Bipod

Just curious: how did you view the image files?

The eye tends to mistake acuity (sharp edges) for resolution (fine detail). As you enlarge an image,
the presence (or absence) of fine detail becomes obvious.

It's hard to tell how much fine detail is in a scene, and usually it varies at different parts of the image.
And there is no way to quantitize it. That's why lens test charts with resolution targets were invented.

Lens testing on digital cameras is greatly hindered because there is no standardized RAW file format,
and because diigital cameras can do a lot of processing in the camera (even to the point of producing a
JPEG file with lossy compreession). On a film camea, you can just look at the negative with a loupe.

RAW require processing before they can be viewed. Sensor geometry (typically hexagonal) has
to be converted to rectilinear in order to be displayed or printed. Colors have to be demosaiced.
There are various algorithms that give different results. So it is very hard to make sure that
you are comparing apples with apples.

Worse, most computer monitors are quite modest resolution. So it's necessary to magnify the image
at sseveral locations, including the center and several points on the periphery.

Also, LCD/LED monitors are low contast. A contrasty lens and one that reduces contrast by three
stops may look the same.

It's really quite difficult to test lenses. Correct focus is essential, AF may not be accurate enough,
so without optical focusing aids, you have to magnfiy the liveview and check. Again, it was
much simpler on an SLR (with ground glass, microprisms and a split ring).

The first step with any lens is to find its sharpest aperture. But on a zoom, that can be different for
different focal settings.

All camera lenss have some Petzval field curvature. So they will be sharper in the center than in the
periphery. Unfortunately, two bad aberrations -- coma and oblique astigmatism -- have the same
symptom. To rule them out, you need to try focusing on the periphery to see if it becomes sharp.
(All lenses will have some oblique astigmatism.)

Good lens test charts are expensive. If you want to be able to use a reasonably sized chart at a reasonably
short distance, then the printing has to be very sharp. For this reason, printing a DIY is difficult. I use the
Century Precision Optics test chart kit made by Schneider: one large chart and five small ones.
Basically, in includes resolution (similar but not identical to USAF 1951) and focus targets (Siemens star).
It's available from Hot Rod Cameras in Hollywood:
https://hotrodcameras.com/camera-department/century-precision-optics-lens-complete-test-chart-kit/

Geometric distortion does not cause unsharpness. For some types of shots it doesn't matter, for others
(e.g, architecture) it matters very much. Using a grid target (or a piece of pegboard) will show distortion.

So it's not enough to "this lens is good", "this lens is bad"--good for what? A lens with a lot of spherical
aberration and Petzval field curvature is perfect for portraits--but only for portaits. But a lens with a lot of
chromatic aberration is only good as a paperweight.

Contrast and flare are a separate issue--but very important. Both highlights in the image and outside the
angle of view can cause flare. Zoom lenses are extremely susceptable to flare (both the visible kind and
the insidious kind). A zoom may perform well in the studio but lose all it's contrast when you take it outside.

MTF graphs do not test with light sources outside the angle-of-view, so the low spacial frequency numbers
are not a good measure of the contrast you will get outdoors.

Far from being "easy to use", zooms are a source of a get deal of complexity and many pitfalls. Even chosing
a lens hood is a problem--for optimal protection at all focal settings, it really needs to be adjustable.
If you want image quality, far from being a "convenience lens" a zoom is a pain-in-the-ass.

I own half a dozen zooms (mostly picked up used), but frankly I can't remember which zoom is sharp at
which focal setting, or what the sharpest aperture is for each zoom and focal setting, or how much contrast
each zoom loses. Nor do I own the best lens hood for each one. So I just don't use them unless I have to
(i.e., I need to rapidly change the focal length, or or for someson I can't carry additional lenses). That
hardly ever happens.

The design of any zoom lens is a compromise. Why compromise if you don't have to?

latebloomer Loc: Topeka, KS

"Nothing to show for it"? You should see my waistline from last year to this year. Also, I have thinned out the weak cells in my brain by engaging in fine wine, bourbons, and scotch.

latebloomer Loc: Topeka, KS

My Tamron 24-70 has been outstanding. I really think it can't be beat. It is a chunk of glass.

classic320

I have both primes and zooms, but use zooms most of the time. Modern, high quality zooms are quite good and I doubt that I can look at a photo and can tell if it was taken with one or the other. Usually use the primes for special purpose, e.g, macro, very high speed, or very long telephotos. Hard to argue with with the convience (less lens changing and weight to carry) and framing ability of a zoom.

ELNikkor

Never was a pixel peeper, but as I compose through the lens, being able to go to the perfect focal length for the right composition in a split second is more valuable to me than wondering if another lens might be 10 lppm sharper. If I need 46mm or 113 mm, I can get it quickly without changing my position, or missing the moment by fiddling for a lens in my bag that will come close, but still need cropping in post. I do have prime lenses, but seldom do they ever see any use.

TriX Loc: Raleigh, NC

Two great lenses, and I completely agree with your description of the 135 f2L - it’s become my favorite lens. I predict those are “heirloom” lenses that you’ll never need to upgrade.

Blurryeyed Loc: NC Mountains.

