# Effects of diffraction and R5/R6 sensor on resolution of f/5.6, f/7.1 and f/11 lenses and TCs



## AlanF (Aug 14, 2020)

Another of my geek articles, which does have some implications for actual use. What I do here is to calculate the contributions of diffraction and sensor Mpx size (R5 vs R6) to the resolving power of the 400mm f/5.6 and 500mm f/7.1 zooms and the 600mm and 800mm f/11 primes and how resolution is affected by 1.4x and 2x teleconverters.

The summary based on just the effects of diffraction and sensor Mpx, and ignoring optical aberrations is:

On an unrealistically high-resolution sensor, the f5.6, f/7.1 zooms and the 800mm f/11 would all have the same resolution and outresolve the 600mm f/11, and the TCs would not increase resolution.
As the number of pixels on the sensor decreases, increasing focal length becomes increasingly advantageous.
The 100-400mm at 400mm f/5.6 is slightly outresolved by the 600mm f/11 on the R5 and more so on the R6.
The100-400mm f/5.6 + 1.4xTC at 560mm f/8 outresolves the 600mm f/11 on the R5 and the two lenses are similar on the R6
The 100-500mm f/7.1 outresolves the 100-400mm f/5.6 and 600mm f/11 on the R5 and R6
The 800mm f/11 outresolves the 100-500mm f/7.1 on the R5 and R6, but adding the 1.4xTC to the zoom brings it closer to the 800mm prime.
Using the 1.4x and 2xTCs on the f/11 lens hardly increases the resolution on the R5 and only a little more on the R6. Further, any additional aberration added by the TCs could well render them even worse.
The f/11 lenses are more suited to the lower resolution R6, and this makes it an attractive lower priced alternative.
Those who are interested can read further – I spent hours doing the calculations and graphs to confirm what I knew intuitively for my own satisfaction. But, my calculations are steering me to what lenses to use with the R5 and where the R6 is appropriate.


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## AlanF (Aug 14, 2020)

In an earlier geek thread

https://www.canonrumors.com/forum/threads/diffraction-airy-disks-and-implications.36639/

there is an introduction to diffraction for non-experts, which explains what is going on here. There is a basic rule that the resolving power of a lens is limited by diffraction to being able to detect two lines separated by the diameter of an Airy Disk, d, or more, where D is the diameter of the front element and f is the focal length according to the equation:

d = 1.22*(wavelength of light)*D/f (1)
or in its usual form:
d = 1.22*(wavelength of light)*f-number (2)

This equation is used to calculate the diffraction-limited aperture of a lens, DLA, the widest f-number that makes best use of the size of pixels on the sensor. Equation 2 is independent of the focal length of the lens. But, that is not the end of the story. The size of the image on the sensor increases with f. So, if, say, you double the focal length of the lens and keep the same D, like adding a 2xTC to the lens, you double the size of the Airy Disk, so halving the resolving power. But, as the image is twice as large, you should see exactly the same amount of detail. In fact, the resolving power of the lens that is determined by diffraction depends simply on the wavelength of light and the diameter D:

Resolution(diffraction limited) varies as (wavelength of light)*D. (3)

But we know that 2x extenders give us more 2x2 more pixels on a target and usually work so we spend hard-earned money on them. So, what is going on? Equation 3 is just for the diffraction of the lens. We have to consider the diffraction of the system as a whole. To do this, we need to know the resolution of the different components, using MTF, which goes from 1, being 100%, down to zero, with MTF = 0.09 being the vale for “just resolvable” (the Rayleigh Criterion).

MTF(system) = MTF(diffraction)*MTF(sensor)*MTF(lens aberration) (4).

I have calculated the contributions of the MTF(diffraction) and the MTF(sensor) pixel size. The effects of Bayer and AA-filters on sharpness have been ignored for the sensor and won’t matter too much when comparing lenses. These are plotted versus lp/mm resolution. I have allowed for the different focal lengths, f, by reference to a 400mm lens as standard and multiplying on the x-axis the lp/mm by a factor of f/400 for each lens (i.e., x2 for 800mm etc).

