on the chip size, and on the fact that the images are displayed in the same size relative to each other. Also, showing the full-frame image and the cropped small-frame image is bad, because it confuses people. He should have shown the uncropped FX version, and the uncropped DX version. Then you see that the latter image is indeed zoomed in. Thats a fact. Its also a fact that this is not due to the lens getting "longer" but to the chip measuring a smaller area of the image that is displayed by the lens.

Also, I don't see differences in bokeh. Thats probably because he used one and the same camera, but I'm not sure about that.

All in all, I don't see the problem with crop-lenses. I use a CF 2.0 olympus myself, and I never get the full-frame machismo of the nikon/canon people. If I don't have to print my images on 3ft canvas, I don't need all that frame size. I like shooting wildlife and love to have the extra "zoom" on my 200mm lens by the crop factor. Its all about what you want to do and not whats the biggest camera.
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0 # Gregory Cazillo 2012-12-23 11:27
I'm not sure you understand the video. You should not see a difference in bokeh because the camera position didn't change. That is the point when it comes to the difference between dx and fx.
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0 # Flo 2013-01-28 07:13
OK, that's part of my answer, then. The bokeh doesn't change, and shouldn't - I get that point. The other point that you are trying to make evades me, however. If I use a 2x crop sensor on a 50mm lens, I get the same result as if I were to use a 100mm lens on a fullframe sensor, or, vice versa, use a fullframe sensor + 50mm lens and crop it (which is what you did w/ the FX and cropped FX mode); that in mind, you disproved your statement, that lenses are not "longer", otherwise you wouldn't have to have cropped the image. Or am I misunderstandin g the terminology of "longer".

If my lens-supplier states, that my 50-200mm lens is 100-400mm EQUIVALENT in fullframe, then what's wrong about that statement?
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0 # Gregory Cazillo 2013-01-31 10:02
You will not get the same image with a 100mm lens on FX and a 50mm lens on a 2x sensor...
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0 # Gregory Cazillo 2013-01-31 10:04
The crop factor may be equivalent but the images won't be, thats the bottom line!
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0 # Flo 2013-02-04 15:12
How so? You said yourself that nothing's different from the images in your video other than crop factor (you used the same lens, but different sensor formats if I'm not mistaken).
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0 # Gregory Cazillo 2013-02-04 15:17
HUH? Field of view changes, Depth of field changes, so does distortion when using a 50mm lens on fx and 50mm on 2x sensor.
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0 # Flo 2013-02-06 05:39
aha. so field of view does change. Which means, that if the crop factor is equivalent, that the 50mm on a 2x sensor can be described as 100mm EQUIVALENT on full frame - which is all that I was trying to say.

The real interesting thing would be, what else changes (DoF, distortion), but that was not covered in the video, because you used one and the same lens, just changed the chip-size.

You confused me, because the title of the video and the first few minutes suggested, that a 50 mil lens produces the same images on full frame and on 2x (1.3x, 1.6x etc.), which it DOES NOT, apparently. So sorry, but I didn't get the point of the video...
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0 # Kevin 2012-12-19 02:57
Hi Greg,
Nicely explained, you now deed to explain some of the differences between FX and DX, done to reduce the size of lens, cameras, weight and costs with digital technology.
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+2 # ser-e-us 2012-12-19 05:57
Hello Greg,
I think you dropped the ball here in terms of explaining the objective of the video.
It is brilliant that you show what the actual effect of different sensor sizes is.
However, what I believe you should have explained is that the lens perspective does not change with the small sensor. You show that with the comparison. Consequently, the 50mm is not giving you the right perspective for head shots even with a small sensor.
On the other hand, the net effect on the small sensor is a shallower angle of view, which is achieved by using a longer focal length. So, you did not bust any myth, since there is not any, but you demonstrate how the facts have been misinterpreted all along. Think along the lines of "How to lie with statistics".
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0 # w. downing 2012-12-19 12:17
every thing you say is correct.

But, you did not take into account pixel density.

