A Canon RF 16-28mm f/2L USM is coming [CR1]

neuroanatomist

I post too Much on Here!!
Jul 21, 2010
24,645
2,159
My 70-200mm f/2.8L IS II USM, may it rest in peace, had dust between the front element and the one behind it, though it doesn't extend.
Of course. The back of the lens is open, so air (and dust, OMG!) get in. Zooming and focusing move element groups within the lens, and that moves around the air (and dust, OMG!) inside the lens.

Some people seem to think non-extending zooms are hermetically sealed. Lol.
 

SwissFrank

from EOS 1N to R
Dec 9, 2018
414
180
Anyway, I'm sure somebody here could do the math and figure out how large the lens would have to be.
Wider than 50mm it's easy to calculate: focal length divided by f-stop gives the size of the "entrance pupil," the hole you see when you hold a lens up and look at a white wall through it going in. So 135 f/2 will have 72mm hole for light to go in, and since the angle of view is narrow the front element needn't be wider than that.

But for wide lenses, there's no formula. 16-28/2 would need at least a 14mm entrance pupil but that's tiny.
Canon makes a point that without the mirror box, they're finding their optimal lens designs are actually smaller front elements and bigger rear elements.

My personal guess is that while there's a night-and-day difference between 400mm f/4 and f/2.8, there won't be much difference between f/2.8, f/2, and f/1.4 on wide-angle zooms. Any enlargement may be due to other factors they're simultaneously addressing, such as minimizing mechanical vignetting by enlarging some elements, or trading compactness for better corrections or something.
 
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uri.raz

EOS RP
Jan 5, 2016
213
134
What happened to it? Hope it wasn’t the dust that killed it!!
I noticed IS went haywire. Gave it to a service center to fix, they claimed it got hit, and required the IS unit to be replaced + realign all the elements. The price was so high, I decided to buy a new mark III and be done with it.

If I could buy MAC insurance for 7 years, it would have been covered. Alas, around here (read: a backwater vilayet of the Ottoman empire) the longest MAC insurance around here is for 3 years. It is also insured as property with my apartment, but that one would cover the lens only if it was broken / stolen along with the camera, which works fine.
 

Jasonmc89

EOS 80D
Feb 7, 2019
226
201
UK
I noticed IS went haywire. Gave it to a service center to fix, they claimed it got hit, and required the IS unit to be replaced + realign all the elements. The price was so high, I decided to buy a new mark III and be done with it.

If I could buy MAC insurance for 7 years, it would have been covered. Alas, around here (read: a backwater vilayet of the Ottoman empire) the longest MAC insurance around here is for 3 years. It is also insured as property with my apartment, but that one would cover the lens only if it was broken / stolen along with the camera, which works fine.
That’s too bad. Our house got broken into a few months ago and my old sigma 17-50 2.8 which was sitting on the TV unit was taken. Home insurance payed out for that no problem. Bit of a price difference though of course!
 

SecureGSM

2 x 5D IV
Feb 26, 2017
2,250
1,095
Wider than 50mm it's easy to calculate: focal length divided by f-stop gives the size of the "entrance pupil," the hole you see when you hold a lens up and look at a white wall through it going in. So 135 f/2 will have 72mm hole for light to go in, and since the angle of view is narrow the front element needn't be wider than that.
except Sigma 105 / f1.4 Art with 105mm front element size ;)
 

SwissFrank

from EOS 1N to R
Dec 9, 2018
414
180
except Sigma 105 / f1.4 Art with 105mm front element size
Right, as an art lens they wanted to reduce vigetting, by making more of the entrance pupil visible from a wider set of angles. Since the entrance pupil moves as you look it from increasingly off-center, the front element has to be wider to take care of that. But by 135/2 angle of view's getting quite tight so the pupil doesn't need to be a full circle from as wide a set of points.

