# Patent: Canon RF 100mm f/2.8L IS USM Macro



## Canon Rumors Guy (Dec 26, 2020)

> It looks like one of the most requested new lenses for the RF mount is getting closer with the latest patent designs from Canon.
> Canon News has uncovered a patent showing off two different, yet very similar optical formulas fora Canon RF 100mm f/2.8L IS USM Macro. A lens I expect will be announced in 2021.
> Canon Japan Patent Application 2020-204744
> 
> ...



Continue reading...


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## Antono Refa (Dec 26, 2020)

RF mount has a flange distance of 20mm. Both formulas have a slightly shorter ~15.5mm backfocus.

Don't tele lenses have longer backfocus? Why is the last elements so curved?


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## Chaitanya (Dec 26, 2020)

Would be interesting to see what new features Canon will add to this lens.


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## deleteme (Dec 26, 2020)

I want V1. I want that extra .56mm of FL for those shots needing the extra reach.
Also it is 5mm shorter. Yay for backpacking.


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## Surab (Dec 26, 2020)

Normalnorm said:


> I want V1. I want that extra .56mm of FL for those shots needing the extra reach.
> Also it is 5mm shorter. Yay for backpacking.



Totally agree and if they bring V2 then Canon is *******!


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## Joules (Dec 26, 2020)

Antono Refa said:


> RF mount has a flange distance of 20mm. Both formulas have a slightly shorter ~15.5mm backfocus.
> 
> Don't tele lenses have longer backfocus? Why is the last elements so curved?


Canon can use any backfocus they want, it just starts portruding into the body at some point.

Canon also has clearly shown that they consider it advantageous to put the last element close to the sensor even for tele designs, which is why the RF 70-200 mm 2.8 and 100-500 4.5-7.1 for example have no / limited compatibility with TCs.


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## snappy604 (Dec 26, 2020)

wish they'd refresh the 180mm Macro.. I still use the EF 180mm 3.5L and love it, but wish autofocus was useful, its pretty useless, though with the adapter and the R5's manual focus aids... new possibilities ;-).. would also love to see them refresh the MP 65mm Macro.. hear good things but don't want to invest in such an old lens for the R series.


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## Antono Refa (Dec 26, 2020)

Joules said:


> Canon can use any backfocus they want, it just starts protruding into the body at some point.



Of course it can, question is why. IIRC, it was explained that the closer the last element is to the sensor, the more vignetting the lens would have, due to the angle at which the light rays would hit the sensor.



Joules said:


> Canon also has clearly shown that they consider it advantageous to put the last element close to the sensor even for tele designs, which is why the RF 70-200 mm 2.8 and 100-500 4.5-7.1 for example have no / limited compatibility with TCs.



No compatibility with TCs is not an advantage.


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## Joules (Dec 26, 2020)

Antono Refa said:


> No compatibility with TCs is not an advantage.


Duh.

But I don't believe Canon compromises on an aspects of their design like this without gaining an advantage by doing so. I won't pretend to understand what that advantage may be. Most likely, it isn't something as cut and dry like 'reduced vignetting by x amount'. I could see it beeing more likely that it is one of many aspects of these designs that allow Canon to produce these lenses which are optically excellent, while reducing the size and / or weight compared to previous version. Maybe it is just about saving costs or making manufacturing easier, but I doubt it.


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## LeBlobe (Dec 26, 2020)

can we tell focus breathing with this ? i got rf 35mm 1.8 macro and feel its alot of breathing for focus stacking , are all 100mm macro about the same?


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## mb66energy (Dec 26, 2020)

Antono Refa said:


> RF mount has a flange distance of 20mm. Both formulas have a slightly shorter ~15.5mm backfocus.
> 
> Don't tele lenses have longer backfocus? Why is the last elements so curved?



From the original patents drawings I see that this lens is focusing internally (2nd and 4th of 5 groups are moved) so maybe they need the space to shift the moving groups and set the last element closer to the sensor. These macros aren't classical tele lenses - they bend the light to do 100mm 1:1 macro which needs 400mm length if you use a single thin lens in a compact package.

I think the last elements try to bend the light that it hits the sensor under an optimized angle to avoid vignetting.