You can lay the part of the image you are interes5ed in over more pixels on a DX versus an FX camera,
D7000 versus D700 for instance, using the same lens.

This is not a lens proprity, gut a camera properity.
What actually changes is the angle of view.
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+2 # Gregory Cazillo 2012-12-23 11:29
This video has nothing to do with pixel density, only lens mm which is busted ;).
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0 # Flo 2013-01-28 07:15
nope. It ain't busted. see my previous post
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0 # Sabe Majeen 2012-12-19 16:23
Great video Greg...

I have wondered what the IQ difference would be between the cropped full frame v/s the smaller sensor...not exact calculations but in theory for example a 23 MP picture on a full frame cropped to the 1.5 or 6 (loosing about a third by cropping) compared to an un-cropped picture of a smaller sensor of approximately 18 MP.

I couldn't find any EXIF material on your examples...

Thanks, Sabe
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0 # Gregory Cazillo 2012-12-23 11:30
EXIF data should be in flickr if you click over. Image quality will be better with FX vs DX because of the larger sensor.
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0 # Jussi 2012-12-20 10:39
Did I understand correctly:

In order to take identically framed photo in FX you need to be closer to the subject (more distortion) compared to the DX (less distortion).
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0 # Gregory Cazillo 2012-12-23 11:31
Yes that is one way to think of it.
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0 # Perry 2013-01-07 14:27
Hey Greg,

Excellent demonstration.

Is it safe to say that this is sort of what happens with a point and shoot when one uses the "digital zoom"? It's actually cropped, and "resized" in the point and shoot camera.

In the DX mode, the "cropping" happens on the sensor so to speak because of a smaller area of exposure on the sensor surface.

In simpler terms; like having a smaller picture frame to fit 2 full size photos on,so you have to "cut" one picture down to size to fit the smaller frame giving the illusion of zoom on the same subject.

Does that accurately describe it?

Thanks, Perry
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+2 # Gregory Cazillo 2013-01-12 12:23
yes, thanks
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0 # Perry 2013-02-05 07:45
An easy way to put this debate to rest is to go to and look at the lens section that gives you a demonstration called "virtual lens" and "virtual camera".

You will see that the DX lens doesn't "zoom in closer", or "multiply 1.5x" I.e. making a 300mm equivalent to a 450mm lens, rather you lose zoom in the demonstrator. This is a useful tool to determine what lens I buy in the future.
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-2 # Flo 2013-02-07 07:01
uhm the NIKKOR Lens Simulator I'm using crops the image w/ a 50mm lens on a DX-format sensor (31° view angle) as oppose to FX-mode (46° view angle); so why do you loose zoom?!? I think it would be helpful to stop confusion by not talking about zoom or multiply, but to talk in terms of mm and view angle.
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-1 # Perry 2013-02-07 07:50
Apparently some people like a "good argument" trying to convince others of their "vast intellect", rather than to listen to the content of what others are saying to them.

I think Greg has belabored the point that a DX lens and camera are not the same class as an FX platform, and what really happens with the DX sensor is that it "crops" the image much in the way that the "digital zoom" on a point and shoot camera does, giving the illusion of zoom. There is a reason that FX cameras sell for a higher price than the DX cameras do. The FX camera has a larger sensor than the DX camera, therefore it's able to capture more information and yield a higher resolution and even give a closer capture than it's DX counterpart using the same size MM lens.

I don't claim to know everything about photography, that's why I follow Greg Cazillo's lessons. I have learned a great deal from his tips, and instead of debating him for weeks on end trying to prove him wrong, I actually get out there (when my camera gets back from it's annual cleaning), and I put what I've learned to use.

I realize that Greg is a portrait photographer for the most part, and most of his tips are geared toward that premise, and I am an outdoor/nature and wild life photographer; so some things are going to be a little different in my approach and settings than someone in a studio with their subject sitting on a stool or standing in front of them.

