RF 24-240mm: No full frame cover at 24mm

CanonFanBoy

Really O.K. Boomer
Jan 28, 2015
4,705
2,625
Irving, Texas
To correct geometric distortion and vignetting in zoom lenses, more optical elements are used and result in expensive and heavy lenses. Since mirrosless has high computing power, you can make lens with uncorrected distortion and vignetting, and leave the job to the camera software. Such a thing could not be done with EF lenses, which need to be compatible with photographic film camera (mirrorless does not need). Canon first makes use of a tactic that Sony has been using for a long time.
I don't quite understand what you are saying, but I guess that is why my two RF lenses only weigh 3.15 and 2.63 pounds each. ;) Thank God for mirrorless computing power and lightweight lenses. :) Seriously, what is inherent to mirrorless that makes them more powerful in computing power than a DSLR. I would have to argue nothing at all. The EF lenses I used to have were mostly from the DSLR era, not film. Every single film era lens I own (more than 40) are very light and small. Even my Mamiya/Sekor 400 mm f/6.3 preset (4 elements) weighs in at just 935gr/33oz.
 
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SteveC

M6 mk II
Sep 3, 2019
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I don't quite understand what you are saying, but I guess that is why my two RF lenses only weigh 3.15 and 2.63 pounds each. ;) Thank God for mirrorless computing power and lightweight lenses. :) Seriously, what is inherent to mirrorless that makes them more powerful in computing power than a DSLR. I would have to argue nothing at all. The EF lenses I used to have were mostly from the DSLR era, not film. Every single film era lens I own (more than 40) are very light and small. Even my Mamiya/Sekor 400 mm f/6.3 preset (4 elements) weighs in at just 935gr/33oz.
I think he's saying that since an EF lens might be used on a film camera, the designers can't rely on software to fix its inherent distortion--the film wouldn't be corrected by it. (Someone else made the point that the purely optical viewfinder wouldn't be corrected, even on a digital camera.) Therefore they have to put more glass in the lens itself. On an RF the software can not only correct the shot image, but it can correct what you see through the viewfinder, too, leaving no trace of what the camera did. Certainly the RF lenses have (up to this point) been bulky, but apparently this one is the first one to rely on software. It may be bulky but it is a 10x full-frame zoom, and that accounts for the bulk by itself.

As a side note I own a Tamron 18-400 which is over 20x zoom, and it's not nearly this distorting (according to the same reviewer). But it is a crop-frame lens; who knows how bad it would be on a full frame sensor?
 

CanonFanBoy

Really O.K. Boomer
Jan 28, 2015
4,705
2,625
Irving, Texas
I think he's saying that since an EF lens might be used on a film camera, the designers can't rely on software to fix its inherent distortion--the film wouldn't be corrected by it. (Someone else made the point that the purely optical viewfinder wouldn't be corrected, even on a digital camera.) Therefore they have to put more glass in the lens itself. On an RF the software can not only correct the shot image, but it can correct what you see through the viewfinder, too, leaving no trace of what the camera did. Certainly the RF lenses have (up to this point) been bulky, but apparently this one is the first one to rely on software. It may be bulky but it is a 10x full-frame zoom, and that accounts for the bulk by itself.

As a side note I own a Tamron 18-400 which is over 20x zoom, and it's not nearly this distorting (according to the same reviewer). But it is a crop-frame lens; who knows how bad it would be on a full frame sensor?
True on the film cameras, but unless I am mistaken, many of the newer DSLR's also provide in camera lens corrections... though the viewfinder is another story.

In a way, I would rather not have the corrections most of the time for myself. I never check the correction box in Lightroom. I can't remember if it was the EF 35mm f/1.4L II or my EF 24-70 f/2.8L II, but one of them never showed any correction when I would check the box. So maybe the lens was already corrected in my 5D Mark III?

Anyway, I tend to add vignette a lot. I just like it. And for me, sometimes the lens distortion looks better uncorrected on some lenses. Then again, I don't generally shoot landscapes or architecture, just people.

As I learn my R better, I'll have to see whether I can turn off the corrections and see how it looks. That might be fun.
 

SteveC

M6 mk II
Sep 3, 2019
570
400

privatebydesign

Would you take advice from a cartoons stuffed toy?
Jan 29, 2011
8,250
1,601
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Yes many of Lightroom's 'corrections' are clumsy at best. They try to force a true rectilinear projection on lenses that often were not designed to do that because off the field of view.