The diameter of the front element (entrance pupil) for 400mm/ f5.6 is 71.4mm, 500mm f/7.1 is 70.4mm, 800mm f/11 is 72.7mm, and the 600mm f/11 is 54.4mm. The first plot shows the MTF(diffraction) lenses with D ~ 71mm have very similar curves and are better than the 600mm f/11. The line across the graph at MTF ~ 0.09 shows the Rayleigh limit where resolution is completely lost. The points where the curves intersect this line shows the relative resolution of the different lines.

These curves would be seen if the MTF(sensor) = 1.0, i.e, extremely high Mpx. There is no gain in resolution on using TCs for such an extreme sensor, and the only important factor is the diameter of the entrance pupil.


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## AlanF (Aug 14, 2020)

The MTF(sensor) vs lp/mm for R5 and R6 sensors.

These curves show that the loss of resolution is progressive and gradual as the lp/mm increase, and the R6 hits the buffer of 0.09 earlier.


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## AlanF (Aug 14, 2020)

Plots of MTF(diffraction)*MTF(sensor) vs lp/mm for different lenses on R5 and R6

1st Plot

The 100-400mm at 400mm f/5.6 is slightly outresolved by the 600mm f/11 on the R5 and more so on the R6.
The100-400mm f/5.6 + 1.4xTC at 560mm f/8 outresolves the 600mm f/11 on the R5 and the two lenses are similar on the R6
The 100-500mm f/7.1 outresolves the 100-400mm f/5.6 and 600mm f/11 on the R5 and R6
2nd Plot

The 800mm f/11 outresolves the 100-500mm f/7.1 on the R5 and R6, but adding the 1.4xTC to the zoom outresolves the 800mm prime.


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## AlanF (Aug 14, 2020)

Adding TCs to the f/11 lenses

Using the 1.4x and 2xTCs on the f/11 lens hardly increases the resolution on the R5 and only a little more on the R6. Further, any additional aberration added by the TCs could well render them even worse.


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## Jonathan Thill (Aug 14, 2020)

@AlanF thank you for putting in the effort to do this, this is extremely valuable information for me. 

I own the R5 and have the R6 on order and will be getting the 600 and the 800. My wife and I shoot together and she loves all things wildlife and really wants the R6 and the 600 and 800 because she is not the strongest little thing. 

She struggles now with 100-400 and a TC on the EOS R


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## BeenThere (Aug 14, 2020)

AlanF said:


> Another of my geek articles, which does have some implications for actual use. What I do here is to calculate the contributions of diffraction and sensor Mpx size (R5 vs R6) to the resolving power of the 400mm f/5.6 and 500mm f/7.1 zooms and the 600mm and 800mm f/11 primes and how resolution is affected by 1.4x and 2x teleconverters.
> 
> The summary based on just the effects of diffraction and sensor Mpx, and ignoring optical aberrations is:
> 
> ...


Great work! So, best is zooms on the R5, with TC if you need it to fill the frame.


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## AlanF (Aug 14, 2020)

BeenThere said:


> Great work! So, best is zooms on the R5, with TC if you need it to fill the frame.


My reaction is for me to get the R5 and use the 100-400mm II +TCs as I love that lens so much. But, the R6 with the 600 f/11 does look a nice light affordable package. But, I'd avoid the RF TCs as they are very expensive and may even make things worse. I want to try the R5 with my Sigma 150-600mm C. I think the IQ will be very good but the AF is an unknown for speed.


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## BeenThere (Aug 14, 2020)

AlanF said:


> My reaction is for me to get the R5 and use the 100-400mm II +TCs as I love that lens so much. But, the R6 with the 600 f/11 does look a nice light affordable package. But, I'd avoid the RF TCs as they are very expensive and may even make things worse. I want to try the R5 with my Sigma 150-600mm C. I think the IQ will be very good but the AF is an unknown for speed.


Sounds like a plan. Also keep in mind that on occasion you may want to photograph something other than birds, and there are a lot of sharp large aperture lenses available for that.


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## SteveC (Aug 14, 2020)

BeenThere said:


> Sounds like a plan. Also keep in mind that on occasion you may want to photograph something other than birds, and there are a lot of sharp large aperture lenses available for that.



The holy trinity: 15-35 RF, 24-105 RF 4.0/L, and the EF 100-400 II L (with an adapter of course). The RF 100-500 L apparently is comparable, but if you've already got the EF, I see little reason to upgrade unless you _must_ have 500mm.