I just think that much more can be learned if you open your eyes and ears and shut your mouth. If you don't agree with Greg, please get your own website and "enlighten us", or go on emulating some ditzy brunette who's a fashion train wreck on a lame car insurance commercial, but please let's move on already.
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0 # Flo 2013-02-08 06:11
I am not claiming to know everything, I am simply saying that we have to be clear what we are talking about. Especially in photography.
Let me add here: yes, I know that FX and DX are different things, and that larger CCD-chips are more expensive than smaller ones. My whole point was that there is a difference between cropping the sensor and zooming digitally, and using a "real" crop-sensor camera with real crop-lenses.

One more thing: I have great respect for what Greg is doing and the time he's investing into those videos. But that does not mean that one should not mention possible mistakes or inaccuracies.

I like to learn new stuff, and get into details of things - sorry for annoying you. But then again, you wouldn't have to read the comments section now would you?
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+1 # Joe 2013-02-08 00:23
Funny some are having issues understanding what Greg is saying about crop factor. Greg I hope you don't mind me referencing a YouTube video but I think this really helps people understand what happens inside the camera. If you go to the link provided and fast forward to the 7 minute mark you will get a visual to see just what is going on inside when you focus on your subject. Hope this puts this to rest.
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0 # Pat Fithian 2013-02-27 23:35
Funny, I've never heard that using the crop sensor mode essentially made your lens "longer." I've heard that using an FX lens on a DX body gives you the equivalent of a "longer" lens. I'm shooting with a D300S but in preparation for eventually purchasing a full size sensor body (dreaming of one day a D4) I have purchased both a 50mm f1.4 and a 70-200mm f2.8 FX lenses and at 200mm my view is close to the 300mm of the DX zoom that I purchased with the camera.
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0 # Flo 2013-02-28 18:24
Hey Pat,
the "equivalent" is the important thing. 50mm FX will be 100mm equivalent on DX in terms of the view angle. But what about image quality? As far as I understand it, DX lenses are made for DX bodies for a reason. Me would interest if chromatic aberration becomes a problem when you use 2x or 1.6x crop factors on those lenses...
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0 # Cletus 2014-01-16 17:41
Thank you. I just randomly came across your video on youtube regarding this issue, though it looks like it has been up for a while.

I am in total agreement and you have proven it well.

However there is one other factor (at least) that should be considered.

For a full frame 20MegaPixel sensor you are covering the full lens area with 20MP. If you have a crop sensor that is also 20MegaPixels then you are covering the cropped area of the lens with the same 20MP, which potentially (italicized) gives you the ability to create the same physical size picture (in. x in.) as if you had zoomed in more or used a longer focal length lens on a non-cropped sensor. However, you are still only getting a center portion of the glass and then enlarging that center portion - and the glass is what delivers the light for the photo to the sensor and that's why the glass is so important.

Relatively it is the density of megapixels vs physical sensor size for which people indicate that a 50mm lens on a 1.5x sensor is like (italicized) a 75mm lens for a full frame sensor.

But when you are enlarging digital pixels information or anything really you will lose quality and effective clarity. However depending on the end usage for the media it may not be that big of a deal.

I think you said it below a little differently but yes...

Equivalent View Angle does not mean Equivalent Image Quality.

Maybe it's more clear to exaggerate what's happening to understand it better:

If I made a 20MP sensor that has a 1000x crop factor (super tiny chip). My 50mm lens is like a 50000mm lens but I'm probably not going to get good details of the lunar surface when I enlarge the image to visible proportion.

When you are dealing with ratios closer than this outrageous example it might not be so pronounced but the image qualities will be different. Are they 5% different? 10% different? Noticeably different to your intended audience? If they are noticeably different then it might not be accurate to say the lens is 1.5x longer range than it really is.
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0 # John 2014-08-12 20:18

Your point is absolutely valid for still photography; however, when shooting video with a DSLR, you get the benefit of a quasi-longer lens because it's not practical to crop every frame of a video.

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0 # Gregory Cazillo 2014-08-13 09:19
Hi John thanks for your comment, but this video has nothing to do with composition of a scene or image. It refers to the myth that having a crop sensor camera magically makes your lenses longer which is false.
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