Patent: Optical formulas for Canon RF macro lenses

[koenkooi]

Thanks, very practical answer. Yes, the longer the lens, extension tube makes less difference. Conversely, the closeup diopter makes more difference but I don't recall trying it on the macro.

I dimly recall figuring out that the 180mm macro is more like 100mm at closest focus. Granted that's a lot longer than 65, and for all I know the 65 also shortens the effective focal length at close focus? I bow to your experience and good results but given that you're still just 30cm/1 foot from the subject I'm surprised to hear the flash doesn't reach that far. (Not questioning you, just not what I would have expected.) (BTW I don't shoot macro with flash, rather with long exposure, so I have zero experience, just supposition.)

The MP-E 65mm is fixed-focus, you can only vary the magnification for 1x to 5x. Both Canon 100mm macro lenses suffer from focus breathing, I haven't tested the EF-S 60mm for that yet.

 

[usern4cr]

Just wanted to point out that whatever magnification you get from the lens is all the mag that rig will give you. Cropping an image, either with a smaller than full frame sensor or in post, creates an enlargement and is not the same as increasing magnification. So even though my 80D has a 1.6x crop sensor when I have my MP-E 65mm set to 2x then twice life is the magnification, for example. It's not 3.2x...

I see your point, and would have to agree with you regarding the technical definition as it would apply to "macro" values claimed for lenses.

But then again, what if you have one FF lens and sensor with 50 lines per millimeter tested resolution and the same lens and better sensor with 100 lines per millimeter tested resolution and try 2 things: 1) put a 2x teleconverter on the first one and the image will be optically enlarged by 2x on the sensor, or 2) just do a 2x crop of the inner portion of the 2nd sensor and use software to interpolate it up by 2x to the same print size as that in 1). By your logic 1) will have a 2x increase in magnification (from both lenses), while 2) will not. But you would probably not see any difference between the prints at all. In fact, I have read many reviews of using the same lens and sensor while comparing one using a 2x teleconverter vs. using a 2x crop and interpolating by 2x up, and finding that they are basically the same quality and sometimes the crop & interpolate version is actually better. I could use the same comparisons of a 0.24x magnification of my 1/2 height image printed to the same height as a .48x magnification of a FF lens.

So it seems that the quality of the lens and sensor in producing an image should be considered in the definition of magnification and macro. In other words, we should be comparing the tested maximum lines per millimeter resolution of the subject in subject (physical) space, which would be a more accurate way to measure the useful magnification (or useful macro). So they should mention this tested measure along with the diagonal size (in physical space) of the subject at maximum magnification. That would give you the real value for any combination of lens / sensor crop & quality / teleconverter combinations for an equivalent comparison between them.

All in all, a royal mess, and one that manufacturers will never supply. So I guess I will just have to sigh and agree with your statement as a definition, and I will refrain from mentioning a doubling of equivalent magnification from a 2x crop sensor.

 

[usern4cr]

The MP-E 65mm is fixed-focus, you can only vary the magnification for 1x to 5x. Both Canon 100mm macro lenses suffer from focus breathing, I haven't tested the EF-S 60mm for that yet.

The 65mm lens keeps the same exact focus length (to sensor) no matter how you zoom it between 1x and 5x macro? That would be an interesting lens to look at on the "optical bench" previously mentioned (I just checked it, but that lens isn't in their list). It would make it truly ideal for you to fix the distance of the tip of the lens to your flower with sugar water and wait for an insect to appear, with the freedom to zoom without messing up the focused shot. Are you able to change the zoom while the bee is there without scaring it off, or do you have to do it beforehand and hope you get the right zoom value?

Also, what distance do you find it is between the focus spot and the front surface of the lens?

 

[Dalantech]

I see your point, and would have to agree with you regarding the technical definition as it would apply to "macro" values claimed for lenses.