(And yes, I'm still missing the 24-105, bought from the Canon store as a refurb with an RP thrown in for 300 bucks over 24-105 list price.)


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## tron (Aug 25, 2020)

Alan congratulations and a big thank you for getting us valuable information about all these camera/lens/tc combinations.


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## Click (Aug 25, 2020)

tron said:


> Alan congratulations and a big thank you for getting us valuable information about all these camera/lens/tc combinations.



+1 Thank you Alan.


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## Stu_bert (Aug 26, 2020)

Click said:


> +1 Thank you Alan.


+2 Thanks for spending all the time to provide that info & education. Very much appreciated.


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## justaCanonuser (Sep 14, 2021)

AlanF said:


> Another of my geek articles, which does have some implications for actual use. What I do here is to calculate the contributions of diffraction and sensor Mpx size (R5 vs R6) to the resolving power of the 400mm f/5.6 and 500mm f/7.1 zooms and the 600mm and 800mm f/11 primes and how resolution is affected by 1.4x and 2x teleconverters.
> 
> The summary based on just the effects of diffraction and sensor Mpx, and ignoring optical aberrations is:
> 
> ...


Alan, this is very interesting, thank you very much. Your last finding "the f/11 lenses are more suited to the lower resolution R6, and this makes it an attractive lower priced alternative" didn't surprise me. That's basically what I try to tell the high MP sensor fans since many years.


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## LogicExtremist (Sep 27, 2021)

AlanF said:


> Another of my geek articles, which does have some implications for actual use. What I do here is to calculate the contributions of diffraction and sensor Mpx size (R5 vs R6) to the resolving power of the 400mm f/5.6 and 500mm f/7.1 zooms and the 600mm and 800mm f/11 primes and how resolution is affected by 1.4x and 2x teleconverters.
> 
> The summary based on just the effects of diffraction and sensor Mpx, and ignoring optical aberrations is:
> 
> ...


Hi Alan, thanks for this information and the huge effort you put into it!


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## stevelee (Sep 28, 2021)

Thanks. I found that very interesting, even though I have no plans to get either of those cameras or any of those lenses.

It seems like people tend to think of diffraction as an all-or-nothing thing, as if light suddenly falls off a cliff at a diffraction limit. 

I have tried taking macro pictures at various apertures to see what is the smallest opening I can get away with. As the openings stopped down, I could see an increasing softness to the image that was not unpleasant. Up to a point getting another millimeter in depth of field is worth that compromise. Even f/32 wasn’t awful though the diffraction effect was quite obvious. I clearly am not going to run similar tests to yours on my equipment, but in controlled situations, mainly macro using a tripod, I will try to see what is the optimum compromise to make.


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## LogicExtremist (Sep 29, 2021)

stevelee said:


> Thanks. I found that very interesting, even though I have no plans to get either of those cameras or any of those lenses.
> 
> It seems like people tend to think of diffraction as an all-or-nothing thing, as if light suddenly falls off a cliff at a diffraction limit.
> 
> I have tried taking macro pictures at various apertures to see what is the smallest opening I can get away with. As the openings stopped down, I could see an increasing softness to the image that was not unpleasant. Up to a point getting another millimeter in depth of field is worth that compromise. Even f/32 wasn’t awful though the diffraction effect was quite obvious. I clearly am not going to run similar tests to yours on my equipment, but in controlled situations, mainly macro using a tripod, I will try to see what is the optimum compromise to make.


With macro, it's a matter of finding the balance between of depth of field, available light and degradation due to diffraction. Many macro photographers settle for the sweet spot of f/11. For static objects, it's possible to use wider apertures when using focus stacking.


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## LogicExtremist (Sep 29, 2021)

Alan, I've always wondered how the real world image quality from the RF 600mm f/11 compares to the Sigma 150-600 Contemporary, curious to know what you think.


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## stevelee (Sep 29, 2021)

LogicExtremist said:


> With macro, it's a matter of finding the balance between of depth of field, available light and degradation due to diffraction. Many macro photographers settle for the sweet spot of f/11. For static objects, it's possible to use wider apertures when using focus stacking.


Yes, if I have a setup that needs stacking, I will use a focusing rail. I might still try several sets of shots at different apertures, say 8, 11, and 16, and see which turns out the best. As long as I have that all set up, it is not a lot of trouble to do more runs. I would do better if I had much more experience and shot macro more often, so I do more redundant steps to make up for judgment and skill.


