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hyperfocal distance
When using the concept of hyperfocal distance, do we need to adjust for the
smaller sensor on 300D? |
#2
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hyperfocal distance
No. It remains the same.
-- http://www.chapelhillnoir.com home of The Camera-ist's Manifesto The Improved Links Pages are at http://www.chapelhillnoir.com/links/mlinks00.html A sample chapter from my novel "Haight-Ashbury" is at http://www.chapelhillnoir.com/writ/hait/hatitl.html "leo" wrote in message k.net... When using the concept of hyperfocal distance, do we need to adjust for the smaller sensor on 300D? |
#3
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hyperfocal distance
leo wrote:
When using the concept of hyperfocal distance, do we need to adjust for the smaller sensor on 300D? No, but good you asked before burning all that film experimenting yourself. I hate all that waste. |
#4
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hyperfocal distance
"leo" wrote:
When using the concept of hyperfocal distance, do we need to adjust for the smaller sensor on 300D? It took me 10 seconds at www.google.com to find this equation for the hyperfocal distance: h = (f*f)/(N*c) f = focal length, N = f-ratio, c = "circle of confusion" diameter. 'c' is going to be proportional to the size of a pixel, not the sensor. |
#5
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hyperfocal distance
eawckyegcy wrote:
leo wrote: When using the concept of hyperfocal distance, do we need to adjust for the smaller sensor on 300D? It took me 10 seconds at www.google.com to find this equation for the hyperfocal distance: h = (f*f)/(N*c) f = focal length, N = f-ratio, c = "circle of confusion" diameter. 'c' is going to be proportional to the size of a pixel, not the sensor. Well, give yourself a gold star, then. Anyway, isn't the circle of confusion a characteristic of the lens, not the sensor? Also, I believe the OP was asking if it's required to adjust the "f" in your formula due to the _apparent_ focal length adjustments required by fractional-frame sensor form factors, n'est-ce pas? |
#6
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hyperfocal distance
"M Barnes" wrote in message
... eawckyegcy wrote: leo wrote: When using the concept of hyperfocal distance, do we need to adjust for the smaller sensor on 300D? It took me 10 seconds at www.google.com to find this equation for the hyperfocal distance: h = (f*f)/(N*c) f = focal length, N = f-ratio, c = "circle of confusion" diameter. 'c' is going to be proportional to the size of a pixel, not the sensor. Well, give yourself a gold star, then. Anyway, isn't the circle of confusion a characteristic of the lens, not the sensor? Also, I believe the OP was asking if it's required to adjust the "f" in your formula due to the _apparent_ focal length adjustments required by fractional-frame sensor form factors, n'est-ce pas? The formula I found was based on 35mm and in fact, I simply use the chart. I don't think the sensor size matters but I think I better inquire. Thanx. |
#7
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hyperfocal distance
"Tony Spadaro" wrote in news:dJCEc.85007
: No. It remains the same. Yes - this is the intuitive answer. But it is not entirely correct. The formula for hyperfocal distans is (just as pointed out in another post): h = (f*f)/(N*c) f = focal length, N = f-ratio, c = "circle of confusion" diameter. The crucial factor here is c (circle of confusion). If you search further on the net you will find that it is 1/1740 of the diagonal of the sensor. Therefore, h will be bigger for a smaller sensors. So - the intuitive answer is wrong. The hyperfocal distance depends on how much you crop your image. Therefore, it is also only valid for the 35 mm film camera if you don't crop the image. /Roland |
#8
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hyperfocal distance
Gisle Hannemyr wrote:
M Barnes writes: Anyway, isn't the circle of confusion a characteristic of the lens, not the sensor? No - it is proportional to sensor size. Hm. Okay, I think I get it. How is the CoC computed for lenses then? And for film body/lens combinations? Also, I believe the OP was asking if it's required to adjust the "f" in your formula due to the _apparent_ focal length adjustments required by fractional-frame sensor form factors, I don't think that was what the OP asked - but if it was, then the answer is "no". "Adjusting" the focal length to 35 mm equivalent will result in a wrong answer. But the crop factor enters in to the formula. You need to use the correct CoC for the 300D. Which - has it happens - shrink compared to 35 mm full frame with an amount equal to the crop factor: 0.025/1.6 = 0.016. Is it "as it happens" or is it "as a function of?" I'm not trying to be snarky here, honestly. I have a D100 (that I haven't used all that much yet) body to replace my N2020, and usehyperfocal focusing a lot in landscape shots to keep the foreground sharp. I'm used to using the lens set I have in a certain way, and am wondering if I need to adjust for the D100, which of course has the "crop factor" you speak of. |
#9
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hyperfocal distance
"M Barnes" wrote: Gisle Hannemyr wrote: M Barnes writes: Anyway, isn't the circle of confusion a characteristic of the lens, not the sensor? No - it is proportional to sensor size. Hm. Okay, I think I get it. How is the CoC computed for lenses then? And for film body/lens combinations? It's computed for a given print size assuming a given viewing distance and a viewer with typical visual acuity. DOF is a perceptual phenomenon in the viewer. Also, I believe the OP was asking if it's required to adjust the "f" in your formula due to the _apparent_ focal length adjustments required by fractional-frame sensor form factors, I don't think that was what the OP asked - but if it was, then the answer is "no". "Adjusting" the focal length to 35 mm equivalent will result in a wrong answer. But the crop factor enters in to the formula. You need to use the correct CoC for the 300D. Which - has it happens - shrink compared to 35 mm full frame with an amount equal to the crop factor: 0.025/1.6 = 0.016. Is it "as it happens" or is it "as a function of?" I'm not trying to be snarky here, honestly. I have a D100 (that I haven't used all that much yet) body to replace my N2020, and usehyperfocal focusing a lot in landscape shots to keep the foreground sharp. I'm used to using the lens set I have in a certain way, and am wondering if I need to adjust for the D100, which of course has the "crop factor" you speak of. To make a long story short, you do have to adjust. A 24mm lens will have less DOF when used as a 36mm lens on a D100 than when used as a 24mm lens on an F100, but will have more DOF when used as a 36mm lens on a D100 than a 35mm lens on an F100. The best thing to do is to test. For each focal length, for each f stop, shoot a series of images of a scene with both near and far detail at various distance settings on the lens starting at infinity. For each focal length/f stop combination, record the closest distance that you find the detail at infinity to remain acceptable. Since it's digital, all it costs is your time. And even then, not much of that since you don't have to scan. David J. Littleboy Tokyo, Japan |
#10
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hyperfocal distance
David J. Littleboy wrote:
The best thing to do is to test. For each focal length, for each f stop, shoot a series of images of a scene with both near and far detail at various distance settings on the lens starting at infinity. For each focal length/f stop combination, record the closest distance that you find the detail at infinity to remain acceptable. Since it's digital, all it costs is your time. And even then, not much of that since you don't have to scan. Got it. I'll set up a 20-meter tape measure in my back yard and put up letter-sized paper sheets labeled with the distance at 1-meter intervals. That should do it. Thanks. |
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