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Author Topic: Canon 50D review out  (Read 22163 times)
Slough
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« Reply #80 on: November 03, 2008, 01:53:34 PM »
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Quote from: Ray
In photographic matters I am informed by what I see. I don't see much difference, or anything I would describe as very significant, at the plane of focus moving from one aperture to the next one, either up or down one stop, within the range where I find most lenses are acceptably sharp and at F stops most often used (by me). It's not a matter for objective argument because the statement 'don't see much difference' is a personal and subjective statement based upon many tests over the years photographing real-world scenes as well as line charts.

Whilst I find there's a significant difference between F5.6 and F16, I find little difference between F5.6 and F8, between F8 and F11 and between F11 and F16, with the Canon 50/1.4. With other lenses and at other apertures, the situation may be different. With the Canon 100-400 at 400mm the difference between F5.6 and F8 is greater than the difference between F8 and F11. The lens is less sharp at F5.6 than I would like.

However, if you are serious and genuine in your assertion that going from F11 to F16 can be very significant, then please show us all a comparison so we can get an idea of your idea of significant.

Edit: I should add, in case anyone is confused by the above, that I concede it might be possible for a lens to have a very significant difference in performance at F11 and F16, but I don't own any such lenses. I imagine such a lens would be an old-fashioned design for large format film cameras, optimised for sharpest results at F16 or F22 and having a maximum aperture of F11.

Ray: As I know you are a fan of Imatest MTF plots, I suggest you take a look at Photo Zone tests. All lenses drop in performance before F16 due to diffraction. It is a physical property which cannot (yet) be avoided. I also see this even in my 5 Nikon micro lenses but Photo Zone tests have the advantage that you are more likely to take notice. There can also be quite large changes away from F16, depending on the lens, and not just old large format lenses.
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Slough
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« Reply #81 on: November 03, 2008, 01:57:00 PM »
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Quote from: Ray
Nothing odd there. The earlier comparisons have been converted using ACR 4.6 with default sharpening. For the latest comparison above, I used DPP and turned off all sharpening. I mentioned this fact in the text. You've made an inappropriate comparison. Even Dpreview advise against comparing current tests with previous tests, possibly because different versions of ACR have been used and at different settings, and general testing procedures might vary slightly over time.

All my comparisons (done at the same time) use the same settings, except for levels and exposure adjustments to get contrast and tonality as similar as possible.


Comparing two different converters is a different exercise. The controls and sliders will tend to produce different effects. One converter's default sharpening might be another converter's 'no sharpening' etc etc. I haven't tried to compare converters here.

Nothing like consistency eh? Now you present photos of the same test subject, at the same ISO and F stop, with each camera. This time you change the processing. And the results look completely different from the first set. In the second case (same F stop) the two images look the same to me.  

Confused, I am.
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Slough
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« Reply #82 on: November 03, 2008, 02:00:06 PM »
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Quote from: GLuijk
Adobe is a team with a lot of people working on it, but still is too much work for them to get the best from every camera.

I have tried a number of converters for Nikon D200 RAW files and none were a patch on the official Nikon software. None could get the colours right. So no, I don't think these companies necessarily do better than the camera maker.

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The View
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« Reply #83 on: November 03, 2008, 03:02:59 PM »
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Quote from: Slough
I have tried a number of converters for Nikon D200 RAW files and none were a patch on the official Nikon software. None could get the colours right. So no, I don't think these companies necessarily do better than the camera maker.

I had the a similar experience with ACR and the Canon 40d.

With RAW processing with ACR the 40d looked almost as bad as my old Pentax, but using DPP it made the camera fly. For example: a path in the hills, rocks on the path. In ACR, the rocks were blending in with the dust, with DPP I could see clearly their sharp edges. the reflections of light from those edges. The light was much more defined. The difference felt like you wore dirty glasses, which ruined clarity and contrast, then cleaned them.

The colors were mute and without depth in ACR, and became gorgeous and brilliant with the manufacturer's software. I can get a clarity and definition to images in that software that is unsurpassed, and I have the impression I even lose a little bit of this by transferring to Photoshop. Colors, shapes, all is well defined.

Part of the problem for third party manufacturers may be, that Nikon and Canon do not disclose everything about their RAW files. And, as GLujik said, it's just an insane amount of work to get the best for so many cameras. Also, if a manufacturer can design the software from the ground up to specialize for their sensors and the way their sensor data are processed.

