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Archive 2013 · Canon EF 24-70mm f/4L IS Resolution Tests!
  
 
gdanmitchell
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p.8 #1 · p.8 #1 · Canon EF 24-70mm f/4L IS Resolution Tests!


RCicala wrote:
Not really disagreeing with your points about images, Dan. It's only a 15% difference in resolution even at MTF50 and a dozen things other than laboratory resolution tests are more important to any image. I'm like you, I tend to love my inexpensive primes (the 40 f/2.8 lives on my camera, at least at the moment).

I got interested because I see circular logic applied in discussing a number of lenses (not particularly this thread, but all over) -- saying X and Y have equal resolution and I'll fix the one with distortion in post. That's perfectly fine, and perfectly correct
...Show more

Darn. That is a very reasonable post that includes lots of reasonable thinking! :-)

Dan



Jan 07, 2013 at 10:38 PM
Gunzorro
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p.8 #2 · p.8 #2 · Canon EF 24-70mm f/4L IS Resolution Tests!


Roger -- I posted the following over on your blog site before I'd read all the responses following your post here. So I've slightly modified and added a point or two:

Roger — Great work!

Taking matters a step further, and possibly touching the “why” of your expectations that the rez fall-off wasn't even greater in the sides and corners: seldom do correction end with correcting distortion. As you mentioned, there is the straightening that crops into the original image. But also very common is the lens profile auto-correcting vignetting. I find this also very destructive of rez, and the programs do little to extrapolate and fill the gaps left by such correction, resulting gritty, moth-eaten corners (blue sky is the really obvious!).

On a worst case scenario, anyone who has ever de-fished a FF fisheye image knows how much space there is to fill in the vacuum left in the corners/edges. My point is I think you are very right in your expectation that the numbers in practical use are considerably lower than what you've come up with here. Sorry to give you any more work, but I’d be curious to see the figures if that area represented by vignetting were “neutralized”.

I’m getting pretty selective in my use of correction tools, and find myself often leaving distortion and lens profile unused so I can keep as much rez for straightening, cropping in, or using skew to correct perspective. I have a terrible habit of tilting the camera body to the side around 4 degrees (correction -- I just examined some images, and my tilt is between 1 and 2 degrees rotated to the right!), losing a lot of valuable real estate! Correcting that is my biggest need -- some of my cameras don't have viewfinder levels built in. So I'm even more sensitive to the lost from distortion correction and vignetting.

Least destructive to me seems to be removing CA, but even here, edge rez goes down. Still, going "grey" as opposed to magenta or green seems a plus to me.

What is a person to do?

Thanks so much for opening the can of worms and shining a Maglite into it.

Edited on Jan 08, 2013 at 12:38 AM · View previous versions



Jan 07, 2013 at 10:47 PM
gdanmitchell
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p.8 #3 · p.8 #3 · Canon EF 24-70mm f/4L IS Resolution Tests!


RCicala wrote:
Not really disagreeing with your points about images, Dan. It's only a 15% difference in resolution even at MTF50 and a dozen things other than laboratory resolution tests are more important to any image. I'm like you, I tend to love my inexpensive primes (the 40 f/2.8 lives on my camera, at least at the moment).

I got interested because I see circular logic applied in discussing a number of lenses (not particularly this thread, but all over) -- saying X and Y have equal resolution and I'll fix the one with distortion in post. That's perfectly fine, and perfectly correct
...Show more

The cool thing about these issues is that we can each test their significance directly by making prints and comparing - and confirm or eliminate the significance of such things on actual photographs.

One of the first times I discovered this was after I got my first DSLR close to 10 years ago. Trying to climb that new learning curve (despite having shot film for many years) I started to read a lot of online stuff, including many, many gear reviews and tests and lots of discussions in photography forums.

