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What enables the Canon RF 70-200 f/2.8 to be much smaller than the EF version?
Canon 70-200 F4 L USM (non-IS) vs Tamron 70-300 VCWhy do mirrorless cameras have quicker autofocus than SLRs using live view?Does the Canon M have actual, significant deficiencies vs. the competition?Does sensor size dictate lens size with all other things equal?Why are SLR lenses so much larger than Sony E-mount lenses?Should lenses of equal quality for smaller sensors be cheaper?What criteria to consider to match cameras and lenses for shooting people at parties?Why is my large format lens so much smaller (in length) than my 35mm-format lens?Why is the kit zoom lens for Olympus so much smaller than that for Nikon?Does a large mount diameter really allow design advantages for large aperture lenses?
Canon announced the RF 70-200 f/2.8L in February 2019. This is notable for being much smaller than the equivalent EF lens, being perhaps two thirds of the length, yet maintaining the speed of the EF version - see for example the fourth picture on this page.
My perhaps naive understanding was that while the short focal plane distance of mirrorless cameras allowed for smaller retrofocal lenses, the advantage was mostly lost for telephoto lenses. Have I misunderstood this, or have Canon just optimised the RF lens for size, thus presumably giving up something else - if so, what?
canon lens-design mirrorless
add a comment |
Canon announced the RF 70-200 f/2.8L in February 2019. This is notable for being much smaller than the equivalent EF lens, being perhaps two thirds of the length, yet maintaining the speed of the EF version - see for example the fourth picture on this page.
My perhaps naive understanding was that while the short focal plane distance of mirrorless cameras allowed for smaller retrofocal lenses, the advantage was mostly lost for telephoto lenses. Have I misunderstood this, or have Canon just optimised the RF lens for size, thus presumably giving up something else - if so, what?
canon lens-design mirrorless
Diffractive optics, like in the Canon-EF-400mm-f/4.0-DO?
– xenoid
Mar 17 at 18:06
2
@xenoid I think it would have been mentioned by Canon if that were the case.
– Philip Kendall
Mar 17 at 18:14
Agreed. Poring over the patent claim there seem to be just a clever stacking of alternating convergent/divergent lens groups with some tight positional relationships: when zooming, 6 lens groups are moving...
– xenoid
2 days ago
It's only shorter at 70mm. At 200mm it's actually longer.
– Michael C
yesterday
add a comment |
Canon announced the RF 70-200 f/2.8L in February 2019. This is notable for being much smaller than the equivalent EF lens, being perhaps two thirds of the length, yet maintaining the speed of the EF version - see for example the fourth picture on this page.
My perhaps naive understanding was that while the short focal plane distance of mirrorless cameras allowed for smaller retrofocal lenses, the advantage was mostly lost for telephoto lenses. Have I misunderstood this, or have Canon just optimised the RF lens for size, thus presumably giving up something else - if so, what?
canon lens-design mirrorless
Canon announced the RF 70-200 f/2.8L in February 2019. This is notable for being much smaller than the equivalent EF lens, being perhaps two thirds of the length, yet maintaining the speed of the EF version - see for example the fourth picture on this page.
My perhaps naive understanding was that while the short focal plane distance of mirrorless cameras allowed for smaller retrofocal lenses, the advantage was mostly lost for telephoto lenses. Have I misunderstood this, or have Canon just optimised the RF lens for size, thus presumably giving up something else - if so, what?
canon lens-design mirrorless
canon lens-design mirrorless
asked Mar 17 at 15:20
Philip KendallPhilip Kendall
16.7k44983
16.7k44983
Diffractive optics, like in the Canon-EF-400mm-f/4.0-DO?
– xenoid
Mar 17 at 18:06
2
@xenoid I think it would have been mentioned by Canon if that were the case.
– Philip Kendall
Mar 17 at 18:14
Agreed. Poring over the patent claim there seem to be just a clever stacking of alternating convergent/divergent lens groups with some tight positional relationships: when zooming, 6 lens groups are moving...
– xenoid
2 days ago
It's only shorter at 70mm. At 200mm it's actually longer.
– Michael C
yesterday
add a comment |
Diffractive optics, like in the Canon-EF-400mm-f/4.0-DO?
– xenoid
Mar 17 at 18:06
2
@xenoid I think it would have been mentioned by Canon if that were the case.
– Philip Kendall
Mar 17 at 18:14
Agreed. Poring over the patent claim there seem to be just a clever stacking of alternating convergent/divergent lens groups with some tight positional relationships: when zooming, 6 lens groups are moving...
– xenoid
2 days ago
It's only shorter at 70mm. At 200mm it's actually longer.
– Michael C
yesterday
Diffractive optics, like in the Canon-EF-400mm-f/4.0-DO?
– xenoid
Mar 17 at 18:06
Diffractive optics, like in the Canon-EF-400mm-f/4.0-DO?
– xenoid
Mar 17 at 18:06
2
2
@xenoid I think it would have been mentioned by Canon if that were the case.