But then again, what if you have one FF lens and sensor with 50 lines per millimeter tested resolution and the same lens and better sensor with 100 lines per millimeter tested resolution and try 2 things: 1) put a 2x teleconverter on the first one and the image will be optically enlarged by 2x on the sensor, or 2) just do a 2x crop of the inner portion of the 2nd sensor and use software to interpolate it up by 2x to the same print size as that in 1). By your logic 1) will have a 2x increase in magnification (from both lenses), while 2) will not. But you would probably not see any difference between the prints at all. In fact, I have read many reviews of using the same lens and sensor while comparing one using a 2x teleconverter vs. using a 2x crop and interpolating by 2x up, and finding that they are basically the same quality and sometimes the crop & interpolate version is actually better. I could use the same comparisons of a 0.24x magnification of my 1/2 height image printed to the same height as a .48x magnification of a FF lens.

So it seems that the quality of the lens and sensor in producing an image should be considered in the definition of magnification and macro. In other words, we should be comparing the tested maximum lines per millimeter resolution of the subject in subject (physical) space, which would be a more accurate way to measure the useful magnification (or useful macro). So they should mention this tested measure along with the diagonal size (in physical space) of the subject at maximum magnification. That would give you the real value for any combination of lens / sensor crop & quality / teleconverter combinations for an equivalent comparison between them.

All in all, a royal mess, and one that manufacturers will never supply. So I guess I will just have to sigh and agree with your statement as a definition, and I will refrain from mentioning a doubling of equivalent magnification from a 2x crop sensor.

Because cropping an image won't reveal more detail, but barring diffraction increasing the magnification can. You can make all kinds of arguments about lens and sensor resolution, but neither one factor into magnification. Magnification is not determined by resolving power, what matters is the scale of the subject that is projected onto the image plane.

 

[Dalantech]

The 65mm lens keeps the same exact focus length (to sensor) no matter how you zoom it between 1x and 5x macro?

No, because the lens extends as the mag increases. So the subject to image plane distance actually goes up, but the working distance drops from 4" at 1x to 1.6" at 5x. I just focused on something at 1x and then ran the lens out to 5x and it extended past the subject (I'd have to back up a little to bring the subject back into focus at 5x). The MP-E is an odd animal. It looks like a reversed lens on a variable length extension tube. In fact adding extension to it doesn't have much of an effect, and the easiest way to get it above 5x is to use a teleconverter. It does have a floating lens group that adjusts the focus as the mag changes, and IMHO is the sharpest macro lens above 1x.

 

[Dalantech]

I dimly recall figuring out that the 180mm macro is more like 100mm at closest focus. Granted that's a lot longer than 65, and for all I know the 65 also shortens the effective focal length at close focus?

The MP-E 65mm is an odd animal -more like a reversed lens on a variable length extension tube. Almost impossible to compare it to a standard macro lens. Adding extension tubes to it doesn't make much of a difference in the mag (better off using a teleconverter).

Canon's 100mm macro lenses are roughly 72mm at close focus, and the EF-S 60mm is the poor man's MP-E cause it's a 37mm lens at 1x (so it only takes 37mm of extension to get to 2x, and a full set of Kenko tubes will get you close to 3x).

I bow to your experience and good results but given that you're still just 30cm/1 foot from the subject I'm surprised to hear the flash doesn't reach that far. (Not questioning you, just not what I would have expected.) (BTW I don't shoot macro with flash, rather with long exposure, so I have zero experience, just supposition.)

The problem isn't getting enough light with the flash, the problem is getting enough good light. The closer the diffuser is to the subject the softer the specular highlights. The closer the flash is to the subject the shorter the flash duration (easier to freeze motion). One of the misconceptions in macro is that the flash is always going to fire fast enough to freeze motion, and it isn't true. Motion while the flash is firing can amplify diffraction softening, an effect I call "macro motion blur", and it won't look like traditional motion blur in the image. You'll just see a loss of detail and blame diffraction for it. Even the quality and the angle of the light can impact the detail that can be captured.