So, even though the interface is clunky (I wish there was an improved work flow edition of it - I'd pay for it), I do all my RAW processing with the manufacturer's software.
« Last Edit: November 03, 2008, 03:08:59 PM by The View » Logged

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« Reply #84 on: November 03, 2008, 03:38:27 PM »
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Quote from: Slough
Ray: As I know you are a fan of Imatest MTF plots, I suggest you take a look at Photo Zone tests. All lenses drop in performance before F16 due to diffraction. It is a physical property which cannot (yet) be avoided. I also see this even in my 5 Nikon micro lenses but Photo Zone tests have the advantage that you are more likely to take notice. There can also be quite large changes away from F16, depending on the lens, and not just old large format lenses.
Aren't you confusing diffraction effects on the projection surface (film or digital sensor) with the "lens performance"?

The problem with diffraction is that smaller apertures leads to larger airy disks, which lowers the resolvable contrast and resolution.

Even if f/16 isn't necessarily where the lenses perform best, it can still be within a performance range where a high density sensor medium can resolve more than a low density sensor medium.

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Jan
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« Reply #85 on: November 03, 2008, 04:02:17 PM »
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Quote from: The View
I had the a similar experience with ACR and the Canon 40d.

The colors were mute and without depth in ACR, and became gorgeous and brilliant with the manufacturer's software. I can get a clarity and definition to images in that software that is unsurpassed, and I have the impression I even lose a little bit of this by transferring to Photoshop. Colors, shapes, all is well defined.

Part of the problem for third party manufacturers may be, that Nikon and Canon do not disclose everything about their RAW files. And, as GLujik said, it's just an insane amount of work to get the best for so many cameras. Also, if a manufacturer can design the software from the ground up to specialize for their sensors and the way their sensor data are processed.

So, even though the interface is clunky (I wish there was an improved work flow edition of it - I'd pay for it), I do all my RAW processing with the manufacturer's software.

I'm on the Nikon side of the house but for the most part agree with you. Most of the Nikon users I know are not ACR fans - while I have no valid statistical evidence being I don't have the time to conduct a scientific poll , from observing forums over the years and talking to other Nikon users, I'd say a slight majority of them don't use ACR as their choice of converter.  I would say amongst most of the Canon users I know, ACR seems to be the majority converter there, but certainly not for Nikon.

I also am in total agreement with you that the manufacturer knows it's sensors spectral response curves and other data the best and can optimize the converter for the sensor better, IMO, than most anyone else. But this industry is still relatively young, and I'm sure down the road more third party converters will challenge the manufacturers converters and might in some cases be the best option for conversion. Soon I almost expect it (the choice of raw converter) to be a "best tool for the job" scenario instead of blindly proclaiming that one and only one converter is the best.

I currently am using Capture NX2, and in my tests it does pull out more detail than ACR, and it's a converter that allows for sharpening to be switched totally off as well, so Rays argument doesn't hold any water for this one either. More importantly, it gets the WB and color/density closer to what I shoot in the studio without a lot of mucking around.

However, I do have to give Adobe a lot of credit. Their very latest verions (4.6 and 5.1) do a LOT better with Nikon files than any previous version, by quite a significant margin. With the new profile editor and the option to roll your own, the previous problems with color and tone have been mitigated quite a bit. So the advantage of the other converters has been cut back drastically with the new versions, and for once I can say that if I was forced to, I could make do with ACR. However, there is still something about the conversions from Capture NX2 that make the image more realistic and alive, and thus while it's a pathetic converter in terms of operational stability, UI design, and speed (and I do mean absolutely pathetic), it still provides the best images.

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In terms of the dpreview discussion, I think it would be nice if they ran three raw converters on the cameras - the manufacturers converter, ACR, and Capture One, but I can totally understand the vast amount of additional time this would take. No single review is perfect, and thus for a while I've been advocating looking at the consensus of opinions, both from reviews and from forums (and other shooters) and then possibly trying something yourself. Unfortunately, some folks seem to want the quick and easy answer - the perfect MTF test that encompasses all about lenses, the single review that is perfect and without flaw to determine which camera is best and so forth, but this isn't a reality at this time, and may never be.