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## dlee13 (Dec 26, 2020)

This is a lens I was initially very excited for but not so much now. The reason is due to the RF 85mm f/2 which I’m really enjoying.

I always used the 100L for still life and product photography so never really needed full 1:1 so the current 85mm suits me well!


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## lexptr (Dec 26, 2020)

Great! I'm finally getting into R world and found my 100mm L macro adapted to R5 being too long/heavy/inconvenient. It could be 150 or 180mm that long and heavy, but it is still 100mm. BTW, I hope to see a longer macro from canon too.


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## SteveC (Dec 26, 2020)

lexptr said:


> Great! I'm finally getting into R world and found my 100mm L macro adapted to R5 being too long/heavy/inconvenient. It could be 150 or 180mm that long and heavy, but it is still 100mm. BTW, I hope to see a longer macro from canon too.



The lens might feel a bit long iwth that adapter on it, but then, the camera is shorter.

Unless you double-count the adapter!


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## dolina (Dec 27, 2020)

Law of diminishing returns


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## Antono Refa (Dec 27, 2020)

Joules said:


> Duh.
> 
> But I don't believe Canon compromises on an aspects of their design like this without gaining an advantage by doing so. I won't pretend to understand what that advantage may be.



The "I know what I'm losing, I don't know what I gain, but it must be worth it" has the scent of fanboyism. At the very least, Canon's PR should have published what the gain is that they've compromised on no TC.


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## mb66energy (Dec 27, 2020)

dlee13 said:


> This is a lens I was initially very excited for but not so much now. The reason is due to the RF 85mm f/2 which I’m really enjoying.
> 
> I always used the 100L for still life and product photography so never really needed full 1:1 so the current 85mm suits me well!


Good to hear - maybe I will buy the RF 85 macro because of its f/2, compactness, low weight and macro functionality to replace my f/2 100.
While the EF 100 macro (usm version w/o IS) will be used adapted for those 1:1 situations which are - as you said - rare for me too.


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## dlee13 (Dec 27, 2020)

mb66energy said:


> Good to hear - maybe I will buy the RF 85 macro because of its f/2, compactness, low weight and macro functionality to replace my f/2 100.
> While the EF 100 macro (usm version w/o IS) will be used adapted for those 1:1 situations which are - as you said - rare for me too.



Well if you do I’m sure you’ll be impressed with it! Although I love the RF 35mm, I find the 85mm a bit more unique and just can’t stop using it!


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## Joules (Dec 27, 2020)

Antono Refa said:


> The "I know what I'm losing, I don't know what I gain, but it must be worth it" has the scent of fanboyism. At the very least, Canon's PR should have published what the gain is that they've compromised on no TC.


And the idea "the market leader dropped features from their new products for absolutely no reason" has a scent of cynicism. What's your point?

As I said, I won't pretend to understand enough about Optics to challenge Canon's claims. Canon has actually already published a number of marketing and white paper documents that touch on these subjects. From page 9 on the R system white paper, they highlight a big advantage of the new system:

"Large diameter rear lens elements that are much closer to the full frame image sensor —enhancing overall optical performance (in particular, tighter control over optical aberrations at image extremities)"

TThey go on to show how this is handled in the EF Mount and contrast it with RF on the subsequent pages, if you want to have a look. Here is the link if you haven't downloaded it yet:






Canon Product Showcases | Canon U.S.A., Inc.


The Product Showcases from Canon U.S.A., Inc. Explore the Canon products further and discover why these are worthy of your attention.




www.usa.canon.com


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## degos (Dec 27, 2020)

Joules said:


> TThey go on to show how this is handled in the EF Mount and contrast it with RF on the subsequent pages, if you want to have a look. Here is the link if you haven't downloaded it yet



They don't actually compare it to an EF lens, just a simulation of a lens using a configuration similar to EF...

Canon have been very careful not to directly compare lenses across the two mounts. The 70-200 2.8 and 50 1.8 certainly don't perform better than heir EF predecessors.


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## Joules (Dec 27, 2020)

degos said:


> They don't actually compare it to an EF lens, just a simulation of a lens using a configuration similar to EF...
> 
> Canon have been very careful not to directly compare lenses across the two mounts. The 70-200 2.8 and 50 1.8 certainly don't perform better than heir EF predecessors.