I have a couple of Sigma Art primes and it is really hard for me to mount my 70-200 II for pics of my granddaughter, The Sigmas wide open are sharper than the Canon L and the backgrounds are stunning.

Blurryeyed Loc: NC Mountains.

Heck, my 135mm weighs more than my 70-200...

bwana Loc: Bergen, Alberta, Canada

Can't beat the convenience of a great zoom lens! No changing lenses and missing shots. No changing lenses and getting dust and grit on sensors.

bwa

TriX Loc: Raleigh, NC

Sigma is making some excellent lenses with their Art line. The Canon 70-200 f2.8L is an excellent and very versatile lens (and in almost every pro’s kit for that reason) but it is no lightweight - the 135 f2L weighs about 1/2 that of the 70-200 f2.8L. Btw, the 135 plus a Canon 1.4x TC is actually sharper than the zoom at 200mm and still only about 2Lbs.

reverand

I recently bought the Nikon 24-70mm f/2.8 zoom, which was highly rated. I already have a Nikon prime 35mm and a prime 24mm lens. So, I put all three of them to the test. I photographed a painted wall, both for the color and the texture (windows, pipes, wires, fire escape, doors, gas meters), with all three lenses. I photographed at f/5.6--I rarely use wider apertures--and at f/11, which I often use to get maximum depth of field. With the zoom, obviously, I made the photographs at 24mm (f/5.6, f/11), and 35mm (f/5.6, f/11).

I then looked at the images side by side, magnifying them greatly, studying the center and the edges. AT f/11, I couldn't detect a difference at the center. At the edges, I thought the zoom was better at 24 than the prime, but my wife couldn't see any difference. At f/5.6, there was a little difference, but very little, at the edges, in favor of the 35mm lens. I couldn't see any difference at 24mm.

I was magnifying these images right up to the point where you're about to see pixels, and I was using a Nikon D850, which has spectacular resolution (47Mpx). The differences, if there were any, were so hard to distinguish, that I concluded that it wasn't worth worrying about. Of course, the 24-70mm lens costs about $2,000. I've been blowing up prints on 17x22 paper, and the sharpness is spectacular.

In short, zooms are a lot better these days than they used to be. Your choice of lens should probably be determined by convenience, rather than by a belief that single-focal length primes beat zoom lenses.

Blurryeyed Loc: NC Mountains.

I agree, I own the 70-200 II, but I also own the Sigma 50mm Art and the 135 Art along with the Canon 85mm f/1.8 which is a very underrated lens in some circles.... I don't seem to be using the 70-200 very often anymore... Maybe I should spend some time with that lens, could be that the reason that I just need to remind myself just how good it is.

TriX Loc: Raleigh, NC

I also own the 85 f1.8, which as you say is underrated. It can be had for $350, and if you believe DXOMark, is one of Canon’s sharpest lenses - a real bargain. I use it all the time indoors. There’s a Christmas party this weekend which draws serious bluegrass pickers from all over. It’s inside a home, and I’ll be using that lens. I think about saving up for the f1.2 or f1.4L, but not sure that extra 2/3- 1 stop and bokeh (and red stripe) is worth 1k$ more (yet). When you’re in a LOW light situation and you’ve turned up the ISO as far as you’re willing, a fast prime will save your a**s!

Blurryeyed Loc: NC Mountains.

Read about the Sigma before you purchase the Canon L, I would not even consider trading my Sigma 50mm Art for the Canon 1.2L simply because wide open the Canon 1.2 is not sharp, you have to stop it down to get really good results, the Sigma Art lenses are extremely sharp wide open, DXO rates the Sigma 85mm f/1.4 Art as its top rated lens, they really are incredible. I have a beautiful Pentax 50mm 1.2 from the film days that I use on my Fuji X-T2 and the 1/2 stop does not make a big difference and if you do shoot that lens wide open your DOF is razor thin, the image quality of the Sigma is fantastic wide open, I really don't think that you would find much opportunity to shoot the Canon at 1.2, the only draw back on the Sigma is that it is a big honker, 86mm filter and 2 1/2 pounds... I know that I am being a bit passionate about the Sigmas, but it is only because they really are that good, I own more Canon L lenses than anything else, from the 16-35 f/4 L IS to the 500mm f/4 IS, but the Sigma Art primes are better than their Canon equivalents. I can't speak to Sigma's new zooms but I do know that I am very happy with my Canon 100-400 II and don't feel like I left anything on the table by not going with the Sigma 150-600 Sport.

User ID

`


10X zoom [28-300] wide open at the long end.
Would a prime do any better ? Probably would.
Does the difference matter ? Probably not. If
you don't like living with probability, then you
are in the wrong universe. No exaggeration.

But what about the corners ? ? ? They do look
great, don't they ? But there's no subject detail
there, to show off the optics. Uhhh huh. And if
if there was detail or texture there, would really
good optics strut its stuff ? No. Not wide open
at 300mm, cuz there's no DoF so it won't focus
the details anywho .... unless you stop down a
few stops to improve DoF. But if you stop down
a few stops, almost any lens will look terrific.

(Download)


(Download)