Stupid EF-S Question

Photo Joe · September 24, 2008

So I feel kinda silly for even asking this question, but I don't think I fully understand the difference between an EF and EF-S lens. I've got an XSi with a 1.6x crop factor sensor, and I know the EF-S style lenses are optimized for those kind of sensors, but at the same time I can still use the regular EF lenses. On the other hand full sensor bodies are not compatible with the EF-S lenses, hence some people don't like to invest too heavily into them.

I guess my basic question is: Is there any reason why I (while using a crop factor body) should use EF-S instead of EF lenses?

Example:
I've got the Canon EF-S 55-250mm IS. Is there any reason I shouldn't consider trading it in for Canon's EF USM 70-300mm IS lens instead? What advantage does the 55-250 give my XSi which the 70-300 may not?

Thanks!

ziggy53 · September 24, 2008

Photo Joe wrote:

...

I guess my basic question is: Is there any reason why I (while using a crop factor body) should use EF-S instead of EF lenses?

Example:
I've got the Canon EF-S 55-250mm IS. Is there any reason I shouldn't consider trading it in for Canon's EF USM 70-300mm IS lens instead? What advantage does the 55-250 give my XSi which the 70-300 may not?

Thanks!

I am not sure that there is that much of a performance advantage moving from the EF-S 55-250mm IS to the EF 70-300mm IS USM. Other than that there is no compelling reason to feel you "have" to use EF-S lenses on the Canon crop bodies.

There is a pretty good comparison here:

http://www.the-digital-picture.com/reviews/Canon-EF-S-55-250mm-f-4-5.6-IS-Lens-Review.aspx

cmason · September 24, 2008

As you may know, a 'crop' sensor camera has a sensor that is smaller than a 'normal' 35mm film. Before these cameras, a lens was made so that the light from it would expose the entire 35mm film rectangle with the image.

When crop cameras came out, the sensor is smaller than a 35mm rectangle so when using a 'regular' 35mm lens, much of the image is falling outside the sensor. Now a '"regular' lens works just fine on a crop sensor camera, because the sensor is effectively positioned in the middle where the 35mm rectangle would be. So a 'regular' lens actually illuminates more than the crop sensor can 'see', effectively cropping the image...this is why it is called a 'crop' sensor...it is doing exactly what you do when you crop an image on your computer.

So, to save $$ and weight, the manufactures created lenses for these crop cameras. Since you don't need to illuminate a full 35mm rectangle, but instead only a smaller one, you don't need as big a lens. You can get by just fine with a lens that illuminates a smaller rectangle. This also makes the lens smaller, lighter, and usually cheaper.

Canon calls these lenses EF-S, and the 'regular' lenses EF. EF lenses can work on all cameras, from film to crop to pro digital. EF-S lenses work only on crop cameras. In addition, these EF-S lenses also have glass that protrudes further into the camera shutter box, so that an EF-S lens has the potential to damage a non-crop camera. This is just for Canon.

Canon makes essentially 3 lines of lenses: basic, standard and pro. These are not necessarily identified as such, and you have to look carefully often to understand this.

Most of the basic lenses are those that are 'kit' lenses on the entry level cameras, like the 18-55, or the older 28-85. These are plastic bodied, plastic mount, and really lightweight when held. These are for the person who drags the camera out at family events and processes at Walmart (IMHO)

The middle range typically are better glass, heavier construction and metal mounts. They range from acceptable quality to amazing. These usually have better focusing motors too. Lenses like the 28-135 IS, or the 70-300IS are in this category.

Finally, there are the pro lenses. Many are 'L" lenses, with the finest optics and heavy metal construction. Some others are similar optics but not as heavy construction, like the 85 1.8, or the 17-55 2.8 IS. These lenses give the finest image, and cost the most money.

A good example of this is the 70-200/300 range: Canon makes 7 lenses in this area: 75-300, 70-300IS, 70-200 f4L, 70-200 f2.8L 70-200f4L IS, 70-200 f2.8L IS (oh and 70-300 DO IS). The first is the basic lens, the second is the standard lens, and then the remainder are the 'pro'. However, the 70-200 f4L is somewhat unique in that it is priced at the same pt as the standard 70-300. I recommend you hold examples of many of these in your hand to quickly understand the difference. You will be able to tell right away.

Sadly, your 55-350 is typically in the first category: it has a basic focus motor, and a plastic lens mount. If you are interested in better performance and better quality images, moving up to the 70-300 IS or my recommendation the 70-200 f4L is a great idea. With the 70-300 IS, you will get better glass as well as a better IS unit. But with the 70-200 F4L you get much better glass, rugged metal construction and blindingly fast and silent focus.

tomauto · September 24, 2008

After reading that review, spend a few more $$$ and buy this lens. If you ever decide to upgrade from the 1.6 you can still use this lens instead of having to sell the EF-S mount.

http://www.the-digital-picture.com/reviews/Canon-EF-70-200mm-f-4.0-L-USM-Lens-Review.aspx

Oh, and there are no stupid questions

Photo Joe · September 24, 2008

hmmm, I didn't even consider the 70-200 lens, mostly because its an L series and typically way out of my budget range. But I suppose the non-IS model is pretty close in price to the 70-300 lens. Though I'm a little leery to get a telephoto lens without build in IS on it. The other reason I might opt against the L lens, despite is obvious improvement in quality, is that most of my photos come from outdoor hiking / climbing. The 70-300 would compact and easier to fit in a small day-pack for hiking around in the mountains.

Gah, everytime I think I've figured something out you guys just have to go and throw a monkey wrench in my plans!

darkdragon · September 24, 2008

I think that the 70-200 F4/L is not much bigger and certainly not much heavier than the 70-300 IS. I'm sure there are many direct comparisons around on the web of those 2 lenses. Without IS, the F4L is a steal and sells for under $500 with IS it is still decent and under $1000 a lot of the time.

I believe that the 70-300IS is a step above the 75-300, but just want to mention that I used the 75-300 when I first got my camera (first lens purchase) and was extremely disappointed with it. I ended up returning it within a week. Of course, that could have be partially my lack of experience with the camera/lens.

divamum · September 24, 2008

The 55-250 has put all the other sub-$400 lenses I've tried with my XT to shame. Yes, it's plastic, yes, the focusing can be finicky if the light's not great, yes, it's louder than the USM lesnses, but for sharpness it is very impressive, especially for the price.

I suspect that unless you jump up to one of the significantly better - and more expensive - lenses, you won't find anything sharper (although I'm willing to accept that some of the mid-range lenses might have other attractions). I personally would give an arm (and maybe even a leg) for something faster - I'm actually wondering about the Tamron 17-55 2.8 myself, but at the moment I'm completely out of money for any more gear, so I'll have to wait!!

cmason · September 24, 2008

divamum wrote:

The 55-250 has put all the other sub-$400 lenses I've tried with my XT to shame. Yes, it's plastic, yes, the focusing can be finicky if the light's not great, yes, it's louder than the USM lesnses, but for sharpness it is very impressive, especially for the price.

I suspect that unless you jump up to one of the significantly better - and more expensive - lenses, you won't find anything sharper (although I'm willing to accept that some of the mid-range lenses might have other attractions). I personally would give an arm (and maybe even a leg) for something faster - I'm actually wondering about the Tamron 17-55 2.8 myself, but at the moment I'm completely out of money for any more gear, so I'll have to wait!!

well the Tamron 28-75 is legendary, inexpensive and very much a rival to many of the most expensive Canon lenes. Always worth owning

Stupid EF-S Question

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