No, they don't compare it to a real EF lens. But I read it as implying that the lens configuration they show are typical conceptual approaches they would take when designing an EF lens.

Both lenses you mentioned are significantly smaller and in the case of the 70-200 also much lighter than their predecessors. In what way is that not better?

I have not bothered looking at side by side comparisons of the 70-200. But the RF 50 mm 1.8 is clearly much better in the edges compared to the EF one.


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## Antono Refa (Dec 27, 2020)

Joules said:


> And the idea "the market leader dropped features from their new products for absolutely no reason" has a scent of cynicism. What's your point?



When did stating a fact, e.g. "Canon has dropped a feature from a new product for, as far as you can tell, absolutely no reason", became cynicism?



Joules said:


> As I said, I won't pretend to understand enough about Optics to challenge Canon's claims. Canon has actually already published a number of marketing and white paper documents that touch on these subjects. From page 9 on the R system white paper, they highlight a big advantage of the new system:
> 
> "Large diameter rear lens elements that are much closer to the full frame image sensor —enhancing overall optical performance (in particular, tighter control over optical aberrations at image extremities)"



Quotes from marketing materials have stopped impressing me a long time ago.


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## Joules (Dec 27, 2020)

Antono Refa said:


> When did stating a fact, e.g. "Canon has dropped a feature from a new product for, as far as you can tell, absolutely no reason", became cynicism?


Making the assumption that the intend behind an action (reducing TC compatibility) is either nefarious or just indifference (or the action is the result of incompetence) is cynical in my mind. At least as long as there is no good reason to believe any of these things.



Antono Refa said:


> Quotes from marketing materials have stopped impressing me a long time ago.



Well, the quote was from the white paper. But of course, you are right in being skeptical of claims put forward by a manufacturer. I presented the quote mostly because you seemed to state that you wished for a statement from Canon about the placement of their rear elements, and I wanted to show you that they have in fact already provided that.

What you do with the information given in this way is up to you. As I said, I don't have the expertise necessary to bring forward a valid criticism of Canon's explanation. If you do have these, please share some of it. 

I don't even know what you are arguing. As far as I can tell, you posed a question and I tried to provide an answer. That does not seemed to have been what you wanted to hear, so maybe you could kindly elaborate. 

All new RF design we have seen are as good or better optically as their EF versions, aren't they? And in the cases where the EF version were already optically great, the RF versions do seem to show improved quality to size/weight ratio. They also do have large rear elements close to the sensor in most cases. Anything wrong with that?

Canon claimed in their white papers that these close rear elements were something that would allow them to bring forward improved designs and I just don't see why you would doubt them. But maybe you are not and what ever you want to hear has just not been clear to me at all.


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## lexptr (Dec 27, 2020)

SteveC said:


> The lens might feel a bit long iwth that adapter on it, but then, the camera is shorter.
> 
> Unless you double-count the adapter!


Camera is shorter, but sensor placed further from camera back, relative to placement in 5D. So the adapter should place the lens further form camera's back to maintain proper sensor to bayonet distance. And therefore the depth of R5+adapter (back to bayonet) is greater, then 5D. Probably, about half an inch, but still. Add to that smaller size and weight of R5 and you get much les comfortable setup for handheld usage.


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## DrToast (Dec 28, 2020)

I wish Canon would update the 180mm macro. Or at least something longer than 100mm.


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## CarlMillerPhoto (Dec 28, 2020)

The EF version is 123mm... these being ~160mm in length? That’ll be a real bummer if the RF version is bigger.


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## Antono Refa (Dec 28, 2020)

Joules said:


> Making the assumption that the intend behind an action (reducing TC compatibility) is either nefarious or just indifference (or the action is the result of incompetence) is cynical in my mind. At least as long as there is no good reason to believe any of these things.



I made no such assumption, merely stated two facts (i) the RF 70-200mm f/2.8 is not compatible with TC, and (ii) you can't present a rationale for the incompatibility. E.g. you haven't compared the RF 70-200mm f/2.8 to the EF 70-200mm f/2.8L IS III USM or the nikkor z 70 200mm f 2.8 vr to show the IQ benefit of the large back element.



Joules said:


> Well, the quote was from the white paper. But of course, you are right in being skeptical of claims put forward by a manufacturer.