I downloaded RAW file from DPReview's gallery for RF24-240 (https://www.dpreview.com/sample-galleries/6204946485/canon-rf-24-240mm-f4-6-3-sample-gallery/8982014006), loaded it into Lightroom and exported WITH and WITHOUT corrections.

Here are results.
Yikes! There's a stripe down the back of that guy's shirt in the uncorrected version, that gets removed in the correction. In the upper right, the angle of the track beyond the curve is different.
 

privatebydesign

Would you take advice from a cartoons stuffed toy?
Jan 29, 2011
8,250
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The lens is faked into to working... never seen anything like it...
Hey people have been demanding Canon give all those Sony features, this is the sh!t that results when people who don't know or care make up the lions share of the market. Canon have been forced into compromises like this by the market, so who should we blame?
 

SecureGSM

2 x 5D IV
Feb 26, 2017
1,752
678
Hey people have been demanding Canon give all those Sony features, this is the sh!t that results when people who don't know or care make up the lions share of the market. Canon have been forced into compromises like this by the market, so who should we blame?
Not typical of Canon. Something is not adding up here. I do not have a lens to play with but I am sure that this issues will be explained.
 

SteveC

M6 mk II
Sep 3, 2019
570
400
Not typical of Canon. Something is not adding up here. I do not have a lens to play with but I am sure that this issues will be explained.
In this case, I'm gathering: Canon felt a demand for a 10x zoom. Canon felt it needed to be cheap. This was the only way to do it. They tend to prefer solving problems in hardware (the optics) rather than software, but they couldn't do that here, not and sell the lens for a non-stratospheric price.

There's an RF camera in my distant future, I think...but the RF lenses are almost all more expensive than I can justify to myself--I'll be using a lot of adapters on EF lenses (many of which are reasonable and/or do things no RF lens can do yet, e.g., the 100-400 II--which is still on my want list).
 
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PCM-madison

EOS 80D
Dec 9, 2013
115
47
I'm very curious how and if this issue shows up in future reviews by Brian at TDP and Roger at lensrentals whose reviews I most respect. For me, an issue that only shows up using non-compatible RAW conversion is a non-issue for my workflow.
 

Joules

EOS 7D MK II
Jul 16, 2017
619
577
Hamburg, Germany
For me, an issue that only shows up using non-compatible RAW conversion is a non-issue for my workflow.
This really isn't an issue. It is just a way of designing a lens that we have not seen from a Canon ILC lens before. It surprised me personally, but if it allows Canon to deliver a lens that seems to be a great value otherwise, I'm all for doing more with software and hopefully some computational photography techniques in the future.

The only true issue I see here is that you give up a bit of sensor area to allow for that crop. So you are not really getting an FF image and therefore your signal is lower and your Signal to noise ratio slightly worse. And you aren't getting your full sensor resolution either. That's a bit cheeky from Canon, to call it an FF 10x zoom, when in truth they basically shrink your sensor to match the projected size on the wide end.
 

Joules

EOS 7D MK II
Jul 16, 2017
619
577
Hamburg, Germany
Not typical of Canon. Something is not adding up here. I do not have a lens to play with but I am sure that this issues will be explained.
Have you looked at the pictures in link from this post?

I don't see what explanation other than the given one could make sense. The lens is wider than 24mm but doesn't cover the whole sensor on the wide end. So the image is cropped to the area that delivers a 24mm equivalent FoV.

This also explains why a new firmware was required to use this lens, as this cropping feature was probably ommited on launch because it was a low priority feature that the lenses so far didn't need.

Something not being typical doesn't mean Canon can't do it. They are working with a new market now, and have different requirements as well as different options to satisfy them.
 
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SecureGSM

2 x 5D IV
Feb 26, 2017
1,752
678
In this case, I'm gathering: Canon felt a demand for a 10x zoom. Canon felt it needed to be cheap. This was the only way to do it. They tend to prefer solving problems in hardware (the optics) rather than software, but they couldn't do that here, not and sell the lens for a non-stratospheric price.

There's an RF camera in my distant future, I think...but the RF lenses are almost all more expensive than I can justify to myself--I'll be using a lot of adapters on EF lenses (many of which are reasonable and/or do things no RF lens can do yet, e.g., the 100-400 II--which is still on my want list).
A lot of assumptions that do not make a lot of sense or aren’t typical of Canon. Sorry. This is not Canon.
 
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