– Philip Kendall
Mar 17 at 18:14
@xenoid I think it would have been mentioned by Canon if that were the case.
– Philip Kendall
Mar 17 at 18:14
Agreed. Poring over the patent claim there seem to be just a clever stacking of alternating convergent/divergent lens groups with some tight positional relationships: when zooming, 6 lens groups are moving...
– xenoid
2 days ago
Agreed. Poring over the patent claim there seem to be just a clever stacking of alternating convergent/divergent lens groups with some tight positional relationships: when zooming, 6 lens groups are moving...
– xenoid
2 days ago
It's only shorter at 70mm. At 200mm it's actually longer.
– Michael C
yesterday
It's only shorter at 70mm. At 200mm it's actually longer.
– Michael C
yesterday
add a comment |
3 Answers
3
active
oldest
votes
They are two totally different designs.
- One is a non-extending lens that does all of the "zooming" internally.
- The other is an extending zoom lens that is considerably shorter at 70mm than at 200mm.
In fact, the RF 70-200mm f/2.8 L IS is slightly longer than the EF 70-200mm f/2.8 L IS III when the RF lens is zoomed all the way in to 200mm.
Yep, this is the point I missed. Probably because Canon "accidentally" forgot to mention it in their press releases about the lens... have you found any photos of the lens in the fully extended state?
– Philip Kendall
yesterday
I haven't really looked. Every "rumor" I've seen regarding this lens says it is an extending design. No one claims that it does not extend.
– Michael C
yesterday
add a comment |
Lens-rumors.com claims that the US-patent #20190004296
is for the RF 70-200mm F2.8L IS USM
. This patent states:
Focal length [mm] | 72.00 | 135.00 | 194.99
Length of the lens [mm] | 172.73 | 227.50 | 242.86
Found in the patent application's p. 7
So the RF-lens is probably extending with increasing focal lengths.
The official length for the EF 70-200mm F2.8L IS USM III
is 199.0 mm
and it is not extending.
However:
Stolen from ephotozine's hands-on article
That's more than 2.6 cm - I'd say that it is closer to 5 cm (~ 2 inches), so something in the numbers is off.
I further browsed through the illusive patent application and I found three different tables for lens sizes:
[Numerical data 1] Zoom ratio 2.71
-------------------------------------------
Focal Length | 72.00 | 135.00 | 195.00
F-Number | 2.87 | 2.91 | 2.96
Tot. Lens Length | 172.73 | 227.71 | 242.23
[Numerical data 2] Zoom ratio 2.71
-------------------------------------------
Focal Length | 72.00 | 135.00 | 194.99
F-Number | 2.92 | 2.92 | 2.92
Tot. Lens Length | 172.73 | 227.50 | 242.86
[Numerical data 3] Zoom ratio 2.71
-------------------------------------------
Focal Length | 72.00 | 135.00 | 194.98
F-Number | 2.90 | 2.90 | 2.90
Tot. Lens Length | 172.73 | 218.46 | 231.71
[Numerical data 4] Zoom ratio 2.71
-------------------------------------------
Focal Length | 72.00 | 135.00 | 194.98
F-Number | 2.89 | 3.15 | 3.35
Tot. Lens Length | 207.73 | 207.72 | 207.71
[Numerical data 5] Zoom ratio 1.95
-------------------------------------------
Focal Length | 100.00 | 150.00 | 195.00
F-Number | 3.93 | 4.02 | 3.96
Tot. Lens Length | 167.73 | 207.60 | 231.68
This totally beats me...
Simply comparing the lens diagram (global.canon/ja/c-museum/wp-content/uploads/2015/05/…) ... it's a whole different beast. I've no idea how to interpret the changes but, it sure is pretty.
– Hueco
2 days ago
Products do not have to match the dimensions of the patent. they have to match the design elements that make them unique from other, previously patented, design elements.
– Michael C
yesterday
@MichaelC I see, so it is something of a draft how the lens could look like?
– flolilolilo
yesterday
Yes. But if you'll notice, in all of the 5 scenarios listed, the lens is longer than 200mm when extended to the maximum focal length of 195mm. It's much shorter than 200mm in four of the five scenarios when zoomed to 70-100mm. All of them are already longer than 200mm in length when zoomed to 135mm.
– Michael C
yesterday
Here's a less distorted view of the two lenses side-by-side.
– Michael C
yesterday
|
show 3 more comments
It is possible to image using a modest single element lens. Sorry to report, the resulting images will be second-rate. That’s because all lenses suffer from aberrations that degrade. Opticians mitigate aberrations by combining numerous lens elements. Some are positive (convex) and some are negative (concave) as to power. Additionally some are cemented together; others are air-spaced. It takes all this to mitigate aberrations. Nevertheless, residual aberrations always remain.
If the camera were to be fitted with a single element lens and focused on a distant vista, we could take a measurement from the center of the lens to the image plane. This value is the focal length. In a complex lens array, finding the point to make this measurement is more obscure. The point we need to find is called the rear nodal.
