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Author Topic: Advantage of EF-S  (Read 6350 times)

runee

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Advantage of EF-S
« on: December 11, 2006, 05:07:52 am »

Hi,

Short intro: Rather green amateur, first time poster, long time reader
(And big fan of the entire LL site - thank you Mr. Reichmann)

I have been wondering about the Canon EF-S lenses. All other disadvantages aside, the biggest issue for me, using an APS-C size sensor, is loosing the wide angle.
A rather expensive 17mm becomes 27mm due to the cropping facter and that...well... frankly, IMO sucks

So - enter EF-S. When I first read about Canon's EF-s lenses, and how they were developed especially for the APS-C sized sensors, I assumed that the reason they were made was that they were taking into account the cropping factor, making an EF-S 17mm lens a true 17mm, giving the same FOV as a normal EF 17mm would yield on a fullframe 35mm sensor.
Alas - from what I can read, this is not the case - as all reviews I read etc. always have the side note "(As compared to 27 on 35mm)".

So, I have to ask - why the EF-S lens? Is it simple production cost, and the fact that the Short back makes it cheaper to produce a 17mm Wide angle lens or am I misunderstanding what I read ?
Because frankly, I must admit I truly assumed that there could be only one compelling reason for Canon to move away from or create a parallel to their standard mount - and that would be to get the technical benefit of true wide angle. Not a "simple" factor as cost... then again... money talks I guess *shrug*
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francois

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Advantage of EF-S
« Reply #1 on: December 11, 2006, 09:33:44 am »

Quote
Hi,

Short intro: Rather green amateur, first time poster, long time reader
(And big fan of the entire LL site - thank you Mr. Reichmann)

I have been wondering about the Canon EF-S lenses. All other disadvantages aside, the biggest issue for me, using an APS-C size sensor, is loosing the wide angle.
A rather expensive 17mm becomes 27mm due to the cropping facter and that...well... frankly, IMO sucks

So - enter EF-S. When I first read about Canon's EF-s lenses, and how they were developed especially for the APS-C sized sensors, I assumed that the reason they were made was that they were taking into account the cropping factor, making an EF-S 17mm lens a true 17mm, giving the same FOV as a normal EF 17mm would yield on a fullframe 35mm sensor.
Alas - from what I can read, this is not the case - as all reviews I read etc. always have the side note "(As compared to 27 on 35mm)".

So, I have to ask - why the EF-S lens? Is it simple production cost, and the fact that the Short back makes it cheaper to produce a 17mm Wide angle lens or am I misunderstanding what I read ?
Because frankly, I must admit I truly assumed that there could be only one compelling reason for Canon to move away from or create a parallel to their standard mount - and that would be to get the technical benefit of true wide angle. Not a "simple" factor as cost... then again... money talks I guess *shrug*
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A 17mm lens is a 17mm lens whatever the size of the sensor/film. So your only option, if you need a 17mm lens, is to purchase the EF-S 10-22 and you'll regain an equivalent to 16mm wide lens on your APS-C camera.

As for "why" EF-S lens, they are tailored for APS-C cameras only and cannot be used on larger sensor cameras (1Ds & 1D) - but I'm sure you already know it.
« Last Edit: December 11, 2006, 09:34:42 am by francois »
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Francois

gochugogi

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Advantage of EF-S
« Reply #2 on: December 11, 2006, 12:14:03 pm »

Quote
All other disadvantages aside, the biggest issue for me, using an APS-C size sensor, is loosing the wide angle.

I'm not a wide angle fan and can live happily with 28-35mm (equivalent) at the wide end. The only thing that truly bugs me about APS-C is the small viewfinder. Both my 10D and 20D were real peepholes and it was difficult to keep horizontals square compared to FF 35mm film viewfinders. Also, everything seems so small, especially when using a wide angle, it's difficult to tell what I'm shooting. So I got a 5D and twee dang that's a fine VF!

Nevertheless, I think Canon could do much better with 1.6x VFs. One peep through a Pentaz K10, Nikon D80 or D200 and you quickly realize the XTi, 20D and 30D could be so much more viewfinder-wise.