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Slough
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« Reply #86 on: November 03, 2008, 04:11:44 PM »
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Quote from: jani
Aren't you confusing diffraction effects on the projection surface (film or digital sensor) with the "lens performance"?

The problem with diffraction is that smaller apertures leads to larger airy disks, which lowers the resolvable contrast and resolution.

Even if f/16 isn't necessarily where the lenses perform best, it can still be within a performance range where a high density sensor medium can resolve more than a low density sensor medium.

No, I am referring to the effect of diffraction on lens resolution and contrast, which for most lenses is significant at F16, though the lenses I have still perform well at that aperture. I am of course referring to 35mm lenses. The actual IQ will of course be the combined effect of sensor and lens. Terms such as 'high density' and 'low density' are too lose for me to agree or disagree. Chose your definition of high and low appropriately, and you are right.

By the way, as a Nikon user I can set the actual aperture. One problem is that unless I am mistaken Ray is a Canon user and can only set the effective aperture. If he has tested on close ups, then that might explain his not seeing the performance hit.
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Slough
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« Reply #87 on: November 03, 2008, 04:16:17 PM »
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Quote from: NashvilleMike
However, there is still something about the conversions from Capture NX2 that make the image more realistic and alive, and thus while it's a pathetic converter in terms of operational stability, UI design, and speed (and I do mean absolutely pathetic), it still provides the best images.


Tell me about it! I can hardly use NX2 on my PC. It is the most unstable crash prone POS I have ever used. Which is why I did not upgrade from the demo to the full product, and I stick with NC. If they let me get at that software, I could make it stable. (I've fixed a fair few professional products. But it would not happen.)
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Ray
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« Reply #88 on: November 03, 2008, 07:14:49 PM »
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Quote from: GLuijk
Maybe ACR was not the right choice. Adobe is a team with a lot of people working on it, but still is too much work for them to get the best from every camera. I was recently surprised to find out that ACR seems to develop Fuji RAF's with two issues:
1. A wrong consideration of the real saturation point of the camera (R sensor) which produces magenta artifacts in the highlights
2. A wrong consideration of the white balance for the highlights (R sensor again)

Nobody and nothing are perfect. Maybe now that you have pointed out this flaw in ACR's treatment of RAF files, Adobe will correct it in their next version   .
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Ray
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« Reply #89 on: November 03, 2008, 07:50:56 PM »
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Quote from: Slough
Ray: As I know you are a fan of Imatest MTF plots, I suggest you take a look at Photo Zone tests. All lenses drop in performance before F16 due to diffraction. It is a physical property which cannot (yet) be avoided. I also see this even in my 5 Nikon micro lenses but Photo Zone tests have the advantage that you are more likely to take notice. There can also be quite large changes away from F16, depending on the lens, and not just old large format lenses.

There can certainly be large changes in the height of a bar chart representing resolution at MTF 50. How these apparently large changes are reflected in real world images is another matter. Bar charts and graphs are usually constructed in such a way as to make any differences, however slight, as obvious as possible.

As I've mentioned, with photographic matters I can respond only to what I see, and I don't see any significant differences between F11 and F16 at the plane of focus. But I do see significant differences away from the plane of focus, which is why I will always use F16 when maximum DoF is a priority.

However, don't misinterpret my words. I make a distinction between a significant difference and a discernible difference. I certainly can discern a slight softening in an image taken at F16, compared with the same scene at F11. The difference is there, but it's slight and is usually easily counteracted with a touch more sharpening.

The following two images were taken with the 40D and 100-400 at 400mm. The lens was on tripod. MLU and remote cord were used. Focussing was manual using LiveView and the two shots were taken within seconds of each other using the same focussing.

One image is at F11 and the other at F16. The focus point was the brick wall of the house. Can you see any significant difference between these two 100% crops, which I might add, on the current monitor I'm using, represent a print size of 17"x25.5"? Do any of the two look oversharpened, as though to compensate for significant softness?

Have I made my point?

[attachment=9438:F11___F1...00__crop.jpg]

I should also add that because I can discern a slight softness in the F16 image before sharpening, I would always prefer to use F11 if the additional DoF is not required. When detail is a concern, there is no point in using a slower shutter speed or higher ISO than necessary, and one never knows when one might want to blow up to an extreme magnification a small section of an image. Differences that are insignificant at 100%, may become almost significant at 200%, clearly significant at 400% and particularly significant at 800%.