Opticians can and do shift the position of the rear nodal. Now a long lens is one that has a long focal length. The longer the focal length, the more magnification it will deliver. A long lens is very desirable if you are into sports or wildlife or the like. However, you might find a long lens to be somewhat awkward.
Opticians have a trick up their sleeve that physically shortens the lens barrel. This is accomplished by shifting the rear nodal forward. If the optician desires, a complex array of lens elements can be constructed so that the rear nodal falls in the air, forward of the front element.
Remember, the focal length is a measure taken from the rear nodal to the image plane. The advantage of such a design is a shorter, less awkward barrel length. Let me add, a true telephoto design differs from the long lens in that the telephoto is foreshortened as to barrel length.
Also, you should know that short wide-angle lenses often place the rear lens group too close to the image plane. If true, there is no room for the mirror mechanism of the SLR. The optician, desiring more room for the back-focus distance, will shift the rear nodal rearward.
1
Your wordy explanation might be interesting...but it doesn't really answer the question in any way.
– osullic
Mar 17 at 16:57
This does not answer my question. Why could Canon design the RF version be shorter than the EF version?
– Philip Kendall
Mar 17 at 16:58
1
The RF version sports a shorter barrel which is less awkward to use. This shorter design is accomplished by shifting the rear nodal forward away from the center point of the lens barrel.
– Alan Marcus
Mar 17 at 21:09
1
It sounds like you are guessing why rather actually knowing.
– Eric Shain
Mar 18 at 1:21
1
I am unable to know about the operation of their mind. In other words, your guess is as good as mine.
– Alan Marcus
Mar 18 at 3:57
|
show 2 more comments
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3 Answers
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active
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votes
3 Answers
3
active
oldest
votes
active
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votes
They are two totally different designs.
- One is a non-extending lens that does all of the "zooming" internally.
- The other is an extending zoom lens that is considerably shorter at 70mm than at 200mm.
In fact, the RF 70-200mm f/2.8 L IS is slightly longer than the EF 70-200mm f/2.8 L IS III when the RF lens is zoomed all the way in to 200mm.
Yep, this is the point I missed. Probably because Canon "accidentally" forgot to mention it in their press releases about the lens... have you found any photos of the lens in the fully extended state?
– Philip Kendall
yesterday
I haven't really looked. Every "rumor" I've seen regarding this lens says it is an extending design. No one claims that it does not extend.
– Michael C
yesterday
add a comment |
They are two totally different designs.
- One is a non-extending lens that does all of the "zooming" internally.
- The other is an extending zoom lens that is considerably shorter at 70mm than at 200mm.
In fact, the RF 70-200mm f/2.8 L IS is slightly longer than the EF 70-200mm f/2.8 L IS III when the RF lens is zoomed all the way in to 200mm.
Yep, this is the point I missed. Probably because Canon "accidentally" forgot to mention it in their press releases about the lens... have you found any photos of the lens in the fully extended state?
– Philip Kendall
yesterday
I haven't really looked. Every "rumor" I've seen regarding this lens says it is an extending design. No one claims that it does not extend.
– Michael C
yesterday
add a comment |
They are two totally different designs.
- One is a non-extending lens that does all of the "zooming" internally.
- The other is an extending zoom lens that is considerably shorter at 70mm than at 200mm.
In fact, the RF 70-200mm f/2.8 L IS is slightly longer than the EF 70-200mm f/2.8 L IS III when the RF lens is zoomed all the way in to 200mm.
They are two totally different designs.
- One is a non-extending lens that does all of the "zooming" internally.
- The other is an extending zoom lens that is considerably shorter at 70mm than at 200mm.
In fact, the RF 70-200mm f/2.8 L IS is slightly longer than the EF 70-200mm f/2.8 L IS III when the RF lens is zoomed all the way in to 200mm.
edited yesterday
Hueco
11.6k32857
11.6k32857
answered yesterday
Michael CMichael C
133k7152378
133k7152378
Yep, this is the point I missed. Probably because Canon "accidentally" forgot to mention it in their press releases about the lens... have you found any photos of the lens in the fully extended state?
– Philip Kendall
yesterday
I haven't really looked. Every "rumor" I've seen regarding this lens says it is an extending design. No one claims that it does not extend.
– Michael C
yesterday
add a comment |
Yep, this is the point I missed. Probably because Canon "accidentally" forgot to mention it in their press releases about the lens... have you found any photos of the lens in the fully extended state?
– Philip Kendall
yesterday
I haven't really looked. Every "rumor" I've seen regarding this lens says it is an extending design. No one claims that it does not extend.
– Michael C
yesterday
Yep, this is the point I missed. Probably because Canon "accidentally" forgot to mention it in their press releases about the lens... have you found any photos of the lens in the fully extended state?
– Philip Kendall
yesterday
Yep, this is the point I missed. Probably because Canon "accidentally" forgot to mention it in their press releases about the lens... have you found any photos of the lens in the fully extended state?
