Help me understand prime IQ vs zoom IQ (canon specific)

[FamilyID]

I'm looking at a 85mm F/1.8. I was wondering if the sharpness would be better than my 24-105mm? I know that primes generally have better optical performance and may be faster, but will a $350 prime beat out a $1150 zoom?

 

[KmH]

Understanding Camera Lenses
Camera Lens Quality: MTF, Resolution & Contrast
Tutorials - Sharpness

 

[Ysarex]

I'm looking at a 85mm F/1.8. I was wondering if the sharpness would be better than my 24-105mm? I know that primes generally have better optical performance and may be faster, but will a $350 prime beat out a $1150 zoom?

Yes. Zoom lenses compromise performance substantially. The extra price you pay for a zoom covers the extra costs of design and manufacture. The extra cost you pay for a red ring around a Canon zoom means they suck less not that they don't suck. For many of us it's worth the compromise for the convenience (I have the same 24 -105mm and compared to primes I have it sucks). If you don't want to compromise this is available in a Canon mount: Duclos Lenses ? Angenieux Optimo 24-290mm T2.8

Joe

 

[bratkinson]

I liked the speed and IQ of my 85 f1.8. I got some shots I otherwise couldn't have gotten without it in low light. But, having a 24-105 f4L and 80-200 f2.8L both covering the 85mm range, I decided to sell the 85. The few times I mounted it were more a "let's see what it'll do" than "I need that lens for these shots because...". I just didn't use it enough to warrant keeping it.

It took a while to 'discover' (re-discover,actually) that I'm more a zoom-lens shooter than a prime-lens shooter. At one point, I had 4 L zooms, 2 L primes and the 85 f1.8. After a year or so, and considering how many pictures I shot with each lens, I finally settled on my 'holy trinity' zooms (16-35, 24-105 and 80-200) and the 135 f2L (which they will have to pry from my cold, dead hands).

Whether or not the 85 f1.8 'fits' your shooting needs can only be determined by you. I liked the 85 results, even with its easily corrected in LightRoom Chromatic Aberration that sometimes surprised me. Already having 2 Ls to cover the same focal length, though, made it extraneous for my purposes.

 

[KmH]

Zoom lens IQ has improved compared to the IQ they delivered in the past.
The same is true, but to a lesser extent, for Prime lenses.

The computer software optics designers use has improved, which is what makes the most difference.
To some degree, advances in glass making, figuring, and polishing also contribute to the improvements.

Both prime and zoom lenses come in 3 grades - consumer, prosumer, and pro.
Many pro grade zoom lenses will outperform prosumer or consumer grade prime lenses.
Most pro grade zoom lenses deliver image quality quite close to the image quality pro grade prime lenses offer.

 

[Derrel]

Okay, look at these two images, both shot within minutes of one another, and pick out which one was shot with the Canon 85mm f/1.8 EF lens, and which one was made with the Canon 70-200mm f/2.8 L IS USM lens. The on-line original size is 1600 pixels on the long axis for both shots.

IMG_3959_Jenny-CROP_1600_Monochrome.jpg photo - Derrel photos at pbase.com

and the second photo:

IMG_4012_Jenni_CROP_1600_BW_V1.jpg photo - Derrel photos at pbase.com

Pretty obvious which is the prime and which is the zoom lens shot. Right?

 

[Mach0]

Okay, look at these two images, both shot within minutes of one another, and pick out which one was shot with the Canon 85mm f/1.8 EF lens, and which one was made with the Canon 70-200mm f/2.8 L IS USM lens. The on-line original size is 1600 pixels on the long axis for both shots. IMG_3959_Jenny-CROP_1600_Monochrome.jpg photo - Derrel photos at pbase.com and the second photo: IMG_4012_Jenni_CROP_1600_BW_V1.jpg photo - Derrel photos at pbase.com Pretty obvious which is the prime and which is the zoom lens shot. Right?

The full size images look much sharper.

 

[Derrel]

The full size images look much sharper.

Yes, yes they do look noticeably sharper and clearer, and that is why I pasted in the links to the pBase "Original" sized images, which are 1,600 pixels on the longer axis. One of the biggest problems on the web is the image re-sampling and the compressing of images to fit into TPF's rather strict size limits. So, to help with that, I posted the direct links to my pBase site, where those who choose can look at a much bigger,sharper, clearer image of both frames.

The simplified answer is found above: Canon's 70-200 f/2.8 L-series zoom at apertures like f/6.3, offers very good imaging performance. At around 130mm, which is where the second shot above was taken, my 70-200 L zoom offers outstanding image quality! In fairness though, the 24-105 f/4 L IS USM Canon zoom I own is not so great at the telephoto end, compared to a good, prime lens in the 85 to 105mm focal length range...at 105mm it's not all that great, and at the short end, it has a lot of distortion, so it's not good for situations where distortion is an issue.

 

[iolair]

I've read people saying some zoom lenses have quality as good as the best primes. - the particular zoom lenses being mentioned were all four versions of Canon's 70-200mm, and Sigma's new 18-35mm f/1.8.

Of course, an 85mm f/1.2 L will beat the 70-200mm at 85mm and f/1.2 - and a 35mm f/1.4 will beat the 18-35mm at 35mm and f/1.4.

Zooms have IS more commonly than prime lenses (though more prime lenses seem to be getting it as time goes on), which can also be a significant factor in the image quality of low-light handheld shots.