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## AlanF (Sep 29, 2021)

LogicExtremist said:


> Alan, I've always wondered how the real world image quality from the RF 600mm f/11 compares to the Sigma 150-600 Contemporary, curious to know what you think.


There aren't much data out there, and I have never handled an RF 600mm f/11. So, here is my indirect opinion. Canon's own MTF values and the-digital-picture show clearly that the RF 100-500mm is significantly sharper and with better contrast at 500mm than the RF 600mm. My 100-400mm II + 1.4x TC at 560mm is pretty close to the Rf 100-500mm in sharpness and contrast. My very good copy of the Sigma 150-600mm C at 600mm had similar resolution but poorer contrast than my 100-400mm II at 560mm, and was definitely inferior to my RF 100-500mm - the RF cropped from 500 was better than the 150-600mm C at 600mm. I would guess that the weaker performance due to diffraction at f/11 of the RF 600mm is not far from the performance of the 150-600mm at f/6.3, which is n ot optimised for optical quality at the longest end. I found the AF and the IS of the Sigma much below those of the Canon lenses on the R5.


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## LogicExtremist (Sep 29, 2021)

AlanF said:


> There aren't much data out there, and I have never handled an RF 600mm f/11. So, here is my indirect opinion. Canon's own MTF values and the-digital-picture show clearly that the RF 100-500mm is significantly sharper and with better contrast at 500mm than the RF 600mm. My 100-400mm II + 1.4x TC at 560mm is pretty close to the Rf 100-500mm in sharpness and contrast. My very good copy of the Sigma 150-600mm C at 600mm had similar resolution but poorer contrast than my 100-400mm II at 560mm, and was definitely inferior to my RF 100-500mm - the RF cropped from 500 was better than the 150-600mm C at 600mm. I would guess that the weaker performance due to diffraction at f/11 of the RF 600mm is not far from the performance of the 150-600mm at f/6.3, which is n ot optimised for optical quality at the longest end. I found the AF and the IS of the Sigma much below those of the Canon lenses on the R5.


Thanks, that's quite helpful. I've been getting more interested in trying out bird photography, and I've put my EF 70-200 f/2.8 III or 55-250 STM on my 80D for more reach, but it's not really long enough. 

I've been considering purchasing a longer telephoto but I can't decide whether to go with the RF 600 f/11, Rf 800 f/11 or wait for the RF 100-400 f/8 when that comes out, to use on my RF mount camera, or to go with something like the Sigma 100-400 or 150-600 on the crop body. The images I've seen from the RF f/11 lenses always look dark to me, like they're shot through a ND filter, guessing that's due to the narrow aperture. I've only ever shot that aperture for macro from an inch or two away!

The prices of the Canon EF 100-400 ($3500) or RF 100-500 ($5000) in my part of the world are hard to justify, even though the exchange rate isn't double, Canon likes doubling the prices here, an R5 with an RF 100-500 is a $10,500 setup!


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## AlanF (Sep 29, 2021)

LogicExtremist said:


> Thanks, that's quite helpful. I've been getting more interested in trying out bird photography, and I've put my EF 70-200 f/2.8 III or 55-250 STM on my 80D for more reach, but it's not really long enough.
> 
> I've been considering purchasing a longer telephoto but I can't decide whether to go with the RF 600 f/11, Rf 800 f/11 or wait for the RF 100-400 f/8 when that comes out, to use on my RF mount camera, or to go with something like the Sigma 100-400 or 150-600 on the crop body. The images I've seen from the RF f/11 lenses always look dark to me, like they're shot through a ND filter, guessing that's due to the narrow aperture. I've only ever shot that aperture for macro from an inch or two away!
> 
> The prices of the Canon EF 100-400 ($3500) or RF 100-500 ($5000) in my part of the world are hard to justify, even though the exchange rate isn't double, Canon likes doubling the prices here, an R5 with an RF 100-500 is a $10,500 setup!


The brightness of images depends on whether you expose or underexpose or on your post processing settings. The RF f/11 lenses are no exception to this, as are any images from any other lens at f/11. (Strictly speaking T-stops are more accurate for absolute transmittance, but the difference between T and f is corrected by your exposure metering or you.)