« Last Edit: November 03, 2008, 08:41:27 PM by Ray » Logged
Slough
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« Reply #90 on: November 04, 2008, 02:28:33 AM »
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Ray: As I have already stated, your two sets of 40D and 50D images are contradictory and in the second set I see no difference between the two suggesting no gain from the 50D. (Not being a Canon user I don't care about the outcome. It is academic to me.)

I cannot really comment on your latest examples (especially given your rather conflicting test methods from earlier posts) except to say that it looks to be somewhat of a miracle lens. My own careful tests with numerous micro/macro lenses agree with online MTF plots and show obvious drops at F16. And take a look at Rorslett's tests to see that he agrees, where he often says to avoid F16. I agree with him. Oh and my Sigma 400mm F5.6 APO macro lens (which is sharp) also softens noticeably at F16. Something is not right in your latest example. BTW I use a solid tripod, Markins ball head, mirror lock up and cable release in my tests.
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Slough
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« Reply #91 on: November 04, 2008, 02:29:49 AM »
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Quote from: Ray
Bar charts and graphs are usually constructed in such a way as to make any differences, however slight, as obvious as possible.

I'm not sure what you mean by that. They give the numeric values on the left scale so you can judge the result accurately. (Ignoring criticisms of MTF plots per se.)
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Ray
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« Reply #92 on: November 04, 2008, 06:21:44 AM »
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Quote from: Slough
Ray: As I have already stated, your two sets of 40D and 50D images are contradictory and in the second set I see no difference between the two suggesting no gain from the 50D. (Not being a Canon user I don't care about the outcome. It is academic to me.)

I cannot really comment on your latest examples (especially given your rather conflicting test methods from earlier posts) except to say that it looks to be somewhat of a miracle lens. My own careful tests with numerous micro/macro lenses agree with online MTF plots and show obvious drops at F16. And take a look at Rorslett's tests to see that he agrees, where he often says to avoid F16. I agree with him. Oh and my Sigma 400mm F5.6 APO macro lens (which is sharp) also softens noticeably at F16. Something is not right in your latest example. BTW I use a solid tripod, Markins ball head, mirror lock up and cable release in my tests.

Slough,
Your comments are very puzzling. What do you find contradictory or conflicting? I provide you with test images I've carefully made for my own purposes. I label each one correctly, at the top of each image (did you notice that?). I tell you which converter I used and I tell you whether or not I applied sharpening (default sharpening in the case of ACR and no sharpening in the case of DPP). What is there to get confused about? I haven't secretly mixed DPP conversions with ACR conversions. I have deliberately mixed F5.6 shots with F11 shots, and F11 shots with F16 shots, in order to demonstrate that the increased resolution of the 50D is roughly (perhaps very roughly) equivalent to the resolution of the 40D stopped up one stop, to a less diffraction limited F stop. That's just to give you an idea of the practical significance of the resolution increase of the 50D, in my view.

To my eyes, the DPP comparison of both cameras at F5.6 (no sharpening other than what's built into the DPP software and not user controllable) shows the 50D crop as having more detail and significantly less aliasing.

The same crops, but at F11 with the 50D and F5.6 with the 40D, and converted with ACR at default sharpening, also show the 50D image as having more detail, but this time the 50D crop has no aliasing whereas the 40D image has similar aliasing to the DPP conversion, but the magenta streaking is more subdued because of the different converter. One might deduce from this particular result that there's little difference in the sharpness of the Canon 50/1.4 at F5.6 and F8, despite the bar graphs at Photozone.

The first comparison of the rural/suburban scene, 40D at F11 and 50D at F16, both converted with ACR at default sharpening, look equally detailed to me depite both having received equal sharpening.

I haven't provided full details of the latest crops of the 40D at F11 and the 40D F16 because I wanted to demonstrate that you would be hard pressed to distinguish between them. The difference is not significant, perhaps even invisible. This is not due to my using a miracle lens but is possibly due to my using a magical sharpening routine.... called 'Focus Magic'.

As I mentioned before, unsharpened one can discern an additional softness in an F16 image, compared with the same scene at F11 (from the same camera & lens). This requires just a little additional sharpening to correct. Both of these images were converted in ACR 4.6 using ACR's default sharpening of 25 at 1 pixel radius and detail at 25. The images were then further sharpened using Focus Magic's default settings for each image. Focus Magic is a deconvolution program which automatically suggests a pixel blur width to use, after a brief analysis of the image. For the F11 shot, it suggested 100% at 1 pixel blur width. For the F16 shot, the recommendation was 100% at 2 pixels blur width. Focus Magic could recognise that the F16 image was slightly soft, just as I could.

