Jman13 wrote:
An interesting thing I found out while doing a quick test of the RF 70-200mm f/2.8L with my EF 70-200/4L IS and my Tamron 70-180/2.8 for Sony:
While a lot of 70-200mm lenses will significantly shorten focal length when focusing closer than infinity, Canon's EF mount 70-200 lenses always somewhat resisted this. Nikon's shorten considerably. Sony's do....and now Canon's RF mount 70-200 (at least the f/2.8 version) does as well. Pretty massively too.
Compared to the EF 70-200/4, the RF 70-200/2.8 at 200mm and around a 1.5m focus distance is very nearly the same framing as the EF 70-200/4 IS at 135mm. If the EF version is 'true', then the RF 70-200/2.8 shortens to around 140-145mm when focused at this distance.
The Tamron 70-180/2.8 at 180mm is actually a little longer at this focus distance than the RF 70-200/2.8 is at 200mm (though still shorter significantly than the EF 70-200/4.
I hope the RF 70-200/4L IS is more like the EF version, rather than the RF 70-200/2.8, but given the extending zoom, I'm thinking it probably shortens quite a bit as well.
These differences should go away at infinity, but it's definitely worth noting.
RF 70-200mm f4 MFD = 0.6m and magnification is .28x
EF 70-200mm f4 II MFD = 1m and magnification is .27x.
So essentially the same magnification, but 40% closer MFD on the RF. Only way that happens is if the lens is focus breathing so bad that it is 40% shorter focal length at MFD. So we'd be talking like 120mm effective. (Or it could have those specs if the closest MFD is somehow not at the 200mm setting)
Ironically the marketing press for the RF lens mentions low focus breathing. Which is laughable if the above specs are true.
RF 70-200mm f4 MFD = 0.6m and magnification is .28x
EF 70-200mm f4 II MFD = 1m and magnification is .27x.
So essentially the same magnification, but 40% closer MFD on the RF. Only way that happens is if the lens is focus breathing so bad that it is 40% shorter focal length at MFD. So we'd be talking like 120mm effective. (Or it could have those specs if the closest MFD is somehow not at the 200mm setting)
Ironically the marketing press for the RF lens mentions low focus breathing. Which is laughable if the above specs are true.
Well one would assume that low focus breathing certainly would indicate that maximum magnification and the minimum focusing distance might be different, and if they are the same they would be occurring at different focal distances.
Edit:
Well rather than snarking back and forth I did some research and found pretty easily that the answer is the EF version has significant focus breathing which results in a longer focal length at MFD. Both of the numbers are at the long end of the zoom range for both lenses according to Canons website.
Wow, that's interesting....so rather than the RF versions really shortening that much, the EF versions are actually lengthening? Huh. There's definitely some shortening going on with the RF, as evidenced by the RF 70-200/2.8 being shorter than my Tamron 70-180 at 200mm vs 180mm. But in that video, it appears the RF version shortens by maybe 10-15%, while the EF version lengthens by like 30%.
That doesn't fully jive with the formulas based on magnification and the stats of the lens, though - the EF version calculates to a focal length of 208mm, which is indeed a little longer, but not nearly as long as what is seen in the video, while the RF version calculates to 131mm. So I think I must be using the wrong formula there, or it doesn't apply to complex lens designs, and only simple lenses.
But we aren't seeing anywhere near that level of focus breathing on the RF version in the video.
And plugging in values until they match, it looks like around 170mm for the EF version at 1.2m and 0.21x magnification. The RF version shows as 103mm in that calculation, which seems WAY off.
So in short, I have no idea how to accurately measure focal length here.
Trying to decide which model, and their price differences, is driven (for me) by how much I will be using the lens and what sort of critical imaging I am expecting.
I bought a very nice used EF 70-200/4L (non-IS) a couple years ago, here on the B&S. It is a lovely lens and very light weight for its focal lengths. It is a bit long, but does fit upright in my larger LowePro shoulder bags with several other lenses. I believe the price was $300, and the glass and mechanism are perfect. Images are very good to excellent throughout its range.