The particular moment of enlightenment had to do with diffraction. (Others followed in areas like sharpening for prints and so forth.) I had read about how diffraction blur has a greater effect on photographs as you stop down (which is, without a doubt, true) and a lot of writing about using optimal apertures that sort of split the difference between better lens performance at somewhat smaller than maximum apertures and the onset of diffraction blur, in an effort to get maximum image quality. To keep it simple, the "take away" from a lot of the theorizing (which was, I'll stipulate, often based on real data) was more or less that one should shoot "at f/8" (or similar apertures) and steer clear of, say, f/16 if one did not want to compromise sharpness. I steered clear of those smaller apertures, not wanting to compromise my image quality when using my new DSLR.

The theory is indeed correct. Diffraction blur does have have a greater negative effect on sharpness at f/16. However, when I got my first full frame body about 7 years ago or so, I got the idea of running some lenses through various apertures and seeing what this "deterioration" actually amounted to in photographs. While one cannot argue with the fact that diffraction blur has a greater effect on a shot at f/16 than a shot at f/8, one should be interested in the magnitude of that effect on actual photographs. It was by testing a few lenses this way and then looking closely at the resulting images that I discovered that the effect is basically insignificant even in very large photographs!

So, both truths can be compatible. It is true that diffraction blur diminishes sharpness as you stop down. It is also true that you won't be able to see this difference even in very large and well-made prints. (Well, OK, some of you won't buy my belief that the latter is true - but you can also run the tests yourself and use the visual results to determine how to best incorporate aperture decisions in your photography.)

To loop this back to the issue of corrections for distortion in post, here we also have two ideas that seem to be mutually exclusive, but which real world tests (and not just measurements resulting in numbers, as useful and interesting as those numbers can be) might prove to be compatible. Once again, I can say without any doubt that correcting distortion in post will diminish the quality of the image. But the magnitude of the degradation is rarely enough to be visible in a print, even a very large one. (Stipulation: there are limits. While typical adjustments, such as the "lens corrections" now offered in most post-processing software or corrections to align vertical and horizontal lines, are small and almost certain to not create a visible degradation, truly extreme adjustments that grossly warp the original image will create more serious degradation.)

My main point here is that it is important to look at the whole picture. (Literally and figuratively! ;-) I think there are sort of three phases:

1. Prediction, based on understanding of how this works, that an image that is adjusted in these ways will be degraded in ways that can be measured. ("Correction in post will degrade the image.")

2. Measurement of these changes that confirms that the prediction is correct. ("We can measure X amount of degradation when distortions are corrected in post.")

3. Assessing the real world impact of these changes in the image by producing real photographic output - typically prints, though screen-sized jpgs could be used as a lower-standard alternative. ("The print of the corrected image looks great." Or, "Aside from the repaired distortion, there are no visible differences in quality between the two images.")

Since we so often get ourselves locked up in semantic battles in these discussions, in a nutshell what I'm saying is that the theory correctly predicts that distortion adjustments in post will degrade the image, but that prints demonstrate that the degradation is insignificant in all but extreme cases.

Dan


Edited on Jan 08, 2013 at 03:24 AM · View previous versions



Jan 07, 2013 at 11:01 PM
StillFingerz
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p.8 #4 · p.8 #4 · Canon EF 24-70mm f/4L IS Resolution Tests!


Perhaps some just have more discriminating eyes Dan, the masses of P&Shooter eyes see not, but then how many actually appreciate and or view prints anymore. A sad state yes, but a cost of advanced technology and LCD's sized large enough for living rooms to be theaters in home


Jan 07, 2013 at 11:28 PM
RCicala
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p.8 #5 · p.8 #5 · Canon EF 24-70mm f/4L IS Resolution Tests!


Fred Miranda wrote:
Do you want me to change your username to "LensGuruGod1" so you don't have to test this out?
Fred


Fred, I'll probably have to get a new keyboard - you made me spit coffee all over mine. But no thank you, I think my avatar might give me away. More to the point, this is why I love this forum - unlike some we can have an intelligent discussion and see how point of view is pertinent. Threads like this are what give me the ideas to do the stuff I love to do. GDan, Gunzoro, Alendeb and others, thank you for the ideas!

