Prime vs. Zoom Lenses: How Much Does Image Quality Really Differ?

The debate between prime and zoom lenses is a common one. Prime lenses offer fixed focal lengths and are prized for sharpness and contrast, while zoom lenses provide versatility and convenience at the expense of some image quality. The real question is: how noticeable is the difference in real-world use?

Coming to you from Jason Row Photography, this in-depth video explores the differences in image quality between a mid-range prime lens and a comparable zoom lens. Row uses the Sony 85mm f/1.8, a budget-friendly prime, and the Sony 24-105mm f/4, a versatile mid-range zoom. Both lenses are tested at comparable settings, with images captured on a tripod-mounted, 61-megapixel camera. The goal was to compare sharpness, contrast, and overall image quality at various apertures to see if the prime lens lives up to its reputation for superior performance.

The findings are revealing. At an average aperture like f/5.6, the prime lens is significantly sharper than the zoom. Examining the details of a brick building, the 85mm shows greater clarity in texture and fine detail. The zoom, while slightly softer, still holds its own for practical use, especially when images are viewed or printed at standard sizes. At smaller apertures like f/8, the differences remain noticeable, with the prime lens continuing to outperform in sharpness.

Row also compares the lenses at their widest apertures: f/1.8 for the prime and f/4 for the zoom. Interestingly, the prime lens loses some sharpness wide open, showing results closer to the zoom at its maximum aperture. However, the two extra stops of light from the prime offer a clear advantage in low-light situations, making it more versatile for certain conditions.

The video emphasizes that these comparisons are specific to the lenses tested. A higher-end zoom might outshine a budget prime in some cases, and vice versa. For most uses, particularly if you're not making large prints, the sharpness differences may be negligible. Factors like convenience, flexibility, and cost can often outweigh marginal improvements in sharpness, depending on your shooting needs. Check out the video above for the full rundown from Row.

Alex Cooke's picture

Alex Cooke is a Cleveland-based portrait, events, and landscape photographer. He holds an M.S. in Applied Mathematics and a doctorate in Music Composition. He is also an avid equestrian.

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8 Comments

Well hands down yes the prime has it as it is most obvious to the casual observer!!! IF you pixel pep!
A landscape photographer stays at f/8 to f/11 or a little more out in the field looking at the small camera screen even zooming in, it is a jpeg they are looking at there and there are camera settings that affect just the jpeg and should be known and selected before hand. Way back when the Sony cameras came out Brian Smith published a couple of books that showed what a jpeg and how settings differed in camera out put. There is even a story in Gary L. Friedman's book of the A7RM5 of a National Geographic photographer that would send images back to home plate and saying he wanted his final RAW edited images to look like the jpegs and later was told it can not be done due to the cameras editing settings of the jpeg. But today using Sony's IEDT Edit you can edit a RAW using the jpeg settings and save as a TIFF, just added info. Mark Denney on YouTube some time ago did a compare between a very high MP camera Stop OBSESSING Over SENSOR SIZE! 102MP (Fuji GFX100s) vs 26MP (Fuji X-T4) , I believe between a 100MP and a 50MP camera and yes when zoomed in the 100MP captured an image of something way down in a valley that the 50MP did not and stated no one will using a magnifying glass on a print or even zooming 400% on a digital image so no real difference, just my remembrance of the video.
To the point of your findings and carrying a bunch of primes and changing out in the field day or night and getting number one stuff on a sensor.
A prime lens has no IS/OSS where as most but not all zoom lenses do have IS/OSS (the FE 12-24mm not, used a lot for landscape) the 24-105mm does and paired with a IBIS camera you get to use slower SS, and if using auto ISO even in manual mode maybe even slower SS, just a guess.
Then capturing a raw you may also get less noise also.
I carry the FE 24-240mm f3.5-6.3 OSS that in APS-C is 36-360mm, E 10-18mm f/4 OSS (15-27mm in 35mm) that can be used in full frame at 12-18mm and the FE 24-105mm f/4 OSS on my A7RM5 for fast capture when spotting something all in a small teardrop over the shoulder bag with extra supplies also. I have a range of 12mm to 360mm on hand at a moment and from day to night.
My main thing is to edit a raw and see a jpeg with setting for jpeg to compare to as I saw it. With the many programs like Lrc, ON1 Photo RAW and Dxo PureRaw or IEDT Edit I get some great images that are sharp even pixel peeping.
Saying here that Software is the king today vs in the past, few today have lived through it in the past! Example in the past if doing say Astro Milky Way and did all the extra of 10 multiple images with NR off and stacking you get red and white noise dots or doing Bracketed 3 at +/- 1, 2EV when shooting below 1 sec NR is turned off and you get the same But today HDR processing those noise specks are gone.
Also most all cameras have IBIS being mirrorless today and even my A7RM5 will do Bracketed 5 at +/- 2EV handheld doing a sunset way into the blue hour and back in 2017 My A7RM2 would do 3 at +/- 2EV in a dim lit Antelope Canyon. Even better it will do a pixel shift hand held. So good by to that tripod also!
Just saying that the modern day mechanic's and software combined kina of makes primes not needed.
1. a 2015 A7SM1 bracketed 3 at +/- 1 ev edited in Lrc with noise red and white dots gone
2. 2017 A7RM2 Bracketed 3 at +/- 2EV
3 A cropped image on the A7RM5
4. A cropped image of a A7RM5 + FE 24-105mm f/4 OSS Handheld enlarged to 61MP 9504