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## LogicExtremist (Sep 29, 2021)

AlanF said:


> The brightness of images depends on whether you expose or underexpose or on your post processing settings. The RF f/11 lenses are no exception to this, as are any images from any other lens at f/11. (Strictly speaking T-stops are more accurate for absolute transmittance, but the difference between T and f is corrected by your exposure metering or you.)


That's what I would have thought, you'd just just adjust the exposure meter to the centre, and brighten the images in post if necessary. I've seen this 'image darkness' for lack of a better expression in most 600 and 800 f/11 image I've seen posted on the internet, and that put me off. I can't imagine they're all shooting jpegs SOOC. I'm at loss to explain it, though you might have some ideas of why this might be the case.

Not sure if I'm allowed to link to the dpreview image gallery:
https://www.dpreview.com/sample-gal...f-800mm-f-11-is-stm-sample-gallery/2421245585 

To me many of these images seem to have a grey cast, does it seem that way to you? Thanks


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## koenkooi (Sep 29, 2021)

LogicExtremist said:


> That's what I would have thought, you'd just just adjust the exposure meter to the centre, and brighten the images in post if necessary. I've seen this 'image darkness' for lack of a better expression in most 600 and 800 f/11 image I've seen posted on the internet, and that put me off. I can't imagine they're all shooting jpegs SOOC. I'm at loss to explain it, though you might have some ideas of why this might be the case.
> 
> Not sure if I'm allowed to link to the dpreview image gallery:
> https://www.dpreview.com/sample-gal...f-800mm-f-11-is-stm-sample-gallery/2421245585
> ...


You can download the RAW files and see if it's due to how DPReview processed them or present in the picture itself, the gallery states "_Edited in Adobe Camera Raw 12.2 with Adobe Standard profile and sharpening set to 25. Adjustments limited to exposure, shadows, highlights and white balance."_

DPReview complained about the R pictures having a green cast and took a long time to admit that they manually set the camera to green+1, which was recorded in the EXIF. Since then I download the RAWs they provide and check how they look in both LR and DPP4 instead of relying on the JPEGs in their gallery.

Adobe produces horrible colours of R series out of the box, so check the RAW in DPP4 to see what Canon thinks the picture should look like. The RF24-240 RAWs DPReview provided showed how much work DPP4 did for corrections and how well it did.


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## LogicExtremist (Sep 29, 2021)

koenkooi said:


> You can download the RAW files and see if it's due to how DPReview processed them or present in the picture itself, the gallery states "_Edited in Adobe Camera Raw 12.2 with Adobe Standard profile and sharpening set to 25. Adjustments limited to exposure, shadows, highlights and white balance."_
> 
> DPReview complained about the R pictures having a green cast and took a long time to admit that they manually set the camera to green+1, which was recorded in the EXIF. Since them I download the RAWs they provide and check how they look in both LR and DPP4 instead of relying on the JPEGs in their gallery.
> 
> Adobe produces horrible colours of R series out of the box, so check the RAW in DPP4 to see what Canon thinks the picture should look like. The RF24-240 RAWs DPReview provided showed how much work DPP4 did for corrections and how well it did.


Thanks, that great advice,, I'll download the raw files and post process them to see if I can get them to look any better. Much appreciated!


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## AlanF (Sep 29, 2021)

LogicExtremist said:


> That's what I would have thought, you'd just just adjust the exposure meter to the centre, and brighten the images in post if necessary. I've seen this 'image darkness' for lack of a better expression in most 600 and 800 f/11 image I've seen posted on the internet, and that put me off. I can't imagine they're all shooting jpegs SOOC. I'm at loss to explain it, though you might have some ideas of why this might be the case.
> 
> Not sure if I'm allowed to link to the dpreview image gallery:
> https://www.dpreview.com/sample-gal...f-800mm-f-11-is-stm-sample-gallery/2421245585
> ...


I occasionally use the RF 800 f/11 and find no problems with it regarding image exposure. There are others like @usern4cr who have posted nice bright images with it in the birds thread.