I'm not sure I'll have time to do all the work involved, but I can at least check out some other lenses and see if:
1) How much the amount of correction affects resolution. I could do some with less distortion and maybe the Nikon 16-35 fisheye zoom
2) if tilt correction has this big of an effect (barrel and pincushion would seem much more complex, but I don't know).
3) How much effect CA correction has
4) If doing two types of correction is additive, multiplicative, or something else.

For a retired guy I sure seem to be finding a lot to do.



Jan 07, 2013 at 11:54 PM
gdanmitchell
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p.8 #6 · p.8 #6 · Canon EF 24-70mm f/4L IS Resolution Tests!


StillFingerz wrote:
... a cost of advanced technology and LCD's sized large enough for living rooms to be theaters in home


The large LCD - no matter how large - will not reveal the sorts of degradation we are talking about here since 1080 televisions have far fewer pixels than our cameras, and the best such video images interpolate many original pixels to produces one pixel on the screen. If I understand the technology correctly, even the new 4k televisions have fewer pixels in the image that your typical new DSLR.

Dan



Jan 08, 2013 at 03:30 AM
alundeb
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p.8 #7 · p.8 #7 · Canon EF 24-70mm f/4L IS Resolution Tests!


There may be some disagreement on the significance / visibility of minute differences in image quality when the image quality is already on a high level, suitable for large print. This is my take on it:

The conditions for tests / comparisons made must be taken into account when evaluating the results. For example (this may have happened or not), if Dan presents a test made with the 5D and 24-105 at the long end of the zoom range to demonstrate the effect of diffraction at f/8 versus f/16, his results are not directly transferrable to me when using a D800E and a prime lens at that focal length. This is not because diffraction would get worse, of course it wouldn't, but my setup has a potential for higher image quality when all factors are optimal. So I will see a bigger difference. In fact, I can see that my images with the D800E at f/5.6 are more affected by diffraction than at f/4. It is visible, but totally insignificant compared to the difference between f/4 and f/8. The difference between f/5.6 and f/16 is striking when viewing the files at 100% on a monitor.

Now for the correction of distortion. This is really interesting. With my setup, the image degradation from software correction of distortion will be less than with Dan's setup in the scale of the whole picture. This is because the degradation from resampling is proportional to the pixel dimension. With higher megapixel cameras, it will be easier to live with distortion and perspective correction in software.

After this, as has already been mentioned, sharpening will compensate for most of the loss in acuity. But not for loss in resolving power (measured at a lower MTF than 50%). Regarding diffraction, if you stop down beyond f/16 with a Canon camera, you will start lose real detail. Between f/8 and f/16 I may argue that sharpening a soft image is never as solid visually as having a sharp image to begin with, but this time I will not.

As for visibility of a difference in resolution, after the image has been processed to compensate for the loss in acuity, it really takes very fine detail and close side-by-side examination to see a 10% difference in linear resolution. 20% is easier to see, and 40% is significant. As I see it. And in my experience, the single most important factor for image resolution is the sensor resolution, there is no substitute for megapixels.

In the end, when we look at a printed photograph, not comparing side by side, these small differences will not affect the way the photograph is experienced. Here I totally agree with Dan. Still, when discussing the differences, it is not without connection with reality. The cumulative effect of many small differences may be significant, and especially after fixing a dominant limiting factor.



Jan 08, 2013 at 12:25 PM
gdanmitchell
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p.8 #8 · p.8 #8 · Canon EF 24-70mm f/4L IS Resolution Tests!


alundeb wrote:
In the end, when we look at a printed photograph, not comparing side by side, these small differences will not affect the way the photograph is experienced. Here I totally agree with Dan. Still, when discussing the differences, it is not without connection with reality. The cumulative effect of many small differences may be significant, and especially after fixing a dominant limiting factor.


:-)

If we just discuss the theoretical projections of what should happen, the connection to the reality that matters in photography remains extraordinarily tenuous until we see how these projects play out in actual photographs.

The world of technology is replete with examples of predictions and claims about things that were, no doubt, based on data and conceptual understanding yet which turned out to not at all what was projected.

