L Lenses for crop bodies

[Loswr]

[quote author=Canon USA]
Highly regarded among professional photographers, Canon L-series lenses are distinguished by a bold red ring around the outer barrel. What makes them truly distinctive, however, is their remarkable optical performance — the result of sophisticated Canon technologies, such as Ultra-low Dispersion (UD) glass, Fluorite and Aspherical elements, and Super Spectra Multi Coating.

Yep. I read that marketing schpeil. 'What makes them truly distinctive, however, is their remarkable optical performance' yet there are non-L's that out-perform or match equivalent L's. The use of 'such as' supports my point.

There are other lenses with UD and Aspherical elements, and not every L uses flourite elements.

I have a set of expectations that go along with spending the extra money on an L lens. And with the exception of the 17-40, my expectations have been met or exceeded. But to me, that is all that L means.

And to go back to the OP's debate, I therfore don't think that there is any need for 'L' ef-s lenses, as L doesn't actually define anything.
[/quote]

I agree that there's not a firm 'definition' of what comprises an L-series feature set, there are a few points worth making. First is time - lens designs span many years. You mention the 135L - that lens was released in 1996 and is still 'current'. If I may be permitted a car analogy, for the base model Honda Civic in 1996, air conditioning was optional and power windows/locks were not available; on the 2013 base model Civic, those features are standard.

Second, there are differences beyond just the top line specs. For example, you mentioned aspherical lenses – there are actually four different types of aspherical elements that Canon uses. In decending order of quality (and cost), they are:

1. ground and polished glass aspherical lens element.
2. molded glass aspherical lens element.
3. molded plastic aspherical lens element produced by a high-precision molding technology.
4. replica aspherical lens element, ultraviolet-light-hardening resin layer on a spherical glass lens element.

L-series Lenses tend to use the first two types, where as non-L lenses tend to use aspherical elements from further down the list, but again there are no strict rules.

So, overall I guess I'd say that "what makes an L lens" is a gestalt sort of thing.

 

[Pi]

I sold my 17-40 as, optically at least, the 18-55 IS mk1 was quite a bit better than it, on APS-C obviously. I don't know that IQ is strictly speaking always a parameter.

It is but on the format it was designed for.

 

[vscd]

I would go further...

...when a L-Lense is released, there is no better Lense from Canon available in the same focalrange. This doesn't mean that a new EF-Lense isn't capable to beat an older L-Lense-Design.

For example a good comparision is the 100mm 2.8 and the 100mm 2.8 L IS. On the optical formular, both are nearly identical and there is no need to upgrade to the "L"-Lense if you just need a Macro. The difference between both are features like a 9 Blade Aperture, Image Stabilization, weathersealing, LensHood or even a leatherbag. You don't need those features to get a picture but you will appreciate them if you use the lense more regularly. This is called "luxury" in some terms. So, the meaning of "L" is to extend the normal lense to something more "professionall" or to get around the budgetplanning and lowcost-hunters.

If you buy a Carl Zeiss Lense, you always get an "L" Lense price and quality, but you won't get something in normal price-ranges. Canon gives you the choice... budget or as it was meant to be.

 

[Marsu42]

For example a good comparision is the 100mm 2.8 and the 100mm 2.8 L IS. On the optical formular, both are nearly identical and there is no need to upgrade to the "L"-Lense if you just need a Macro.

The non-L has more CA wide open and the L is a tad sharper - but as you pointed out nothing to write home about and it's rather unlikely to get this with macro, it's matters more for dual use which is also the reason the L has the focus limiter switch.

http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=107&Camera=736&FLI=0&API=0&LensComp=674&Sample=0&CameraComp=736&FLIComp=0&APIComp=0

 

[dgatwood]

Yep, but in a cropped sensor context, we are discussing whether there is a need for EF-s L lenses.

I think there's a need for EF-S prime lenses, if only because they would be significantly lighter than their EF counterparts. There's also a need for weather-sealed EF-S lenses. Whether you want to then call them "L" lenses or not is a purely marketing decision.

 

[Busted Knuckles]

Wading in....