Gasp! You don't say!



Joules said:


> I presented the quote mostly because you seemed to state that you wished for a statement from Canon about the placement of their rear elements, and I wanted to show you that they have in fact already provided that.



No. I'm looking for a specific & measurable benefit that could be reasonably said to outweigh the incompatibility with TCs.



Joules said:


> All new RF design we have seen are as good or better optically as their EF versions, aren't they?



I wouldn't call having twice the vignetting @200mm f/2.8 better. I've heard Canon sacrifices vignetting & radial distortion for sharpness, but at this point I think it has become ridiculous.



Joules said:


> And in the cases where the EF version were already optically great, the RF versions do seem to show improved quality to size/weight ratio. They also do have large rear elements close to the sensor in most cases. Anything wrong with that?



Not if you can show said improved image quality.



Joules said:


> Canon claimed in their white papers that these close rear elements were something that would allow them to bring forward improved designs and I just don't see why you would doubt them.



I care not about what it would allow them to bring forward as much as what I would[n't] actually get for $2,300. Which is why I'm delaying the move to MILC, and looking at what Nikon & Sony have to offer.


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## Del Paso (Dec 28, 2020)

Even though I usually tend to prefer OEM lenses, this new RF 100mm macro will face competition from the new Sigma 100 macro, which all reviews report to be outstanding...
Much will depend on the RF's features (2:1 ?) and on its price.
Since, with EOS R bodies, there are no more focusing issues with foreign lenses, the Sigma could offer a much better value.


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## Bennymiata (Dec 28, 2020)

It's about time Canon brought out a 1:1 macro RF lens.
My ef 100mm macro is getting noisy.


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## figiko (Dec 28, 2020)

I want 2 times magnification ratio, not just 1:1 or I don't see the need the get rid of the ef-rf adapter. A 2:1 macro lens with autofocus (even slow) and good stabilization (in body or both, just the best possible) and my dream would come true for handheld wildlife macro photography!


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## Joules (Dec 28, 2020)

Antono Refa said:


> I made no such assumption, merely stated two facts (i) the RF 70-200mm f/2.8 is not compatible with TC, and (ii) you can't present a rationale for the incompatibility.


Your second statement is not a fact. I can present plenty of rationales. If they are the ones that compelled Canon to design their lenses as they did, is another matter. I have no insight into that, so can only put forward speculation.

For example, as the resolution of their bodies has gone up, Canon may believe sufficient parts of the market do not require TCs any more and therefore they reduce the cost of their development process by dropping it as a design requirement (or more likely, not add it as a requirement - the EF 70-200mm lenses never were on an official compatibility list, we're they?).

I was under the impression that you acknowledged that Canon also put forward a rationale on their own (more flexible in design with large, closer rear element) and dismissed it because it is something a big Company put forward. You mused that assuming an aspect of a design was compromised in order to improve another was Fanboying. And I mused assuming a lack of a good rationale is cynical.

Where does this leave us? Nowhere in particular, I think. Even if I were a Fanboy and you a Cynic, so be it. Sorry for trying to be snarky.



Antono Refa said:


> No. I'm looking for a specific & measurable benefit that could be reasonably said to outweigh the incompatibility with TCs.


I think that's where you run into trouble. By comparing full, released designs, it is infeasible to determine how much impact each aspect of the design has on each of the metrics you could measure (resolution, contrast, vignetting, distortion, weight, AF, IS, weather resistence...).

For example, the RF 70-200 2.8 being only ~ 70 % the weight of the EF version or the Nikon Z one is a factor that is probably the result of multiple design aspects. 

So ideally you would get your information from an unbiased expert, but I would imagine input of that sort to become very technical and academic and hard to access.

As for your second part, the value of TC compatibility is very subjective. Depending on where Canon takes the resolution of future bodies and whether they release a TC that doesn't portrude into the lens body, it may change further.


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## Antono Refa (Dec 28, 2020)

Joules said:


> Your second statement is not a fact. I can present plenty of rationales. If they are the ones that compelled Canon to design their lenses as they did, is another matter. I have no insight into that, so can only put forward speculation.



Speculation is not rationale. Its guesses as to what Canon's rationale might be.

