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09-01-2009, 01:52 PM   #16
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QuoteOriginally posted by pingflood Quote
God damn it, you need to stop taking pictures and sit around and theorize instead!
I can fully subscribe to this, it is just that it seemed to be kind of an "implied truth" that FF have better noise performance just based on ISO numbers without many people reflecting on what typically goes into composing an image, and comparing low noise performance based on that instead (i.e. equal FOV, DOF and shutter speed). If those are kept equal when comparing, there seems to be no noise advantage with FF vs APS-C, contrary to what has been said a number of times in different threads.

As I said I do not know about others, but to me this came as somewhat of a surprise. But it was a pleasent surprise

Best regards,
Haakan

09-01-2009, 01:56 PM   #17
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QuoteOriginally posted by Torphoto Quote
hummm Try and explain that to me again.
YOur 5D takes "better" pictures (less noise and less DoF) if you use a lens with the same f-stop. But because of longer focal length, this same f-stop lens will be bigger (larger diameter), heavier and more expensive.

If you could find an equally big lens for the shorter focal required on APS-C, then your 5D wouldn't make better images anymore. If you can find and afford it.

Or as I prefer to say: FF may provide more options.
09-01-2009, 01:57 PM   #18
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QuoteOriginally posted by StigVidar Quote
But then, Pentax should start making a 16-50/2 zoom instead of f/2.8. Olympus understand this fact, but not Pentax. And we are also missing a lot of f/1 prime lenses.
I'm not missing at all an f/1 prime lens, as it would cost both arms and legs, and a kidney on top of that
09-01-2009, 02:02 PM   #19
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QuoteOriginally posted by falconeye Quote
YOur 5D takes "better" pictures (less noise and less DoF) if you use a lens with the same f-stop. But because of longer focal length, this same f-stop lens will be bigger (larger diameter), heavier and more expensive.

If you could find an equally big lens for the shorter focal required on APS-C, then your 5D wouldn't make better images anymore. If you can find and afford it.

Or as I prefer to say: FF may provide more options.
Another brilliant treatise to this confusing topic Falk.
Does clear things up quite well
Thanks again mate.

09-01-2009, 02:26 PM   #20
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QuoteOriginally posted by Ash Quote
Another brilliant treatise to this confusing topic Falk.
I found an even shorter way to put it:

It isn't the sensor which collects the photons, it is the lens!
09-01-2009, 02:32 PM   #21
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I'd consider FF pretty much only for the increased DOF range. Sometimes I prefer razor thin DOF over a slightly out of focus shot.
09-01-2009, 02:40 PM   #22
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QuoteOriginally posted by krypticide Quote
I'd consider FF pretty much only for the increased DOF range. Sometimes I prefer razor thin DOF over a slightly out of focus shot.
Mmmm. good point.
09-01-2009, 03:54 PM   #23
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Say you have a group of 3 sitting around a dimly-lit circular table. You have a 75/F2.8 lens on an APS-C camera. You find to frame the group (FOV) you have to move back to a certain distance. To get all the group in focus (DOF) you find you need to stop down to F5.6.

Now put the same lens on a FF that has the same sensor technolology (with the same Fill Factor) and with the same ADC performance. Now you find you have a wider DOF so you have to move closer to get the same framing. At the closer distance not all the group are in focus so you find you need to stop down to F8 to get the same DOF. Now you have 1 stop less light hitting the sensor. So the approx. 1 stop increase in sensor sensitivity due solely to the FF's larger sensor size is negated by the 1 stop reduction in aperture at the same FOV to get the same DOF.

The thing about the 5D/5DII is that it's not the FF, per se, that makes it such a good performer. It's the sensor technology & ADC performance that the camera has that makes it so good, as regards sensitivity. (Leaving besides other areas of performance such as AF.) But you're paying a lot more for this leading-edge performance.

There is another argument that you could make about comparing an equivalent level of vignetting. At the same aperture, the FF will have more vignetting than the APS-C. So you can either stop down the lens on a FF more, losing light (and increasing noise), or you electronically brighten the outside of the picture (either automatically in the camera or in PP), hence increasing noise on the outside of the image.

Dan.


Last edited by dosdan; 09-06-2009 at 12:45 AM.
09-01-2009, 04:05 PM   #24
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All I know is I've been looking at D700 ISO12800 shots all afternoon and they're way cleaner than my K20D ISO1600 shots.
09-01-2009, 05:15 PM   #25
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QuoteOriginally posted by deadwolfbones Quote
All I know is I've been looking at D700 ISO12800 shots all afternoon and they're way cleaner than my K20D ISO1600 shots.
That might be an unfair comparison.

The D700 is the FF DSLR lowlight king of the hill at the moment (DXOMark lowlight ISO result of 2303) whereas the K20D is only an average APS-C lowlight ISO performer (DXOMark lowlight ISO result of 639). That's a pretty substantial difference that complicates the discussion here perhaps, since if you factor into the discussion sensor quality/sensitivity that's a whole new kettle of fish.

D90 vs D700 comparisons make more sense, since the D90 is currently the APS-C lowlight champ (at 977 lowlight), according to the DXOMark numbers.
09-01-2009, 06:50 PM   #26
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QuoteOriginally posted by deadwolfbones Quote
All I know is I've been looking at D700 ISO12800 shots all afternoon and they're way cleaner than my K20D ISO1600 shots.
OK, but did you control the other parameters as stated, or did you allow yourself a longer shutter speed, shallower DOF, larger lens, etc, on the D700?
09-01-2009, 06:51 PM   #27
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According to Equivalence the difference in sensitivity between a APS-C & a FF is about 1.33 stops, everything else being equal.

Dan.
09-01-2009, 07:23 PM   #28
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QuoteOriginally posted by dosdan Quote
According to Equivalence the difference in sensitivity between a APS-C & a FF is about 1.33 stops, everything else being equal.
Except the whole point of the article is to point out that that "everything else being equal" doesn't mean what it is commonly assumed to mean in this context. In particular, in order to get a 1.33 stop advantage in sensitivity at a given FOV, you need a physically larger lens (longer focal length, wider diameter), and/or have to accept a shallower DOF. If on the other hand you decide you want to keep the lens size and DOF the same as well, the advantage disappears. You could get the same benefit for APS-C by simply buying a larger diameter lens, assuming one were available (the problem is that one generally isn't); and you'd pay for it with shallower DOF just as you do with FF.

The bottom line is that the advantage in sensitivity for FF comes *only* from the fact that it is possible to buy larger lenses for that format than for APS-C, and you also pay for that in decreased DOF.

Last edited by Marc Sabatella; 09-01-2009 at 07:32 PM.
09-01-2009, 08:21 PM   #29
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While I agree that the D700 gives you good images even at 12800 ISO, there's still significant loss of detail in the noise reduction that occurs. I think the "good" quality of its high ISO images are due in no small part to a good NR algorithm in addition to the bigger and better sensor.
09-01-2009, 08:22 PM   #30
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QuoteOriginally posted by Marc Sabatella Quote
Except the whole point of the article is to point out that that "everything else being equal" doesn't mean what it is commonly assumed to mean in this context.
I should have said "equivalent", rather than "equal"
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