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01-22-2009, 06:19 PM   #31
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QuoteOriginally posted by *isteve Quote
We are talking about a digital image, the dimensions of the sensor are not relevant. It matters on film only because the grain is always the same size for a given emulsion, so to get more information you need more grain so you need a bigger neg.

.
Actually fine grain films hold more information. And the sensor size does matter. Size always matters.

01-22-2009, 06:48 PM   #32
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QuoteOriginally posted by newarts Quote
I think the following is true:

A perfect lens' resolution is fixed by diffraction at something like its Rayleigh limit of
r=1.22(f-stop)(wavelength).
I took care of diffraction in my argument above.

I you really need all the nasty details, here we go, my friend...

r = 1.22 f lambda is the distance of the first minimum of the Airy disk from its center. Two lines separated by r can be separated because the sum of their diffraction curves still have a (marginal) minimum at r/2. The contrast of separation would be very low, though.

Therefore, the smallest resolvable feature size x is r/2
x = 0.61 f lambda
(which is about f/16 for green light with a K20D. If you want contrast, better stay below f/8, though).

A lens like the Zeiss 35mm f/2 should be able to resolve (at f/2.8) 0.9 µm and is the only lens in the 1µm class I am aware of. I verified myself that a Zeiss 50mm resolves 1.5 µm. A full frame lens resolving 3 µm (where Zeiss already delivers good contrast) delivers 100 MPixel at f/4. To compete, an APS-C lens would have to be diffraction limited at f/2.8 and up to date, I am not aware of any such lens.
01-22-2009, 09:16 PM   #33
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Absolutely YES - For Many Reasons.

QuoteOriginally posted by FunkyMonk Quote
If so how is it affected on the K10D and the K20D?
For quite some reasons, say:

1. To maintain the same Field/Angle of View and with the same aperture number (so as to maintain the same exposure), cropped APS-C DSLR will reach the physical diffraction limit of light easier as the lens aperture opening is always smaller, e.g., just at f/8. In this case, increasing the sensor pixel density will not help.

2. When full frame 135 lenses are used on cropped sensor, e.g. the FA50/1.4 or simply any FA lenses. It is because the lenses were designed to have an image circle to cover 24x36mm but not 16x24mm. As the 16x24 1.5X APS-C sensor is about only 44% of the total area of the 24x36, there are much resolution loss here, by 1/1.5, i.e., only 66% of the original resolution is maintained.

3. Smaller sensors have more sensor noise for the same pixel count and generation (of technology), if the noise have to be removed by noise reduction software, details are lost and resolution is decreased.

4. Lenses that are cropped without redesigning the whole form factor, e.g., Pentax DA lens line, with the same back focus register distance could be a problem with wide lenses and they are made to be bulkier and optically not as good as their film counterparts, e.g., less resolving power and more CAs. This hold true when you compare against the FA20/2.8 on FF against the DA14/2.8 on cropped as well as the FA 17-28 Fisheye Vs the DA 10-17 FE and so on..

Bottom Line: APS-C is by no means as good as Full Frame, not only resolution is concerned but also other image quality differences.
01-22-2009, 10:03 PM   #34
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QuoteOriginally posted by *isteve Quote
How do YOU explain the numbers?
I'd say the lenses used were up to the task of making sensor resolution the dominant factor. Looks like he used a 85mm prime at f/6.3 on the D700 and a 50mm prime at f/8 on the D300. My point has been that if you're going to have a smaller sensor, you need corresponding higher resolution from your lens. I don't really know the specific lenses involved, but if you're looking for a lens that can exceed an 85mm at f/6.3, mounting a 50 and setting it to f/8 would be my first choice.

More interesting to me would be if you mounted a 70-300 on the D700 and a 50-200 on the D300, set both to maximum focal length, and repeated the test that way.

01-23-2009, 07:59 AM   #35
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QuoteOriginally posted by Marc Sabatella Quote
I'd say the lenses used were up to the task of making sensor resolution the dominant factor. Looks like he used a 85mm prime at f/6.3 on the D700 and a 50mm prime at f/8 on the D300. My point has been that if you're going to have a smaller sensor, you need corresponding higher resolution from your lens. I don't really know the specific lenses involved, but if you're looking for a lens that can exceed an 85mm at f/6.3, mounting a 50 and setting it to f/8 would be my first choice.