Again, anyone who wants to base their notions about the effect of something like distortion correction in post entirely on "the math" or even careful side-by-side scrutiny at 100% magnification is on very thin ice when it comes to drawing conclusions about the real world importance of such things.

And testing this last thing is so darned easy! ;-)

Dan



Jan 08, 2013 at 01:58 PM
ultimaterowdy
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p.8 #9 · p.8 #9 · Canon EF 24-70mm f/4L IS Resolution Tests!


my main problem with the high distortion of the 24-105 was, once corrected, the lens didn't capture "24mm" FOV anymore.

Also, that the distortion was there at all apertures. Is that a fair statement? I assume all lenses act the same in this regard... so many things improve stopped down, but distortion doesn't and that makes it all the more annoying. (somebody call me on it if I am spewing hogwash here)

this 24-70 IS seems like a lovely travel lens to me. so much versatility in such a nice compact package. a jack of all trades to be sure.

thanks Roger for bringing such respect & discipline & data & god-bless-you SAMPLE SIZE to the forum.



Jan 08, 2013 at 02:58 PM
gdanmitchell
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p.8 #10 · p.8 #10 · Canon EF 24-70mm f/4L IS Resolution Tests!


ultimaterowdy wrote:
my main problem with the high distortion of the 24-105 was, once corrected, the lens didn't capture "24mm" FOV anymore.

Also, that the distortion was there at all apertures. Is that a fair statement? I assume all lenses act the same in this regard... so many things improve stopped down, but distortion doesn't and that makes it all the more annoying. (somebody call me on it if I am spewing hogwash here)

this 24-70 IS seems like a lovely travel lens to me. so much versatility in such a nice compact package. a jack of all trades to be sure.


Basically, the "issue" that people observe about barrel distortion at the wide end on the 24-105mm f/4L IS is real. The lens also exhibits a bit more vignetting at the wide end and at f/4 than some alternatives. While the vignetting issue diminishes as you stop down, stopping down has no effect on the barrel distortion.

Whether or not (or to what extent) that barrel distortion seems like a problem depends on a lot of subjective factors. Imagine two extreme perspectives to understand what I'm thinking about:

  1. The photographer photographs subjects with lots of lines parallel to the frame edges and often shoots these subjects at 24mm and likes to shoot in-camera jpg and do little or no post-processing work - and also doesn't need the larger focal length or IS that the 24-105mm lens provides. This person can probably find alternative lenses that will be better.
  2. The photographer wants to minimize the flexibility of the lenses he/she uses, often finds that the barrel distortion isn't particularly visible in the resulting image, shoots raw and is willing to let the post-processing software apply built-in corrections in post when it is noticeable or perhaps just all the time. This person will probably find the 24-105 to be a fine lens.

I'm not suggesting that these are the only two possibilities - just that it is not hard to see how two different yet serious photographers might come to very different conclusions about the value of two excellent lenses with different strengths and weaknesses.

For me it isn't a question of whether the 24-70mm f/2.8L, the 24-105mm f/4L IS, or the 24-70mm f/4L IS is "best," but rather which is the best fit for the intended use by a particular photographer. If I had all three (I don't), I'm pretty certain that in covering a variety of shooting situations I would probably prefer each of the three above the others in different situations. :-)

Dan



Jan 08, 2013 at 04:41 PM
 

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alundeb
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p.8 #11 · p.8 #11 · Canon EF 24-70mm f/4L IS Resolution Tests!


alundeb wrote:
In the end, when we look at a printed photograph, not comparing side by side, these small differences will not affect the way the photograph is experienced. Here I totally agree with Dan. Still, when discussing the differences, it is not without connection with reality. The cumulative effect of many small differences may be significant, and especially after fixing a dominant limiting factor.

gdanmitchell wrote:
:-)

If we just discuss the theoretical projections of what should happen, the connection to the reality that matters in photography remains extraordinarily tenuous until we see how these projects play out in actual photographs.

The world of technology is replete with examples of predictions and claims about things that were, no doubt, based on data and conceptual understanding yet which turned out to not at all what was projected.