Resolution is a great point. I didn't upgrade from the 5DmkII to mkIII, then mkIV for the resolution. I would be plenty happy with 20MP. Which leads me to...

Take this as an open question, without a shred of cynicism: which combo would give me better results, an R5 & RF 70-200mm cropped 50%, or a Nikon Z6II & TC 1.4x & Z 70-200mm f/2.8? With a hand on your heart, does the difference justify spending $1,450? Would you consider me a cynic for considering a switch to Nikon Z?



Joules said:


> I was under the impression that you acknowledged that Canon also put forward a rationale on their own (more flexible in design with large, closer rear element) and dismissed it because it is something a big Company put forward.



Its marketing material, unless quantifiable, e.g. the RF 70-200mm f/2.8 IS USM is that much sharper than the EF 70-200mm f/2.8 IS III USM.



Joules said:


> You mused that assuming an aspect of a design was compromised in order to improve another was Fanboying. And I mused assuming a lack of a good rationale is cynical.



My point is your willingness to assume there's an improvement, though you can't name it. Not being compatible with a TC is a concrete limitation. If you linked reviews comparing the EF version on a 5Ds to the RF on an R5 to show the new lens is twice as sharp, I would agree a 1.4x TC is redundant. But you don't.



Joules said:


> Where does this leave us? Nowhere in particular, I think. Even if I were a Fanboy and you a Cynic, so be it. Sorry for trying to be snarky.



The point isn't I'm a cynic. The point is I think Canon made a mistake by making the RF 70-200mm f/2.8 incompatible with TCs.



Joules said:


> I think that's where you run into trouble. By comparing full, released designs, it is infeasible to determine how much impact each aspect of the design has on each of the metrics you could measure (resolution, contrast, vignetting, distortion, weight, AF, IS, weather resistence...).
> 
> For example, the RF 70-200 2.8 being only ~ 70 % the weight of the EF version or the Nikon Z one is a factor that is probably the result of multiple design aspects.



Saving 30% on weight is an excellent example. I could buy "Canon sacrificed TC compatibility for 30% weight save".



Joules said:


> As for your second part, the value of TC compatibility is very subjective. Depending on where Canon takes the resolution of future bodies and whether they release a TC that doesn't portrude into the lens body, it may change further.



Indeed, which is one reason I'm waiting with the move to MILC. When I raised the point of other manufacturers making TCs that do not protrude into the lens body, I was told that compromised on image quality. I'm no expert, so I can't say whether this is true, much the less what the technical reasons why.


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## Joules (Dec 28, 2020)

Antono Refa said:


> Which combo would give me better results, an R5 & RF 70-200mm cropped 50%, or a Nikon Z6II & TC 1.4x & Z 70-200mm f/2.8? With a hand on your heart, does the difference justify spending $1,450? Would you consider me a cynic for considering a switch to Nikon Z?
> [...]
> If you linked reviews comparing the EF version on a 5Ds to the RF on an R5 to show the new lens is twice as sharp, I would agree a 1.4x TC is redundant.


I do not care if or how cynical you are. I already apologized for the silliness that debating it has brought, please consider that the end of that exchange on my part.
Your choice of camera system or your reason for chosing it is nothing I have any right or interest in judging anyway. To answer anyway, no I would not consider you a cynic for considering a switch to any system. Properly evaluating and questioning the benefits proposed by manufacturers and to a degree existing customers is perfectly reasonable.

As for your example, I can't judge what better means for you. The images will be extremely similar as the reach is virtually the same and both sensors and lenses are nothing to sneeze at in this comparison. For specific measurements, you may find one combination ahead of the other of course. There are many factors to the shooting experience that go beyond the result and would go into my personal judgement on whether or not a price difference is justified. I'm not interested in either combination, so I can't justify going through the pros and cons of each.

I'm not linking any reviews or charts since it is not my intend to convince you of anything here. You initially seemed to me to ask what's up with the rear element, and all I did want to do is provide my understanding and a quote of what that is based on for you to consider.

Anyway, even if a comparison of the EF lens on a 5Ds and the RF lens on the R5 that illustrates the RF combination beeing twice as sharp, I don't follow you how that would make a TC redundant. Assuming you are equating sharpness to resoultion here, without a higher resolution (or pixel density) body available you could still benefit from a TC in order to increase reach (when using fast enough lenses, of course).


