Sweet Spot for Landscape Photography
Dec 12, 2018 12:56:33 #
selmslie wrote:
Do they report it at the center or across the entire image?
As we have seen with Lens MTF Test Results, it depends on whether you want sharpness across the entire image, as you would for a landscape image, or near the center as you might for a closeup.
The whole question can be overthought. There are just too many numbers and plots to look at.
As we have seen with Lens MTF Test Results, it depends on whether you want sharpness across the entire image, as you would for a landscape image, or near the center as you might for a closeup.
The whole question can be overthought. There are just too many numbers and plots to look at.
Candidly, I don't know the answer as they use a fairly complex target and their algorithm is proprietary, but I have found their acuity numbers very useful in evaluating a new lens - if it's in the 1000-1100 range (or below), there's a problem, but 1300-1400 or higher can generally be expected to be a sharp lens.
Dec 12, 2018 13:44:40 #
TriX wrote:
Candidly, I don't know the answer as they use a fairly complex target and their algorithm is proprietary, but I have found their acuity numbers very useful in evaluating a new lens - if it's in the 1000-1100 range (or below), there's a problem, but 1300-1400 or higher can generally be expected to be a sharp lens.
I have done extensive testing with Focal and different lenses on different cameras and my criteria for "tack sharp" is IQ of about 1700-1800 and up. The best I have been able to achieve is 2400.
Dec 12, 2018 14:47:41 #
IDguy wrote:
No, the easiest solution is higher fstop. As you note, diffraction is overrated. The masters of sharpness, like Ansel Adams, belonged to the f64 group.
Focus stacking isn’t easy. You have to know how to take the images and process them. Neither is trivial.
But I might try focus stacking since my Z6 automates the first step.
Focus stacking isn’t easy. You have to know how to take the images and process them. Neither is trivial.
But I might try focus stacking since my Z6 automates the first step.
If someone doesn't use high-quality optics (say he only uses zoom lenses), then indeed f/11
or f/22 may be the sharpest aperture. But that doesn't make it sharp--just the least unsharp.
And if he never makes a large print or looks at an image file on a large, high-res
monitor, he may never see the unsharpness. But it's there.
Francesco Maria Grimaldi, Sir Isaac Newton, James Gregory and Thomas Young
aren't wrong. Ansel Adams and Bruce Barnbaum aren't wrong. Optical engineering
and physics textbooks aren't wrong.
On miniature format (= "full frame") or smaller cameras, f/22 is decidedly unsharp
if displayed or printed at 8" x 10" or larger.
Grab a copy of *Langford's Basic Photography* by Prof. Michael Langford, FIIP, FRPS (hon.),
of the Royal College of Art.
Dec 12, 2018 15:06:38 #
Focus stacking is a technique designed to increase depth-of-field by taking
multiple shots of the same scene with the lens set to a series of focal distances.
But focus stacking cannot possibly correct any lens aberration that causes
the image plane to be unsharp regardless of focus: Spherical Aberration, Coma,
Astigmatism, Petzval Field Curvature, or Chromatic Aberration.
That's because the same aberration is present in each image taken by that lens.
A detail that isn't resolved in any of the images is lost forever. Makes sense,
doesn't it? Software isn't magic.
(Backfocus stacking could theoretically be used to correct Petzval Field Curvature
on a camera that has an adjustable back focus. Never heard of being done, though.)
In any case, focus stacking requires a very steady tripod and very accurate focusing.
And nothing in the image (e.g, leaves in the breeze) can move while all this fussing is
going on.
Other software programs can sometimes correct for some types of Geometric
Distortion, because it doesn't make the image unsharp, merely distorted.
If you plan to enlarge your images to the point where people can actually see
detail, there is no substitute for having a high-resolving-power lens.
Alas, Hamburger Helper will not make ground rat taste like top sirloin.
multiple shots of the same scene with the lens set to a series of focal distances.
But focus stacking cannot possibly correct any lens aberration that causes
the image plane to be unsharp regardless of focus: Spherical Aberration, Coma,
Astigmatism, Petzval Field Curvature, or Chromatic Aberration.
That's because the same aberration is present in each image taken by that lens.