You want to be able to see color and texture in the specular area, and not a white hot spot. Here's an example of my worse case lighting, cause the image was taken at 1x (at higher mags the diffuser to subject distance drops and the specular highlights get softer):

Violet Darter II by John Kimbler, on Flickr

See how the bright areas in the dragon's eye still have color and texture in them? Same subject and light source, but now at 3x:

Violet Darter I by John Kimbler, on Flickr

See how the bright area in the eye gets softer? There's a difference between getting enough light, and creating soft light that doesn't blow out detail. So much more than just diffraction to worry about where detail is concerned, and that's one of the reasons I don't care about diffraction.

FWIW: Both of those images are single frames (I don't focus stack) and I don't allow myself to crop in post unless I want to make a square print. Forcing myself to nail the framing with the view finder has made my composition skills better, something that the cropping tool in post can't do...

 

[usern4cr]

See how the bright area in the eye gets softer? There's a difference between getting enough light, and creating soft light that doesn't blow out detail. So much more than just diffraction to worry about where detail is concerned, and that's one of the reasons I don't care about diffraction.

FWIW: Both of those images are single frames (I don't focus stack) and I don't allow myself to crop in post unless I want to make a square print. Forcing myself to nail the framing with the view finder has made my composition skills better, something that the cropping tool in post can't do...

1st: These pictures are just stunning - thanks for the post!
2nd: Thanks for explaining the issue of lighting distance and flash speed for sharpness.
3rd: I'm glad to hear you don't focus stack. I've tried doing focus stacking and find (for me) it's usually more trouble than it's worth. I'm having similar issues with stitching multiple images in panoramas when there is perceivable motion (waves, clouds, leaves etc). I've also had issues while doing HDR merging where there's motion between the various exposure shots even thought they're so close together. I'm about to the point to mainly taking a single instance picture after composing via moving around & zooming so there's no cropping after the fact, other than slight edge trimming to make them ideal for printing.
4th: Your method of attracting insects via sugar water in flowers got me thinking that I should try to use my existing Oly 60mm f2.8 1:1 macro and make my own insect attractor setup like you did with flash so that I can get better to eventually take 1:1 shots similar to those you have shown. Then when I get my Canon R... setup I can consider getting an appropriate lens to increase the macro reach and sensor quality. If you don't mind, do you have any posts of ways one can use certain lower attracter plants / sugarcane climbing tubes / final flowers (or whatever) baited with sugar water / flash speed etc to get up to speed?

 

[Dalantech]

1st: These pictures are just stunning - thanks for the post!
2nd: Thanks for explaining the issue of lighting distance and flash speed for sharpness.
3rd: I'm glad to hear you don't focus stack. I've tried doing focus stacking and find (for me) it's usually more trouble than it's worth. I'm having similar issues with stitching multiple images in panoramas when there is perceivable motion (waves, clouds, leaves etc). I've also had issues while doing HDR merging where there's motion between the various exposure shots even thought they're so close together. I'm about to the point to mainly taking a single instance picture after composing via moving around & zooming so there's no cropping after the fact, other than slight edge trimming to make them ideal for printing.
4th: Your method of attracting insects via sugar water in flowers got me thinking that I should try to use my existing Oly 60mm f2.8 1:1 macro and make my own insect attractor setup like you did with flash so that I can get better to eventually take 1:1 shots similar to those you have shown. Then when I get my Canon R... setup I can consider getting an appropriate lens to increase the macro reach and sensor quality. If you don't mind, do you have any posts of ways one can use certain lower attracter plants / sugarcane climbing tubes / final flowers (or whatever) baited with sugar water / flash speed etc to get up to speed?

