# Canon's MTF Plots for RF 100-400mm f/5.6 - 8



## AlanF (Sep 16, 2021)

Canon has published the diffraction corrected MTFs for the new 100-400mm, which is both cheap (relatively) and light, weighing only 635g. The new MTF charts from Canon are pretty reliable from what I have seen. Contrast at 400mm is not far off the EF 100-400mm II and the RF 100-500mm. The resolution is down a bit. It gets softer to the edges, but that won't be a problem if an APS-R is produced, and is good enough over the centre of FF, the important area. Unfortunately, they haven't posted the results with the RF 1.4x and 2x (and they haven't for the RF 400 f/2.8 and 600 f/4 either). There should be some happy customers. It may be a consumer lens but it looks quite good. If we start travelling again, I'll get one for my wife, and maybe for me as well if I have conference trips with minor opportunities for nature photography. Maybe @digigal will find it useful for its light weight.

(Apology from Canon published today: "From 9/14 (Tuesday) 19:00 to 9/15 (Wednesday) 14:00, the structure was described as "dust-proof / drip-proof", but it has been corrected due to an error. It is not a "dust-proof / drip-proof" structure. We apologize for the correction.*")*


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## Czardoom (Sep 16, 2021)

Thanks Alan. If these are accurate, this will be a lens that is hard to pass up for those of us who can't afford the big "L" lenses. MFT charts certainly look close enough to make this lens a bargain! Now, if I only had an RF crop camera to put it on!


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## dcm (Sep 16, 2021)

Thanks for sharing. Like the RF800, this zoom definitely appears to be good enough for most of my purposes as I look for a lighter carry than the 1DXii and L glass.


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## Jethro (Sep 16, 2021)

Thanks for extracting this Alan - surprisingly strong results!


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## ColorBlindBat (Sep 17, 2021)

Thank you for this. If these turn out as sharp as the graphs suggest, it will make a wonderful walk around lens and reduce the overall weight by around 2.5 pounds versus using my EF 100-400mm II and adapter.


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## Jack Douglas (Sep 19, 2021)

Much appreciated. If you find something relative to the extenders be sure to post it. I may recommend this for my daughter's R.

Jack


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## LogicExtremist (Sep 26, 2021)

Hi all, I'm new here but a regular reader on this site. From the graphs the RF 100-400 looks to have a bit less contrast and sharpness than the EF 100-400 and RF 100-500, looks quite promising despite f/8 aperture.

Surprisingly, one thing that nobody has mentioned is the PMo (plastic-molded) aspherical lens element.

We've also recently seen the use of a molded plastic aspherical lens element in the RF 50mm f/1.8.

This seems like a strange trend in new Canon RF lenses, considering that PMo aspherical lens element were reserved for cheap kit lenses in the past. The next level of lenses used molded glass aspherical elements, with ground glass aspherical lens elements being the mainstay in L-series glass from what I can figure.

Scouring the internet, I can only find the following Canon lenses which utilise pMo aspherical elements:


Canon EF-S 18-200mm f/3.5-5.6 IS - one PMo (precision molded) aspherical element
Canon EF-S 18-135mm f/3.5-5.6 IS STM - one PMo (precision molded) aspherical element
Canon EF-S 18-135mm f/3.5-5.6 IS USM - one PMo (precision molded) aspherical element
Canon EF-S 10-18mm f/4.5-5.6 IS STM - two aspherical lens elements, one is a high-precision large-diameter PMo (Plastic-Molded) lens.
Canon EF-M 15-45mm f/3.5-6.3 IS STM - three aspherical elements, one is glass-molded and the other two are precision molded,
RF 50mm f/1.8 STM - one precision molded optic (PMO) aspherical element 
Canon RF 100-400mm F5.6-8 IS USM - one precision molded optic (PMO) aspherical element 
This lens looks so much like a full frame version of the EF-S 55-250mm IS STM, (which provides the crop equivalent of 88-400mm @ F9). Even though Canon was so miserly as to not even put a metal lens mount on that lens, its optics were really good, and from what I can ascertain, this lens had no PMo elements. This lens also had no sealing, so it wasn't dust proof and drip proof either.

From the Canon Camera Museum - https://global.canon/en/c-museum/special/exhibition1.html

_Plastic-molded (PMo) aspherical lens elements

PMo aspherical lens elements are formed by injecting resin into an aspherical surface mold. Highly suitable for mass production, they play a major role in improving the image quality of entry-level lenses, such as the EF-S10-18mm f/4.5-5.6 IS STM (released in 2014), which need to be kept relatively affordable. Resin is injected into a high-precision mold that takes the shape of an aspherical lens. After the lens element is separated from the mold, coatings are added to finish the lens._

Trying to find the life expectancy of optical resins proved frustrating. I've yet to hear of an optical plastic as durable as glass., and I suspect that all plastics degrade over time, and won't have the life expectancy of molded or ground glass elements. I've had a Canon EF-S 10-18mm for many years, and the optics are still good. Perhaps only time will tell if or when these resins decrease in optical clarity as they age.

I'm not sure what this trend indicates. Is it cost cutting to increase profits, or is Canon cutting back on its construction of 'budget' lenses, even more so than in the past? 

Looking forward to seeing how the RF 100-400mm compares against the EF 100-400mm II, RF 100-500mm and even the EF-S 55-250mm. Then we'll know what kind of image quality, construction and durability we're getting for our money ($649 USD, £699, 730 €, $1,200 AUD).


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## AlanF (Sep 26, 2021)

LogicExtremist said:


> Hi all, I'm new here but a regular reader on this site. From the graphs the RF 100-400 looks to have a bit less contrast and sharpness than the EF 100-400 and RF 100-500, looks quite promising despite f/8 aperture.
> 
> Surprisingly, one thing that nobody has mentioned is the PMo (plastic-molded) aspherical lens element.
> 
> ...


Interesting point. Photo-oxidation is the major source of degradation of plastics. So, an f/8 lens with an internal plastic element that is not in use 24/7 should last a good few years.


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