35mm L lenses on APS-C sensor cameras?

[Rubar]

Hi!

I've been searching around the net to find out what happens if I attach a Canon L series lenses to a APS-C sized sensor cameras. I found several sites with images and lots of information, but did not get a clear answer. I understand the framing difference, but I can’t figure out the thing with numbers.
If I attach for example Canon EF 70-200mm f/4.0 L IS USM lens to my Canon 600D, do I get at maximum zoom the same results as wit Canon EF-S 18-200mm f/3.5-5.6 IS Lens? Or I get with EF 70-200 L lens 200x1.6=320mm which is more zoom than EF-S 18-200 lens?

Thanks in advance!

[Sean Setters]

If you attach a 70-200mm lens to a camera with an APS-C sized sensor, it will have a Full Frame equiv. focal range of 112-320mm. If you attach a 35mm lens to a camera with an APS-C sized sensor, it will have an equiv. focal length of 56mm.

[clemmb]

If you attach a 70-200mm lens to a camera with an APS-C sized sensor, it will have a Full Frame equiv. focal range of 112-320mm. If you attach a 35mm lens to a camera with an APS-C sized sensor, it will have an equiv. focal length of 56mm.

And if you attach an 18-200 to your camera it will have a Full Frame equiv. focal range of 28.8-320mm. The crop factor is 1.6 regardless of whether it is an EF or EF-S lens.

[neuroanatomist]

If I attach for example Canon EF 70-200mm f/4.0 L IS USM lens to my Canon 600D, do I get at maximum zoom the same results as wit Canon EF-S 18-200mm f/3.5-5.6 IS Lens? Or I get with EF 70-200 L lens 200x1.6=320mm which is more zoom than EF-S 18-200 lens?

Focal length is an intrinsic property of the lens, and is a measure of the distance between the rear nodal point of the infinity-focused lens and the focal plane (sensor). Sensor size (APS-C vs. FF) has nothing to do with it and no effect on focal length. The numbers printed on the barrel of the lens are not somehow 'adjusted' for the sensor size, at least with dSLR lenses (some point-and-shoot cameras do have the FF equivalent focal lengths printed on them). What a smaller sensor like APS-C does is only capture a smaller portion of the image circle projected by an EF lens, and EF-S lenses are designed with a smaller image circle (which is why they don't work on FF cameras) to reduce size, weight, and cost.

So, in theory for your example of the EF 70-200mm L lens vs. the EF-S 18-200mm, if you use them both on the same camera, 200mm will give you the same field of view. In practice, there is a difference in this case - the 18-200mm lens doesn't really deliver 200mm at the long end; I tested one a while back, and it was more like ~160mm at the long end when compared to the same shot taken with the 70-200mm f/2.8L IS II.

[clemmb]

I tested one a while back, and it was more like ~160mm at the long end when compared to the same shot taken with the 70-200mm f/2.8L IS II.

Interesting

[HDNitehawk]

Hi!


If I attach for example Canon EF 70-200mm f/4.0 L IS USM lens to my Canon 600D, do I get at maximum zoom the same results as wit Canon EF-S 18-200mm f/3.5-5.6 IS Lens? Or I get with EF 70-200 L lens 200x1.6=320mm which is more zoom than EF-S 18-200 lens?

Thanks in advance!

No, they will be the same. All of the 1.6 hype is talking about camera bodies and sensors. Unless you plan on buying a full frame camera all of the Crop to FF comparisons are really useless information for you.

There is one thing you will get out of the 70-200mm L. Better IQ....

[HDNitehawk]

. In practice, there is a difference in this case - the 18-200mm lens doesn't really deliver 200mm at the long end; I tested one a while back, and it was more like ~160mm at the long end when compared to the same shot taken with the 70-200mm f/2.8L IS II.

That one is odd. I think I would go back and check the testing methods. Canon could owe allot of people money for false advertising, I wonder what 40mm would be worth in a class action lawsuit

[ChadS]

I tested one a while back, and it was more like ~160mm at the long end when compared to the same shot taken with the 70-200mm f/2.8L IS II.

I'm curious to the testing method as well. Stars are the only target I can think of that one could use as an infinite-distance source. I've used systems in the lab that are functionally 25% less magnification than their quoted values at "real" distances but if we test them with a collimated source they generally are right where the manufacturer says they are. Though I would not be shocked if these lenses (or at least the one tested) did not turn out to perform as spec'd. That happens all the time in the lab as well...

[Daniel Browning]

I found several sites with images and lots of information, but did not get a clear answer.

It may help to compare camera format with digital zoom. Let's say you start with a 5D2 and 200mm lens, and want to compare various methods of "zooming in":

1. Optical zoom: switch to a 320mm lens.
2. Digital zoom: use the 200mm lens, but crop the 21 MP image down to 8MP.
3. Digital zoom: use the 200mm lens on a Canon 30D (8 MP).
4. Digital zoom with high resolution: use the 200mm lens on a Canon 60D (18MP).

Options 2 and 3 yield nearly identical resolution, even though they are different cameras, because they have the same pixel size, pixel count, and focal length. But option 4 is going to have superior resolution as long as diminishing returns don't cancel out the benefit of smaller pixels.

[Daniel Browning]

That one is odd. I think I would go back and check the testing methods. Canon could owe allot of people money for false advertising, I wonder what 40mm would be worth in a class action lawsuit

The 18-200mm *is* 200mm at infinity. I'm sure that Neuro's test was for a much closer focus distance. Focal length can vary with normal manufacturing tolerances, and +/- 5% wouldn't surprise me, but 20% certainly would.