You probably know that DoF extends a greater distance beyond the focus plane than it does in front of it. Below are crops of the same images showing the foreground. Are you now able to tell which is F11 and which is F16?

For the record, the histogram of both images is very similar, same ETTR. The exposure of the F11 shot at ISO 100 is 1/80th, and the exposure of the F16 shot is 1/40th at the same ISO.

[attachment=9443:F16___F11_40D.jpg]  [attachment=9444:F16___F1...reground.jpg]

Is everything now crystal clear?  
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Ray
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« Reply #93 on: November 04, 2008, 06:33:31 AM »
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Quote from: Slough
I'm not sure what you mean by that. They give the numeric values on the left scale so you can judge the result accurately. (Ignoring criticisms of MTF plots per se.)

The bar charts make very clear the difference between (for example) 1800 lines per picture height and 1825 lines per picture height. You'd have to be half blind not to see it.

If I were to show you two large prints, one consisting of 1800 lines and the other consisting of 1825 lines (or even 1850 or 1900 lines), would you immediately be able to see the difference?
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Slough
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« Reply #94 on: November 04, 2008, 07:16:41 AM »
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Quote from: Ray
The bar charts make very clear the difference between (for example) 1800 lines per picture height and 1825 lines per picture height. You'd have to be half blind not to see it.

If I were to show you two large prints, one consisting of 1800 lines and the other consisting of 1825 lines (or even 1850 or 1900 lines), would you immediately be able to see the difference?

Now you are being silly. Anyone would discount 1800 and 1825 as being as near as the same.

Let's take a lens I own, namely the Nikon 105mm F2.8 AFD. According to Photo Zone (chosen as a respected Imatest reviewer), tested with a D200, the resolution at F11 and F16 is roughly 2,000 and 1,700. Now those are rough estimates from the graph, but even allowing for error, the difference in linear resolution is significant i.e. 15%. In practice when used for close ups at F11 and F16 I see a noticeable change in resolution and contrast. In other words, the PZ data (from a different lens sample) correlates to experience. Yes this is only visible on small prints, but that is what we are talking about c.f. 50D isn't it? On an A4 print you probably would not see it, but in the context of your discussion, it is significant. I tried to find other F16 data on PZ but failed. But I have tested with other lenses e.g. Nikon 200mm micro (both), Nikon 60mm AFD F2.8 micro etc.

Maybe you think lens resolution does not vary much with F stop due to reading MTF plots obained with a ~8-10 MP sensor?

On the D200, diffraction starts visibly softening the image from about F13. So at wider apertures the lens is outperforming the sensor except perhaps near wide open on lesser lenses. So the resolution versus F stop would be roughly flat to ~F11.
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Ray
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« Reply #95 on: November 04, 2008, 10:04:51 AM »
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Quote
Let's take a lens I own, namely the Nikon 105mm F2.8 AFD. According to Photo Zone (chosen as a respected Imatest reviewer), tested with a D200, the resolution at F11 and F16 is roughly 2,000 and 1,700. Now those are rough estimates from the graph, but even allowing for error, the difference in linear resolution is significant i.e. 15%.

I think you might have misunderstood the significance of the charts. Your Nikkor lens will also be capable of resolving 2,000 lines at F16, but not at 50% MTF; maybe 40% MTF. The additional sharpening mostly takes care of that MTF difference, but probably not quite.

Quote
Maybe you think lens resolution does not vary much with F stop due to reading MTF plots obained with a ~8-10 MP sensor?

This seems to be a very odd situation. I'm the one providing the real world evidence, demonstrating a point, walking the talk. You are the one providing no evidence at all, but instead accuse me of being misled by MTF charts. Seems to be something very wrong here???

The following 200% crops of the banknote were taken on a carbon fibre tripod, placed on a tiled floor on a solid concrete slab, indoors away from any breeze, passing truck, train or aircraft that might have been flying overhead. There was no vibration in the air (from heavy rock music, for example), no earthquakes, tremors or bomb explosions. I used MLU, remote cord and focussed extremely accurately with the aid of the high resolution LiveView screen that the 50D boasts. (In any case, at F11 and F16, absolutely accurate focussing would not be critical, but I did it in any case.)

