Another leak: 5D replacement spec...

[lukesky]

Imagine REALLY CLEAN ISO 12,800 images from 12 MP sRAW files... very attractive... a LOT more so than the unusable ISO 12800 images from D3/D700... :bsmilie:

Let the BBB virus start... :devil:

if the ISO 12800 from the 5D mk2 is really as clean as u say, won't Canon up the ISO even higher? If I can get really clean images from ISO 12800, why stop there? Might as well go to ISO 25600 and Canon marketing can announce that a semi pro FF can rival Nikon's best pro cam and have a field day.
But since we're just imagining, I can imagine the 12800 from the 5D mk2 might be like the 25600 on the D3, or 3200 on 5D cos they are the max ceilings already unless the 5D mk2 is intentionally crippled by Canon from the start.

 

[doodah]

The next date to watch out for: Sep-18th. Doesn't seem that Canon is interested in the date of release for the A900.

Well, as for me, I am sticking to the 50D. :bsmilie:

 

[doodah]

...there is the problem of diffraction. As pixels get smaller the effect of Airey's Disks comes into effect with small apertures. Check out this link for a simple tutorial on the effects of Airey's Disks. http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm

Please ignore that garbage posted at cambridgeincolor. It's total gibberish.

Diffraction occurs at the aperture blades of the lens. It happens because of the wave nature of light, and is apparent only when the size of the aperture is very small.

The sensor does NOT in any way affect it. Greater pixel density (or smaller pixels) only serves to SHOW the effect more clearly, the same way the optical quality of lesser lenses is made more obvious.

 

[KangS]

if the ISO 12800 from the 5D mk2 is really as clean as u say, won't Canon up the ISO even higher? If I can get really clean images from ISO 12800, why stop there? Might as well go to ISO 25600 and Canon marketing can announce that a semi pro FF can rival Nikon's best pro cam and have a field day.
But since we're just imagining, I can imagine the 12800 from the 5D mk2 might be like the 25600 on the D3, or 3200 on 5D cos they are the max ceilings already unless the 5D mk2 is intentionally crippled by Canon from the start.

I think its a matter of guiding principles in design and marketing? Notice that over the past years, Canon have never released any DSLR onto the market with picture quality that less than the large majority of seasoned photographers cannot accept? ISO 6400 meaning useable ISO6400, at least very comparable to film level ASA / ISO 800 quality? Like in the example of the 1DMk3 and 1DsMk3??

I think its something which is hard to appreciate unless you look at some of he PnS claiming ISO 3200 that's really not useable unless you downsample a 10mp pict down to about 800x600 pixels! I'm sure its not something we want to see right ?

 

[kencfk]

Wow, war of the High ISO....very keen to see the comparisons.

 

[peteloud]

Hi doodah,

Please ignore that garbage posted at cambridgeincolor. It's total gibberish.

I find you comment rather childish. I am confident that Sean McHugh, the guy who produced that webpage, is considerably more knowledgeable on optics than you. Incidentally he uses a Canon 5D.

In comparison to your puerile comment this is what was said about the same webpage by
Nathan Myhrvold, the former Chief Technology Officer at Microsoft,
". . . I was going to launch into a full treatment of this topic in rebuttal to
spell out what happens, but then I discovered the following site that has
an excellent description, complete with examples
http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm "

I think that you are out of your depth when compared to these guys.

Cheers,


Pete

 

[lennyl]

I am confident that Sean McHugh, the guy who produced that webpage, is considerably more knowledgeable on optics than you. Incidentally he uses a Canon 5D.

I find that page to be very well written and superbly illustrated, though using a 5D is hardly proof of his knowledge on optics You may want to revise the language in your post, however, before the moderators slap you with an infraction.

And I'm very interested in why doodah thinks the page is gibberish.

 

[doodah]

Hi doodah,
I find you comment rather childish. I am confident that Sean McHugh, the guy who produced that webpage, is considerably more knowledgeable on optics than you. Incidentally he uses a Canon 5D. I think that you are out of your depth when compared to these guys.
Cheers,
Pete

Errr... optics IS my bread and butter. I am a laser physicist, and my PhD research area was in optical physics.

Everything I said in post 43 is correct. I suggest you go read some basic optics textbooks such as Optics by Eugene Hecht. What you THINK is IRrelevant here. What camera that guy uses is also IRrelevant. We are talking basic optical physics.

Next time, you should do your homework before you tell us what you THINK.

 

[Pinoy]

Chill off guys. I think that peteloud's post was in referrence to Sean McHugh's profile... just that the other lines on his post was uncalled for.

:Later,

 

[lsisaxon]

Please ignore that garbage posted at cambridgeincolor. It's total gibberish.

Diffraction occurs at the aperture blades of the lens. It happens because of the wave nature of light, and is apparent only when the size of the aperture is very small.

The sensor does NOT in any way affect it. Greater pixel density (or smaller pixels) only serves to SHOW the effect more clearly, the same way the optical quality of lesser lenses is made more obvious.

Yes. This is correct. For the same piece of optics at a certain aperture, the 'airy-disc' (it's a term used in astronomy optics), basically its just a diffraction pattern (sinc function) due to a point source (impulse response) passing through the finite aperture of lens, would be the same size. For a small aperture, the airy disc would be larger (basically it can be approximated to be just a 2D Fourier transform of the aperture size), therefore a sensor with a higher pixel density would just resolve the 'airy-disc' better, so that at 100% crop, you could see the 'blurness' because you are magnifying the image more when you view it at 100%.