There are very few, if any, lenses that can fully resolve corner to corner the precision of the current batch of sensors. Even the $4000 zeiss is does not fully resolve a 1dx sensor - don't even think about the d800

With the pixel size of the APC sensor, (heaven forbid the 12 mp micro sensors on phones & P&S or if Canon just went FF w/ the 70d sensor) all the glass has to get better to meet the capabilities of the current fleet of sensors. One need only compare the fuzziness of ISO images on TDP between a FF and APC sensor - pixel size does matter for the same framing/effective focal length. (composition is different between APC & FF equivalents and Brian at TDP has a great comparison in one of his reviews relative to background vs foreground - just wish I could remember which one. oooof I am getting old)

So back to the subject at hand. L glass for the APC sensor size. Sigma 18-35, canon (perhaps now sigma) 24-105, canon 55-250, represents a lot of image quality, overlap so you aren't changing out a lens every 30 seconds, and not a whole lot of money.

 

[vscd]

Fast primes for APS-C? ...for example the new Canon 24mm or 28mm IS is some kind of "L" Lenses for APS-C in my opinion. It has fantastic optics, stands for standard focal range on APS-C (Equiv 38.4/44.8), has IS and is listed for a higher price actually. It has no "L" designation, but I think this is aimed to the APS-C users

 

[dgatwood]

Fast primes for APS-C? ...for example the new Canon 24mm or 28mm IS is some kind of "L" Lenses for APS-C in my opinion. It has fantastic optics, stands for standard focal range on APS-C (Equiv 38.4/44.8), has IS and is listed for a higher price actually. It has no "L" designation, but I think this is aimed to the APS-C users

Sure, you can use EF lenses on an APS-C camera. That still misses the point, which is that an EF-S prime would be about two-thirds the size of an EF prime at the same focal length. Folks who shoot solely with crop bodies are carrying around a lot of extra weight and bulk if they carry EF primes.

 

[Loswr]

Sure, you can use EF lenses on an APS-C camera. That still misses the point, which is that an EF-S prime would be about two-thirds the size of an EF prime at the same focal length. Folks who shoot solely with crop bodies are carrying around a lot of extra weight and bulk if they carry EF primes.

What's the basis for that? The only current EF-S prime is the 60/2.8 macro, and it's bigger and heavier than the 50/1.4 and 50/2.5 macro, and the 85/1.8 is similar in size and 25% heavier. Or maybe you're comparing the Sigma 30/1.4 DC to the Canon 35/1.4L, not really a fair comparison, IMO.

 

[Zv]

Sure, you can use EF lenses on an APS-C camera. That still misses the point, which is that an EF-S prime would be about two-thirds the size of an EF prime at the same focal length. Folks who shoot solely with crop bodies are carrying around a lot of extra weight and bulk if they carry EF primes.

What's the basis for that? The only current EF-S prime is the 60/2.8 macro, and it's bigger and heavier than the 50/1.4 and 50/2.5 macro, and the 85/1.8 is similar in size and 25% heavier. Or maybe you're comparing the Sigma 30/1.4 DC to the Canon 35/1.4L, not really a fair comparison, IMO.

There are plenty of "light" EF lenses - let me see now, there's the 40mm f/2.8 pancake (don't get much lighter than that), the 35mm f/2 and newer IS version, the 28mm 1.8, the plastic (not so) fantastic 50mm f/1.8II, the 50mm f/1.4 isn't that heavy either and then there's the 24&28 f/2.8IS are quite small and compact too. The 85mm f/1.8 and 100mm f/2 are relatively light too.

I really don't see why we need more lighter EF-S lenses when there already are a bunch of very good EF lenses that cover a wide range of focal lengths and work on all cameras.

To me light = will break easily, like the 50mm f/1.8II. I don't want that. I'd rather have something with some weight for counterbalance and sturdiness.

And really, are the crop body users carrying a lot of unnecessary weight?? I don't think a couple of extra grams is going to make any significant difference. If they are that feeble maybe they ought to leave the DSLRs to the big adults and just use their little toy lego camera instead.

 

[vscd]

I really don't see why we need more lighter EF-S lenses when there already are a bunch of very good EF lenses that cover a wide range of focal lengths and work on all cameras.

I second that. There are already some (really!) fantastic EF_Primes out there like the 40mm 2.8. You can't make it much smaller even if you want to.

