Lens design comparison: Canon EF 50mm f/1.8 STM and the Canon RF 50mm f/1.8 STM

canonnews

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I consider 35 1.8 RF great on R5. hope 50 1.8 RF is close, that's all I am hoping for
I wouldn't expect it as good as the RF 35mm.
I think people have to measure their expectations a bit. it's a pretty simple design. it's going to have it's flaws wide open.

you don't usually get small, cheap and optically great all in one package.

you get two of the three.
 

mb66energy

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[...]

What I actually find interesting is the element offset, the RF lens elements are set further forwards than the EF version and are an effective 'adapter', they are not using the advantages of the shorter flange distance here one bit, merely rejigging the thing to do the same. I'd expect performance to be somewhere between the EF 1.8 and EF 1.4, the key will be the way they have used the special element in green.
I think that making a shorter 50mm leads to flatter angels of the light reaching the sensor and increases
I'm pretty sure the aspherical lens in the old EF-S 18-55 kit lens was plastic, which Canon didn't actively promote because quite honestly the idea of a plastic element doesn't come across well! Maybe this will be the same. I think it was stated in an early press release, but marketing material just describes it as "aspherical". If it works, who cares?!
I think so, it is much easier to mould. My glasses have too plastic lenses and they are optically very good - only contrast suffers after cleaning them several times compared to glass lenses - but the lens element in the RF 50 is not exposed so I think you are right: No problem here.
 

tiggy@mac.com

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I'm pretty sure the aspherical lens in the old EF-S 18-55 kit lens was plastic, which Canon didn't actively promote because quite honestly the idea of a plastic element doesn't come across well! Maybe this will be the same. I think it was stated in an early press release, but marketing material just describes it as "aspherical". If it works, who cares?!
2 things:
1) The "blue goo" tech that Canon put it some of its very best lenses, like the 35mm f/1.4 L II is essentially a plastic element. They cleverly call it an "organic optical compound," which essentially is code for plastic. I can't say anything bad about it, as the lenses in which it's been used have been amazing. The person who started the "blue goo" term was doing so to poke fun at their wording, referencing a Dr. Seuss book Fox in Sox.
2) The quality of the EF 50mm f/1.8 was excellent, but the autofocus consistency was pretty bad. People's unsharp results weren't due to the optical formula. The new design will likely be a small improvement relative to coatings improvements and (hopefully) a more reasonable focus registration.
 
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gruhl28

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Jul 26, 2013
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Does anyone else find it odd that Canon makes "medium" quality and aperture lenses with IS in moderate wide angle (35mm RF, 24mm, 28mm, and 35 mm EF) and moderate telephoto focal lengths (85mm RF), but in the "standard" 50 mm they only make very high end and low end without IS? This was true in EF, and now it's the case with RF as well.

I'm actually surprised I haven't seen anyone complaining yet that this lens doesn't have IS. There is still no standard focal length prime lens from Canon with IS. Why?
 

privatebydesign

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Does anyone else find it odd that Canon makes "medium" quality and aperture lenses with IS in moderate wide angle (35mm RF, 24mm, 28mm, and 35 mm EF) and moderate telephoto focal lengths (85mm RF), but in the "standard" 50 mm they only make very high end and low end without IS? This was true in EF, and now it's the case with RF as well.

I'm actually surprised I haven't seen anyone complaining yet that this lens doesn't have IS. There is still no standard focal length prime lens from Canon with IS. Why?
Because the market isn’t there anymore. The concept of a ‘standard prime’ can be defined as a niche, that niche can be fairly subdivided into people new to the medium who are told over and over again “you need to get a nifty fifty” and committed amateurs and pros who actually love and use the focal length. The first group buy the cheap option the second either buy or aspire to the second,. The number of undecideds in between is a subgroup within a niche within a niche and from a corporate point of view simply not large enough to cater to.
 
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gruhl28

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Jul 26, 2013
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Because the market isn’t there anymore. The concept of a ‘standard prime’ can be defined as a niche, that niche can be fairly subdivided into people new to the medium who are told over and over again “you need to get a nifty fifty” and committed amateurs and pros who actually love and use the focal length. The first group buy the cheap option the second either buy or aspire to the second,. The number of undecideds in between is a subgroup within a niche within a niche and from a corporate point of view simply not large enough to cater to.
I understand what you're saying, but is 50mm more of a niche than 35mm or 85mm (or 24 or 28 in EF)? You could say that every prime focal length is a niche, couldn't you?
 
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mangobutter

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It's almost as if this (seemingly) double-gauss design was largely lifted from the EF version, tweaked with a replaced asph element, and the entire lens group was shifted forward to keep a similar distance to the sensor as it would with the SLR version. I imagine this to be better optically than the EF version--it has to... so my guess is it will be sharper wide open but I think that extra/added/replaced element in green is going to cause some slightly harsh bokeh (relative to the EF version) or at least be similar or same.