I only use my EF 70-200/4L and EF 100-400/4.5-5.6L IS once or twice a year, so as much as I like the look and modern design of the new RF tele-zooms, I won't be inclined to purchase a new RF telephoto. My usage is unusually low at these focal lengths, making it extremely hard to justify. Still, I don't feel particularly out-gunned when I put them on my 5DsR or a7R4, let alone my EOS R.
It is a constant mental/emotional battle to resist all the newest and "bestest" gear coming out during our digital photo renaissance.
Now, I must attend to re-enforcing my crumbling resistance to the Sigma 14-24 Art! (and the R5!)
PS -- My favorite backpack for maneuvering gear is the LowePro Flipside 400. The Flipside designs (various sizes) are made to rotate while supported by the hips, and unzip on the back-facing side of the carry position. This makes it much less likely to drop items in outdoor situations. The 400 can accommodate a fair amount of gear.
I'm holding off on the EF version of the Sigma 14-24 in hopes that sometime in the next year or two, Sigma will port over their mirrorless redesign of that lens to RF. I own it on Sony, and it is quite simply the best UWA lens I've ever used. Sharp to the corners at all focal lengths from wide open, even on the 60MP A7R IV, and considerably smaller than the EF version with an adapter, though I hear the EF version is fairly close optically.
Gunzorro wrote:
Trying to decide which model, and their price differences, is driven (for me) by how much I will be using the lens and what sort of critical imaging I am expecting.
I bought a very nice used EF 70-200/4L (non-IS) a couple years ago, here on the B&S. It is a lovely lens and very light weight for its focal lengths. It is a bit long, but does fit upright in my larger LowePro shoulder bags with several other lenses. I believe the price was $300, and the glass and mechanism are perfect. Images are very good to excellent throughout its range.
I only use my EF 70-200/4L and EF 100-400/4.5-5.6L IS once or twice a year, so as much as I like the look and modern design of the new RF tele-zooms, I won't be inclined to purchase a new RF telephoto. My usage is unusually low at these focal lengths, making it extremely hard to justify. Still, I don't feel particularly out-gunned when I put them on my 5DsR or a7R4, let alone my EOS R.
It is a constant mental/emotional battle to resist all the newest and "bestest" gear coming out during our digital photo renaissance.
Now, I must attend to re-enforcing my crumbling resistance to the Sigma 14-24 Art! (and the R5!)
PS -- My favorite backpack for maneuvering gear is the LowePro Flipside 400. The Flipside designs (various sizes) are made to rotate while supported by the hips, and unzip on the back-facing side of the carry position. This makes it much less likely to drop items in outdoor situations. The 400 can accommodate a fair amount of gear.
Jman13 wrote:
That doesn't fully jive with the formulas based on magnification and the stats of the lens, though - the EF version calculates to a focal length of 208mm, which is indeed a little longer, but not nearly as long as what is seen in the video, while the RF version calculates to 131mm. So I think I must be using the wrong formula there, or it doesn't apply to complex lens designs, and only simple lenses.
But we aren't seeing anywhere near that level of focus breathing on the RF version in the video.
And plugging in values until they match, it looks like around 170mm for the EF version at 1.2m and 0.21x magnification. The RF version shows as 103mm in that calculation, which seems WAY off.
So in short, I have no idea how to accurately measure focal length here. ...Show more →
I get 103mm for RF 70-200 f4 and 167mm for EF 70-200 f4 II. So that seems to be about the same that you have above.
Based on the same equation, we get 77mm effective for the 85mm f2, 125mm for the Tamron 70-180mm, and 106mm for the RF 70-200mm f2.8
Of course there is a chance that the listed MFD for the RF isn't at 200mm. The tamron's true MFD is at 70mm and it's much longer at 180mm. But the highest magnification is at 180mm. Nikon's 70-200mm f2.8 Z is the same way at .5m at 70mm and 1m at 200mm.