The thought of making "smaller" Lenses for APS-C only (on Canonbodies) is a wrong one, because the Bayonett (and so the diameter) plus the Flange focal distance are the same. If you design a new Camera with a smaller bayonett like an EOS-M you could get advantages in size, but as the EF-S is just a trimmed EF-mount... you get all the downsides but no real gain.

The only chance is to get shorter lenses if they reach into the mirrorbox.

 

[dufflover]

I don't think you can really count the Canon pancake lenses as being an example given their respective FLs (40mm on mirrored bodies, 22mm on mirrorless) allow it for those systems.

 

[Loswr]

The only chance is to get shorter lenses if they reach into the mirrorbox.

The EF-S 10-22mm does just that.

 

[dgatwood]

The only chance is to get shorter lenses if they reach into the mirrorbox.

The EF-S 10-22mm does just that.

And it's not just about length. Output pupil diameter at a given focal length is proportional to the lens diameter. An EF-S lens can get away with a smaller exit pupil (smaller sensor to cover), so you can make the lens diameter smaller and use less glass for each element, which translates to a much lighter lens.

 

[Loswr]

And it's not just about length. Output pupil diameter at a given focal length is proportional to the lens diameter. An EF-S lens can get away with a smaller exit pupil (smaller sensor to cover), so you can make the lens diameter smaller and use less glass for each element, which translates to a much lighter lens.

That's a nice theory (although it doesn't apply to all lens design types), but does it work that way in practice? Do you have any evidence to support your earlier statement:

Sure, you can use EF lenses on an APS-C camera. That still misses the point, which is that an EF-S prime would be about two-thirds the size of an EF prime at the same focal length. Folks who shoot solely with crop bodies are carrying around a lot of extra weight and bulk if they carry EF primes.

What's the basis for that? The only current EF-S prime is the 60/2.8 macro, and it's bigger and heavier than the 50/1.4 and 50/2.5 macro, and the 85/1.8 is similar in size and 25% heavier. Or maybe you're comparing the Sigma 30/1.4 DC to the Canon 35/1.4L, not really a fair comparison, IMO.

Another example: the Nikon 35/1.8 DX is the same weight, is longer and has a larger diameter than the 35/2 FX lens.

I think the bottom line is that other design considerations (more elements for better optical correction, glass vs. plastic elements, etc.) will mostly trump the theoretical size/weight advantages of the smaller image circle.

 

[candc]

And it's not just about length. Output pupil diameter at a given focal length is proportional to the lens diameter. An EF-S lens can get away with a smaller exit pupil (smaller sensor to cover), so you can make the lens diameter smaller and use less glass for each element, which translates to a much lighter lens.

That's a nice theory (although it doesn't apply to all lens design types), but does it work that way in practice? Do you have any evidence to support your earlier statement:

Sure, you can use EF lenses on an APS-C camera. That still misses the point, which is that an EF-S prime would be about two-thirds the size of an EF prime at the same focal length. Folks who shoot solely with crop bodies are carrying around a lot of extra weight and bulk if they carry EF primes.

What's the basis for that? The only current EF-S prime is the 60/2.8 macro, and it's bigger and heavier than the 50/1.4 and 50/2.5 macro, and the 85/1.8 is similar in size and 25% heavier. Or maybe you're comparing the Sigma 30/1.4 DC to the Canon 35/1.4L, not really a fair comparison, IMO.

Another example: the Nikon 35/1.8 DX is the same weight, is longer and has a larger diameter than the 35/2 FX lens.

I think the bottom line is that other design considerations (more elements for better optical correction, glass vs. plastic elements, etc.) will mostly trump the theoretical size/weight advantages of the smaller image circle.

another good example is the sigma 50-150 dc lens which is supposed to be equivalent to the 70-200 ff version. they are the same size and weight, in fact i think they use the same barrel and most other parts.

 

[WPJ]

Any L lens will perform just as good is not better on a crop as you won't get as much of the soft corners people always complain about.

it all comes down to put it on your body, if you like the field of view it offers shoot. If not change glass and try again, L or non L

 

[dgatwood]

What's the basis for that? The only current EF-S prime is the 60/2.8 macro, and it's bigger and heavier than the 50/1.4 and 50/2.5 macro, and the 85/1.8 is similar in size and 25% heavier. Or maybe you're comparing the Sigma 30/1.4 DC to the Canon 35/1.4L, not really a fair comparison, IMO.