– Philip Kendall
yesterday
I haven't really looked. Every "rumor" I've seen regarding this lens says it is an extending design. No one claims that it does not extend.
– Michael C
yesterday
I haven't really looked. Every "rumor" I've seen regarding this lens says it is an extending design. No one claims that it does not extend.
– Michael C
yesterday
add a comment |
Lens-rumors.com claims that the US-patent #20190004296
is for the RF 70-200mm F2.8L IS USM
. This patent states:
Focal length [mm] | 72.00 | 135.00 | 194.99
Length of the lens [mm] | 172.73 | 227.50 | 242.86
Found in the patent application's p. 7
So the RF-lens is probably extending with increasing focal lengths.
The official length for the EF 70-200mm F2.8L IS USM III
is 199.0 mm
and it is not extending.
However:
Stolen from ephotozine's hands-on article
That's more than 2.6 cm - I'd say that it is closer to 5 cm (~ 2 inches), so something in the numbers is off.
I further browsed through the illusive patent application and I found three different tables for lens sizes:
[Numerical data 1] Zoom ratio 2.71
-------------------------------------------
Focal Length | 72.00 | 135.00 | 195.00
F-Number | 2.87 | 2.91 | 2.96
Tot. Lens Length | 172.73 | 227.71 | 242.23
[Numerical data 2] Zoom ratio 2.71
-------------------------------------------
Focal Length | 72.00 | 135.00 | 194.99
F-Number | 2.92 | 2.92 | 2.92
Tot. Lens Length | 172.73 | 227.50 | 242.86
[Numerical data 3] Zoom ratio 2.71
-------------------------------------------
Focal Length | 72.00 | 135.00 | 194.98
F-Number | 2.90 | 2.90 | 2.90
Tot. Lens Length | 172.73 | 218.46 | 231.71
[Numerical data 4] Zoom ratio 2.71
-------------------------------------------
Focal Length | 72.00 | 135.00 | 194.98
F-Number | 2.89 | 3.15 | 3.35
Tot. Lens Length | 207.73 | 207.72 | 207.71
[Numerical data 5] Zoom ratio 1.95
-------------------------------------------
Focal Length | 100.00 | 150.00 | 195.00
F-Number | 3.93 | 4.02 | 3.96
Tot. Lens Length | 167.73 | 207.60 | 231.68
This totally beats me...
Simply comparing the lens diagram (global.canon/ja/c-museum/wp-content/uploads/2015/05/…) ... it's a whole different beast. I've no idea how to interpret the changes but, it sure is pretty.
– Hueco
2 days ago
Products do not have to match the dimensions of the patent. they have to match the design elements that make them unique from other, previously patented, design elements.
– Michael C
yesterday
@MichaelC I see, so it is something of a draft how the lens could look like?
– flolilolilo
yesterday
Yes. But if you'll notice, in all of the 5 scenarios listed, the lens is longer than 200mm when extended to the maximum focal length of 195mm. It's much shorter than 200mm in four of the five scenarios when zoomed to 70-100mm. All of them are already longer than 200mm in length when zoomed to 135mm.
– Michael C
yesterday
Here's a less distorted view of the two lenses side-by-side.
– Michael C
yesterday
|
show 3 more comments
Lens-rumors.com claims that the US-patent #20190004296
is for the RF 70-200mm F2.8L IS USM
. This patent states:
Focal length [mm] | 72.00 | 135.00 | 194.99
Length of the lens [mm] | 172.73 | 227.50 | 242.86
Found in the patent application's p. 7
So the RF-lens is probably extending with increasing focal lengths.
The official length for the EF 70-200mm F2.8L IS USM III
is 199.0 mm
and it is not extending.
However:
Stolen from ephotozine's hands-on article
That's more than 2.6 cm - I'd say that it is closer to 5 cm (~ 2 inches), so something in the numbers is off.
I further browsed through the illusive patent application and I found three different tables for lens sizes:
[Numerical data 1] Zoom ratio 2.71
-------------------------------------------
Focal Length | 72.00 | 135.00 | 195.00
F-Number | 2.87 | 2.91 | 2.96
Tot. Lens Length | 172.73 | 227.71 | 242.23
[Numerical data 2] Zoom ratio 2.71
-------------------------------------------
Focal Length | 72.00 | 135.00 | 194.99
F-Number | 2.92 | 2.92 | 2.92
Tot. Lens Length | 172.73 | 227.50 | 242.86
[Numerical data 3] Zoom ratio 2.71
-------------------------------------------
Focal Length | 72.00 | 135.00 | 194.98
F-Number | 2.90 | 2.90 | 2.90
Tot. Lens Length | 172.73 | 218.46 | 231.71
[Numerical data 4] Zoom ratio 2.71
-------------------------------------------
Focal Length | 72.00 | 135.00 | 194.98
F-Number | 2.89 | 3.15 | 3.35
Tot. Lens Length | 207.73 | 207.72 | 207.71
[Numerical data 5] Zoom ratio 1.95
-------------------------------------------
Focal Length | 100.00 | 150.00 | 195.00
F-Number | 3.93 | 4.02 | 3.96
Tot. Lens Length | 167.73 | 207.60 | 231.68
This totally beats me...
