35mm L lenses on APS-C sensor cameras?

[neuroanatomist]

I'll have a go at a clear answer. If you put any lens labeled 200mm on your camera, and set it to 200mm if it's a zoom lens, you'll get essentially the same picture. Doesn't matter if it's EF-S, EF, or L.

[thekingb]

I'll have a go at a clear answer.

Admirable concision!

[Rubar]

If you put any lens labeled 200mm on your camera, and set it to 200mm if it's a zoom lens, you'll get essentially the same picture. Doesn't matter if it's EF-S, EF, or L.

If this is true, then at least some numbers must be incorrect (converted). As I said before, I’ve been surfing around a lot on this subject and found some images. For example at Wikipedia they have this image:

From this illustration I can see, that EF lens which is made for full frame 35mm cameras gives on APS-C sensor cameras more zoom at the same focal length. Correct?

Another great illustration at BobAtkins:

To get the same field of view as a 28mm lens on the full frame camera, you'd need a shorter focal length lens when used with the APS-C crop sensor. That's illustrated by the green lines in the image above. In the case of EOS DSLRs, the focal length would need to be 17.5mm.

These both images and explanations make sense to me, but I'm really confused by neuroanatomist’s statement. If EF-S and EF lenses give the same results at the same focal lengths, then it means that illustrations above are incorrect. But they look quite logical to me. Still, if both images and neuroanatomist are true, then it means numbers on either EF-S or EF lenses are incorrect. With this theory it means EF-S focal length at 200mm is actually less to project the same image on a smaller sensor. Which means that EF-S lens at 200 mm is actually 200/1,6=125mm and Canon writes on a camera not true focal length, but equivalent of 35mm. Could this be true?

[Steve U]

This is getting too complicated.
Neuro's quote above is, "If you put any lens labeled 200mm on your camera," please note he said your camera, an APS-C not a FF. And he is right any 200mm lens that fits will show the same image on your camera.

If you put those lenses on a FF the image will be different. The 1.6 crop factor hold for APS-C basically means on crop bodies or smaller sensor cameras like your 600D the image you obtain with a 200mm lens is the equivalent to an image of 200mm x 1.6 = 320mm lens on a FF or 35mm camera.

Neuro's response agrees with your diagrams, in the quote you highlighted he was only referring to your camera, not other formats.

[conropl]

I'll have a go at a clear answer. If you put any lens labeled 200mm on your camera, and set it to 200mm if it's a zoom lens, you'll get essentially the same picture. Doesn't matter if it's EF-S, EF, or L.

Hopefully I do not add to the confusion. However, Neuro is correct in his statement. The lens passes light through it and projects it in a round circle at the focal plan. The FF sensor then crops (only looks at) a rectagular sample of that projected image equivilant to the sensor size. If that FF sensor is replaced with a smaller "Crop sensor", then that round circle of light projected onto the sensor only sees the portion of the light that hits it, and therefore an even smaller portion of the projected area of light is recorded (thus the 1.6X crop factor).

What I thought he was saying is at the focal plan the lens produces the same image, and then whatever sensor you put in the focal plan will then crop that circle of light down to the size of the sensor. The problem with this comes with the EF-S lenses... with these the circle of light that is projected onto the focal plan is smaller than the size of the FF sensor so if you could put a EF-S lens on a FF camera, then the corners would be blackened.

If I have anything wrong here, please correct me; but that is my understanding.

[HDNitehawk]

Rubar

Neuro's assessment is correct. Your post on the charts makes me wonder if you think that EF lenses are "Full Frame" lenses. While EF-S lenses are made for crop bodies. EF lenses are made for all bodies. The diagrams you show are referring to the difference in sensors. EF lenses are not full frame lens, nor are they crop lenses they are just lenses. If you want more reach, you should be looking at longer lenses.

I will disagree with conropl on what you would see if you put on the EF-S lens on your full frame. I will speculate a bit. You would most likely just see black after you broke your mirror. Or maybe a error message on your lcd telling you the camera no longer functions.

[conropl]

I will disagree with conropl on what you would see if you put on the EF-S lens on your full frame. I will speculate a bit. You would most likely just see black after you broke your mirror. Or maybe a error message on your lcd telling you the camera no longer functions.

That is why I said "if" you could put an EF-S on a FF camera.

[HDNitehawk]

I noticed you qualified it with "if you could". You know I never tried to mount one on my FF bodies, fear always kept me from it. But I see no reason why it wouldn't mount right up so a person could break their camera.

[neuroanatomist]

Hi again!
To be honest, I did not expect so many replies. Thank you all for your input. As I see there are many different opinions and excitement, but still no clear answer. At least I still don’t get it. I shoot different objects with Canon EOS 600D at about 100-300 meters (328-980 feet). With EF-S 18-200mm f/3.5-5.6 IS lens I get quite satisfying results for my purpose. Only thing I’m missing is a little extra zoom. While planning to get a new lens I consider getting a higher quality one.

By extra zoom, you mean longer focal length. That means you need a lens longer than your current max of 200mm. An EF 70-200mm L lens will give you better quality, but no more 'reach'. So, consider lenses like the 70-300mm f/4-5.6L IS, or the 100-400mm, the 300mm f/4L IS, or the 400mm f/5.6L. All of those will give you better quality, and a longer focal length (some more than others).

Bottom line, for you right now, only the number matters. You can get any lens, EF-S, EF, or L, but if you want more zoom than your current 18-200mm lens, you need a lens longer than 200mm. All of the diagrams you posted and the discussions that you referred to will only apply to you if/when you decide to get a full frame camera like a 5DII. At that point, a 200mm lens on that full frame camera will give you the same field of view as a 125mm on your current camera, so if you go FF, you may need longer lenses, too. But for now, don't worry about any of that.

[Rubar]

I think I’m starting to get it. Thanks to all of you!
Just to clarify, please tell me am I right or wrong stating:
With the same 200mm L lens I get on 35mm (full frame) camera wider frame and on APS-C will get a more close-up (more zoom).