I get 103mm for RF 70-200 f4 and 167mm for EF 70-200 f4 II. So that seems to be about the same that you have above.
Based on the same equation, we get 77mm effective for the 85mm f2, 125mm for the Tamron 70-180mm, and 106mm for the RF 70-200mm f2.8
Of course there is a chance that the listed MFD for the RF isn't at 200mm. The tamron's true MFD is at 70mm and it's much longer at 180mm. But the highest magnification is at 180mm. Nikon's 70-200mm f2.8 Z is the same way at .5m at 70mm and 1m at 200mm. ...Show more →
All of these are based on the thin lens equation, which is only used to model camera lenses (which are *not* thin lenses) when focused at infinity.
I'm not saying that these numbers are meaningless in every way, but if you are reading that number and you think that an object appears to shrink in half as focus is shifted closer to the MFD of the RF 70-200 f/4 due to its thin lens equation focal length changing, you are mistaken.
These equations are not generally useful for complex thick lenses. The thin lens equation does not effectively model how lens elements inside of a camera lens transfer the image between each other. When approaching the minimum focusing distance of a lens, you have to start computing object and imaging distance for each lens element, and its relation to the lens element in front of and behind it. This doesn't even account for aspherical elements.
I was interested in following up on this topic, and thinking about how to best think about the matter of focus breathing and "effective focal length".
Here is what I came up with.
1. Effective focal length is determined using a thin lens formula measured with the lens focused "at infinity". For a 200mm lens, this results in the angle of view of 12 degrees.
2. To determine the amount of breathing, we do not want to ask "what is the focal length at minimum focus distance?" but rather "what is the angle of view at minimum focus distance?" and more importantly, how much does it differ from the original angle of view.
3. The angle of view for the RF 70-200 f/4L IS or any other 200mm lens is about 12.3 degrees.
4. So, how do we determine the angle of view at minimum focusing distance? This is possible using some data that Canon provided along with the pythagorean theorem and some trigonometry.
We know that the magnification at the minimum focusing distance of 600mm is 0.28x. We also know the diagonal of the sensor is 43mm. We can calculate the size of an object precisely filling the dimensions of the sensor (aka a diagonal of the visible focal plane) at 600mm as 43mm * (1 / 0.28x) = 153.57mm. If we divide that by half we get 76.79mm. We now have the two necessary components to build our calculations.
The two known sides of our triangle a=76.78mm and b=600mm yielding a hypotenuse c=604.89mm.
We can then calculate the half angle of view using trigonometry: arcsin(a/c)=rad->deg
This yields the half angle:
arcsin(76.78/604.89) = arcsin(0.12693160466492) = 0.12727 rad = 7.292°
So our half angle is 7.292° and our full angle of view is 14.584°. So, the RF 70-200 F/4L IS does very slightly widen its angle of view as it focuses closer. At MFD the 14.584° view is a 170mm lens focused at infinity.
This same calculation applied to the EF 70-200 F/4L IS results in an angle of view at MFD of 9.75°. This means that the angle of view has shrunk significantly, putting it closer to a 250mm lens angle of view when focused at infinity. This ends up being the same calculation for the EF 70-200 f/2.8L IS II and III.
For the EF 70-200 F/4L IS II the angle of view at MFD is 9.102°, or near to the angle of view of a 280mm lens focused at infiinity.
For the RF 70-200 f/2.8L IS the angle of view at MFD is 15.212°, or near to the angle of view of a 160mm lens at infinity.
Edit to add Tamron:
The Tamron 70-180 f/2.8 Di III has an angle of view of 13.43° at 180mm zoom when focused at infinity. When focused at MFD this is 13.278°, making the Tamron the winner in terms of non-focus breathing design.
Thanks for running the numbers, and that does indeed seem to be the best way to do it. Crazy how much the EF versions breathe by narrowing field of view.