Again, anyone who wants to base their notions about the effect of something like distortion correction in post entirely on "the math" or even careful side-by-side scrutiny at 100% magnification is on very
...Show more

Of course I have tested this.

Here is an example with a 100% crop of a scene taken at apertures f/5.6 and f/16 with the D800E an a 58 mm prime lens. Processed in Capture One with zero sharpening. The image at aperture f/16 also had a small amount of correction for distortion. In CS5, I applied different sharpening, trying to match the images as close as I could. The finest detail from the f/5.6 image could not be restored with any sharpening.

When printed at 240 ppi, corresponding to a 30 x 20 inch image size, I can tell the two apart viewing at an arms length distance. No need to label them to get it right.

When printed at 360 ppi it becoms difficult to tell them apart, but it can be done by close inspection.















Jan 08, 2013 at 08:36 PM
gdanmitchell
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p.8 #12 · p.8 #12 · Canon EF 24-70mm f/4L IS Resolution Tests!


alundeb wrote:
When printed at 240 ppi, corresponding to a 30 x 20 inch image size, I can tell the two apart viewing at an arms length distance. No need to label them to get it right.

When printed at 360 ppi it becoms difficult to tell them apart, but it can be done by close inspection.


I'm not quite certain I'm following you here, so let me see if I'm getting it. You made two photographs of the same scene using a D800 and a 58mm lens. Presumably you did not change focus between them. One was shot at f/5.6 and the other at f/16.

You have provided two sample images, one from each full-sized image. Both samples were sharpened, but not necessarily quite the same way, since your goal was to choose settings that would optimize each one. You also applied some distortion correction to the f/16 example - but not to the f/5.6 example, right? I'll assume that you controlled for the three-stops slower shutter speed of the f/16 sample by using a tripod, live view (or whatever the Nikon equivalent is called), and a remote release - and that you used the same ISO for both samples.

When we look at the two 100% crops it can be seen that the f/16 sample is not as sharp as the f/5.6 example. Let's look at that first, and then go on to the observations about the print samples that we have not seen.

The pixel dimensions of the D800 are 7360 x 4912. At the moment I'm looking at two monitors. One provides 90 ppi resolution and the other 114 ppi, and they probably are fairly typical of what many people are using. One is a laptop monitor and the other is that of an attached external monitor. On my 90 ppi monitor, the test images are displayed at a dimension equivalent to cutting them out of a 82" wide monitor full image or a print that is nearly seven feet wide. On the 114 ppi monitor I am seeing an image that would correspond to its size if clipped out of a 64.5 inch print, or one that is about 5 1/2 feet wide.

So, what the 100% crops tell us is that we would see this much difference (accounting for the differences between print and screen display, of course) if we were to compare prints that are between about 65" and 82" wide - e.g. really huge! Building on that idea - and having inspected some really large (and highly regarded) prints very closely - what I'm seeing here is an indication of some very remarkable performance from your lens at f/5.6! I can't recall ever viewing a gallery print of that size that closely and seeing resolution quite this high. On the other hand, the resolution at f/16, while visibly a bit less sharp is still also quite good for an image that would be equivalent to a slice of such a gigantic print.

So, yes, you are getting somewhat more resolution at f/5.6 than at f/16 when you inspect quite closely, just as expected. I can certainly see it, too.

So, you then took the additional step I wrote about and made prints at a considerably smaller size, equivalent to a 30" long dimension. You observed that you can see a difference between the two images, and said, "I can tell the two apart viewing at an arms length distance" when viewing prints made with a resolution of 240. That resolution should be plenty high to not reveal pixelation in the print, so it seems like a reasonable choice for your print test. (I assume here that you are still talking about the f/5.6 and f/16 examples as described above.) I'm a bit surprised at what you saw, but I can't argue that you did not see what you saw, can I? ;-)

(An interesting additional test would be to show one of the prints to a viewer, take it away, show the other print, take it away, and then show one of the previous two and ask the viewer which one it matched. Or hang one at each end of a large room and allow people to walk back and forth between then and note differences. But I digress...)

