DPreview of 50D is flawed ..please read

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Archive 2008 · DPreview of 50D is flawed ..please read

astrolucida
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p.4 #1 · DPreview of 50D is flawed ..please read

bushwacker wrote:
astrolucida wrote:

40D has f8.7 as the limit, 450D f7.7, 30D f9.6, 1DIII f10.8 and 5D f12.2!
The new 1DsIII and 5D II both have f9.6, having equal pixel size to the 30D.

so let's say we load up a 40d and 450d with canon 17-40mm f4 L set apeture at f/10.0 --- you are saying I am already having diffraction probelms? this means we cannot use smaller apertures on these cameras.--- meanng it's useless?

Of course you can use it. Just that you get a (slightly) less sharp image than with the same lens at f8!

So, if you don't need the depth of field, you should use f8 instead of f10. That's why I want to find out the limit of diffraction for each camera. When I need the maximum sharpness (but not the maximum DoF), I use that aperture (or larger, if the lens is sharp still).

Nov 07, 2008 at 12:00 PM

bushwacker
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p.4 #2 · DPreview of 50D is flawed ..please read

astrolucida wrote:

Of course you can use it. Just that you get a (slightly) less sharp image than with the same lens at f8!

So, if you don't need the depth of field, you should use f8 instead of f10. That's why I want to find out the limit of diffraction for each camera. When I need the maximum sharpness (but not the maximum DoF), I use that aperture (or larger, if the lens is sharp still).

The f- stop values that you posted for each camera sensors... are they from Canon Technical documentation or we just did a manual calculations?

I'd like to have one of these documentations so i can maximize lens-sensor image sharpness.. and also for each lens' diffraction and maximum resolution values.

thanks very much... this cleared a lot of my confusions.

Nov 07, 2008 at 05:46 PM

bushwacker
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p.4 #3 · DPreview of 50D is flawed ..please read

astrolucida

oh by the way... since we are talking about this... you posted that the 20d\30d has the same pixel size 1DsIII and 5D II --- from this we can safely say that image sharpness from 20D\30D is much greater [ compared to new - higher mega-pixel EOS bodies ] because it has more usable lens f-stop without hitting diffraction.?

Nov 07, 2008 at 05:56 PM

Caleb Williams
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p.4 #4 · DPreview of 50D is flawed ..please read

Speaking of flawed reviews. On Dpreview's 1DsMkIII review, the listed as testing the Canon 5D's resolution with a Canon 85 f/1.4.

"Canon EOS 5D: Canon 85 mm F1.4 lens"

http://www.dpreview.com/reviews/canoneos1dsmarkiii/page19.asp

Could be a leak, but most likely its either a 85 1.8 or 50 1.4.

Nov 07, 2008 at 06:25 PM

astrolucida
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p.4 #5 · DPreview of 50D is flawed ..please read

bushwacker wrote:
The f- stop values that you posted for each camera sensors... are they from Canon Technical documentation or we just did a manual calculations?

I'd like to have one of these documentations so i can maximize lens-sensor image sharpness.. and also for each lens' diffraction and maximum resolution values.

Diffraction depends only on the f-stop. However, where the maximum resolution for a specific lens is, can only be found out by actual measurements. Typically primes are at their best 2-3 stops from wide open until f8, although some supertelephotos max already at f5.6 (but are not bad at f8, either).

As for the diffraction vs pixel size, I have made my own Excel sheet, which for each camera first calculates the pixel size (sensor size divided by the number of pixels - both directions give the same result) and then the f stop where the size of the Airy disc equals twice the pixel size.

Here's the formula: f-stop=(X*1000)/(550*2.43932)*2
X is the pixel size in um, 1000 scales it to nm, 550 is the wavelength of yellow-green light in nm. 2.43932 scales it to f stop values and 2 makes it two pixels wide.

Nov 08, 2008 at 07:46 AM

astrolucida
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p.4 #6 · DPreview of 50D is flawed ..please read

bushwacker wrote:
oh by the way... since we are talking about this... you posted that the 20d\30d has the same pixel size 1DsIII and 5D II --- from this we can safely say that image sharpness from 20D\30D is much greater [ compared to new - higher mega-pixel EOS bodies ] because it has more usable lens f-stop without hitting diffraction.?

Depends on the lens and the way you define sharpness. If the lens is sharper than what is required for smaller pixels, then there is no difference, if you dont stop too much.

However, when you print (to a fixed size), then more pixels mean more sharpness when the print size is large (and when the lens keeps up).

For inspection at 100% pixel size, the larger pixels are sharper if the lens cannot keep up with the smaller pixels. But the prints would still be equal.

Even when you want to stop for more depth of field, there is no difference in prints. Though, you can consider that an advantage to the camera with larger pixels - the file size is smaller but the result is still equal.

