Started by kevinlearns, 14 Dec 2025. 12 replies, 493 views
Gear in this topic: Canon EOS R50, RF 50mm f/1.8 STM, RF-S 18-150mm f/3.5-6.3 IS STM
Hi all! Still pretty new (R50 with the 18-150 since the summer) and every YouTube video I watch says primes are SO much sharper than zooms and I need to get the 50mm 1.8. Is that actually true?? My 18-150 seems sharp to me but maybe I don't know what I'm looking at! Also does a prime make you a better photographer because you have to 'zoom with your feet'? That's what one guy said. If it's true I'm going to ask for one for Christmas. Thanks!!
Yes. And it's not close wide open.
Sharper, usually. The bigger difference is f/1.8 against f/6.3 at the long end of your zoom. That's what you'll actually notice indoors.
The honest answer is 'it depends which prime and which zoom, at which aperture'. A cheap 50 1.8 wide open is usually noticeably softer than the same lens at f/4, and a modern superzoom like the 18-150 at f/8 in the middle of the frame is closer to it than people want to believe.
Where the cheap prime wins is light. f/1.8 against f/6.3 is roughly three and a half stops, which is the difference between ISO 6400 and ISO 640-ish in your living room at night. That matters far more for how sharp a photo looks than any MTF chart, because noise, noise reduction and motion blur eat detail long before lens resolution becomes the limit on a 24MP APS-C file.
'Zoom with your feet' is half true. Walking closer changes perspective, it doesn't replicate zooming, so you get a different picture, not the same one. What a prime really does is take one decision away from you, and some people find that freeing and some find it annoying.
imo the 50 1.8 is the most useful cheap thing you can add to that kit, but not because it's 'sharper'.
rawtherapist said:the difference between ISO 6400 and ISO 640-ish
Wow ok that's way more than I thought!! So it's more about the light than the sharpness. That actually makes sense. Is 1.8 what people mean when they say a lens is 'fast'?
Yes sir, 'fast' just means a wide maximum aperture. More light, so you can use a faster shutter speed, which is where the name comes from.
FWIW I shoot mostly zooms these days. The 24-120 f/4 lives on my Z8 more than anything else and it's plenty sharp for 20x30 prints on the wall. Back in the film days I carried a 28, a 50 and a 105 everywhere and swapped them in the dust out by Saguaro until I'd sanded half the paint off the mount... then zooms got good and I never looked back. For 90% of us prime vs zoom is a convenience question.
Kevin, here's how I'd think about it. Your 18-150 is your daylight lens, and a good one. The 50 1.8 is your indoor and evening lens, for birthday parties and the grandparents at Christmas when the light's poor. Different jobs. IMHO the folks telling you a prime makes you a better photographer would be better photographers with a zoom too...
WaltK_AZ said:For 90% of us prime vs zoom is a convenience question.
And for the other 10% it's the whole point. Shoot a 50 at 1.4 for a month and tell me it's convenience.
f2point8 said:Shoot a 50 at 1.4 for a month
You say this in every thread, you know. Some of us have done it for thirty years and still pack a zoom on holiday... Just saying
kevinlearns said:does a prime make you a better photographer
No. Two small primes on the fells for me, but that's about weight and what I like looking at, not sharpness. Kevin, get the 50, it's cheap, and then go and shoot more with both lenses. Honestly that's the answer to most of these threads. Cheers
The 50 1.8 STM is the cheapest lesson in photography there is. Then you'll want a 35. Then an 85. Then you'll be me and its too late. I genuinely started with a 50 1.8 on a Sony and now my partner refers to the lens shelf as "the problem". Kevin learn from my mistakes
OneMoreLens said:Then you'll be me and its too late
Or don't, and learn the camera you have.
Lol I can feel the OneMoreLens thing happening already. Ok I'm going to save up for the 50 1.8 and keep the 18-150 for everything else. Thanks everyone this was super helpful!! Sorry Jim, I'll learn it too I promise!
OneMoreLens said:Then you'll want a 35
This part is true.