Conflicting info on "crop factor", zoom, etc.

Still have not found ONE definative answer, and I have read numerous explanations on the web and in books. I keep finding conflicting info regarding the length/crop factor/etc created by smaller (APSC) vs full frame sensor sizes. With Canon, the 1.6x factor is mentioned a lot when talking about lenses. A common train of thought is that you get 1.6x magnification while using an APSC sensored camera vs a full framed camera. Some people say it ONLY is in regards to field of view or cropping, and does not at all involve focal length or zoom. I hear people tell me over and over that a 200mm lens will zomm out just like a 320mm lens on an APSC sensored Canon. I hear people tell me that this is BS as well. I've heard people with both types of cameras say they have tested this side by side, and it's true, there is a "zoom factor". Others say there is nothing but a "crop factor". What's the scoop? If I take a 70-200mm EF lens, and stick it on my 1.6x Canon camera, the images should look like I shot them with a 320mm lens at full zoom, right?
Then, how does the EF-S lens come into play. I've heard these have the 1.6x thing factored in, and they are labeled "correctly" for 1.6x cameras. So, a 250mm EF-S lens is equal to a shorter EF lens?
I'm just looking for someone to point me to some accurate side by side comparisons and straight answers. Hours of reading and searching have done nothing but make it all that much more confusing. I don't see how a smaller sensor makes a lens zoom 1.6x closer. But I know people who claims it does. But I do completely understand how a 1.6x camera crops out more image than a full framed or 35mm, that makes perfect sense.

http://www.the-digital-picture.com …-of-View-Crop-Factor.aspx

That will explain it for you. The smaller sensor merely uses the smaller, inside area of the image. Crop factor refers to field of view only. There is no difference in magnification. Period.

Harvey_G wrote in post #7862738
http://www.the-digital-picture.com …-of-View-Crop-Factor.aspx

That will explain it for you. The smaller sensor merely uses the smaller, inside area of the image. Crop factor refers to field of view only. There is no difference in magnification. Period.

I've heard that time and time again, and yet I still see where people claim to opposite to be true. I've even read that the magnification IS there on some reputable websites. I've even heard about side by side comparisons that show it to be possible....but have yet to see an actual pics myself. I've seen dozens of those colored graphics showing 35mm with smaller sensor sizes imposed over it. But I've also seen examples like this.............

http://www.kenrockwell​.com/tech/crop-factor.htm

Either he's completly off his rocker, or his examples are complete BS. There is a drastic amount of magnification going on there.

Also, lenses are ALWAYS marked with the real focal length...there is never a conversion specified, since the focal length never actually changes depending on the format. The 1.6x factor is ONLY useful for comparing the field of view of lenses on two different formats...the APS-C format and the 135 (35mm) format. If you know what a 28mm looks like on full frame, it can help you, as you can then use the factor to determine that you need roughly a 17mm lens on APS-C to get the same field of view. There is no other purpose for the crop factor. I have never used it in my daily photographic life...I know that on APS-C, wide is ~17mm, ultra wide is ~12mm and wider, and normal is ~30mm. I know that on my 1Ds II, wide is ~28mm, ultra wide is ~20mm or wider, and normal is ~50mm (45mm).

It's not magnification you are seeing...it's a narrower field of view, which IS the case on a smaller format.

Those who insist that a 200mm lens becomes a 320mm lens on APS-C are simply flat out wrong...the problem is, it's a LOT of people.

HeathNC wrote in post #7862694
Still have not found ONE definative answer, and I have read numerous explanations on the web and in books. I keep finding conflicting info regarding the length/crop factor/etc created by smaller (APSC) vs full frame sensor sizes. With Canon, the 1.6x factor is mentioned a lot when talking about lenses. A common train of thought is that you get 1.6x magnification while using an APSC sensored camera vs a full framed camera. Some people say it ONLY is in regards to field of view or cropping, and does not at all involve focal length or zoom. I hear people tell me over and over that a 200mm lens will zomm out just like a 320mm lens on an APSC sensored Canon. I hear people tell me that this is BS as well. I've heard people with both types of cameras say they have tested this side by side, and it's true, there is a "zoom factor". Others say there is nothing but a "crop factor". What's the scoop? If I take a 70-200mm EF lens, and stick it on my 1.6x Canon camera, the images should look like I shot them with a 320mm lens at full zoom, right?
Then, how does the EF-S lens come into play. I've heard these have the 1.6x thing factored in, and they are labeled "correctly" for 1.6x cameras. So, a 250mm EF-S lens is equal to a shorter EF lens?
I'm just looking for someone to point me to some accurate side by side comparisons and straight answers. Hours of reading and searching have done nothing but make it all that much more confusing. I don't see how a smaller sensor makes a lens zoom 1.6x closer. But I know people who claims it does. But I do completely understand how a 1.6x camera crops out more image than a full framed or 35mm, that makes perfect sense.

Dude, it's all semantics. Isn't it? I say this: What is "zooming"? "Zooming" is nothing more than cropping an image "in-camera." What is the fundamental distinction between a 1.6x format camera and a so-called "full frame" camera? The 1.6x camera crops an image "in-camera." Therefore, a 1.6x camera, by definition, "gives you more zoom."

It really is that simple.

Once you get hang of that, you can read about real factor here:

http://www.nicolasgene​tte.com …s/CropFactor/in​dex_us.php

It's not simply 1.6x, but actually depends on the bodies (sensors) you are comparing.