On my 1280x1024 monitor, these 200% crops represent a print size of 105"x70" (or almost 9ftx6ft). If you were to make prints this size, walk right up to them and peer at the small banknote in the centre of each print from a distance of a foot or so, you would see a very small amount of detail in the F11 print that isn't there in the F16 print.

There is no trickery here. These are the results. They speak for themselves.

The previous shots were taken with the 100-400 zoom at a significant distance. These shots below were taken with the Canon 50/1.4 from a distance of around 8ft. The same converter and sharpening amounts have been applied, as in the previous 40D shots at F11 and F16, ie. default ACR sharpening then Focus Magic with a 2 pixel blur width applied to the F16 shot, and 1 pixel to the F11 shot.

[attachment=9445:F16___F1...banknote.jpg]


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Slough
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« Reply #96 on: November 04, 2008, 03:09:38 PM »
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Quote from: Ray
I think you might have misunderstood the significance of the charts. Your Nikkor lens will also be capable of resolving 2,000 lines at F16, but not at 50% MTF; maybe 40% MTF. The additional sharpening mostly takes care of that MTF difference, but probably not quite.



This seems to be a very odd situation. I'm the one providing the real world evidence, demonstrating a point, walking the talk. You are the one providing no evidence at all, but instead accuse me of being misled by MTF charts. Seems to be something very wrong here???

Here are some comments from lens review by B. Rorslett who is very respected:

55 mm f/3.5 Micro-Nikkor-PC: "Maximum sharpness needs an aperture setting of f/8. Beyond f/11-f/16, sharpness rapidly deteriorated."
AFS Micro-Nikkor 60 mm f/2.8 ED G N: "Images are super sharp already from f/2.8 and keep their bite up to f/11, from which point a graceful decline kicks in. "
AF Micro-Nikkor 60 mm f/2.8: "For those utilising it, however, sharp images are obtained at apertures from f/5.6 to f/11. Beyond that range image quality deteriorates. "
AF-Micro-Nikkor 105 mm f/2.8: "It reaches optimum sharpness at f/5.6 and delivers good results to f/11 or so, thereafter image quality is quickly lost."

I pose the above quotes as I have several of those lenses and I agree with the comments.

I do not post example images as I have no imaging host, and cannot be bothered to repeat tests I perform when I buy a lens. I do not keep the images as I delete unwanted images to reduce clutter in my archives. MTF 50 is usually taken as a measure of resolution. It matches the above quotes and my experience.

Quote from: Ray
The following 200% crops of the banknote were taken on a carbon fibre tripod, placed on a tiled floor on a solid concrete slab, indoors away from any breeze, passing truck, train or aircraft that might have been flying overhead. There was no vibration in the air (from heavy rock music, for example), no earthquakes, tremors or bomb explosions. I used MLU, remote cord and focussed extremely accurately with the aid of the high resolution LiveView screen that the 50D boasts. (In any case, at F11 and F16, absolutely accurate focussing would not be critical, but I did it in any case.)

On my 1280x1024 monitor, these 200% crops represent a print size of 105"x70" (or almost 9ftx6ft). If you were to make prints this size, walk right up to them and peer at the small banknote in the centre of each print from a distance of a foot or so, you would see a very small amount of detail in the F11 print that isn't there in the F16 print.

There is no trickery here. These are the results. They speak for themselves.

The previous shots were taken with the 100-400 zoom at a significant distance. These shots below were taken with the Canon 50/1.4 from a distance of around 8ft. The same converter and sharpening amounts have been applied, as in the previous 40D shots at F11 and F16, ie. default ACR sharpening then Focus Magic with a 2 pixel blur width applied to the F16 shot, and 1 pixel to the F11 shot.

[attachment=9445:F16___F1...banknote.jpg]

What I do not understand is why you had to make it so complex, and add extra uncertainty by using a different F stop. That meant you could not draw a conclusion without making an assumption about the lens resolution versus F stop for which no evidence was provided beyond hand waving. Then when you posted the next set of images now both at the same F stop, you changed the processing for some reason, which added yet more confusion. And back on the ranch ...