Simply comparing the lens diagram (global.canon/ja/c-museum/wp-content/uploads/2015/05/…) ... it's a whole different beast. I've no idea how to interpret the changes but, it sure is pretty.
– Hueco
2 days ago
Products do not have to match the dimensions of the patent. they have to match the design elements that make them unique from other, previously patented, design elements.
– Michael C
yesterday
@MichaelC I see, so it is something of a draft how the lens could look like?
– flolilolilo
yesterday
Yes. But if you'll notice, in all of the 5 scenarios listed, the lens is longer than 200mm when extended to the maximum focal length of 195mm. It's much shorter than 200mm in four of the five scenarios when zoomed to 70-100mm. All of them are already longer than 200mm in length when zoomed to 135mm.
– Michael C
yesterday
Here's a less distorted view of the two lenses side-by-side.
– Michael C
yesterday
|
show 3 more comments
Lens-rumors.com claims that the US-patent #20190004296
is for the RF 70-200mm F2.8L IS USM
. This patent states:
Focal length [mm] | 72.00 | 135.00 | 194.99
Length of the lens [mm] | 172.73 | 227.50 | 242.86
Found in the patent application's p. 7
So the RF-lens is probably extending with increasing focal lengths.
The official length for the EF 70-200mm F2.8L IS USM III
is 199.0 mm
and it is not extending.
However:
Stolen from ephotozine's hands-on article
That's more than 2.6 cm - I'd say that it is closer to 5 cm (~ 2 inches), so something in the numbers is off.
I further browsed through the illusive patent application and I found three different tables for lens sizes:
[Numerical data 1] Zoom ratio 2.71
-------------------------------------------
Focal Length | 72.00 | 135.00 | 195.00
F-Number | 2.87 | 2.91 | 2.96
Tot. Lens Length | 172.73 | 227.71 | 242.23
[Numerical data 2] Zoom ratio 2.71
-------------------------------------------
Focal Length | 72.00 | 135.00 | 194.99
F-Number | 2.92 | 2.92 | 2.92
Tot. Lens Length | 172.73 | 227.50 | 242.86
[Numerical data 3] Zoom ratio 2.71
-------------------------------------------
Focal Length | 72.00 | 135.00 | 194.98
F-Number | 2.90 | 2.90 | 2.90
Tot. Lens Length | 172.73 | 218.46 | 231.71
[Numerical data 4] Zoom ratio 2.71
-------------------------------------------
Focal Length | 72.00 | 135.00 | 194.98
F-Number | 2.89 | 3.15 | 3.35
Tot. Lens Length | 207.73 | 207.72 | 207.71
[Numerical data 5] Zoom ratio 1.95
-------------------------------------------
Focal Length | 100.00 | 150.00 | 195.00
F-Number | 3.93 | 4.02 | 3.96
Tot. Lens Length | 167.73 | 207.60 | 231.68
This totally beats me...
Lens-rumors.com claims that the US-patent #20190004296
is for the RF 70-200mm F2.8L IS USM
. This patent states:
Focal length [mm] | 72.00 | 135.00 | 194.99
Length of the lens [mm] | 172.73 | 227.50 | 242.86
Found in the patent application's p. 7
So the RF-lens is probably extending with increasing focal lengths.
The official length for the EF 70-200mm F2.8L IS USM III
is 199.0 mm
and it is not extending.
However:
Stolen from ephotozine's hands-on article
That's more than 2.6 cm - I'd say that it is closer to 5 cm (~ 2 inches), so something in the numbers is off.
I further browsed through the illusive patent application and I found three different tables for lens sizes:
[Numerical data 1] Zoom ratio 2.71
-------------------------------------------
Focal Length | 72.00 | 135.00 | 195.00
F-Number | 2.87 | 2.91 | 2.96
Tot. Lens Length | 172.73 | 227.71 | 242.23
[Numerical data 2] Zoom ratio 2.71
-------------------------------------------
Focal Length | 72.00 | 135.00 | 194.99
F-Number | 2.92 | 2.92 | 2.92
Tot. Lens Length | 172.73 | 227.50 | 242.86
[Numerical data 3] Zoom ratio 2.71
-------------------------------------------
Focal Length | 72.00 | 135.00 | 194.98
F-Number | 2.90 | 2.90 | 2.90
Tot. Lens Length | 172.73 | 218.46 | 231.71
[Numerical data 4] Zoom ratio 2.71
-------------------------------------------
Focal Length | 72.00 | 135.00 | 194.98
F-Number | 2.89 | 3.15 | 3.35
Tot. Lens Length | 207.73 | 207.72 | 207.71
[Numerical data 5] Zoom ratio 1.95
-------------------------------------------
Focal Length | 100.00 | 150.00 | 195.00
F-Number | 3.93 | 4.02 | 3.96
Tot. Lens Length | 167.73 | 207.60 | 231.68
This totally beats me...
edited Mar 17 at 16:44
answered Mar 17 at 16:15
floliloliloflolilolilo
5,05411835
5,05411835
Simply comparing the lens diagram (global.canon/ja/c-museum/wp-content/uploads/2015/05/…) ... it's a whole different beast. I've no idea how to interpret the changes but, it sure is pretty.
