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Old Jun 29, 2004, 12:17 PM   #1
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Hi.

I´recently got me a S2 Pro to use with my older 105mm F2.8 Nikon Micro. I do dental photography. I´m having unexpected problems with DOF. At F22 where normally I got about everything in focus with analogic cameras, DOF is very little with my digital SLR.

Does anybody knows what I´m doin wrong ?



Thanks
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Old Jun 29, 2004, 10:27 PM   #2
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The S2 Pro has a focal length multiplier of 1.5x because its sensor is physically smaller than a 35mm film frame. Therefore your 105mm lens is seen as a ~158mm focal length lens on the S2. As focal length increases the DOF decreases and this is more pronounced at macro distances. You might want to try the AF Micro Nikkor 60mm f/2.8D which will look like a 90mm on the S2.

http://www.bhphotovideo.com/bnh/cont...987&is=USA


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Old Jun 30, 2004, 4:53 PM   #3
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Thak you Steeve. I´ll try with my 50mm (Macro) Sigma lens.

ShouldFuji or Nikon camera dealers be aware of this "little" problem and therefore tell any possible buyers ?

Some friends ( 2 at least) asked at a local Nikon dealer if the the D70 would work fine with the 120mm Nikkor Medical, and they were told nothing about DOF !

Do you think the Oly E-1 with their 50mm Macro would have been a better option?

Thanks again
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Old Jun 30, 2004, 5:01 PM   #4
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They should have been aware of the focal length multiplierand said something. While some call it a problem, others call it a blessing. The extra magnification that the Canon 10D gives me means that my long lenses are even longer! Now that is really nice.

But the decreased DOF is usually not desirable (less DOF isn't always bad, but it usually is.

But in my opinion, they should have said something.

Eric
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Old Jul 1, 2004, 11:22 AM   #5
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Theoritically, the Depth of Field should not change between your cameras, using the same 105mm lens, even though the S2 Pro has a 1.5x "crop factor" (a.k.a., focal length multiplier), making your lens appear to be much longer.

It should not change, because Depth of Field is based on the actual (versus 35mm equivalent) focal length of the lens, distance to subject, and aperture.

Here is a handy online Depth of Field Calculator. You'll find your Fuji S2 Pro listed.

http://dfleming.ameranet.com/dofjs.html

Use the actual (105mm) versus 35mm equivalent (~158mm) focal length when computing DOF with your S2 Pro.

The reason that Digital Cameras have more depth of field, at a given aperture, distance to subject and 35mm equivalent focal length; is because you can use a shorter actual focal length lens, to get the same equivalent focal length on a 35mm camera. This is not your case (you are using the same focal length lens on both cameras).

In conclusion, I don't know why you'd see a DOF difference between cameras, using the same lens and aperture setting, unless one camera is using a different focus point.

Given the 1.5 crop factor, you should be able to get the same field of view from a further distance with the S2 Pro, givingit a DOF advantage (since distance to subject could be greater, for the same field of view you'd get with your 35mm camera).
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Old Jul 1, 2004, 11:20 PM   #6
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JimC wrote:
Quote:
Theoritically, the Depth of Field should not change between your cameras, using the same 105mm lens, even though the S2 Pro has a 1.5x "crop factor" (a.k.a., focal length multiplier), making your lens appear to be much longer.
Yeah, I was thinking that when I first read the question, but I didn't want to be the one to disagree.

Depth of field is a function only of the true focal length of the lens. That's why consumer digicams have such deep focus fields (and are hard to get good background blur out of). If you had a camera with a tiny sensor, such that there was a 10x multiplier, and you put a 50mm lens on it, the resulting images would have the same composition as a full-frame camera with a 500mm lens, but the depth of field would be the same as a 50mm lens. The "multiplier" is the same as taking a photo with a film camera, cropping it, and enlarging the crop up to the same size as a standard print. It's not optically magnifying the image from the lens.

That said, the 1.6x or 1.5x crop IS effectively a multiplier, for everything except DOF. Imagine the same picture is taken with a 200mm lens on both a Canon 1Ds and a Canon 10D. The 10D crops the image and gives eqivalent field of view to a 320mm lens, while the 1Ds gives the standard 200mm field of view. If a 1.6x crop of the 1Ds image is made(so that it has the same composition as the 10D image), it will be slightly smaller than the image from the 10D.
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