Having looked at the second set on my good CRT monitor at home (and not the crap TFT monitor I use at work) I agree there is a slight but noticeable improvement in the 50D image. Not a big deal, but it is there. Is it worth having? I cannot answer that. And that is interesting.

But ... do you think that is due to the greater resolution of the sensor, or the weaker AA filter? I would assume the 50D has a weaker AA filter due to the smaller pixels.

Regarding Moire, they both seem to have obvious Moire, but in different areas, which is consistent with different pixel pitches. After all Moire appears when the spatial frequency of a pattern nearly matches that of the sampling spatial frequency.
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« Reply #97 on: November 04, 2008, 07:23:29 PM »
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Slough,
We once had an argument regarding one of Ken Rockwell's provocative and unscientific aricles. I had little problem with his ideas because I realised they were not intended to be scientific and precise, but provocative and rhetorical. But you hung on to the fact that words have (or should have) literal and precise meanings.

With this notion in mind, that words should have precise meanings, let's look at some of the language in B. Rorslett's comments you've quoted. "Beyond f/11-f/16, sharpness rapidly deteriorated." Which is it? Beyond F11 or beyond F16? Does the rapid deterioration begin at F11, or at F13 or at F16? Or is he perhaps comparing one aperture with the next? That is, the resolution difference between apertures F11 anf F16 is small, but such differences rapidly escalate beyond F11-F16. That is, the difference between F16 and F22 is greater than the difference between F11 and F16.

There's one sure way to find out what Rorslett actually means, and that is to do your own tests.

What I do not understand is why you had to make it so complex, and add extra uncertainty by using a different F stop. That meant you could not draw a conclusion without making an assumption about the lens resolution versus F stop for which no evidence was provided beyond hand waving. Then when you posted the next set of images now both at the same F stop, you changed the processing for some reason, which added yet more confusion. And back on the ranch ...

I thought I had explained that already, but here goes again. Differences always have to be compared with a standard, that is, quantified, or it's difficult have a meaningful discussion. 2 millimetres is twice the size of one millimetre. 100 lp/mm at 50% MTF is twice the resolution of 50 lp/mm at 50% MTF. With such language you know precisely what is meant. I was searching for a simple way of describing the resolution differences between the 40D and 50D that would be of practical use to me in the field when making a choice of aperture. If they are of no use to you, I can't help it.

I now know, as a result of my very careful and meticulous testing, that the resolution increase of the 50D, although small, is at least sufficient for me to use F16 and yet get a result at the plane of focus that is very, very close to what I would have got using the 40D at F11. So close in fact that the differences (at the plane of focus) are entirely irrelevant on prints as large as my Epson 7600 can handle (24"x36"). That's what I call useful information.

As regards using DPP on one occasion instead of ACR, I did it because I wanted to see what sort of result DPP would produce. Why do you think I did it? Just to confuse you?
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Slough
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« Reply #98 on: November 05, 2008, 02:29:37 AM »
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Quote from: Ray
Slough,
We once had an argument regarding one of Ken Rockwell's provocative and unscientific aricles. I had little problem with his ideas because I realised they were not intended to be scientific and precise, but provocative and rhetorical. But you hung on to the fact that words have (or should have) literal and precise meanings.

No. Most people argued against Rockwell with a few lone souls such as yourself applauding him. I do not interpret words literally, but I do expect precision when it comes to a technical discussion. If someone says "Your equipment does not matter" I assume they mean that your equipment does not matter.  

If you want to go the way of Humpty Dumpty, then fine.
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Slough
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« Reply #99 on: November 05, 2008, 07:04:39 AM »
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Quote from: Ray
"Beyond f/11-f/16, sharpness rapidly deteriorated." Which is it? Beyond F11 or beyond F16? Does the rapid deterioration begin at F11, or at F13 or at F16? Or is he perhaps comparing one aperture with the next? That is, the resolution difference between apertures F11 anf F16 is small, but such differences rapidly escalate beyond F11-F16. That is, the difference between F16 and F22 is greater than the difference between F11 and F16.

There's one sure way to find out what Rorslett actually means, and that is to do your own tests.

1) I have done my own tests as explained in my post. You did read it didn't you?
2) You suggest ambiguity in one comment on one lens and ignore all the other comments on other lenses.

Why don't you just accept that your statement that all lenses - with a few old exceptions - show negligible change in resolution down to and including F16 is, errr, not completely founded in reality?
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