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Old Apr 29, 2008, 10:05 PM   #1
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I am a scientist (not a photographer) needing a DSLR Camera to take pictures that (as close as possible) mimic the Human Eye. Can you help me select a current DSLR model that fits my specification?

A) I need a similar integration time (-1/45 second)
B) Similar "Pixel" size (4.65um vs. 3um in fovea)
C) Matching focal length (25mm vs. 22mm)
D) Matching F/# (f/5.6 vs f/3-f/8)


If you said Nikon DXXX with XXX lens available at leading stores - that would be perfect.
It will only be uses occasionally at work - but then again if you said a Nikon D300 (I think this is the latest Nikon nice model) then I could get it and also use it for my family. - which would be nice


Thanks all you experts ahead any feedback
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Old Apr 30, 2008, 2:23 AM   #2
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Well heck, you're going to need a LOT of resolution.

http://www.clarkvision.com/imagedeta...esolution.html

So I reckon the closest you can get at the moment that is the Canon 1Ds MkIII with the 24mm f1.4 L lens.

See if you can sell that one. :-)

Or how about a Leica M8 with Zeiss Distagon 18mm f4 ZM lens?

That should be fun to work with too!

If you have your heart set on a D300 then you could try it with the 18mm f2.8 D lens.

Or you could wait a little longer because both Nikon and Sony are expected to release 24Mp cameras this year. Pair with the very lovely Zeiss 25mm Distagon MF lens, or hope for an equivalent Alpha-mount lens.






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Old Apr 30, 2008, 10:16 AM   #3
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In addition to the points raised by peripatetic, I'd like to mention some other points, some of which are obvious and some of which might not be.

First, the human eye is spherical, and the image sensor is on the interior of that sphere. Cameras, however, have a flat image sensor, which throws off any optical comparison between them. And because of its spherical image sensor, the human eye can get by with a simple convex lens (albeit malleable and able to deform at will.) Also, I believe that the human retina has a higher resolution at the center of the visual field, but a lesser resolution at the periphery, especially with respect to color perception. So a very simple view of a camera might lead one to see its similarities to the eye, but a closer examination reveals that there are considerable, and fundamental differences.

In addition, the effect of thefocal length of a lens differs depending on the image sensor. For instance, a 22mm lens on a full frame SLR would provide a 90° angle of view, but the same lens would provide only a 60° angle of view on an APS-C dSLR. A 22mm lens on a P&S digicam might even qualify as a telephoto lens. So 'focal length' all by itself probably is not an adequate indicator of what you might be looking for, especially when you consider the complexity required for a camera lens to project an in-focus image on a flat surface.

If you want to simulate the mechanisms in the human eye, I think you'll have to jump through a lot more hoops that just buying something at your local Best Buy.
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Old Apr 30, 2008, 5:57 PM   #4
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Peripatetic, - Thanks - this is a great start.

The Sony A900and Nikon D3x are later this year, butmy Metrology task- to best match the camera to the Human eye - needs to start in two weeks max. The M8 is probably too pro for me. It is also low on pix vs Canon.I think I would have to go with the Canon 1Ds.I also want an auto focus lens soI can use it personally on weekends For the $7k-8K cost - no point sitting around in lab with kids to capture!

A) Thepix sizemay be close enough, but do you know how i could confirm the size?. In mytests, (to do with measuring laser speckle BTW), its the CCD pix size (?um)itself that is also important to match up with the fovea rod size.

C) The 24mm is fine

D)Problem isthe lens F/# spec. - The range I wanted to be in is f/3-f/8?

Any further tips or advice - BTW the site you recommended was very interesting
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Old Apr 30, 2008, 8:18 PM   #5
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Scientist wrote:
Quote:
A) Thepix sizemay be close enough, but do you know how i could confirm the size?. In mytests, (to do with measuring laser speckle BTW), its the CCD pix size (?um)itself that is also important to match up with the fovea rod size.
In the Canon EOS-1Ds Mark III, the pixel pitch is 6.4µm, but it seems Canon has also greatly reduced the interpixel gap and is claiming a pixel size of 6.4µm as well. See http://www.usa.canon.com/uploadedima...per_070817.pdf

Scientist wrote:
Quote:
A) Thepix sizemay be close enough, but do you know how i could confirm the size?. In mytests, (to do with measuring laser speckle BTW), its the CCD pix size (?um)itself that is also important to match up with the fovea rod size.

D)Problem isthe lens F/# spec. - The range I wanted to be in is f/3-f/8?
The Canon 24mm f1.4 L lens that peripatetic mentioned has a maximum aperture of f/1.4 and a minimum aperture of f/22. That will encompass the f/3-8 aperture range you're looking for.


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Old May 1, 2008, 1:32 AM   #6
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If you need to get the pixel pitch downwards, you could have a look at the Olympus E3, which is probably just about the smallest you will find in DSLR at about 4.7 microns.

But you'll need to look for a 24/2=> 12mm lens for it.

There is an 11-22mm f2.8-3.5 zoom lens which should just about do it. Probably giving an aperture range of f2.8-f22 at 12mm focal length.
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Old May 1, 2008, 10:39 PM   #7
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If you shared more of your objectives you mightreceive more useful information. The bottom line is that no camera mimics the human eye.

Beyond the factors TCav and others have mentioned I'll mention that the eye is not color corrected [bringing all colors (or at least two)] into focus at same time as camera lenses. The eye/brain system simply refocuses as it encounters different colors. You canfeel this if you look at bold red text on a bold blue background.

The human imaging system might be described as a Holga controlled by at least four high speed servo mechanisms (azimuth, elevation, aperture and focus) tightly coupled to a truly powerful image processing engine. This processing engine uses its coupled servo systems to identify subjects of interest, scan and assemble composite images to expand resolution over a wider area the the optics can handle while using the aperture contol to expand dynamic range (HDR?). Finally the brain throws out peripheral information not required (digital zoom or cropping?) and fills in missing information (jpeg?).

Camera systems simplyproduce a result which permits the brain to suspend disbelief.
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Old May 3, 2008, 9:01 PM   #8
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As ac noted, the eye is a very weak optical instrument backed by a masivly parallel processing system. In your quest to mimic the eye are you going to:

** damage the sensor to mimic the blind spot?
** somehow decrease the resolution off axis?
** make the perpheral areas very sensitive to motion albeit very low resolution?
** make the system degrade with age?

Any manufacturer who made a camera that mimiced the human eye would be bankrupt within a week.
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