As for cost, the EF-s 17-55 2.8 IS USM and EF-s 60 2.8 USM probably settles budget as an overriding advantage of EF-s. I'm guessing a smaller imagine circle allows a lot more design flexibility. Perhaps it allows a better marketing angle as well. I know folks that think EF-s is better than EF because they were "digital" designs to begin with. Of course lots of teenagers think the MP3 is more "advanced" than full rez noncompressed audio...
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howiesmith

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Advantage of EF-S
« Reply #3 on: December 11, 2006, 07:39:18 pm »

It is my understanding (can't ptove it) that the smaller sensor size allows a smaller image circle, resulting in easier to design and manufacture lenses (cheaper).
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francois

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Advantage of EF-S
« Reply #4 on: December 12, 2006, 03:05:53 am »

Quote
It is my understanding (can't ptove it) that the smaller sensor size allows a smaller image circle, resulting in easier to design and manufacture lenses (cheaper).
[a href=\"index.php?act=findpost&pid=89950\"][{POST_SNAPBACK}][/a]
Unfortunately, street prices for EF-S lenses are in the same range as for "normal" EF lenses.
« Last Edit: December 12, 2006, 03:06:35 am by francois »
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Francois

runee

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Advantage of EF-S
« Reply #5 on: December 12, 2006, 09:33:11 am »

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Unfortunately, street prices for EF-S lenses are in the same range as for "normal" EF lenses.
[a href=\"index.php?act=findpost&pid=90013\"][{POST_SNAPBACK}][/a]

Excactly my point... then what is the justification for the existance of EF-S ? More revenue to Canon?
Certainly, I see no added benefit for the customers?
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francois

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Advantage of EF-S
« Reply #6 on: December 12, 2006, 10:44:32 am »

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Excactly my point... then what is the justification for the existance of EF-S ? More revenue to Canon?
Certainly, I see no added benefit for the customers?
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A few years ago, French magazine Chasseur d'images had a nice article about a new-just-about-to-be-released Canon DO lens (it was the 400mm DO). The claimed advantages would be a lower weight (right), smaller size (right) and much cheaper price (wrong). I don't know if Canon could have been selling this lens at a lower price point and still make money but they choose to set the price much higher than most anticipated.

Every product has a target price - in other words, how much the consumer will agree to pay for that product. Canon has decided that EF-S lenses have to be sold in the same price range as other EF lenses. For a wide-angle zoom, there's simply no equivalent (at least Canon has no equivalent) and it's your only choice if you use a 1.6 APS-C camera and need a wide-angle zoom.

So, you're right, the advantage is on Canon's side!

 
« Last Edit: December 12, 2006, 10:48:32 am by francois »
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Francois

Eric Myrvaagnes

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Advantage of EF-S
« Reply #7 on: December 12, 2006, 11:20:36 am »

Quote
Excactly my point... then what is the justification for the existance of EF-S ? More revenue to Canon?
Certainly, I see no added benefit for the customers?
[a href=\"index.php?act=findpost&pid=90039\"][{POST_SNAPBACK}][/a]
The one benefit to customers is that they should be smaller and lighter than their full-sized brethren, so you have less to carry around for the same "effective" focal length.
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francois

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Advantage of EF-S
« Reply #8 on: December 12, 2006, 11:38:21 am »

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The one benefit to customers is that they should be smaller and lighter than their full-sized brethren, so you have less to carry around for the same "effective" focal length.
[a href=\"index.php?act=findpost&pid=90066\"][{POST_SNAPBACK}][/a]
Interestingly, the benefit mirrors those of the Canon EF DO lenses.
« Last Edit: December 12, 2006, 11:38:39 am by francois »
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Francois

aaykay

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Advantage of EF-S
« Reply #9 on: December 12, 2006, 07:00:51 pm »

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The one benefit to customers is that they should be smaller and lighter than their full-sized brethren, so you have less to carry around for the same "effective" focal length.
[a href=\"index.php?act=findpost&pid=90066\"][{POST_SNAPBACK}][/a]

Well, my take is that the real advantages of a small sensor (small and light lenses) are simply not being obtained through an EF-s or DX series of lenses, since the mounting point is still designed the cover  the old 35mm imaging circle.  The advantage with the large mounting point is that the EF or FF lenses will still work with these crop sensored cameras and manufacturers will not have to design a completely new line of lenses (eg. a small and light 70-200mm f2.8  that will **only** cover the 1.6x imaging circle, and mounts onto a tinier mounting point that will **only** cover the 1.6x sensor area etc).