You'll notice I said "for a given focal length". To be completely precise, I should have said, "for a given focal length, maximum aperture, and minimum focusing distance". You can't really compare apples to oranges.

That said, making the lens smaller and lighter is just one possible option, obtained by using a similar number of elements and a similar design. Alternatively, instead of making the lens smaller and lighter, you could instead choose to provide a larger maximum aperture, add macro capabilities, or correct for CA and other artifacts more completely (which is arguably more critical when you're dealing with the higher pixel density on crop bodies). Either way, there's still a benefit over the full-frame glass.

 

[Loswr]

You'll notice I said "for a given focal length". To be completely precise, I should have said, "for a given focal length, maximum aperture, and minimum focusing distance". You can't really compare apples to oranges.

That said, making the lens smaller and lighter is just one possible option, obtained by using a similar number of elements and a similar design. Alternatively, instead of making the lens smaller and lighter, you could instead choose to provide a larger maximum aperture, add macro capabilities, or correct for CA and other artifacts more completely (which is arguably more critical when you're dealing with the higher pixel density on crop bodies). Either way, there's still a benefit over the full-frame glass.

Perhaps...but the point seems rather moot for the original discussion concerning EF-S primes, since there's only one. Also, I wasn't questioning that an EF-S lens could be smaller and lighter than the same focal length/aperture in an EF lens, but rather your figure of 'two-thirds' the size.

Any L lens will perform just as good is not better on a crop as you won't get as much of the soft corners people always complain about.

I disagree. First, you have to take the sensor into account - you'll get better IQ out of the combination of L-lens and FF sensor than that lens on APS-C, even considering the soft corners of an UWA zoom. Second, an L-lens on crop won't necessarily outperform an EF-S lens - for example, the EF-S 17-55mm is better than both the 17-40L and 24-105L on the same crop body.

 

[dgatwood]

I second that. There are already some (really!) fantastic EF_Primes out there like the 40mm 2.8. You can't make it much smaller even if you want to.

Well, you probably could, but then you would have to choose between being able to manually focus the lens and being able to grip it to attach it and remove it.

But seriously, yeah, that's one nice piece of engineering, IMO. Making medium to wide lenses smaller than that almost certainly isn't very useful. Making long lenses smaller, however, is useful if you can pull it off without losing too much image quality.

Any L lens will perform just as good is not better on a crop as you won't get as much of the soft corners people always complain about.

That is true only if the crop body's resolution is areally proportionate to that of the full-frame sensor—that is, if the crop body is the equivalent of cropping a full-frame shot down to APS-C size. In practice, however, that's almost never the case, because nobody wants to buy an 8MP crop body these days.

A given lens can only resolve features up to its angular (spatial) resolution. So suppose you have a lens whose resolution is barely good enough for a full-frame sensor. Assuming that the crop sensor has the same number of pixels as the full-frame sensor, the pixels are smaller which means that the circle of confusion covers more pixels on the crop sensor. As a result, if you use foot zooming to get an identical shot on a crop body and a full-frame body (ignoring parallax differences for the moment), the full-frame shot would be, on the whole, sharper than the same shot taken on the crop body.

The fact that you're using the sharper, center part of the lens mitigates that difference somewhat, of course. The result, as I understand it, is that the corners tend to be sharper, but the center is much less sharp. Of course, if the center of the lens is way sharper than it needs to be for a full-frame body, then you'll get a sharper image overall. In practice, this is usually not the case, however, because when you design a lens, you can only get more sharpness by giving up something else (e.g. by making the objective lens bigger and bulkier, which also makes the lens and filters more expensive).

Perhaps...but the point seems rather moot for the original discussion concerning EF-S primes, since there's only one. Also, I wasn't questioning that an EF-S lens could be smaller and lighter than the same focal length/aperture in an EF lens, but rather your figure of 'two-thirds' the size.

My point was that you could make them that much smaller, not that any manufacturer necessarily would. It's probably better to compromise between making them smaller and increasing the resolution.