Nov 08, 2008 at 07:51 AM

garyvot
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p.4 #7 · DPreview of 50D is flawed ..please read

If you compare the 100 ISO samples posted at Imaging Resource, the 50D clearly outresolves the 12Mp bodies, including the Nikon D3/D700. High ISO samples (NR off) look pretty good up to 1600, and even 3200 is proabaly usable with some NR in post.

It's true these are in-camera JPEGs, but I'm sure that RAW files would retain more, not less, sharpness.

Yes, there may be diffraction limts and more apparent issues with some lenses, but I'm not sure what more people could want from this camera at this price point...

Nov 08, 2008 at 03:27 PM

hardlyboring
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p.4 #8 · DPreview of 50D is flawed ..please read

Next time you are selling a photo to someone taken with your 50D ask them if they can tell how many lines per mm they are getting and if it makes a difference to them. They will look at you and the picture and then think "This person is losing his mind" and then if the picture looks good most likely still buy it.

Nov 08, 2008 at 03:39 PM

thw2
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p.4 #9 · DPreview of 50D is flawed ..please read

Honestly, I am surprised people are still debating this topic of diffraction even after so many threads about it. Sensors have ZERO effect on diffraction. A high pixel density sensor merely serves to tell the honest truth about what has happened AFTER lens diffraction has taken place. If there is no detail to be gleaned, then there's nothing to see. A low pixel density sensor merely gives the illusion that everything appears sharp 'cos it is incapable of showing the truth.

Nov 08, 2008 at 04:36 PM

n0b0
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p.4 #10 · DPreview of 50D is flawed ..please read

astrolucida wrote:
That's why I want to find out the limit of diffraction for each camera.

Here's a 100% crop image with effective f-stop of 20.

This image is copyrighted by the owner

And here's one with effective f-stop of 48 though not a 100% crop.

This image is copyrighted by the owner

Both taken with the 450D.

Nov 08, 2008 at 06:13 PM

astrolucida
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p.4 #11 · DPreview of 50D is flawed ..please read

n0b0 wrote:
astrolucida wrote:
That's why I want to find out the limit of diffraction for each camera.

Here's a 100% crop image with effective f-stop of 20.

And here's one with effective f-stop of 48 though not a 100% crop.

In the first case you can clearly see the softening. For the second, hard to say as it is not 100% pixels. However, when you don't need 100% pixel sharpness, stopping down past the diffraction limit is not a problem. But when you need the utmost quality, it is good to keep the limit in mind.

Nov 09, 2008 at 09:45 AM

n0b0
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p.4 #12 · DPreview of 50D is flawed ..please read

astrolucida wrote:
In the first case you can clearly see the softening. For the second, hard to say as it is not 100% pixels. However, when you don't need 100% pixel sharpness, stopping down past the diffraction limit is not a problem. But when you need the utmost quality, it is good to keep the limit in mind.

The first image didn't receive any sharpening or any other post processing at all though and I think it's perfectly acceptable as it is, unless you're pixel peeping. A little PP and sampling down to 10MP and I'm confident I can get a sharper image than the one taken with a 40D at 100%.

There is no such thing as "the diffraction limit", it's not like the image stays sharp up to a certain f-stop and just get blurry afterwards. Diffraction increases gradually as we stop down. It's up to the shooter to decide at what point it is acceptable. Obviously pixel peepers will be limited by their own misconception much earlier than others.

Nov 09, 2008 at 11:14 AM

astrolucida
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p.4 #13 · DPreview of 50D is flawed ..please read

n0b0 wrote:
There is no such thing as "the diffraction limit", it's not like the image stays sharp up to a certain f-stop and just get blurry afterwards. Diffraction increases gradually as we stop down. It's up to the shooter to decide at what point it is acceptable. Obviously pixel peepers will be limited by their own misconception much earlier than others.

I agree. However, apparent sharpness and resolution are two different things. You can increase apparent sharpness by sharpening in post-processing but you cannot increase actual resolution. I am not talking about the number of pixels but the amount of actual subject detail.

Whether you need the pixel-level detail, depends on what you do with the image. Low level of detail in the image limits how large you can print and still have enough detail.

Also, if your pixels do not contain any real information, why store the files with the "empty" (=devoid of real detail) pixels? In that case, using a smaller resolution in the camera would produce the same results when printing. In your first example, Medium size would capture all the same detail as Large does but in a file with a size 1/2th of the large one. If you need more pixels, you can uprez the file in Photoshop.

Edit: I performed an experiment with this file and it seems that 50% size dropped some actual detail while 75% size did not. My test was done by first downsizing the image to 75% and the uprezzing that file to 133% to regain the original pixel dimensions. I then flip-compared that file with the original. It was hard to get exactly the same sharpness - my first attempt actually looked better than the original!

With very sharp originals, even 200% size looks good, so there is some potential that the camera has but that gets lost through diffraction. Whether you really need that much resolution, is another question, of course. However, consider it as a digital 2x teleconverter with no loss of light, and you'll see the benefits, even to non- pixel peepers.