Obviously if they truly designed the lens mounting point to only cover the 1.6x crop imaging circle, the lenses when compared to FF lenses at equivalent F-stop numbers and FL, should be **much lighter** than the FF equivalent with identical FL and aperture numbers.  As an extreme example, take the case of a small sensored camera (1/2.5" etc) and observe the f2.0 zoom lens on such a camera with a FL range that goes from say 6mm to 70mm or so.  Those are **tiny**.  That is because the lens is designed to mount to a point that would only cover the tiny sensor, unlike the EF-S or Nikon DX lenses that are designed to attach to same mount as the regular FF lenses with the only advantage being a shorter backfocus distance and probably **slightly** less heavy than an equivalent FF lens with the same aperture and FL range.

Due to the above, I am not fully convinced about the EF-s or DX line, from the perspective of obtaining light lenses, even if they are able to shrink the body down with a small sensor (eg the D40).

So bottomline, are we (the consumers) truly reaping any big advantages from the small crop sensors or are the manufacturers making a killing by marketing the small sensors as an "advantage", without truly translating the real advantages of the small sensors, into their products (cameras and lens lineup) ?  I think the manufacturers making a killing, is closer to the mark.
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BJL

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Advantage of EF-S
« Reply #10 on: December 13, 2006, 09:11:42 pm »

Quote
Unfortunately, street prices for EF-S lenses are in the same range as for "normal" EF lenses.
[a href=\"index.php?act=findpost&pid=90013\"][{POST_SNAPBACK}][/a]
I think you are comparing the wrong things. If you are using an EF-S body and want a zoom lens giving wide angle coverage of 18mm in that format, you get it far more economically with an EF-S lens like the 18-55 EF-S than with any EF (35mm format) zoom reaching 18mm (17-40, 16-35). And if you want wide angle coverage on that EF-S body that needs 10mm, you can get it with the 10-22 EF-S, but cannot get it at any price with a Canon EF (35mm format) lens.

I suppose you are comparing EF lenses (35mm format) giving the same angular FOV on a 35mm body as EF-S lenses give on an EF-S body. Lens costs might be similar then, but the total cost is far higher for the 35mm format option due to the far higher price of the 35mm format DSLR body.

It is of course that huge body cost advantage which makes Canon (and every other DSLR maker) so interested in smaller-than-35mm DSLR formats like EF-S.
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francois

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Advantage of EF-S
« Reply #11 on: December 14, 2006, 07:11:57 am »

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I think you are comparing the wrong things. If you are using an EF-S body and want a zoom lens giving wide angle coverage of 18mm in that format, you get it far more economically with an EF-S lens like the 18-55 EF-S than with any EF (35mm format) zoom reaching 18mm (17-40, 16-35). And if you want wide angle coverage on that EF-S body that needs 10mm, you can get it with the 10-22 EF-S, but cannot get it at any price with a Canon EF (35mm format) lens.

I suppose you are comparing EF lenses (35mm format) giving the same angular FOV on a 35mm body as EF-S lenses give on an EF-S body. Lens costs might be similar then, but the total cost is far higher for the 35mm format option due to the far higher price of the 35mm format DSLR body.

It is of course that huge body cost advantage which makes Canon (and every other DSLR maker) so interested in smaller-than-35mm DSLR formats like EF-S.
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BJL,
Indeed, you're right, but Canon makes price comparisons a bit more difficult as build quality of wide-angles zooms for 35mm cameras (17-40 & 16-35) is not in the same league as for EF-S lenses. For some, build quality is important and for some others it's just luxury.