The point of your observation is to support the idea that there are significant enough differences between the f/5.6 test and the the f/16 test that you can see them in a 30" wide print.

Then you went on to say that you repeated the test with higher resolution prints, or at least I think that is what you are saying: "When printed at 360 ppi it becoms difficult to tell them apart, but it can be done by close inspection." This confuses me. If there is a "distortion" or "softening" of some sort tied back to the aperture choice (or the use of post-processing correction in the f/16 example), it doesn't seem to me that printing at a higher resolution would improve that in any way, since those issues are optical and not related to print resolution. Especially it does not seem that whatever change this created would benefit an image that was supposedly more damaged by diffraction blur and/or distortion correction in post - how would increasing print resolution do that?

If the difference between the samples decreases as you increase print resolution, isn't that telling you something about your post-processing workflow and some potential difference between printing resolutions rather than apertures at the time of exposure? I'm assuming that the difference is that both of your 20" x 30" equivalent samples are otherwise processed the same way with the exception of using a print resolution of 360 instead of 240. If that is the difference, it seems that it could not be explained by anything in the camera or the capture or even the post-processing, right? (Unless your different sharpening methods for the two samples somehow play into this.)

Or maybe I'm misunderstanding... It has happened before.

Dan



Jan 09, 2013 at 12:17 AM
alundeb
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p.8 #13 · p.8 #13 · Canon EF 24-70mm f/4L IS Resolution Tests!


I think you are misunderstanding, and that I wrote something that could be misunderstood

When I wrote "printed at 360 ppi" I actually meant "changed the image properties from 240 to 360 ppi without resampling". In other words resized the image without resampling, and then printed. This resulted in a smaller print from exactly the same pixels.



Jan 09, 2013 at 08:26 AM
gdanmitchell
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p.8 #14 · p.8 #14 · Canon EF 24-70mm f/4L IS Resolution Tests!


One other thought regarding print sharpening. Forgive me if you are already expert enough at this stuff to know this, but if you haven't tried it, there is a little sharpening step for print that many people seem to miss.

Do your normal sharpening, which in photoshop might consist of some combination of large radius/small amount sharpening for local area contrast and higher amount/small radius for small details. (As starting points I do a smart sharpen operation on the background layer with perhaps amount:150 and radius:.7 plus a USM operation at radius:50 and amount:12 - though there are other ways to skin this cat.)

Then duplicate the file. Flatten the copy and size for printing. Go ahead and interpolate to get a resolution of perhaps 300 for large prints if you prefer. (I tend to not worry about reinterpolating to get a resolution that is a multiple of 60 - like your 240 and 360 values - but I'll spare you the reasoning for now.)

Now do an additional sharpening operation to compensate for dot gain, or the tendency of the ink droplets to spread slightly as they land on the paper. The exact values will vary depending on a number of factors, including what paper you use (really! You have to test it!) and the nature of the image (some like more sharpening and some like to be softer). A decent starting point might be to smartsharpen with a relatively high amount of perhaps 200 and a very small radius of perhaps .3 or maybe .4.

When you view this on the screen it will not look good - the effect has been described as looking "crunchy." It will seem over-sharpened. But you are not sharpening here for screen display - you are compensating in advance for the expected dot gain on the paper print.

Indeed, as with any sort of sharpening, you have to be a bit cautious, as over-doing it can make the print look bad in the ways that over-sharpening often can. But get it right and the print can look distinctly sharper than it might if you forego this step.

I mention all of this because, to my eye, your 100% crop examples look like they could benefit from some careful sharpening, especially the f/16 example. As I wrote earlier, both examples look like they would produce very fine quality prints, but if you are especially concerned about print sharpness I think this might be something that you would like.

Take care,

Dan



Jan 09, 2013 at 02:25 PM
alundeb
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p.8 #15 · p.8 #15 · Canon EF 24-70mm f/4L IS Resolution Tests!


We are drifting a bit off topic, but it still has some relevance to lens sharpness.