– Hueco
2 days ago
Products do not have to match the dimensions of the patent. they have to match the design elements that make them unique from other, previously patented, design elements.
– Michael C
yesterday
@MichaelC I see, so it is something of a draft how the lens could look like?
– flolilolilo
yesterday
Yes. But if you'll notice, in all of the 5 scenarios listed, the lens is longer than 200mm when extended to the maximum focal length of 195mm. It's much shorter than 200mm in four of the five scenarios when zoomed to 70-100mm. All of them are already longer than 200mm in length when zoomed to 135mm.
– Michael C
yesterday
Here's a less distorted view of the two lenses side-by-side.
– Michael C
yesterday
|
show 3 more comments
Simply comparing the lens diagram (global.canon/ja/c-museum/wp-content/uploads/2015/05/…) ... it's a whole different beast. I've no idea how to interpret the changes but, it sure is pretty.
– Hueco
2 days ago
Products do not have to match the dimensions of the patent. they have to match the design elements that make them unique from other, previously patented, design elements.
– Michael C
yesterday
@MichaelC I see, so it is something of a draft how the lens could look like?
– flolilolilo
yesterday
Yes. But if you'll notice, in all of the 5 scenarios listed, the lens is longer than 200mm when extended to the maximum focal length of 195mm. It's much shorter than 200mm in four of the five scenarios when zoomed to 70-100mm. All of them are already longer than 200mm in length when zoomed to 135mm.
– Michael C
yesterday
Here's a less distorted view of the two lenses side-by-side.
– Michael C
yesterday
Simply comparing the lens diagram (global.canon/ja/c-museum/wp-content/uploads/2015/05/…) ... it's a whole different beast. I've no idea how to interpret the changes but, it sure is pretty.
– Hueco
2 days ago
Simply comparing the lens diagram (global.canon/ja/c-museum/wp-content/uploads/2015/05/…) ... it's a whole different beast. I've no idea how to interpret the changes but, it sure is pretty.
– Hueco
2 days ago
Products do not have to match the dimensions of the patent. they have to match the design elements that make them unique from other, previously patented, design elements.
– Michael C
yesterday
Products do not have to match the dimensions of the patent. they have to match the design elements that make them unique from other, previously patented, design elements.
– Michael C
yesterday
@MichaelC I see, so it is something of a draft how the lens could look like?
– flolilolilo
yesterday
@MichaelC I see, so it is something of a draft how the lens could look like?
– flolilolilo
yesterday
Yes. But if you'll notice, in all of the 5 scenarios listed, the lens is longer than 200mm when extended to the maximum focal length of 195mm. It's much shorter than 200mm in four of the five scenarios when zoomed to 70-100mm. All of them are already longer than 200mm in length when zoomed to 135mm.
– Michael C
yesterday
Yes. But if you'll notice, in all of the 5 scenarios listed, the lens is longer than 200mm when extended to the maximum focal length of 195mm. It's much shorter than 200mm in four of the five scenarios when zoomed to 70-100mm. All of them are already longer than 200mm in length when zoomed to 135mm.
– Michael C
yesterday
Here's a less distorted view of the two lenses side-by-side.
– Michael C
yesterday
Here's a less distorted view of the two lenses side-by-side.
– Michael C
yesterday
|
show 3 more comments
It is possible to image using a modest single element lens. Sorry to report, the resulting images will be second-rate. That’s because all lenses suffer from aberrations that degrade. Opticians mitigate aberrations by combining numerous lens elements. Some are positive (convex) and some are negative (concave) as to power. Additionally some are cemented together; others are air-spaced. It takes all this to mitigate aberrations. Nevertheless, residual aberrations always remain.
If the camera were to be fitted with a single element lens and focused on a distant vista, we could take a measurement from the center of the lens to the image plane. This value is the focal length. In a complex lens array, finding the point to make this measurement is more obscure. The point we need to find is called the rear nodal.
Opticians can and do shift the position of the rear nodal. Now a long lens is one that has a long focal length. The longer the focal length, the more magnification it will deliver. A long lens is very desirable if you are into sports or wildlife or the like. However, you might find a long lens to be somewhat awkward.
Opticians have a trick up their sleeve that physically shortens the lens barrel. This is accomplished by shifting the rear nodal forward. If the optician desires, a complex array of lens elements can be constructed so that the rear nodal falls in the air, forward of the front element.