And as I said above, if one uses an APS-C camera, the EF-S 10-22 lens (on Canon bodies) is the only way to go if wide coverage is needed.
« Last Edit: December 14, 2006, 07:13:53 am by francois »
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Francois

aaykay

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Advantage of EF-S
« Reply #12 on: December 16, 2006, 12:52:59 am »

Another disadvantage to the "EF-S system" that people fail to mention is that you simply cannot design a fast wide prime (10 mm etc), while retaining the existing mount.  It is a design impossibility, unless we are talking about a super-heavy super-expensive lens that few can afford.  

Even though the 10-22mm EF-S variable zoom is available to cater to the wider focal lengths (to provide a FF 16-35 equivalent FL coverage), it cannot be called as a "fast lens" by any stretch of the imagination.
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ErikKaffehr

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Advantage of EF-S
« Reply #13 on: December 16, 2006, 02:33:54 am »

Hi,

EF-S lenses have shorter distance between exit pupil and sensor. The cameras accepting EF-S lenses have smaller mirrors. Making the exit pupil closer to the sensor has advantages from lens design, because the lens can be less telecentric. I'm not an expert of optics, but the impression I have is that field curvature is less with less telecentric design.

In practice you would win about one aperture in DOF (Depth Of Field) with an AF-S lens, same DOF at 5.6 on APS-C as with 8.0 on full frame. AF-S makes a lot of sense if used with APS-C cameras:

1) Cost saving
2) Image quality can be optimized for image size
3) Size and weight of optics will be much smaller if other parameters equal
4) Lens shade and internal buffling can be optimized for the image circle actually used

There is one advantage with full frame lenses on APS-C cameras and that is that vignetting and sharpness fall off will be minimal, simply because the most critical part of the image is not used.

Best regards

Erik

Quote
Hi,

Short intro: Rather green amateur, first time poster, long time reader
(And big fan of the entire LL site - thank you Mr. Reichmann)

I have been wondering about the Canon EF-S lenses. All other disadvantages aside, the biggest issue for me, using an APS-C size sensor, is loosing the wide angle.
A rather expensive 17mm becomes 27mm due to the cropping facter and that...well... frankly, IMO sucks

So - enter EF-S. When I first read about Canon's EF-s lenses, and how they were developed especially for the APS-C sized sensors, I assumed that the reason they were made was that they were taking into account the cropping factor, making an EF-S 17mm lens a true 17mm, giving the same FOV as a normal EF 17mm would yield on a fullframe 35mm sensor.
Alas - from what I can read, this is not the case - as all reviews I read etc. always have the side note "(As compared to 27 on 35mm)".

So, I have to ask - why the EF-S lens? Is it simple production cost, and the fact that the Short back makes it cheaper to produce a 17mm Wide angle lens or am I misunderstanding what I read ?
Because frankly, I must admit I truly assumed that there could be only one compelling reason for Canon to move away from or create a parallel to their standard mount - and that would be to get the technical benefit of true wide angle. Not a "simple" factor as cost... then again... money talks I guess *shrug*
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Paul Kay

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Advantage of EF-S
« Reply #14 on: December 16, 2006, 05:08:30 am »

"There is one advantage with full frame lenses on APS-C cameras and that is that vignetting and sharpness fall off will be minimal, simply because the most critical part of the image is not used."

The opposite is rarely true BUT the 60EFS macro lens CAN be used on FF if it is used with the Extension tube 12 (MkII version!) when it becomes a restricted range macro (slightly greater than 1:1 to about 40cm focus). Whilst this is an anomaly due to the specific nature of this being a macro lens, its quality is surprisingly good and it offers all the advantages of fast usm internal focus & non-changing physical size. I've tried it at higher magnifications where it does not perform as well, but if anyone is wondering about the optical costruction of these lenses it does seem to indicate that the quality is well up to that associated with FF lenses, and I'd have no hesitation in recommending this as a FF lens given its restrictions.
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