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## melgross (Dec 28, 2020)

17 elements. I remember when a lens like this would have 5 or 6!


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## Sludz (Dec 28, 2020)

Blaaaarg. Even the shorter design is longer than the EF 100 with an adapter. it’s also 3/4” longer than the RF 70-200 2.8.


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## melgross (Dec 28, 2020)

Sludz said:


> Blaaaarg. Even the shorter design is longer than the EF 100 with an adapter. it’s also 3/4” longer than the RF 70-200 2.8.


Well, maybe you read my post? It’s a more complex optical design. That takes room. All new lenses seem to be more complex than older designs. canon’s older 50 f1.2 lenses used to be 8 elements. Look at what they have now!


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## Tremotino (Dec 28, 2020)

Antono Refa said:


> Of course it can, question is why. IIRC, it was explained that the closer the last element is to the sensor, the more vignetting the lens would have, due to the angle at which the light rays would hit the sensor.



That's NOT the case for Canon and Nikon.
But very likely for the small Sony mount since it's very tiny and lense elements at the back have to be smaller than the sensor...


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## Del Paso (Dec 29, 2020)

melgross said:


> 17 elements. I remember when a lens like this would have 5 or 6!


An intelligent lens-design isn't about "the more lenses, the better".
One of the very best macro lenses, the Leica M Macro Elmar 90mm f4, has only 4(!) lenses, and doesn't miss a single one.
I often use it with macro rings on my EOS R, and it beats,without discussion,the EF 100 L IS.
Of course, it's an f4 lens, without AF.
And what should I say about the Apo Macro Elmarit 2,8/100mm, 8 lenses, so sharp at any setting and aperture that it almost hurts?


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## David - Sydney (Dec 31, 2020)

The current RF lenses have brought something new to the table vs their EF counterparts. Either short/light or outstanding quality and autofocus speed for the L lenses. The RF24-105mm is not quite in this class though. An interesting review of the different ~100mm macros at:




Given the quality of the Laowa macro, a new RF100mm should have >1:1 magnification, IS and lens coatings and it will regain its lead in the current market.


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## SteveC (Jan 1, 2021)

David - Sydney said:


> The current RF lenses have brought something new to the table vs their EF counterparts. Either short/light or outstanding quality and autofocus speed for the L lenses. The RF24-105mm is not quite in this class though. An interesting review of the different ~100mm macros at:
> 
> 
> 
> ...



Unfortunately I'm not in a position to watch the video, so could you clarify which of the two RF24-105 mm lenses you're talking about (there's an f/4 L and an f/4-7.1 [non L]).


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## LeBlobe (Jan 1, 2021)

can we see amount of focus breathing with a patent? or gotta wait for real life tests?


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## Mt Spokane Photography (Jan 1, 2021)

LeBlobe said:


> can we see amount of focus breathing with a patent? or gotta wait for real life tests?


The location of the focus group usually determines focus breathing. Real life tests determine how much. Macro lenses tend to put focus groups close to the front so they don't change the angle of view. They are very aware that focus breathing for a macro lens is undesirable because of focus stacking. As focusing gets more complex and multiple lens groups move, it can be impossible for us to know. I hope there is essentially none.

The patent site is down now for maintenance, so I can't read the patent to see how its constructed and what they might say about focus breathing.


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## snappy604 (Jan 1, 2021)

Joules said:


> I do not care if or how cynical you are. I already apologized for the silliness that debating it has brought, please consider that the end of that exchange on my part.
> Your choice of camera system or your reason for chosing it is nothing I have any right or interest in judging anyway. To answer anyway, no I would not consider you a cynic for considering a switch to any system. Properly evaluating and questioning the benefits proposed by manufacturers and to a degree existing customers is perfectly reasonable.
> 
> As for your example, I can't judge what better means for you. The images will be extremely similar as the reach is virtually the same and both sensors and lenses are nothing to sneeze at in this comparison. For specific measurements, you may find one combination ahead of the other of course. There are many factors to the shooting experience that go beyond the result and would go into my personal judgement on whether or not a price difference is justified. I'm not interested in either combination, so I can't justify going through the pros and cons of each.
> ...



well said, there are a lot of different needs and each person needs to evaluate if the system they invest in will or won't meet those.. having said that, there are times when the choices given by the manufacturer do appear frustrating ;-)

btw there were comments about higher resolution.. after going from 80D to R5 ... all I can say is don't underestimate the ability to crop.. I still get sharp and detailed images after sometimes fairly heavy crops. Like all good tools though, need to learn how to maximize it and that certainly takes time.