1. Thank you!

2. Happy to help

3. Focus stacking is a "solution" that creates more problems that in solves.

4. You can load up a spray bottle with some sugar water and spray plants with it. The down side is the the resulting images won't look "natural" cause critters normally don't lick leaves. But I can't say that it's all that bad. Better still to get a syringe, fill it with a 1:1 sugar syrup (one part sugar to one part water), and inject flowers.

Honeybee in a Passion Flower by John Kimbler, on Flickr

...or put some on your finger...

Finger Fed Bumblebee III by John Kimbler, on Flickr

Be careful though, you don't want to put so much bait out that you empty out an entire beehive. *cough* Not that I've done that or anything *cough*

 

[usern4cr]

1. Thank you!

2. Happy to help

3. Focus stacking is a "solution" that creates more problems that in solves.

4. You can load up a spray bottle with some sugar water and spray plants with it. The down side is the the resulting images won't look "natural" cause critters normally don't lick leaves. But I can't say that it's all that bad. Better still to get a syringe, fill it with a 1:1 sugar syrup (one part sugar to one part water), and inject flowers.

Honeybee in a Passion Flower by John Kimbler, on Flickr

...or put some on your finger...

Finger Fed Bumblebee III by John Kimbler, on Flickr

Be careful though, you don't want to put so much bait out that you empty out an entire beehive. *cough* Not that I've done that or anything *cough*

Thanks for the feedback, pictures, & time spent in these posts.

I haven't decided what site to use to get my pictures up yet, but I wanted to post one back for you to see since you've been so kind in posting yours. This one isn't in the same ballpark as the ones you've posted, and isn't my best one (which is why I'm willing to post it here in much reduced resolution). It's what my MFT 300mm f4 can deliver hand held, uncropped. I can't wait to get an R5 and some sweet lenses!

 

[Dalantech]

Thanks for the feedback, pictures, & time spent in these posts.

I haven't decided what site to use to get my pictures up yet, but I wanted to post one back for you to see since you've been so kind in posting yours. This one isn't in the same ballpark as the ones you've posted, and isn't my best one (which is why I'm willing to post it here in much reduced resolution). It's what my MFT 300mm f4 can deliver hand held, uncropped. I can't wait to get an R5 and some sweet lenses!
View attachment 190059

Very nice!

If you wanna give yourself a little more time to work load up a syringe with 1:1 sugar syrup.

Bees in a Wallflower Series 1-2 by John Kimbler, on Flickr

 

[usern4cr]

Very nice!

If you wanna give yourself a little more time to work load up a syringe with 1:1 sugar syrup.

Bees in a Wallflower Series 1-2 by John Kimbler, on Flickr

I just checked out your wallflower series - wow! There are so many insects there that I've never seen, it's amazing! Do you handhold all your shots vs using a tripod? And do you use 50% or so flash illumination from 2 diffuse sides?

 

[Dalantech]

I just checked out your wallflower series - wow! There are so many insects there that I've never seen, it's amazing! Do you handhold all your shots vs using a tripod? And do you use 50% or so flash illumination from 2 diffuse sides?

I always shoot hand held because I can adjust the position and focus faster, and with the techniques I use I actually have more control over motion because a tripod only braces the camera, but it does nothing for the flower (or other perch) that the subject is on.

I'm using Canon's MT-26EX RT macro twin flash. Here's a video of my rig and I explain my lighting in it.

 

[usern4cr]

I always shoot hand held because I can adjust the position and focus faster, and with the techniques I use I actually have more control over motion because a tripod only braces the camera, but it does nothing for the flower (or other perch) that the subject is on.

I'm using Canon's MT-26EX RT macro twin flash. Here's a video of my rig and I explain my lighting in it.

Thanks for the video of your rig. It really helps someone like me consider jumping into the "deep macro waters", as I need to know as much as possible about how to do it and what to buy before I spend the money. I've always preferred taking hand-held photos if possible, and your successful single-shot technique without a tripod is something that would be ideal for me.