I actually didn't know this Sigma lens, but it illustrates exactly a design concept I myself had come up with on my own. Without looking at specs I'd bet the Sigma has far less gigetting than other fast 100mm's, am I right? And extremely round bokeh circles even in the corners?
 

neuroanatomist

I post too Much on Here!!
Jul 21, 2010
24,645
2,159
except Sigma 105 / f1.4 Art with 105mm front element size ;)
The front element of a telephoto lens must be at least as large as the entrance pupil (focal length / f-number), certainly it can be larger.

All lenses need to fill the entrance pupil with light, of course, but with telephoto designs the entrance pupil is essentially located at the position of the front element.
 

Kannon

I'm New Here
Jul 2, 2019
22
11
Of course. The back of the lens is open, so air (and dust, OMG!) get in. Zooming and focusing move element groups within the lens, and that moves around the air (and dust, OMG!) inside the lens.

Some people seem to think non-extending zooms are hermetically sealed. Lol.
Mine is not open. There's a lens fixed inside, not moving or rotating. lol
 

YuengLinger

EOS R6
Dec 20, 2012
2,928
1,211
Southeastern USA
Without noticing at first, I've gotten sand on the zoom barrel of my 24-70mm f/2.8L II. And then the inevitable grinding noise inside the lens.

Then there are misty, drizzly days when droplets get on the extended barrel and could lead to fungus in the lens.

It's not all about "microscopic" dust. The extending barrel does make the lens more vulnerable, offsetting some of the expected L build advantages.

That said, I've learned to be more careful. Would I prefer all lenses to be internal zoom? Sure! But I wouldn't want Canon to NOT make the 100-400mm just because they couldn't come up with a practical, affordable way to make it exactly the way I want...

And this reminds me of what my first photography teacher said way back in 5th grade (something we've all heard): "Photography is all about compromises."
 
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degos

EOS RP
Mar 20, 2015
291
209
Of course. The back of the lens is open, so air (and dust, OMG!) get in. Zooming and focusing move element groups within the lens, and that moves around the air (and dust, OMG!) inside the lens.
The internal elements moving don't need to expel or inhale air, though; they can displace the internal air volume through spillage around their rims.

Sealing a fixed-length lens is a magnitude easier than an extending-barrel. lol!
 
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3kramd5

EOS R6
Mar 2, 2012
3,084
405
The internal elements moving don't need to expel or inhale air, though; they can displace the internal air volume through spillage around their rims.

Sealing a fixed-length lens is a magnitude easier than an extending-barrel. lol!
If you ever fly with your gear it will breathe anyway.
 

kaptainkatsu

1DX Mark II
Sep 29, 2015
166
63
I might be the odd man out, but what if, instead of 70-xxx, they made something like a 50-140 f/2 lens? It would most assuredly be a great portrait lens, especially if it were sharp and had great bokeh. It would definiately be the king of portraiture or at least royalty in that realm.
I want to see something like this. I shoot a lot of floor gymnastics and 70 is too long when the gymnasts come up close to you. You can crop on the long end so you don't need 200mm
 

kaptainkatsu

1DX Mark II
Sep 29, 2015
166
63
I just got my 100-400Lii last week and it's been a joy to use on the 5Div and EOS R. I've only owned constant aperture lenses until the 100-400Lii, which was my biggest turn-off with it until I used it. It might even replace my 70-200/2.8L IS.


Answer: Extending Barrel L-series lenses; not a concern.
Theres a menu option to simulate constant aperture. On my 1dx2, C.Fn2:Exposure: Same expo. for new aperture. You can have the camera automatically increase the ISO or decrease the shutter speed (or a combination of both) to maintain the same exposure when the aperture changes.
 
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AlanF

Stay alert, control the camera, save photos
Aug 16, 2012
6,838
5,883
I noticed IS went haywire. Gave it to a service center to fix, they claimed it got hit, and required the IS unit to be replaced + realign all the elements. The price was so high, I decided to buy a new mark III and be done with it.