A detail that isn't resolved in any of the images is lost forever. Makes sense,
doesn't it? Software isn't magic.
(Backfocus stacking could theoretically be used to correct Petzval Field Curvature
on a camera that has an adjustable back focus. Never heard of being done, though.)
In any case, focus stacking requires a very steady tripod and very accurate focusing.
And nothing in the image (e.g, leaves in the breeze) can move while all this fussing is
going on.
Other software programs can sometimes correct for some types of Geometric
Distortion, because it doesn't make the image unsharp, merely distorted.
If you plan to enlarge your images to the point where people can actually see
detail, there is no substitute for having a high-resolving-power lens.
Alas, Hamburger Helper will not make ground rat taste like top sirloin.
Dec 12, 2018 17:50:31 #
gordone wrote:
I have done extensive testing with Focal and different lenses on different cameras and my criteria for "tack sharp" is IQ of about 1700-1800 and up. The best I have been able to achieve is 2400.
Interesting - I’m using an early version and need to upgrade because mine only shows the correction, not accuitance vs f stop. I want my “Ls” to read 2400 too - I’m jealous!
Dec 12, 2018 18:42:20 #
TriX wrote:
Interesting - I’m using an early version and need to upgrade because mine only shows the correction, not accuitance vs f stop. I want my “Ls” to read 2400 too - I’m jealous!
I have the Pro version that graphs the IQ at every F stop. It's very informative. I posted a graph that shows different lenses at different f stops
Dec 12, 2018 18:50:06 #
gordone wrote:
I have the Pro version that graphs the IQ at every F stop. It's very informative. I posted a graph that shows different lenses at different f stops
Thanks. I’m going to update tomorrow.
Dec 12, 2018 18:55:31 #
TriX wrote:
Thanks. I’m going to update tomorrow.
On page 7 of this post I included a graph from Focal output for my 1DX mark ii. I also have graphs for my 5DS-R and 7D and 7D mark ii. I took the Focal output and put them into Excel to give a composite of all lenses that I tested.
Dec 12, 2018 20:08:50 #
gordone wrote:
On page 7 of this post I included a graph from Focal output for my 1DX mark ii. I also have graphs for my 5DS-R and 7D and 7D mark ii. I took the Focal output and put them into Excel to give a composite of all lenses that I tested.
Just upgraded. These snowy days are a good time to recheck calibration and check optimum apertures for each.
Dec 12, 2018 21:15:22 #
TriX wrote:
Just upgraded. These snowy days are a good time to recheck calibration and check optimum apertures for each.
The Pro version also shows in real time how your lens compares to other copies that have been tested by all users
Dec 12, 2018 21:19:03 #
gordone wrote:
The Pro version also shows in real time how your lens compares to other copies that have been tested by all users
Cool! You would think I was on their payroll as many times as I’ve recommended this product, but it is really some of the best $ I’ve spent in photography. This is one great tool to optimize your system.
Dec 13, 2018 10:24:11 #
IDguy
Loc: Idaho
gordone wrote:
I agree 100%. On the graphs of image quality at different F stops you can clearly see the degradation in image quality above say F11. If image quality is not important then you may still choose to shoot F22 or whatever. Just taking a picture at F22 and printing it may still look ok but you don't know how much better it would have looked at F8
What is the ordinate?
Dec 13, 2018 11:15:47 #
IDguy wrote:
What is the ordinate?
They do not specify what the actual units are, but they analyze lines in the horizontal and vertical direction separately and for each color channel and outs a combined final QoF number. With the Pro version you get a QoF for each color channel as well as the best microfocus adjustment spread for each channel.
Dec 13, 2018 11:23:10 #
IDguy
Loc: Idaho
gordone wrote:
They do not specify what the actual units are, but they analyze lines in the horizontal and vertical direction separately and for each color channel and outs a combined final QoF number. With the Pro version you get a QoF for each color channel as well as the best microfocus adjustment spread for each channel.
OK. What does QoF stand for? (assume “Quality of” something?)
Dec 13, 2018 11:30:33 #
IDguy wrote:
OK. What does QoF stand for? (assume “Quality of” something?)
Quality of Focus
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