I am familiar with the sharpening techniques you mention. Normally, I would sharpen more for print, but this example was meant both for display presentation and for print testing. If I presented a crop that was sharpened more, I would expect comments the other way, that it looked oversharpened.

And my ppi numbers are not multiples of 60. They are fractions of 720. It has been proven beyond any doubt whatsoever that the printer driver for mye Epson 3800 interpolates the image to 360 or 720 (if "finest detail" is checked) ppi using Nearest Neighbour interpolation before sending it to the printer. I don't know if you printer drives does that. If I print directly from resolutions that are not fractions of 720, I get jaggies and interference patterns.



Jan 09, 2013 at 02:45 PM
StillFingerz
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p.8 #16 · p.8 #16 · Canon EF 24-70mm f/4L IS Resolution Tests!


gdanmitchell wrote:
The large LCD - no matter how large - will not reveal the sorts of degradation we are talking about here since 1080 televisions have far fewer pixels than our cameras, and the best such video images interpolate many original pixels to produces one pixel on the screen. If I understand the technology correctly, even the new 4k televisions have fewer pixels in the image that your typical new DSLR.

Dan


Ah Dan, my point; guess your analysis missed this, is that your regular joe 'doesn't give a flying flock about distortion and or image degradation' they don't have 'print centered' critical eyes, they don't care, it's just a pretty picture and the easier viewed the better. That was my point...basic pixel/monitor knowledge would reveal this...but again the average Joe 'don't care', has not clue of resolution.

Due try not to over analyze or take prose out of context simply to fuel your continue diatribe...it looks silly.



Jan 09, 2013 at 02:55 PM
gdanmitchell
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p.8 #17 · p.8 #17 · Canon EF 24-70mm f/4L IS Resolution Tests!


alundeb wrote:
We are drifting a bit off topic, but it still has some relevance to lens sharpness.

I am familiar with the sharpening techniques you mention. Normally, I would sharpen more for print, but this example was meant both for display presentation and for print testing. If I presented a crop that was sharpened more, I would expect comments the other way, that it looked oversharpened.

And my ppi numbers are not multiples of 60. They are fractions of 720. It has been proven beyond any doubt whatsoever that the printer driver for mye Epson 3800 interpolates the image to 360 or 720
...Show more

It has also been suggested that interpolation in software followed by sending the interpolated image to the printer results in interpolating the image twice rather than only a single time in the printer. There have been some test of prints made both ways (e.g. allowing the resolution to end up being whatever it is, such as maybe 325.76 versus interpolating to get 240 or 300 or 360 or whatever) and the results have included a) the former looks better than the latter, b) the latter looks better than the former, and c) no one can see the difference in the print.

For my part, I don't interpolate in software unless the resolution will fall to quite low levels, though I do a test print to check and then try both approaches if there is a question.

It sure would be fun to look at prints rather than speculating about what one another's prints look like! Maybe we or the FM forum could consider some sort of local meetups where some of us who print and so forth could share prints and actually meet real people!

StillFingerz wrote:
Ah Dan, my point; guess your analysis missed this, is that your regular joe 'doesn't give a flying flock about distortion and or image degradation' they don't have 'print centered' critical eyes, they don't care, it's just a pretty picture and the easier viewed the better. That was my point...basic pixel/monitor knowledge would reveal this...but again the average Joe 'don't care', has not clue of resolution.

Due try not to over analyze or take prose out of context simply to fuel your continue diatribe...it looks silly.


I can't persuade you, perhaps, to consider that trying to take a thoughtful and analytical look at something is not equivalent to "diatribe," so that will be what it will be.

I think that if you look at what I write from a slightly different perspective you will figure out that I agree about how the "average joe" would look at all this stuff. I agree with you more or less completely that the stuff we are discussing here is insignificant in normal viewing of photographs, especially as a whole on a monitor.

There is an obvious trap in forum discussions of stuff, and I think this topic illustrates it well. Some issues are technical and they raise some occasionally arcane questions. There are two possible responses to those, leaving aside for the moment the possibility of simply not participating.

