STM vs USM L glass difference

[EK25]

Please can we talk about how huge the actual difference between STM vs L USM lenses is... I am looking at 50 mm RF lenses and the $2000 price difference is killing me. I understand that different AF systems, sound vs no sound for videos. I am NOT a sports photographer (the fastest moving objects I am shooting are running kids). So if I took 2 images seconds apart, same settings and camera, with a STM vs USM lens what the actual difference between them will be? Sharpness? Bokeh pattern + background separation? What else??? Thank you in advance!

[FloridaDrafter]

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@EK25 wrote:

If you were shooting with a mirrorless, and were to choose between EF L glass vs RF consumer grade STM glass, what would go with? Same price, both zooms (EF 24-70mm 2.8 L II USM vs RF 28-70 2.8 IS STM? Thank you very much in advance! 

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I have the EF L version but not the RF. But from reading Canons specs on the RF it looks to be just as good as an L quality lens. To see the full specs CLICK HERE. Be sure and look at the lens and element diagram and weather sealing placement.

I think I would give the RF version a try.

Newton

[EK25]

Thank you very much!

[ebiggs1]

"Please can we talk about how huge the actual difference between STM vs L USM lenses is... "

Not to beat a dead horse but that quote was the question, sir.

"As I've mentioned several times, this thread is about two specific RF 50mm lenses "

And as you may have repeated "several times" but the 50mil was an example.

"... if I took 2 images seconds apart, same settings and camera, with a STM vs USM lens what the actual difference between them..."

[ebiggs1]

If you have a R series camera always go for RF lenses as the first choice even though you may be comparing it to EF "L" lenses. IQ is a single spec and any lens choice should be evaluated by its entirety and not just IQ. Especially as I have attempted to make clear, because IQ may not be significantly different in real world applications.

[justadude]

"Lastly just because a lens got the red ring and the "L" name does not absolutely prove it has better IQ than any other lens. There are lots of non-L lenses that perform very well and can hold their own even some so called "kit" lenses as well."

It never fails to amaze me on how many photographers in the Facebook photography groups tell new members that if you want good quality, you MUST have L glass, or your photos will be junk.  I'll often speak up and mention a few lenses that are not L glass that are pretty impressive, including the RF 24-105mm f/4-7.1 kit, or the RF 50mm f/1.8... but those of us that say things like this get dismissed as someone who doesn't have a clue.

On a semi related topic (comparing gear) one FB group member asked today if they would notice any improvement at all in image quality moving from their EOS 70D to the R6 Mk ll if they use the same EF lenses with an adapter.  A surprising amount of people said there would not be a single amount of difference with the end results in IQ if they used the same lens on both bodies.  Others said IQ is 100% lens, not body.  Of course when I spoke up and mentioned the difference in sensors, in camera processors, improvements in noise and dynamic range, I still had people arguing that I was wrong... it's all in the lens.  One member said the only thing they would notice is improved AF, but not IQ.  Frustrating, but I stay only because it's rewarding when I do help someone.