So in other words this will be a great value buy but don't expect image quality miracles. It'll be sharp and practical, but i dont think the rendering and softness quality will be blowing anyone away.

I'll still buy it just because =) $149 seems appropriate for such a lens.

Now Canon, can you replicate the 40mm pancake a la EF? =)
 

mangobutter

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I'm going with $199 to $249.

RF mount tax ;)
On one hand I want to say $199 but that would prevent Canon from making this lens make headlines and gain people into the RF system. I think this lens has to be Canon's RF gateway drug to entice over SLR users. $199 limits how "big" this lens can get
 

privatebydesign

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I understand what you're saying, but is 50mm more of a niche than 35mm or 85mm (or 24 or 28 in EF)? You could say that every prime focal length is a niche, couldn't you?
Yes, and it is, and it is a shrinking niche which bodes poorly for more options. I do not believe the RF line will ever have the depth and range the EF line had.
 
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SUNDOG04

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New optics are good. I'm more like to get than I was a couple hours ago.

And how does Nikon have to make theirs twice as big? I don't get it.
I don’t get it either that the S lens is so long. But, it is optically outstanding and the same price (or it was) as a Nikon Z body with a 24-70 f4 when purchased as a kit.
 
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GMCPhotographics

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Yes, and it is, and it is a shrinking niche which bodes poorly for more options. I do not believe the RF line will ever have the depth and range the EF line had.
I've always found if frustrating and slightly amusing that Canon just couldn't seem to be able to design and build a good / sharp 50mm. 85mm f1.2...double gauss optics...really sharp. 35mm f1.4 retrofocus double gauss...again...really sharp. 50mm f1.2...50mm f1.4 USM all soft wide open...all double Gauss designs. I use an original metal mount 50mm f1.8 from the first year of EOS manufacture which came bundled with my EOS 650. It's way sharper wide open than any of the 50mm f1.2 L's I've handled and the F1.4 USM's too.
It'll be interesting if this new RF lens will be any sharper than the current EF version. IF it is...then Canon really could have built a better EF version if they wanted too.
Looking at the lens placement, it looks like they ahve moved the optics forwards and the mechanicals back to where the mirrir box flange would normaly be. It's basically an EF lens with a space behind the rear optic. The old EF design sets the machanicals in front and round the set back optics to act as a sort of integral hood. So i'm guessing that this lens will have a much larger hood becuase the elements are very close to the front of the lens body.
 

ctk

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Mar 25, 2020
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Not only that.
The basic double Gauss design stayed the same.
But I see different gaps between the elements.
And I see elements cut on both sides where one was only cut on one side (two working steps = more expensive).
And as the rear element seems to be bigger the exit pupil seems to be bigger, too.
= less refracting of the light rays in that last element = maybe less CA (but just guessing)

This is an at least much modifyed optical formula, if not totally redesigned (still based on the same double Gauss design).

Edit: and you don't see just from this drawing if they maybe added some new and better coatings.
ff
I'm going to go against my gut and look at this optimistically. The EF 50 1.8 STM's optical design was unchanged from the original 50 1.8 from the 80s, so the starting point for improvement is basically ground zero. Modern design + manufacturing and new coatings might go a really long way.
 

swkitt

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Dec 8, 2015
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If I was Canon I would make it the same price as EF version, as the chinese will certainly be able to copy this quite easily and sell it for 50 bucks.
 

jvillain

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Sep 29, 2018
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My guess is that we will see a decent increase in IQ from better tooling & CAD being available now as compared to when the plastic fantastic first rolled out.
 

jvillain

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Does anyone else find it odd that Canon makes "medium" quality and aperture lenses with IS in moderate wide angle (35mm RF, 24mm, 28mm, and 35 mm EF) and moderate telephoto focal lengths (85mm RF), but in the "standard" 50 mm they only make very high end and low end without IS? This was true in EF, and now it's the case with RF as well.

I'm actually surprised I haven't seen anyone complaining yet that this lens doesn't have IS. There is still no standard focal length prime lens from Canon with IS. Why?
With IBIS now becoming a thing in Canon land that will dampen some of the demand for IS in the lenses.
 

mangobutter

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I don’t get it either that the S lens is so long. But, it is optically outstanding and the same price (or it was) as a Nikon Z body with a 24-70 f4 when purchased as a kit.
Because the Nikon is using a modern, multi-element design with plenty of correction. It's better optically, but also expensive, heavy, large.

This new RF lens, to me, appears to be a simplistic double-gauss design. I'll take it a step further and say it even seems to be simply the EF 50 STM with lens groups shifted forward to make up for the flange distance with some (probable) slight projection tweaking and an additional element (maybe aspherical?) for improved sharpness wide open. Think about what the RF EF adapter is doing when you mount this lens, it's simply moving the elements forward. I think that's what this re-work is.

In other words, this new RF lens, to me, looks like a low-investment re-work of the 50 STM for mirrorless flange distance and RF mount, albeit with small changes to the lens formula to further enhance IQ (over the EF STM version)