So I caved and pre-ordered the 70-200/4L. I was contemplating buying the f/2.8, but the more I thought about it, the less I could truly justify spending $2,700 on one lens, considering I'd have had to sell 5 of my Sony lenses to pay for it. In the end, I'm going to sell 2, and my EF 70-200/4L, and in turn gain a lens with far better IS than my current 70-200, and something supremely compact, which will be fantastic. I still think the price is about $200 steeper than it should be, but if it is as optically good as it should be, then it's going to be an absolute joy to use.
Interesting note on pre-order availability: B&H, which has shown "Expected availability, December 11, 2020" for the 70-200/4L has just changed today to "Expected availbility: January 29, 2021." I'm hoping that's for any new orders...and the initial batch coming on Friday is still scheduled for that time frame, but who knows. I pre-ordered with my local store, as they almost always get it in the day of general release, but I hope the whole production hasn't been pushed back 45 days.
Jman13 wrote:
Interesting note on pre-order availability: B&H, which has shown "Expected availability, December 11, 2020" for the 70-200/4L has just changed today to "Expected availbility: January 29, 2021." I'm hoping that's for any new orders...and the initial batch coming on Friday is still scheduled for that time frame, but who knows. I pre-ordered with my local store, as they almost always get it in the day of general release, but I hope the whole production hasn't been pushed back 45 days.
I've pre-ordered mine through Best Buy, and I sure hope that the initial batch does get shipped out as originally scheduled.
I'm gradually phasing out my EF lens collection in order to fund my new RF collection. I just received the RF 24-105 f/4L, and its dimension (height, girth, weight) are about the same as the RF 70-200 f/4L, except the latter is much sexier. The latter actually weighs less but not by much.
Jman13 wrote:
Interesting note on pre-order availability: B&H, which has shown "Expected availability, December 11, 2020" for the 70-200/4L has just changed today to "Expected availbility: January 29, 2021." I'm hoping that's for any new orders...and the initial batch coming on Friday is still scheduled for that time frame, but who knows. I pre-ordered with my local store, as they almost always get it in the day of general release, but I hope the whole production hasn't been pushed back 45 days.
Same on Adorama as well. "Manufacturer will start shipping this item on 01/28/2021."
Typical excellent work from Gordon, thanks for the heads up!
And now I want one... never had one the EF versions, actually used the 70-300 lenses instead, but the versatility and quality here just looks so promising!
The lens is crippled by the lack of both TC compatibility and tripod mount, so I'd say versatility is quite less than the past three 70-200/4 lenses.
If the lens is really good, I might have to figure out a tripod collar. There should be third party TCs at some point.
EB-1 wrote:
The lens is crippled by the lack of both TC compatibility and tripod mount, so I'd say versatility is quite less than the past three 70-200/4 lenses.
'Crippled' sounds a bit dramatic, doesn't it? At least in the scope of users that would need and actually use a TC, which I assume is pretty small, and in the scope of users that would need and actually use a tripod collar, which given the size of the lens also seems like it'd be pretty small.
These are issues that I have with the lens in theory, but for me (and not you!), I don't see them as real limitations.
EB-1 wrote:
If the lens is really good, I might have to figure out a tripod collar. There should be third party TCs at some point.
EBH
I am genuinely surprised that Canon didn't provide for the option. They make f/11 lenses, so why not make a TC that works, or make the lens work with TCs?
As for the tripod collar, I'm honestly not convinced that it's necessary; if I were to use the lens in a situation where it would be an advantage, I'd probably try to use a long A/S plate for the camera that puts a support under the end of the non-extending portion of the lens barrel, and balance the combo on whatever head I am using. Or even put some sort of 'clamp' on the plate to secure the end of the lens to it.
I just don't think that I'll need to figure that out
Really? No tripod collar? Wow, what a disappointment. Otherwise, it seemed like the perfect landscape 70-200mm zoom to me. . . . However, this is the first "print" review I've found of the lens, not the greatest optically but I don't know that site, and it sounds like the reviewer thinks that his particular sample may have had an issue: https://www.digitalcameraworld.com/reviews/canon-rf-70-200mm-f4l-is-usm-review