Remember, the focal length is a measure taken from the rear nodal to the image plane. The advantage of such a design is a shorter, less awkward barrel length. Let me add, a true telephoto design differs from the long lens in that the telephoto is foreshortened as to barrel length.
Also, you should know that short wide-angle lenses often place the rear lens group too close to the image plane. If true, there is no room for the mirror mechanism of the SLR. The optician, desiring more room for the back-focus distance, will shift the rear nodal rearward.
1
Your wordy explanation might be interesting...but it doesn't really answer the question in any way.
– osullic
Mar 17 at 16:57
This does not answer my question. Why could Canon design the RF version be shorter than the EF version?
– Philip Kendall
Mar 17 at 16:58
1
The RF version sports a shorter barrel which is less awkward to use. This shorter design is accomplished by shifting the rear nodal forward away from the center point of the lens barrel.
– Alan Marcus
Mar 17 at 21:09
1
It sounds like you are guessing why rather actually knowing.
– Eric Shain
Mar 18 at 1:21
1
I am unable to know about the operation of their mind. In other words, your guess is as good as mine.
– Alan Marcus
Mar 18 at 3:57
|
show 2 more comments
It is possible to image using a modest single element lens. Sorry to report, the resulting images will be second-rate. That’s because all lenses suffer from aberrations that degrade. Opticians mitigate aberrations by combining numerous lens elements. Some are positive (convex) and some are negative (concave) as to power. Additionally some are cemented together; others are air-spaced. It takes all this to mitigate aberrations. Nevertheless, residual aberrations always remain.
If the camera were to be fitted with a single element lens and focused on a distant vista, we could take a measurement from the center of the lens to the image plane. This value is the focal length. In a complex lens array, finding the point to make this measurement is more obscure. The point we need to find is called the rear nodal.
Opticians can and do shift the position of the rear nodal. Now a long lens is one that has a long focal length. The longer the focal length, the more magnification it will deliver. A long lens is very desirable if you are into sports or wildlife or the like. However, you might find a long lens to be somewhat awkward.
Opticians have a trick up their sleeve that physically shortens the lens barrel. This is accomplished by shifting the rear nodal forward. If the optician desires, a complex array of lens elements can be constructed so that the rear nodal falls in the air, forward of the front element.
Remember, the focal length is a measure taken from the rear nodal to the image plane. The advantage of such a design is a shorter, less awkward barrel length. Let me add, a true telephoto design differs from the long lens in that the telephoto is foreshortened as to barrel length.
Also, you should know that short wide-angle lenses often place the rear lens group too close to the image plane. If true, there is no room for the mirror mechanism of the SLR. The optician, desiring more room for the back-focus distance, will shift the rear nodal rearward.
1
Your wordy explanation might be interesting...but it doesn't really answer the question in any way.
– osullic
Mar 17 at 16:57
This does not answer my question. Why could Canon design the RF version be shorter than the EF version?
– Philip Kendall
Mar 17 at 16:58
1
The RF version sports a shorter barrel which is less awkward to use. This shorter design is accomplished by shifting the rear nodal forward away from the center point of the lens barrel.
– Alan Marcus
Mar 17 at 21:09
1
It sounds like you are guessing why rather actually knowing.
– Eric Shain
Mar 18 at 1:21
1
I am unable to know about the operation of their mind. In other words, your guess is as good as mine.
– Alan Marcus
Mar 18 at 3:57
|
show 2 more comments
It is possible to image using a modest single element lens. Sorry to report, the resulting images will be second-rate. That’s because all lenses suffer from aberrations that degrade. Opticians mitigate aberrations by combining numerous lens elements. Some are positive (convex) and some are negative (concave) as to power. Additionally some are cemented together; others are air-spaced. It takes all this to mitigate aberrations. Nevertheless, residual aberrations always remain.
If the camera were to be fitted with a single element lens and focused on a distant vista, we could take a measurement from the center of the lens to the image plane. This value is the focal length. In a complex lens array, finding the point to make this measurement is more obscure. The point we need to find is called the rear nodal.
Opticians can and do shift the position of the rear nodal. Now a long lens is one that has a long focal length. The longer the focal length, the more magnification it will deliver. A long lens is very desirable if you are into sports or wildlife or the like. However, you might find a long lens to be somewhat awkward.
Opticians have a trick up their sleeve that physically shortens the lens barrel. This is accomplished by shifting the rear nodal forward. If the optician desires, a complex array of lens elements can be constructed so that the rear nodal falls in the air, forward of the front element.
Remember, the focal length is a measure taken from the rear nodal to the image plane. The advantage of such a design is a shorter, less awkward barrel length. Let me add, a true telephoto design differs from the long lens in that the telephoto is foreshortened as to barrel length.
Also, you should know that short wide-angle lenses often place the rear lens group too close to the image plane. If true, there is no room for the mirror mechanism of the SLR. The optician, desiring more room for the back-focus distance, will shift the rear nodal rearward.