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## koenkooi (Jan 2, 2021)

Mt Spokane Photography said:


> The location of the focus group usually determines focus breathing. Real life tests determine how much. Macro lenses tend to put focus groups close to the front so they don't change the angle of view. They are very aware that focus breathing for a macro lens is undesirable because of focus stacking. As focusing gets more complex and multiple lens groups move, it can be impossible for us to know. I hope there is essentially none.
> 
> The patent site is down now for maintenance, so I can't read the patent to see how its constructed and what they might say about focus breathing.



Both 100mm macro lenses from Canon have severe focus breathing, they go from 100-ish mm at infinity to 65-ish mm at MFD. And yes, I've been bitten by it when trying to do focus stacking without moving the lens.


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## LeBlobe (Jan 2, 2021)

Mt Spokane Photography said:


> The location of the focus group usually determines focus breathing. Real life tests determine how much. Macro lenses tend to put focus groups close to the front so they don't change the angle of view. They are very aware that focus breathing for a macro lens is undesirable because of focus stacking. As focusing gets more complex and multiple lens groups move, it can be impossible for us to know. I hope there is essentially none.
> 
> The patent site is down now for maintenance, so I can't read the patent to see how its constructed and what they might say about focus breathing.



yes site is still down . I didnt look into it before i thought it would be too technical for me hehe




koenkooi said:


> Both 100mm macro lenses from Canon have severe focus breathing, they go from 100-ish mm at infinity to 65-ish mm at MFD. And yes, I've been bitten by it when trying to do focus stacking without moving the lens.



yes im curious what is average across popular macro lenses , i just use rf 35mm f/1.8 so far and hoped the new 100mm would be better.


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## Mt Spokane Photography (Jan 3, 2021)

I finally discovered that there is a error in the link to the patent site and then looked up the patent. The goal is high quality with higher magnification. Although they have examples with various magnifications from 0.5 to 2.0, I'd expect that 1.5 is their preferred magnification.

I think example 3 is interesting with a magnification of 1.0 - 2.0. 

These will be expensive lenses if they were to be actually made.

Image surface infinity
Various data
Focal distance 99.75 
F number 2.92 
Half field angle (degree) 12.24 
Whole-length-of-the-lens 168.47 
BF 14.00 


Magnification ∞ - 1.0 - 2. 0


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## melgross (Jan 5, 2021)

Del Paso said:


> An intelligent lens-design isn't about "the more lenses, the better".
> One of the very best macro lenses, the Leica M Macro Elmar 90mm f4, has only 4(!) lenses, and doesn't miss a single one.
> I often use it with macro rings on my EOS R, and it beats,without discussion,the EF 100 L IS.
> Of course, it's an f4 lens, without AF.
> And what should I say about the Apo Macro Elmarit 2,8/100mm, 8 lenses, so sharp at any setting and aperture that it almost hurts?


You mean, the more elements. And you’re wrong. They couldn’t do it in years past for a number of reasons. Calculation, even with lens design programs, was a real bear. Each extra element adds significantly to the problem. Then there was the mechanical integrity of the lens. Back when, Cooke was known for superb designs that never performed that well, because they couldn’t make them properly. The technology wasn’t up to it. Glasses are being developed every day, new coatings, etc. All of this allows designers to take more advantage of additional elements than they could use decades ago.

‘So yes, designers do look at more elements as being beneficial. It’s pretty obvious, because new lenses are all about more elements when performance, and speed, are the main thrust.

you mention a 90 f4, which I’ve used. It’s pretty good, but bested by a number of faster lenses these days. Now, try to make that Ken’s a more realistic f 2.8, as most macro’s are. Or an f 2, as we see more of them come out. How many elements do you think it would need?

and back in the days of film, what was considered as sharp would be though of today as being just ok.


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