If I could buy MAC insurance for 7 years, it would have been covered. Alas, around here (read: a backwater vilayet of the Ottoman empire) the longest MAC insurance around here is for 3 years. It is also insured as property with my apartment, but that one would cover the lens only if it was broken / stolen along with the camera, which works fine.
I was once advised by a financial expert only to insure for events that are very rare and expensive and that you would not be able to cover yourself. Insurance is worthwhile if you are a klutz who breaks things more than average, forgets to lock up or your budget is so tight you don't have the savings on hand to replace. If you are careful, then your insurance premiums have a large factor for the nice profits and running costs of the insurance company and subsidizing the careless klutzes, and you would be far better off putting aside each month the insurance premiums into your own savings. But, having insurance keeps some people happy.
 

SecureGSM

2 x 5D IV
Feb 26, 2017
2,250
1,095
The front element of a telephoto lens must be at least as large as the entrance pupil (focal length / f-number), certainly it can be larger.

All lenses need to fill the entrance pupil with light, of course, but with telephoto designs the entrance pupil is essentially located at the position of the front element.
Yes, the OP statement was though : needn't be wider than that. Please see the post I have replied to.
I suggested that in many cases front element of a telephoto lens is larger than the formula suggests.
Then, OP went to explain that larger than needed front element is there to reduce vignetting.
I further explained that it was not correct as vignetting levels reduction was only marginal...

However, corner and edge sharpness was dramatically improved for obvious reason
 

uri.raz

EOS RP
Jan 5, 2016
213
134
I was once advised by a financial expert only to insure for events that are very rare and expensive and that you would not be able to cover yourself.
True, except reality isn't black & white. If my apartment burnt down, I couldn't buy a new camera + 3 lenses all at once, so I added them to the contents insurance. One lens I can buy new out of pocket. What if two or more broke at the same time, e.g. because they were in a car accident?

Insurance is worthwhile if you are a klutz who breaks things more than average, forgets to lock up or your budget is so tight you don't have the savings on hand to replace.
Which is why I don't insure anything else I have, except as part of contents insurance.
 

Photo Hack

Hi there
Apr 8, 2019
145
186
They are still a bit top big in combinatiën with the mirroroess body imo ...
Seeing that two of them now have IS, where the EF versions did not, I would expect them to be slightly larger and heavier - especially if the trend continues of creating a lens that is sharper and performs better than the EF versions.

They also have a few more electronic tricks up their sleeves with the hardware changes to allow stored data, better focusing, and faster data communication. I’m not sure how much all that affects design, but with the addition of the control rings, that should have an impact.

And the 70-200? At least when retracted and for some of the working range, it’s certainly much smaller than the EF version.

So I’m confused on how they’re too big in combination with mirrorless? Have you used any of them yet?

Also not forgetting the 24mm shorter back flange will bring the lenses closer to the back of the camera and a body that’s a few hundred grams lighter, the girth of the lens may be the only real noticeable characteristic. The grip on my RP, as tiny as the camera is, still feels great vs my Mark IV. We’ll see.

If Canon achieves all of that on their 24-70 and is close to Sony’s physical specs on their G master, it’s a win for Canon. As it sits, Sony’s is 100g heavier and .9” longer than Canon’s EF and doesn’t have all those great additions the RF version will have.
 
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3kramd5

EOS R6
Mar 2, 2012
3,084
405
Some people seem to think non-extending zooms are hermetically sealed. Lol.
Boy that would be fun. Then you’d need worry about desiccant refills in something hard to service, and they’d have to design the front element with rigidity in mind due to burst pressure for air travelers.
 
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Aregal

EOS M6 Mark II
Oct 3, 2018
59
45
Some people see rain, and run around like Chicken Little screaming that the sky is falling.

Some people obsess over a tiny dust speck in their lens. Almost as if it’s the apocalypse.
I have a friend who specifically looks for scratched/dusty lenses; character. haha
 

Del Paso

M3 Singlestroke
Aug 9, 2018
842
877
I have a friend who specifically looks for scratched/dusty lenses; character. haha
An easy and intelligent way to get an excellent lens for much less money.
I still use my 180 mm Apo Telyt , with its cracked front lens, plus dust inside, without any quality issues. Dust is most of the time a non-existing problem that can result in a cost advantage for the buyer! ;)