I wonder if Canon will come out with a RF version of the MP-E 65 macro, and if they do then what might they do in the design that makes it better that just using the EF version with EF-to-RF adapter (empty extension tube with electrical control pass-through) ?

 

[Dalantech]

Thanks for the video of your rig. It really helps someone like me consider jumping into the "deep macro waters", as I need to know as much as possible about how to do it and what to buy before I spend the money. I've always preferred taking hand-held photos if possible, and your successful single-shot technique without a tripod is something that would be ideal for me.

Happy to help! Check out the tutorial and blog links in my signature for more tips and tricks.

I wonder if Canon will come out with a RF version of the MP-E 65 macro, and if they do then what might they do in the design that makes it better that just using the EF version with EF-to-RF adapter (empty extension tube with electrical control pass-through) ?

I think that as a hand held field shooter I'd like for an RF version of the MP-E to be lighter (maybe carbon fiber for the barrel) and weather sealed.

The EF version has a bit of a design flaw, where the cable that runs between the electrical contacts and the aperture assembly will break over time. In the ten years I've owned mine I've had to get it repaired trice, and it's cost me roughly 600 USD total. If my copy breaks again I probably won't repair or replace it, I'll just use the EF-S 60mm + tubes until Canon comes out with an RF MP-E lens. That flaw needs to be addresses in the RF version.

Although I don't focus stack it would be cool if the magnification of the RF version could be controlled by the camera, so that it could be stepped by the camera for an in camera focus bracket sequence. Bonus points if the camera could output a stacked RAW file.

Last, at the risk of the lens costing as much as a good used car, I'd like to see a red ring on it...

 

[usern4cr]

Happy to help! Check out the tutorial and blog links in my signature for more tips and tricks.


I think that as a hand held field shooter I'd like for an RF version of the MP-E to be lighter (maybe carbon fiber for the barrel) and weather sealed.

The EF version has a bit of a design flaw, where the cable that runs between the electrical contacts and the aperture assembly will break over time. In the ten years I've owned mine I've had to get it repaired trice, and it's cost me roughly 600 USD total. If my copy breaks again I probably won't repair or replace it, I'll just use the EF-S 60mm + tubes until Canon comes out with an RF MP-E lens. That flaw needs to be addresses in the RF version.

Although I don't focus stack it would be cool if the magnification of the RF version could be controlled by the camera, so that it could be stepped by the camera for an in camera focus bracket sequence. Bonus points if the camera could output a stacked RAW file.

Last, at the risk of the lens costing as much as a good used car, I'd like to see a red ring on it...

I looked again at the patents Japan Patent Application 2020-060661 mentioned in the initial post of this thread. It mentions 4 lenses, of which I assume the 65mm f2.8 is 1. The image height and f# are exactly the same for all 4 lenses, and the patent images (I can't read Japanese) show that they are all the same basic design with 2 moving groups, where the front, back & overall length does not move. So I don't see how this 65mm macro could be the same as the MP-E 65. And I wonder if it is even possible for these non-telescoping designs to go beyond 1:1 all the way to 5:1 since it doesn't have the crazy long lens zoom moving extension used in the MP-E 65. And if it did allow 5:1 then you'd think that all the other 3 similar macros shown would be able to go way beyond 1:1 macro as well, which I really doubt will happen.

So I'm going to hazard a guess that we may not see a new RF version of this lens, at least not related to these patents (I hope I'm wrong). There are a lot of posts from serious macro users that find the MP-E 65 the best macro lens, but I don't know how many actually buy it vs all the other more mainstream ones. Since you are the published expert with history (& repairs) with this lens, have you contacted Canon to try and make them aware of what they should fix in a future design as well as lobbying for a new improved RF version of it? They might value what you have to say.