From what I understand, correct me if I'm wrong.

All lenses, doesn't matter if they're EF or EF-S, the focal length marked on the lens is what is is. The focal length will not change no matter which format body you have the lens mounted on (talking about EF lenses here since you can't mount EF-S lenses on FF/35mm bodies).

The difference between an EF and an EF-S lens is the image circle (amount of glass) used on the lens. The difference here is to taken account of how cropped camera bodies/sensors are designed.

Regarding the magical "1.6x factor." The focal length hasn't been change but rather it's the field of view that has been changed. So when you have an EF/EF-S lens at 17 mm on a 1.6 crop factor camera it has the equivalence field of view of 27 mm on a FF/film camera. Basically because of the smaller sensor your field of view is narrower compare to FF/film cameras.

So a 17 mm EF-S lens is exactly the same as a 17 mm EF lens. When they're both mounted on a cropped camera they will give the exact same field of view (equivalent of 27 mm on FF). When you mount the 17 mm EF lens on a FF you will get exactly 17 mm field of view.

Jman13 wrote in post #7862819
It's not magnification you are seeing...it's a narrower field of view, which IS the case on a smaller format.

Semantics. Narrower field of view with the same amount of pixels is higher magnification, as long as you're not out resolving the lens.

HeathNC wrote in post #7862781
I've heard that time and time again, and yet I still see where people claim to opposite to be true. I've even read that the magnification IS there on some reputable websites. I've even heard about side by side comparisons that show it to be possible....but have yet to see an actual pics myself. I've seen dozens of those colored graphics showing 35mm with smaller sensor sizes imposed over it. But I've also seen examples like this.............

http://www.kenrockwell​.com/tech/crop-factor.htm

Either he's completly off his rocker, or his examples are complete BS. There is a drastic amount of magnification going on there.

Well that is because the smaller sensor images are resized (enlarged) to the same size as all the other images. And the difference is indeed significant.

1.6X linear, because that is what we are talking about here, is 2.56 X from an area POV. IOW, you will only see about 39 % of the frame compared to FF with the same lens.

This is also why new lenses had to be designed for APS-C to give you similar FoVs as lenses on FF, it is why we needed new UWAs amongst others.

Kind regards, Wim

Synovia wrote in post #7862932
Semantics. Narrower field of view with the same amount of pixels is higher magnification, as long as you're not out resolving the lens.

Aha...but you've added a qualifier I didn't...the same number of pixels.

HeathNC wrote in post #7862694
Still have not found ONE definative answer, and I have read numerous explanations on the web and in books. I keep finding conflicting info regarding the length/crop factor/etc created by smaller (APSC) vs full frame sensor sizes. With Canon, the 1.6x factor is mentioned a lot when talking about lenses. A common train of thought is that you get 1.6x magnification while using an APSC sensored camera vs a full framed camera. Some people say it ONLY is in regards to field of view or cropping, and does not at all involve focal length or zoom. I hear people tell me over and over that a 200mm lens will zomm out just like a 320mm lens on an APSC sensored Canon. I hear people tell me that this is BS as well. I've heard people with both types of cameras say they have tested this side by side, and it's true, there is a "zoom factor". Others say there is nothing but a "crop factor". What's the scoop? If I take a 70-200mm EF lens, and stick it on my 1.6x Canon camera, the images should look like I shot them with a 320mm lens at full zoom, right?
Then, how does the EF-S lens come into play. I've heard these have the 1.6x thing factored in, and they are labeled "correctly" for 1.6x cameras. So, a 250mm EF-S lens is equal to a shorter EF lens?
I'm just looking for someone to point me to some accurate side by side comparisons and straight answers. Hours of reading and searching have done nothing but make it all that much more confusing. I don't see how a smaller sensor makes a lens zoom 1.6x closer. But I know people who claims it does. But I do completely understand how a 1.6x camera crops out more image than a full framed or 35mm, that makes perfect sense.

This illustration shows what happens if you use the same FL lens on APS-C and on FF camera (same as what was explained in Post #2), and is in no way contracdictory to the Rockwell article which you linked, and is in agreement with what Jman13 posted, too...

I know it's not really an increase in focal length when I use my lenses on the 30D (crop) instead of the EOS-3, but like a lot of other people, it's an easy way to think.

Yes, you will continue to see comments like "My 400mm lens with a 1.4x TC on my crop body is the equivilent of almost 900mm". I don't give myself a hard time about it, although I know it's still only a 400mm lens and I'm enlarging a tiny rectangle out of a larger field of view.

As long as you understand what's really happening, then live and let live.

Synovia wrote in post #7862932
Semantics. Narrower field of view with the same amount of pixels is higher magnification, as long as you're not out resolving the lens.

There are many wrong ways to express the effect. Can be called longer focal length, narrower field of view, magnification etc. However, the millimeters or FOV on a lens won't change no matter what body you attach to it.

It's called crop, because it's a smaller "cropped" area of film/FF. The confusion is caused by pixel density of that area. Crop sensors often have higher density than FF, thus it appears to give longer FL or magnification.

Canon scales both its EF and EF-S lenses in 35mm terms. This of course means that an 18-55mm EF-S kit lens will never "truly" be an 18mm lens in the conventional sense.

nice images wilt

this site might help to to show the FOV given
http://lens-reviews.com …w-Visualisation-Tool.html

but to the o.p. have you ever used a FF film/digital camera? if not just forget about the whole crop factor thing