While the video is interesting and well done I just wonder how does it apply to a real life situation. The other question you would need to ask is what situation might it apply to? The only real life situation I could think of where these lenses might well compete is in portraiture and as such would a portraiture test have been more revealing? I can understand why that location was chosen but I would argue that it’s not really a reflection of real world usage or go to answering a purchasing dilemma one might face. How many people would reach for a 85mm when shooting landscapes? Not that many I would suggest. On the other hand I can well see the 25-105 being an option for some for portraits or for a dynamic situation like wedding photography. The other question that needs to be asked is would the 24-105 if selected be sharp enough in that situation after the image has been processed? Would it produce an acceptable image. While some people shoot jpg. I doubt those who have shelled out 3.5K, like myself, for an A7R5 would confine themselves to shooting in jpg and using an image out the camera. Most people would be shooting RAW, processing the image applying NR and sharpening to wring every bit of quality they can from the image. For me is Jason asking the right question and doing a really meaningful test? Though having said that we are all different and many photographers have vastly different needs and workflows to match. While it’s well known primes tend to be sharper for the technical reasons Jason gave, possibly the question should have been; is a short zoom sharp enough in a real world situation after processing when compared to a prime. My own experience when shooting in a studio with an 85mm on a A7R5 ( I used the Zeiss 85 f1.8) is that shots can look scarily sharp, almost too sharp. I’ve seen myself applying negative clarity on some areas of an image to soften it slightly. Would therefore a 24-105 do the job? My own experience has shown that it does an acceptable job. While not fast at f4 it produces an image that most would find acceptable. At the end of the day the quality of the image, composition and overall appeal will always override any slight drop in perceived sharpness. So the question is would the image using a 24-105 be acceptable? I would suggest that it would be.

Today there's no noticeable difference between good primes and zooms. Only pixel peepers freak out over so imaginary differences. When pictures are viewed at realistic distances you can see no difference. I can make a 10' x 8' print with Nikon's best prime and my 100-400mm L and standing at the appropriate viewing distance you couldn't see any difference at all.
Period.

About pixel peeping detractors:
In cameras, sharpness and colors are like everything else in life: some people like a good wine, others prefer to drink water or Coca-Cola. It's all fine.
The only thing that's not fine is someone saying that a good wine is like drinking Coca-Cola or water.

I bought an early Sony A7 and some knipon adapters so I could use the nikkors I already had - all primes. I shoot our trips entirely to show the results as "screen savers" on our big TV. I convert the raws to jpegs using sony's app and results are better than the jpegs the camera records.

Dust on the sensor turned out to be problem with using primes. changing lenses made it possible to get dirt on the sensor that might sit there for a couple of hundred shots. It drove me nuts.

So I bought two more an A6000 and an a7II so I wouldn't need to change lenses so often, and a 24-240 to use on the A6000 - which produces 35-360 and a 16-35 for one of the A7's which gets 16-35. The second usually gets a prime maybe a 21 nikkor or a 55 1.4 depending on what I'm trying to do.

So my thought is that given the resolution of the sensors and the projection on the TV, I don't think I'm missing much. Does that make sense to you?

But there is also the issue of auto-focusing which I think I can do better with a manual prime and sony's wonderful focus frame enlargement.

So yes, I'd rather use primes, but since I'm not printing, I'd like to think my sony zooms are up to the job.

Does this sound reasonable?

This is like wine: it's fine if you like it.

In my case, I wouldn't be satisfied, because I edit each photo in raw, one by one, and although the Canon 18-200 is very good (for the focal lengths it supports), in sharpness and colors it doesn't even come close to a Tamron 17-50 F2.8. Therefore, in my case, I preferred to go with the 17-50 rather than the 18-200. But of course, it's all a matter of taste.

By the way, if the sensor gets dirty, you can buy liquid and brushes to clean it.

Hi toni,
of course sensors can be cleaned but when you're in the field and changing lenses, it isn;'t always obvious that you have aproblem until you get home.

A typical trip produces between 2,000 and 4,000 shots. I do the raw to jpeg and then load them on hard dirve on raspberrypi based server which lets me choose the trip to stream from a VNC computer, and having chosen, they flip screens about every 8 seconds. So if you're just looking at your shots on a 60 inch 4k tv, how much difference can there really be.

Tamron 17-50 F2.8 produces sharper images and more vibrant colours than Canon 18-200. For me there is a noticeable difference. But of course, this depends on each person, and what you compare.