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Archive 2017 · Sharpness is a worthless measuring stick for lenses

  
 
Coltrane
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p.3 #1 · p.3 #1 · Sharpness is a worthless measuring stick for lenses


rek101 wrote:
So how do you research a lens before buying one then? I get these people are all biased, usually you can read between the lines and figure out what's really going on...with lenses I find it almost impossible. Users trumpet the marketing messages of the manufacturers with as much vigor as the marketing departments themselves.


Reviews and MTF graphs can certainly be helpful, but the main thing that allows me to make a decision on a lens is sample images. After looking at hundreds of sample images from a given lens, I either like what I see or I don't. You don't have to be concerned about "marketing messages" if you just trust your eyes.




Jun 20, 2017 at 06:42 AM
rek101
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p.3 #2 · p.3 #2 · Sharpness is a worthless measuring stick for lenses


I kind of like borka...it has a nice ring to it. I suppose I just wish some reviewers would test lenses in a way that would show what is is you're really paying for when you pay around two to three times more. The very expensive stuff uses low dispersion elements I'm assuming to cut down on haze and glare and produce that crisp image. Assuming these coatings emphasize certain colors more than others or some coatings work better than others, I would imagine it can be seen in some of the photos taken with the lens or measured with MTF charts.

As for taste, I think there are general purpose looks that are pretty neutral and then there are very specialized looks. The 135L to me is pretty much the best example I can think of. I bought it thinking I was getting a general purpose portrait lens that could also be used for sports or candids, but I got a very dramatic look that turns everything into a rockumentary from the 80s. I like it sometimes, but I think it's a lot more specialized than I realized.





Jun 20, 2017 at 07:19 AM
dmacmillan
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p.3 #3 · p.3 #3 · Sharpness is a worthless measuring stick for lenses


jcolwell wrote:
I spell it "bokeh" and pronounce it "boquet" (i.e. "bo-kay").

Are you sure you're not Mrs. Bucket from "Keeping Up Appearances?".



Jun 20, 2017 at 07:33 AM
jcomer82
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p.3 #4 · p.3 #4 · Sharpness is a worthless measuring stick for lenses


Yup. It is worthless. It's crazy how much a "photographer" worries about such a thing. Personally,I have yet to come across a lens that renders a completely blurry photo when I *know* it is in focus....


Jun 20, 2017 at 07:38 AM
AmbientMike
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p.3 #5 · p.3 #5 · Sharpness is a worthless measuring stick for lenses


Sharpness isn't worthless, but it does get overblown. I want the sharpest lenses, but if sharpness was the #1 biggest thing, one would rarely if ever shoot wide open. Very few lenses are sharpest wide open.

And nobody would use the 24-105 or 100-400 v1 if extreme sharpness was needed. Probably wouldn't use the 50/1.2 wide open, or probably the 85/1.2 v1 or 35/1.4 v1, wide open, either.

But those zooms have produced TONS of great photos. They are sharp enough, I suspect (haven't used 24-105, 100-400 was sharp enough) and great zoom range. And I suspect the primes used at max aperture have prodiced a ton of great photos, as well.

You need a certain amount of sharpness, but probably not as much as you think.

Contrast is another thing. I want as much as possible, but it can be a problem in midday sun, imo.

BTW the video didn't see much difference between the 1.4 & 1.8. It actually recommended the 1.8 more strongly.



Jun 20, 2017 at 05:13 PM
EB-1
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p.3 #6 · p.3 #6 · Sharpness is a worthless measuring stick for lenses


rek101 wrote:
So how do you research a lens before buying one then? I get these people are all biased, usually you can read between the lines and figure out what's really going on...with lenses I find it almost impossible. Users trumpet the marketing messages of the manufacturers with as much vigor as the marketing departments themselves.

Cadaver wrote:
Reviews and MTF graphs can certainly be helpful, but the main thing that allows me to make a decision on a lens is sample images. After looking at hundreds of sample images from a given lens, I either like what I see or I don't. You don't have to be concerned about "marketing messages" if you just trust your eyes.


It's often not so easy to find the RAW files and the subject matter and other camera settings may not be relevant to the particular application. Is there some site that you find particularly useful?

EBH



Jun 20, 2017 at 06:57 PM
Paul Mo
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p.3 #7 · p.3 #7 · Sharpness is a worthless measuring stick for lenses


RustyBug wrote:
Head over to the Alt Forum ... the folks there can tell you



No thanks - too much bitching like in the Leica R Series Lenses thread.



Jun 20, 2017 at 08:03 PM
RustyBug
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p.3 #8 · p.3 #8 · Sharpness is a worthless measuring stick for lenses


Paul Mo wrote:
No thanks - too much bitching like in the Leica R Series Lenses thread.


Hopefully not too much. I haven't been there for a few years (since my SLR/C finally hit the dust rack and I'm now vested in EF glass to boot). Those folks taught me a ton of stuff back in the day. Props to the Alt forum (as long as it isn't a "fan-boy" fest), as surely there are still some very helpful, talented and intelligent FM'ers over there.

Other forums are full of good FM'ers too ... but the Alt group just seemed to have willingness to "dig deeper" than others had the temperament for. Just don't ask which is better "Zeiss or Leica"

I always found the wording is what are the DIFFERENCES ... not which is BETTER ... to generate the least fan-boy type of response.



Jun 20, 2017 at 10:03 PM
ashton lamont
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p.3 #9 · p.3 #9 · Sharpness is a worthless measuring stick for lenses


I find I have some empathy with the OP.

Its all well and good testing to destruction / measurabating / pixel-peeping or whatever you want to call it, but for real-world actual photos shot and printed often its far from clear why one lens might be better than another.