Nov 10, 2008 at 09:08 AM

bushwacker
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p.4 #14 · DPreview of 50D is flawed ..please read

according to DPR's [ 50D ] CONS

- Per-pixel detail not as good as on good 10 or 12 megapixel cameras
- High-end lenses required to get the most out of the camera

Does anyone here tried any of those prime "L" lens vs the one that DPR used? Canon 50mm f/1.4

if this is the case... we should start using L lenses for the 50D.

Nov 11, 2008 at 02:01 AM

orangefirefish
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p.4 #15 · DPreview of 50D is flawed ..please read

n0b0 wrote:
astrolucida wrote:
That's why I want to find out the limit of diffraction for each camera.

Here's a 100% crop image with effective f-stop of 20.

This image is copyrighted by the owner

And here's one with effective f-stop of 48 though not a 100% crop.

This image is copyrighted by the owner

Both taken with the 450D.
Man that's creepy.

Nov 11, 2008 at 03:04 AM

brainiac
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p.4 #16 · DPreview of 50D is flawed ..please read

bushwacker wrote:

according to DPR's [ 50D ] CONS

- Per-pixel detail not as good as on good 10 or 12 megapixel cameras
- High-end lenses required to get the most out of the camera

The first point is probably because DPR didn't use a good enough lens.
The second point suggests that the DPR reviewer knew how to do an appropriate review, but decided not to.

Nov 11, 2008 at 09:55 AM

toonhorse
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p.4 #17 · DPreview of 50D is flawed ..please read

brainiac wrote:

The second point suggests that the DPR reviewer knew how to do an appropriate review, but decided not to.

+1

you just made me laugh out loud at work.

Nov 11, 2008 at 03:20 PM

bushwacker
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p.4 #18 · DPreview of 50D is flawed ..please read

The guy at the digital picture com

also checks-out what DPR says... but this one claiming 50D is pulling more details than 40D.

http://www.the-digital-picture.com/Reviews/Canon-EOS-50D-Digital-SLR-Camera-Review.aspx
========================================

While not quite as sharp at the pixel level, the 50D is still pulling more detail out of the scene. The fabric example above show this. As you drag your mouse pointer up and down over the 50D and 40D labels, watch the tiny threads appear in the 50D image that are not present in the 40D image.
========================================

oh yeah the guy used a Canon EF 200mm f/2 L IS USM... well let's see the reults..

also about astrolucida's comments about diffractions--- the guy [ at digital-picture.com ] also created table for each EOS body's diffraction limits..

Nov 16, 2008 at 01:07 PM

George.ML
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p.4 #19 · DPreview of 50D is flawed ..please read

Hehe. The digital-picture guy is presenting the exact same facts as DPreview but puts a positive spin at the end of the review.

Nov 16, 2008 at 10:36 PM

abam
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p.4 #20 · DPreview of 50D is flawed ..please read

i'm with molson.

Nov 16, 2008 at 10:43 PM

ohcello
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p.4 #21 · DPreview of 50D is flawed ..please read

Guys,

I did a test of the 50D vs. the 5D with the 50mm f/1.4... here is what I found:

http://www.ohcello.com/50d_5d_test.htm

Jan 26, 2009 at 04:36 PM

brainiac
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p.4 #22 · DPreview of 50D is flawed ..please read

Great test. In places I can see more detail in the 50D file. About 2.3 megapixels more detail.

Jan 26, 2009 at 05:04 PM

DavidJB
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p.4 #23 · DPreview of 50D is flawed ..please read

James B wrote:
I am having great success shooting high iso .jpgs with my 50d with saturation, sharpness zeroed and contrast at 1. The jpgs look a lot better than what I have been getting from lightroom.

After shooting with a new 50D this past weekend, I have the same experience. I'm a bit embarassed that my post-processing workflow isn't nearly as solid as I thought it was! The .jpegs are super sharp and rich with colour, I might actually start using auto mode for family snapshots I'm so impressed.

One of the guys in the store recommended I drop ACR 5.2 and use the DPP tool, as he felt it did a better job with the Canon output. I'll start working with it this week accordingly.

Jan 26, 2009 at 06:28 PM

abqnmusa
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p.4 #24 · DPreview of 50D is flawed ..please read

DavidJB,

When you process with ACR v5.2 set ACR from "Adobe Standard" to one of the camera xxxx modes.

For example, "camera faithful". That produces an almost exact match to DPP processed as "Faithful".

Adobe even has an editor where you can modify one of the profiles and make your own. Similar to Canons profile editor for DPP.

Jan 26, 2009 at 08:01 PM

Don Clary
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p.4 #25 · DPreview of 50D is flawed ..please read

Man that's creepy

I'd hate to meet a 300 pound one of those in a dark alley at night! Me: don't look at me like that! Please close your eyes! All four of them!

Jan 26, 2009 at 08:46 PM


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