It is possible to image using a modest single element lens. Sorry to report, the resulting images will be second-rate. That’s because all lenses suffer from aberrations that degrade. Opticians mitigate aberrations by combining numerous lens elements. Some are positive (convex) and some are negative (concave) as to power. Additionally some are cemented together; others are air-spaced. It takes all this to mitigate aberrations. Nevertheless, residual aberrations always remain.
If the camera were to be fitted with a single element lens and focused on a distant vista, we could take a measurement from the center of the lens to the image plane. This value is the focal length. In a complex lens array, finding the point to make this measurement is more obscure. The point we need to find is called the rear nodal.
Opticians can and do shift the position of the rear nodal. Now a long lens is one that has a long focal length. The longer the focal length, the more magnification it will deliver. A long lens is very desirable if you are into sports or wildlife or the like. However, you might find a long lens to be somewhat awkward.
Opticians have a trick up their sleeve that physically shortens the lens barrel. This is accomplished by shifting the rear nodal forward. If the optician desires, a complex array of lens elements can be constructed so that the rear nodal falls in the air, forward of the front element.
Remember, the focal length is a measure taken from the rear nodal to the image plane. The advantage of such a design is a shorter, less awkward barrel length. Let me add, a true telephoto design differs from the long lens in that the telephoto is foreshortened as to barrel length.
Also, you should know that short wide-angle lenses often place the rear lens group too close to the image plane. If true, there is no room for the mirror mechanism of the SLR. The optician, desiring more room for the back-focus distance, will shift the rear nodal rearward.
answered Mar 17 at 16:36
Alan MarcusAlan Marcus
25.7k23060
25.7k23060
1
Your wordy explanation might be interesting...but it doesn't really answer the question in any way.
– osullic
Mar 17 at 16:57
This does not answer my question. Why could Canon design the RF version be shorter than the EF version?
– Philip Kendall
Mar 17 at 16:58
1
The RF version sports a shorter barrel which is less awkward to use. This shorter design is accomplished by shifting the rear nodal forward away from the center point of the lens barrel.
– Alan Marcus
Mar 17 at 21:09
1
It sounds like you are guessing why rather actually knowing.
– Eric Shain
Mar 18 at 1:21
1
I am unable to know about the operation of their mind. In other words, your guess is as good as mine.
– Alan Marcus
Mar 18 at 3:57
|
show 2 more comments
1
Your wordy explanation might be interesting...but it doesn't really answer the question in any way.
– osullic
Mar 17 at 16:57
This does not answer my question. Why could Canon design the RF version be shorter than the EF version?
– Philip Kendall
Mar 17 at 16:58
1
The RF version sports a shorter barrel which is less awkward to use. This shorter design is accomplished by shifting the rear nodal forward away from the center point of the lens barrel.
– Alan Marcus
Mar 17 at 21:09
1
It sounds like you are guessing why rather actually knowing.
– Eric Shain
Mar 18 at 1:21
1
I am unable to know about the operation of their mind. In other words, your guess is as good as mine.
– Alan Marcus
Mar 18 at 3:57
1
1
Your wordy explanation might be interesting...but it doesn't really answer the question in any way.
– osullic
Mar 17 at 16:57
Your wordy explanation might be interesting...but it doesn't really answer the question in any way.
– osullic
Mar 17 at 16:57
This does not answer my question. Why could Canon design the RF version be shorter than the EF version?
– Philip Kendall
Mar 17 at 16:58
This does not answer my question. Why could Canon design the RF version be shorter than the EF version?
– Philip Kendall
Mar 17 at 16:58
1
1
The RF version sports a shorter barrel which is less awkward to use. This shorter design is accomplished by shifting the rear nodal forward away from the center point of the lens barrel.
– Alan Marcus
Mar 17 at 21:09
The RF version sports a shorter barrel which is less awkward to use. This shorter design is accomplished by shifting the rear nodal forward away from the center point of the lens barrel.
– Alan Marcus
Mar 17 at 21:09
1
1
It sounds like you are guessing why rather actually knowing.
– Eric Shain
Mar 18 at 1:21
It sounds like you are guessing why rather actually knowing.
– Eric Shain
Mar 18 at 1:21
1
1
I am unable to know about the operation of their mind. In other words, your guess is as good as mine.
– Alan Marcus
Mar 18 at 3:57
I am unable to know about the operation of their mind. In other words, your guess is as good as mine.
– Alan Marcus
Mar 18 at 3:57
|
show 2 more comments
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Diffractive optics, like in the Canon-EF-400mm-f/4.0-DO?
– xenoid
Mar 17 at 18:06
2
@xenoid I think it would have been mentioned by Canon if that were the case.
– Philip Kendall
Mar 17 at 18:14
Agreed. Poring over the patent claim there seem to be just a clever stacking of alternating convergent/divergent lens groups with some tight positional relationships: when zooming, 6 lens groups are moving...
– xenoid
2 days ago
It's only shorter at 70mm. At 200mm it's actually longer.
– Michael C
yesterday