 

[bclaff]

The 65mm lens keeps the same exact focus length (to sensor) no matter how you zoom it between 1x and 5x macro? That would be an interesting lens to look at on the "optical bench" previously mentioned (I just checked it, but that lens isn't in their list). It would make it truly ideal for you to fix the distance of the tip of the lens to your flower with sugar water and wait for an insect to appear, with the freedom to zoom without messing up the focused shot. Are you able to change the zoom while the bee is there without scaring it off, or do you have to do it beforehand and hope you get the right zoom value?

Also, what distance do you find it is between the focus spot and the front surface of the lens?

I haven't located the patent for that lens. If anyone knows I'd be happy to add it to the Optical Bench.

 

[Dalantech]

I looked again at the patents Japan Patent Application 2020-060661 mentioned in the initial post of this thread. It mentions 4 lenses, of which I assume the 65mm f2.8 is 1. The image height and f# are exactly the same for all 4 lenses, and the patent images (I can't read Japanese) show that they are all the same basic design with 2 moving groups, where the front, back & overall length does not move. So I don't see how this 65mm macro could be the same as the MP-E 65. And I wonder if it is even possible for these non-telescoping designs to go beyond 1:1 all the way to 5:1 since it doesn't have the crazy long lens zoom moving extension used in the MP-E 65. And if it did allow 5:1 then you'd think that all the other 3 similar macros shown would be able to go way beyond 1:1 macro as well, which I really doubt will happen.

So I'm going to hazard a guess that we may not see a new RF version of this lens, at least not related to these patents (I hope I'm wrong). There are a lot of posts from serious macro users that find the MP-E 65 the best macro lens, but I don't know how many actually buy it vs all the other more mainstream ones. Since you are the published expert with history (& repairs) with this lens, have you contacted Canon to try and make them aware of what they should fix in a future design as well as lobbying for a new improved RF version of it? They might value what you have to say.

Not sure who I could contact though, or if they'd listen to an amateur.

 

[usern4cr]

I haven't located the patent for that lens. If anyone knows I'd be happy to add it to the Optical Bench.

I take it that you're the developer of the Optical Bench? If so, hat's off to you! It's a remarkable piece of work. I spent a lot of time reading your tutorial of how the optics work relating to what you've done. Now I feel that I'm very much better informed on how lenses work, so that when I make camera & lens suggestions to others on what I think should be done I might be a little bit more wiser and a whole lot less clueless.

Thanks, again!

 

[usern4cr]

Not sure who I could contact though, or if they'd listen to an amateur.

A week or so ago I sent a customer request to Canon (https://www.usa.canon.com/internet/...duct-showcases/projectors/contact-a-sales-rep) to make a suggestion on RF lenses and camera features (like aperture bracketing) that I'd like to see them add in the future. To me surprise, I got a very nice response from Tim at Camera Support <[email protected]> thanking me, with a few nice personally written paragraphs, and saying that my suggestion would be passed on. I responded with a few more suggestions, getting a nice response from Jacob. I have no idea if it will make any difference, but I will say that they were amazingly responsive and friendly and I think others interested in Canon might find that good to hear.

If they see your work, and history with the MP-E 65, the people that matter in Japan might take you very seriously and you might just make a difference. If they decide to design a new version of a RF MP-E 65 with AZ (user controlled auto-zoom, which also does the auto-focus when zooming) then the whole macro community can celebrate!

 

[bclaff]

I take it that you're the developer of the Optical Bench? If so, hat's off to you! It's a remarkable piece of work. I spent a lot of time reading your tutorial of how the optics work relating to what you've done. Now I feel that I'm very much better informed on how lenses work, so that when I make camera & lens suggestions to others on what I think should be done I might be a little bit more wiser and a whole lot less clueless.

Thanks, again!

Yes, PhotonsToPhotos is my site. Best known for my sensor measurements but I think the Optical Bench and patent data are under-appreciated.

Thanks for the positive feedback. You seem to be getting just what I hoped out of that material I have prepared.

Feel free to email (contact is at the bottom of the main page) if you have additional feedback or requests.