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 Post subject: Full Sensor = More DOF??
PostPosted: Sun May 13, 2012 10:33 pm 
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I "may" be getting a 5D with 24-105L for the Army. I've been studying up on it a bit and have read a few comments that full sensor users enjoy more DOF. How does the larger EF sensor over an EF-S create more DOF? I thought DOF was purely based off your F-stop vs> relationship of your subject to background vs> focal length

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PostPosted: Sun May 13, 2012 10:46 pm 
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A bigger sensor can have LESS depth of field. If you take a photo from the same position, with the same field of view (longer focal length on bigger sensors), and use the same f number, then you will have less depth of field on the bigger sensor. When converting equivalence between sensors, the crop factor applies to both the focal length and aperture value.

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PostPosted: Sun May 13, 2012 11:03 pm 
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Hi Mike,

I explored some ideas about this in my thread Size Matters. On a practical level, it's much easier to source lenses which can offer a shallow depth of field when using a large sensor. For example, on my crop factor 2 camera if I bought a 25mm f/0.95 lens then I'd get the same FoV and DoF as a 50mm f/1.9 lens on a full framer.

Bob.

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PostPosted: Mon May 14, 2012 11:49 am 
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It's probably always important to add the little note about "equivalent framing". If you shoot at a constant distance, a 50/1.8 on a crop has the same real DoF as a 50/1.8 on a full-frame. But if you shoot the same framing between crop and FF, then yes, the FF has less DoF because you're actually physically closer to the subject... meaning a closer focusing distance, and therefore a more-shallow DoF. If you wanted the same apparent DoF with identical framing (i.e. filling the frame on both crop and FF), then you have to stop down the lens on FF by the crop factor to achieve the same "look".

It's confusing if you let it be :)

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PostPosted: Tue May 15, 2012 8:52 am 
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I liked this explanation form Janern
viewtopic.php?f=2&t=29951

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PostPosted: Thu May 31, 2012 7:35 pm 
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Yes, it is true, look at small cameras, they have f1.8, still nearly everything is in focus...

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PostPosted: Fri Jun 01, 2012 12:53 am 
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When you mention you will be getting it "for the Army", I immediately think you probably should be worried more about weatherproofing, unless you have a very specific idea in mind. You can increase DoF by using a narrower Aperture, such as f/8 or f/11, or you can even take multiple images with different focus points and combine them in post if needed. But if dust / salt water / mud / rain etc gets inside your camera in the middle of the mission, you could get unlucky and nothing short of bringing it back to Canon for repairs will work.

So if you're an army guy looking for a camera for your off-time, sure, you can look into a crop camera such as the 7d, but if you're looking for a camera to use on the battlefield, training camps or any other such active duty period, I strongly suggest you go with the best weatherproofing. In order of best to acceptable it would be 1DX > 5dIII > 7d, and all other cameras (in the Canon lineup) I would completely ignore.

For video, a GoPro could also be very interesting, with great DoF, and crazy weather / shock proofing.

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PostPosted: Fri Jun 01, 2012 5:57 am 
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good thinking on the GoPro stuff. The photos from them don`t look too bad either.

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