One response is to try to address the technical (or aesthetic) question in an analytical and thoughtful manner. Of course, if you do that, someone will remind you that the average joe doesn't care and might even describe this discussion as a "diatribe." (Some will point out, with some justification, that I've made the point often enough myself that something that can be measured may or may not be important.)

A second response is to respond to the technical question by making the case that the issues doesn't really affect the photographs that people are producing in any real way - a sort of thoughtful and analytical "average joe" response, if you think about it. Of course, if you do that, someone will come back with some sort of technical point.

Do you see the irony here? I think I do. ;-)

Dan


Edited on Jan 09, 2013 at 07:45 PM · View previous versions



Jan 09, 2013 at 04:39 PM
alundeb
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p.8 #18 · p.8 #18 · Canon EF 24-70mm f/4L IS Resolution Tests!


gdanmitchell wrote:
It has also been suggested that interpolation in software followed by sending the interpolated image to the printer results in interpolating the image twice rather than only a single time in the printer. There have been some test of prints made both ways (e.g. allowing the resolution to end up being whatever it is, such as maybe 325.76 versus interpolating to get 240 or 300 or 360 or whatever) and the results have included a) the former looks better than the latter, b) the latter looks better than the former, and c) no one can see the difference in the
...Show more

It annoys me a bit that I have to choose between to interpolate and not to interpolate, and both will result in a less than ideal result. It annoys me that my printer driver does NN interpolation, as it should not be necessary. I think there is a good chance that more recent printer drivers do not. Anyway, it helped a lot to discover the real function of the "Finest detail" tick box, as it is much less of a problem with NN to 720 than NN to 360. I think newer printer drivers do not fetaure that tick box, an indication of improved driver implementation.

As for meeting and seeing prints, I would appreciate it very much, but more for seeing your and other people's photographs alive in full size, and for the personal experience.

There is in planning a meetup in Iceland this year for real photography as well. This is organized in the FM alternative forum, and you are welcome to join. However, be warned that most participants will use some Zeiss or Leica lenses or other weird stuff



Jan 09, 2013 at 05:24 PM
gdanmitchell
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p.8 #19 · p.8 #19 · Canon EF 24-70mm f/4L IS Resolution Tests!


alundeb wrote:
As for meeting and seeing prints, I would appreciate it very much, but more for seeing your and other people's photographs alive in full size, and for the personal experience.

There is in planning a meetup in Iceland this year for real photography as well. This is organized in the FM alternative forum, and you are welcome to join. However, be warned that most participants will use some Zeiss or Leica lenses or other weird stuff


I'm in the SF Bay Area, where there are - no surprise - quite a few photographers. I often share prints at the monthly meetings of the San Francisco Photo Meetup Group, and occasionally with others and from time to time my stuff shows up in various shows. (One print will be in the Yosemite Renaissance show in The Valley right about the time of the Horsetail Fall business.)

Iceland. I'd love to go, but it won't be this year!

As for the gear, have photography friends with whom I shoot from time to time that use everything from Leica rangefinder film cameras to LF view cameras and everything in between. It's all good, from my point of view.

I noticed you mentioned the concept of "ideal result" in your previous message. Some people aspire for "perfection." I came to realize - eventually - that "perfection" is often a dangerous and counterproductive goal. I've never, ever seen a "perfect" photograph, though I've seen many that are truly great. I'll try not to start a whole "diatribe" on the notion of perfection here, but often I find that a more useful and still very powerful goal is "excellence," instead.

And, looping back to printing, there are multiple ways to produce truly excellent prints...

Dan



Jan 09, 2013 at 07:49 PM
StillFingerz
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p.8 #20 · p.8 #20 · Canon EF 24-70mm f/4L IS Resolution Tests!


Hi Dan,

Your last paragraph above is SPOT ON, excellence is a reachable goal, that perfection notion is indeed counterproductive...keeps you indoors not shooting way to much IMHO...great point

Jerry



Jan 09, 2013 at 08:12 PM
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