Sharpness the same as resolving ability?

Hi folks.

I would like this question answered. One of my favorite lenses is the 100mm F2 (and it's sister lens the 85 1.8)

I purchased a 5D2 last year and had decided to go back to zooms. I was waiting on my Tamron zoom and my 70-200 F4 L, and was selling my first 100 F2 but it was all I had to use with the 5D2 while I waited for my FF zooms. So I take several shots, portraits oif my daughter with the 5D2 and 100mm. Then my other zooms come and I sell the 100 F2.

But for a year, the few portraits I took with the 100 F2 while I had it were STUNNING in their detail, their resolution. I couldn't stop looking at them. The pics were easily better looking than the pics with the zooms, even the L zoom.

I know primes are better than zooms for the most part, but then I also bought the nifty fifty and the 35 F2, and even those primes, though sharp, still don't have that certain something that my 100 F2 has. Then, looking at the sample threads of L primes, I see the same thing that I see with my 100 F2. there is some kind of extra substance, something deep, like more pixels or something, yet when I look at pics from my L zoom, or even cheaper, lower quality primes, I DO NOT see that certain something, EVEN THOUGH they are eye-lash-counting sharp.

My new EF 35mm F2 is sharp even wide open, I can count the eye lashes, so that makes me feel that I am not seeing any problem with sharpness. That doesn't look like the difference I am seeing between cheaper primes or good zooms and the 100 F2 and L primes I see in the sample threads.

So that's the question, what difference am I seeing that makes the 100 F2 (85 1.8 too) and L primes look like they have such a deep substance to them and the zooms and cheaper primes don't have even though I can pixel peep to 100 percent and count eye lashes on them? They don't appear to have any problem in sharpness, but yet they don't look like they have some kind of substance that I can't even put in to words.

Am I seeing the difference in their ability to resolve details, or show more pixels? Is the difference resolving ability?

If this is the difference I am seeing, then how come people aren't discussing that far more often as the difference, yet they discus sharpness all the time as a reason to buy a lens. How come most people aren't discussing resolving power or whatever it is instead of how sharp a lens is? When my nifty fifty gets a sharp shot, you can zoom in to 100 percent and count those individual eye lashes perfectly, yet it still doesn't have that solid, thick, substance to the picture itself.

So what's that thing i am seeing in the good lenses if it isn't sharpness?

Sorry for rambling, but this question has been in my mind for a while, so I wanted to make sure and get it across clearly.

One mistake people often make when comparing lenses is to compare the resolution on similar subjects but taken at a different magnification. For instance comparing the eyelashes on a subject taken with an 85 and a 35. Because people rarely frame the 35 the same at the 85, nor should they, they the 85 will often resolve more detail in the face than the wider lens simply because its a bigger part of the frame. I'm not saying thats happening to you, but its a complaint thats often made with people purchasing wider lenses and then comparing them with a lens that has more magnification. Just make sure you have a level playing field when you compare.

Resolving power is only one component of what people recognise as sharpness. The other, which could be the factor you're describing, is contrast.

And a couple examples. Here's a pic of my daughter with my first 100 F2 before I sold it using my 5D2. I kept staring at this pic for a year wondering what it is about it that I love. It's like there is a depth to it that my other lenses don't have. Then, the next pic of my daughter and her boyfriend is a few days old using my new 35mm F2. and the pic of my cousin after that using the Nifty fifty. Look at the substance difference between them. To me the 100 F2 has a richness to it that is beautiful, and the other lenses don't have it as much yet the pics are sharp too. So what's the difference consist of?

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Here's a good article discussing sharpness in terms if acutance and resolution:

http://www.cambridgein​colour.com/tutorials/s​harpness.htm

But I think what most people mean by 'sharpness' is how well optical aberration is controlled in addition to the above.

I agree with GG above though. I have some razor sharp close-up images from the 100mm f/2 myself. Great lens!

WOW, finally I now know the difference I have been seeing. That site, so easily, so simply explains the differences I have been seeing. And that's the first time I have ever even seen the word acutance. The sample pics on that page show EXACTLY the difference I have been seeing. My new 35 F2 seems right in the middle ground. I actually sold my 70-200 F4 L to buy my second 100 F2, and I am glad I did. I loved my 70-200 L zoom, and I couldn't fault the pics and sharpness at all, but it still did not have that wow factor that the 100 F2 prime gives. It was close, it had beautiful colors and looked sharp, but I still did not see both resolution and this acutance thing together as much.

Finally I now know why the pics in the L prime sample threads look so rich, detailed, like you can dive in to 500 percent crop and still not reach the depth of the pics.

Now I know what to look for. I am selling my Nifty fifty and I am going to buy a new Sigma 50 1.4, as i see the same acutance and resolution in sharp copies of that lens as I do the 100 F2. Just got to hope for a good copy of one, but I now know what the difference is.

This leaves me kind of stuck as far as my 35 F2 goes, because it does have some of that richness of the 100, just not as much.

Thank you all so much. Now I kow what I want, and more importantly, WHY I want the lenses I want. Now i know that the lenses that don't have that resolution and acutance can't take advantage of my 5D2 fully. If my 5D2 could talk to me it would say, "Hey, buy lenses that can actually hang with what I am capable of. That Nifty fifty, and those zooms, they can't let me express myself as well as good primes do"

frugivore wrote in post #15687632
Here's a good article discussing sharpness in terms if acutance and resolution:

http://www.cambridgein​colour.com/tutorials/s​harpness.htm

But I think what most people mean by 'sharpness' is how well optical aberration is controlled in addition to the above.

I agree with GG above though. I have some razor sharp close-up images from the 100mm f/2 myself. Great lens!

If you think the Canon 100/2 is good in that regard, you better stay the heck away from the Zeiss 100/2 then! or at least try it out, just make sure not to have money with you, lest you accidentally buy it on the spot.

I'm sure I could never afford a lens like that. My eye sight isn't good either so I definitely need AF. I bet they are stunning pics from hat lens.

I like my Sigma 50 (and this is on a 7D nonetheless)