I have the original Lensalign from Michael Tapes but i probably haven't tested it in years. Rather I just shoot on a tripod of a regular brick wall to check a lens is OK! Occasionally I've had a decentered lens (Canon 24-105 f4L) which I had repaired by Fixation (Canon Professional Services in London).

Currently, prime wise I use a Canon 50mm f1.2L and 50mm f1.8 (mark I). Did also have a Canon 15mm f2.8L but that is pretty much knackered now. And A Sigma 180mm f3.5 macro and Sigma 20mm f1.4 Art. Zoom wise a Canon 20-35mm f2.8L which is 27 years old, a Canon 24-70 f2.8L Mark I, Canon 24-105 f4 L Mark 1, Canon 70-200mm f2.8 L IS, Canon 24mm f3.5 L Tilt Shift. Canon extender 1.4 Mark II. The Canon 28-135,, f3.5 - f5.6, and Canon 75-300 f4 - f5.6 IS USM don't get used for obvious reasons.

I tested the Canon 28-135mm recently as I needed that sort of range on a locked off video dSLR setup. Its done a great job. I also tested the Canon 75-300; it was nice in the centre but the edges are pretty soft so limited use. My old Canon 20-35 f2.8L is not as sharp at the edges as the latest similars but it is very nice none the less.

My main paid work is from low-light event stuff and the camera body performances are far more important e.g. the Canon 5D Mark IV is a revelation. I wouldn't be using the 28-135 instead of the 50mm f1.2L, or the 20-35mm f2.8L instead of the 20mm f1.4 Art unless for a very good reason (e.g. multiple dSLR's shooting video simultaneously locked down) obviously but these lenses are not shabby.

Pete



Jun 21, 2017 at 04:49 AM
Mikehit
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p.3 #10 · p.3 #10 · Sharpness is a worthless measuring stick for lenses


Sharpness, like size and weight, are measurable - almost everything else is not and are subjective. All factors taken together will enable you to make your mind up as to whether the purchase is worthwhile and the reviewer has no idea what your priorities are.

You can spend paragraphs analysing MTF charts and test photos, and all you can say about bokeh (as an example) is 'it's nice'. Of course the reviews are going to be biased towards the technical.

I don't really understand what is being asked of them.



Jun 21, 2017 at 06:11 AM
shutterbug guy
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p.3 #11 · p.3 #11 · Sharpness is a worthless measuring stick for lenses


Sharpness has it's place and is needed depending on what you are trying to capture imho.

Take for instance the 50mm Canon, 1.2L and the 1.8 STM. The cheaper of the pair is actually sharper and probably better for stuff like landscapes than the L lens is. Even though the 1.2 lens doesn't rank as sharp as the STM it will knock the socks off of the STM especially in close up shots where background out of focus quality and even superior, yes I'll say it, bokeh results are needed.

I could go on about micro contrast and the like but there is something about the way the L renders an image that to me is more pleasing and superior. So imho, sharpness is just another tool in the toolbox that you may want to grab when warranted or needed.

Here are a couple Imatest MTF (resolution) charts from

Photozone, the 50L and the 50 STM.

Note the results are from 21mp, not 30 or 50.



Jun 21, 2017 at 07:25 AM
Mike Jacks0n
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p.3 #12 · p.3 #12 · Sharpness is a worthless measuring stick for lenses


IMO, sharpness is very important. As mentioned above, it's one of the few performance metrics that can be accurately measured. Yes, understanding the MTF charts come in a multitude of biased flavors does help, but even the biased corrected charts show a lens' inherent design flaws. Without the charts, you would likely need to purchase to see otherwise... or worse take someone's word on its performance. Let's not forget, most reviewers on the "Internets" have a bias. Sometimes financial and other times brand loyalty, but in either case, a bias is still a bias.

Another pro-sharpness argument revolves around post processing. Its tough to make a soft lens sharp, but it's relatively easy to make a sharp lens soft.



Jun 21, 2017 at 11:52 AM
shutterbug guy
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p.3 #13 · p.3 #13 · Sharpness is a worthless measuring stick for lenses


Mike Jacks0n wrote:
IMO, sharpness is very important. As mentioned above, it's one of the few performance metrics that can be accurately measured. Yes, understanding the MTF charts come in a multitude of biased flavors does help, but even the biased corrected charts show a lens' inherent design flaws. Without the charts, you would likely need to purchase to see otherwise... or worse take someone's word on its performance. Let's not forget, most reviewers on the "Internets" have a bias. Sometimes financial and other times brand loyalty, but in either case, a bias is still a bias.

Another pro-sharpness argument revolves around
...Show more

While I agree with your assessment about sharpness being very important but I do beg to differ as the sharpness is being the be all to end all. There are many other virtues to a lens that are imho of equal importance if not more so. Some that come to mind are color saturation, white balance, bokeh quality, micro contrast, tonality, weather resistance, focus speed, focus accuracy along with many more.



Jun 22, 2017 at 07:28 AM
Mike Jacks0n
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p.3 #14 · p.3 #14 · Sharpness is a worthless measuring stick for lenses


shutterbug guy wrote:
While I agree with your assessment about sharpness being very important but I do beg to differ as the sharpness is being the be all to end all...


Please note... at no point did I say it was an "end all" criteria. That's not they way I view it. My criteria is weighted by the following factors in descending order:

-Need/Desire
-Sharpness
-Wide-open performance
-CA Resistance
-Contrast
-Color Rendition
-Flare Resistance - More important in wide and ultra wides

Personally, I'm not terribly sensitive to vignetting.




Jun 22, 2017 at 11:11 AM
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