It has nothing to do with what body one is using. However, I would refrain from saying the website is not entirely gibberish. It's meant more for lay people, not optical engineers and physicists. ;p

Do you find anything wrong with the opening paragraph from the website? I think it serves well to tell laymen about diffraction limits without going through all the wave boundary conditions and Fourier transform approximations mumbo-jumbo.

Diffraction is an optical effect which can limit the total resolution of your photography-- no matter how many megapixels your camera may have. Ordinarily light travels in straight lines through uniform air, however it begins to disperse or "diffract" when squeezed through a small hole (such as your camera's aperture). This effect is normally negligible, but increases for very small apertures. Since photographers pursuing better sharpness use smaller apertures to achieve a greater depth of field, at some aperture the softening effects of diffraction offset any gain in sharpness due to better depth of field. When this occurs your camera optics are said to have become diffraction limited. Knowing this limit can help you to avoid any subsequent softening, and the unnecessarily long exposure time or high ISO speed required for such a small aperture.

 

[coolsigg]

Please ignore that garbage posted at cambridgeincolor. It's total gibberish.

Diffraction occurs at the aperture blades of the lens. It happens because of the wave nature of light, and is apparent only when the size of the aperture is very small.

The sensor does NOT in any way affect it. Greater pixel density (or smaller pixels) only serves to SHOW the effect more clearly, the same way the optical quality of lesser lenses is made more obvious.

does it mean that different aperture shape/design will affect the amount of diffractions? how can it be miminised? :think:

 

[lsisaxon]

does it mean that different aperture shape/design will affect the amount of diffractions? how can it be miminised? :think:

Use a 'soft edge' so that the aperture is not a 2D rect function? ;p

 

[lennyl]

Everything I said in post 43 is correct.

I do not dispute that what you posted in 43 is correct (and I'm not the one who attacked you, BTW), however I'm interested in why you state that the article is gibberish. As far as I can tell, the author of the article did not dispute what you said, that diffraction is caused by a small aperture. He went on to say that as photosites grow smaller, loss of resolution due to diffraction is seen at larger apertures. Do you dispute his conclusion or his explanation? Dismissing it as gibberish is not very helpful. I'm not trying to antagonize you, I really want to know.

 

[coolsigg]

Use a 'soft edge' so that the aperture is not a 2D rect function? ;p

soli...abit chim for layman like me...

how about the number of aperture blades? does it mean the more the merrier? :think:

 

[chopper]

Wah... Don't know so many physicist, optical scientist in this clubsnap forum. Now I feel so proud I'm among crowd of brainy bunch... Respect, respect.

Just one stupid question from me, since my only knowledge in physics was from my A-level physics several decades ago, understand difraction, but isn't the role of the optical elements in the lens to correct/compensate the various difraction effects... that was why some better lens have sharper image across all aperture range, while some suffer from lost of resolution when aperture is close down to f16, f22 ? So, it boils down to the layman term of higher resolution sensor will demand more resolving power from the lens ?

 

[StrifeYun]

hmm can we get canon to explain haha....
gd 5mins read on this thread heee

 

[peteloud]

Hi doodah,

If you have a doctorate in optics then perhaps you can tell us the diameter of the Airey Disk for a standard lens at f22, for say red light.

Does this mean that this diameter is the minimum resolving power for that lens at f22?

How does this diameter compare with the pixel size on the 50D?


Pete Loud

 

[Lenpalien]

Hi Pete

Is there a point to this question? Or are you just testing him?

Hi doodah,

If you have a doctorate in optics then perhaps you can tell us the diameter of the Airey Disk for a standard lens at f22, for say red light.

Does this mean that this diameter is the minimum resolving power for that lens at f22?

How does this diameter compare with the pixel size on the 50D?


Pete Loud

 

[peteloud]

It is a very serious point.

If you go back to my original posting I was saying that if the 5D MkII has the same sensor technology as the 50D then it could have just under 40Mp. What I want to know, because I intend to buy a MkII, is at what point do diffraction effects limit the resolution of the lens so that lots of pixels become irrelevant.

Incidentally I did not suggest that Sean McHugh was an expert because he owned a 5D, it was an incidental point, which I thought might be of interest as we were were discussing the 5D. When I see a guy strutting around with a 5D or any other bit of fancy equipment hanging round his neck I do not think him an expert in optics, an expert photographer, or socially sophisticated, I simply think "that guy strutting around with that expensive bit of kit has chosen to spend his money on an expensive bit of kit".

 

[lennyl]

It is a very serious point.

If it's the answer you're really interested in, read through the top portion of this page :

http://en.wikipedia.org/wiki/Airy_disk

where it states x = 1.22 * F * λ where F is the F number (2.8, 8, 11, 22, etc.) and λ is the wavelength.

Get your wavelength from this page :

http://en.wikipedia.org/wiki/Visible_spectrum

You can approximate the photosite size yourself for whatever resolution you're interested in.

I admit ignorance on how the use of a Bayer filter will affect the results of this calculation.