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## HenryL (Sep 29, 2021)

LogicExtremist said:


> That's what I would have thought, you'd just just adjust the exposure meter to the centre, and brighten the images in post if necessary. I've seen this 'image darkness' for lack of a better expression in most 600 and 800 f/11 image I've seen posted on the internet, and that put me off. I can't imagine they're all shooting jpegs SOOC. I'm at loss to explain it, though you might have some ideas of why this might be the case.
> 
> Not sure if I'm allowed to link to the dpreview image gallery:
> https://www.dpreview.com/sample-gal...f-800mm-f-11-is-stm-sample-gallery/2421245585
> ...


Those images are just underexposed. The worst offenders seem to be examples where the intent might have been to protect the highlights (ie the kingfishers, geese and osprey, even Space Needle). Clearly still underexposed, bumping +1 on some of them and still no blown highlights. I'd say it's the photographer not the lens in those examples.


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## LogicExtremist (Sep 29, 2021)

AlanF said:


> I occasionally use the RF 800 f/11 and find no problems with it regarding image exposure. There are others like @usern4cr who have posted nice bright images with it in the birds thread.


Thanks, I'll check those out too! Great to know you have this lens, I've been considering it. 

How would you rate the 800mm f/11 against the EF 100-400 without any extender. Does the 800mm focal length resolve way more than the bare zoom at 400? How does the contrast compare in your opinion?

From your graphs, the theoretical performance at the lens centre (if I'm reading the graphs correctly) is as follows:

400mm @ f/5.6 resolves around 225 lp/mm (R5) and *150* lp/mm (R6)
600mm @ f/11 resolves around 275 lp/mm (R5) and 225 lp/mm (R6) 
800mm @ f/11 resolves around 370 lp/mm (R5) and *300* lp/mm (R6)
This shows the 800mm f/11 resolving twice the detail of the bare 100-400 @ 400mm on the R6 (150 vs 300 lp/mm). Does this really reflect real world experience?


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## AlanF (Sep 29, 2021)

LogicExtremist said:


> Thanks, I'll check those out too! Great to know you have this lens, I've been considering it.
> 
> How would you rate the 800mm f/11 against the EF 100-400 without any extender. Does the 800mm focal length resolve way more than the bare zoom at 400? How does the contrast compare in your opinion?
> 
> ...


On the R5, the RF 800mm f/11 resolves about 1.6x the EF 100-400mm II at 400mm (my copies of the lenses). The factor will be higher on the R6. The contrast of both lenses is good. If you want resolution, the 800mm f/11 will significantly outperform the 600mm f/11. They have similar MTF values but the 33% extra length of the 800 will increase its resolution by 1.33x. An 800mm f/11 although having the same f-number as the 600mm f/11, has effectively nearly an extra stop of iso (~0.8) in its favour as it projects 77% more photons per duck.


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## stevelee (Sep 29, 2021)

“photons per duck” should be an international standard.


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## PhotonShark (May 26, 2022)

justaCanonuser said:


> Alan, this is very interesting, thank you very much. Your last finding "the f/11 lenses are more suited to the lower resolution R6, and this makes it an attractive lower priced alternative" didn't surprise me. That's basically what I try to tell the high MP sensor fans since many years.



I know this thread is old, but was thinking the same thing with the release of the R7. It’s surprising that Canon went with such a high resolution sensor. A 20 megapixel low light APS-C mirrorless would have been great with those f/11 lenses. Or, even the new 100-400.


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## Czardoom (May 26, 2022)

The new R7 and R10 have we wondering about the sensor and pixel size as well. AlanF, I hope you revisit this thread and just give your educated opinion on how you think these two new crop cameras will perform with the RF 100-400 for example. I am leaning towards getting the R10 because I really don't think I will see any resolution gain from the R7's 32 MP sensor compared to the R10's 24 MP sensor. I know it is not a great sample size, but looking at DPReview's sample photos shot with the RF 100-500, they look quite soft to me. I realize that DPReview's sample photos are usually not very high quality, but that's another story...

Any thoughts on the 32 vs 24 MP sensor and the ability of the Canon telephoto lenses to take advantage of all those MPs before diffraction and the ability to hand hold come into play will be welcome.


