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Author Topic: L Lenses for crop bodies  (Read 25978 times)

vscd

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Re: L Lenses for crop bodies
« Reply #210 on: November 29, 2013, 03:10:23 AM »
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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.
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Re: L Lenses for crop bodies
« Reply #210 on: November 29, 2013, 03:10:23 AM »

dufflover

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Re: L Lenses for crop bodies
« Reply #211 on: November 29, 2013, 06:41:49 AM »
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.
Hurry up Canon and do something with your sensors! :P

neuroanatomist

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Re: L Lenses for crop bodies
« Reply #212 on: November 29, 2013, 07:01:32 AM »
The only chance is to get shorter lenses if they reach into the mirrorbox.

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

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Re: L Lenses for crop bodies
« Reply #213 on: November 29, 2013, 08:57:57 AM »
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.

neuroanatomist

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Re: L Lenses for crop bodies
« Reply #214 on: November 29, 2013, 10:01:34 AM »
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.
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candc

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Re: L Lenses for crop bodies
« Reply #215 on: November 29, 2013, 10:40:27 AM »
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.

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Re: L Lenses for crop bodies
« Reply #216 on: November 29, 2013, 10:56:18 AM »
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

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Re: L Lenses for crop bodies
« Reply #216 on: November 29, 2013, 10:56:18 AM »

dgatwood

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Re: L Lenses for crop bodies
« Reply #217 on: November 29, 2013, 11:20:02 AM »
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.

neuroanatomist

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Re: L Lenses for crop bodies
« Reply #218 on: November 29, 2013, 12:25:16 PM »
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.
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dgatwood

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Re: L Lenses for crop bodies
« Reply #219 on: November 29, 2013, 12:35:58 PM »
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.  :D

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.

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Re: L Lenses for crop bodies
« Reply #220 on: November 29, 2013, 02:37:27 PM »


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.

Since I don't have the EF-S 17-55, I can't comment on that lens.  I have read that it is quite impressive, and some argue that it should be the EF-S 17-55L  ;).  However I am pleased with both the 17-40L and the 24-105L on my 7d, and enjoy the added bonus that I can use either on my 5d3 as well. 
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Re: L Lenses for crop bodies
« Reply #221 on: November 29, 2013, 02:52:01 PM »
Surely there are plenty of L lenses for crop bodies. Just snap one on and start shooting.

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Re: L Lenses for crop bodies
« Reply #222 on: November 29, 2013, 03:59:35 PM »
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.

but your not,comparing similar lenses, toss the 25-105,  or you can't say that because the 24-105 is way better at 60mm than the 17-55 considering it won't go there.

and for the 17-55 vs the 17-40, that's f2.8vsf4, I would naturally expect the f2.8 to be better.

lets talk apples to apples, but really there is non.

my point is that there is nothing wrong with using,L glass on a crop

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.

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Re: L Lenses for crop bodies
« Reply #222 on: November 29, 2013, 03:59:35 PM »