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## AlanF (May 26, 2022)

@Czardoom and @PhotonShark - Phoblographer has done one of the better pre-reviews of the R7 and has recommended some lenses, which he has actually tested, and recommends the RF 100-500mm https://www.thephoblographer.com/2022/05/24/the-best-lenses-for-the-canon-eos-r7/
My own thoughts are that the 100-500mm will perform very well. It is a really sharp lens, and the older EF 100-400mm did perform well on the 90D. Although the 500mm is f/7.1 vs f/5.6 on the 400mm II, the extra 100mm compensates for the worse diffraction. A good f/4 lens will be better. What is key is to have good RAW processing software like DxO PL5 DeepPrime or its plugin PureRaw for PS to deal with the noise at higher isos. Unfortunately, we will have to wait for the new modules for the RAW converters but Topaz Denoise does a pretty good job on jpegs from DPP.

The RF 100-400mm punches well above its weight in all senses. The Phoblog wrote it didn't focus as fast though, and I will test that when mine arrives. I think that it will give good images on the R7, but as you speculate not much more detail than from the R10 at the isos I work at. The RF 100-400 does give excellent images on the 45 Mpx R5, and the R10 isn't that much more pixel dense, equivalent to about 62 Mpx full frame, and so I think the RF100-400mm on the R10 will make many birders and naturers very happy. I wouldn't use an extender with the 100-400mm.

I have had no trouble hand holding the R5 with both RF zooms at speeds down to 1/200s with little shake - I crop greatly and look for fine detail so I am much more critical about shake than the normal testers. There has always been mirror slap/shutter shock with all my telephotos on all of my DSLRs, and it is simply so much better using ES on the R5.


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## Czardoom (May 26, 2022)

Thanks, Alan. I look forward to what you find out when you get the new camera!


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## PhotonShark (May 27, 2022)

AlanF said:


> The RF 100-400mm punches well above its weight in all senses. The Phoblog wrote it didn't focus as fast though, and I will test that when mine arrives. I think that it will give good images on the R7, but as you speculate not much more detail than from the R10 at the isos I work at. The RF 100-400 does give excellent images on the 45 Mpx R5, and the R10 isn't that much more pixel dense, equivalent to about 62 Mpx full frame, and so I think the RF100-400mm on the R10 will make many birders and naturers very happy. I wouldn't use an extender with the 100-400mm.



Thanks for the reply. I look forward to your investigations.


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## stevelee (May 28, 2022)

Diffraction is just one of many things you need to take into account in the compromises you have to make. If you stop down enough, everything can be in focus, and wind up equally fuzzy, for example. Most of you guys know better, but it is too easy to see diffraction more like a wall than a gradual slope. Up to some point it is less of an issue than other things. Lots of factors go into determining where that point is.

In some of my messing around, not anything too serious, I have found that the kind of softness that can set it at f/32 with FF or smaller sensors can have a pleasant look. So far I have never used that effect purposely, but maybe some time when I am wanting a more romantic or wistful look, it might be worth trying.


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## justaCanonuser (May 30, 2022)

PhotonShark said:


> I know this thread is old, but was thinking the same thing with the release of the R7. It’s surprising that Canon went with such a high resolution sensor. A 20 megapixel low light APS-C mirrorless would have been great with those f/11 lenses. Or, even the new 100-400.


I am with you - Bryan Carnathan has already calculated that the diffraction limited aperture (DLA) is f = 5.2 only. That's the price you pay for small pixels. So, if you choose e.g. f/8 to get a nice sharp tele shot, if the light is good, you already left the range of maximum resolution. Well, at least, if you downsize the image to the level of a 20 MP sensor, you'll have no losses but the image quality should beat the old 20 MP 7D. Maybe I'd reside more frequently to MRAW images than with my 7D2, when I upgrade.


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## AlanF (May 30, 2022)

justaCanonuser said:


> I am with you - Bryan Carnathan has already calculated that the diffraction limited aperture (DLA) is f = 5.2 only. That's the price you pay for small pixels. So, if you choose e.g. f/8 to get a nice sharp tele shot, if the light is good, you already left the range of maximum resolution. Well, at least, if you downsize the image to the level of a 20 MP sensor, you'll have no losses but the image quality should beat the old 20 MP 7D. Maybe I'd reside more frequently to MRAW images than with my 7D2, when I upgrade.


For people like me who use mainly telephotos with apertures narrower than f/7.1, the the resolution of the R10 is good enough. But, if you are using f/2.8 or f/4, lenses or wider then diffraction isn’t much of a problem.


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