More interesting to me would be if you mounted a 70-300 on the D700 and a 50-200 on the D300, set both to maximum focal length, and repeated the test that way.
By your own admission, he used the better lens (85 and F6.3) on the D700, and on the D300 he used an F stop where diffraction effects are already occuring (F8). This should have shown a major advantage to the D700. Truth is both these lenses even at F8 can resolve far more than the sensor can. For that not to be the case, the lens resolution really has to be pretty lousy.

Now I said all along that cheap lenses would show more of a difference, but DX lenses claw back some advantage. Using your own test, check the resolution (on a D200) of Nikons cheapest zooms, the 55-200 DX and the 70-300 D.

http://www.photozone.de/nikon--nikkor-aps-c-lens-tests/249-nikkor-af-70-300m...report?start=1

At 200mm the DX lens manages 1950lp/ph and the 70-300 manages a meagre 1697. This would easily give the advantage to the D300 in your comparison. Most DX lenses actually do quite well in resolution terms because not having to cover such a wide image circle allows for less correction of spherical aberation and hence sharper lenses.

But why bother? Cheap lenses on FF will certainly suffer more with vignetting, edge softness and lateral CA, all of which increase with distance from the centre with all lenses, but which is minimised on a cropped sensor. And what on earth would I spend $3000 on a camera for only to put up with low contrast, muddy colours and flare common to cheap lenses? You would get far better IQ using an APS camera with decent lenses and save money as well.

No I know you are not one of the FFrenzied FFanatics, so we should compromise I think and agree that even if its not apparent now, it will become apparent soon when pixel densities on APS get a bit tighter. I hope Pentax and others see the light and dont go too crazy here. Most enthusiasts can do a lot with 15MP and if they want 24MP then there are now some excellent options available in the FF world. I hope they dont try and make a 24MP APS sensor.

Last edited by *isteve; 01-23-2009 at 08:28 AM.
01-23-2009, 08:11 AM   #36
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QuoteOriginally posted by falconeye Quote
I took care of diffraction in my argument above.

I you really need all the nasty details, here we go, my friend...

r = 1.22 f lambda is the distance of the first minimum of the Airy disk from its center. Two lines separated by r can be separated because the sum of their diffraction curves still have a (marginal) minimum at r/2. The contrast of separation would be very low, though.

Therefore, the smallest resolvable feature size x is r/2
x = 0.61 f lambda
(which is about f/16 for green light with a K20D. If you want contrast, better stay below f/8, though).

A lens like the Zeiss 35mm f/2 should be able to resolve (at f/2.8) 0.9 µm and is the only lens in the 1µm class I am aware of. I verified myself that a Zeiss 50mm resolves 1.5 µm. A full frame lens resolving 3 µm (where Zeiss already delivers good contrast) delivers 100 MPixel at f/4. To compete, an APS-C lens would have to be diffraction limited at f/2.8 and up to date, I am not aware of any such lens.
Thanks for the numbers, but if it can resolve 100MP at F4 on a FF sensor, then I could resolve 50MP on APSC at F4, yes?

Some way to go yet then .
01-23-2009, 08:15 AM   #37
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QuoteOriginally posted by falconeye Quote
I forsee my breakfast coffee table besides it. So, let's say 50 cm / 2 feet away? And by wall, I mean wall -- at least 4m wide...

I agree, an ambitious vision. But what else makes the world go round?

BTW, the blur thing can be resolved in software. I already do it now for my tripod-free night vision shots. 100 MPixel is just 2.6x more blur than today
OK, fine but what about the breeze and the smell of fresh Alpine meadows....oh oh there I go....

I think I like your window idea, but a 3D holographic movie image with sound and smell would be really cool.....you could use it as a VR gaming console too. I imagine most graphics cards will be able to cope by then.
01-23-2009, 08:38 AM   #38
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QuoteOriginally posted by graphicgr8s Quote
Actually fine grain films hold more information. And the sensor size does matter. Size always matters.
I said, grain size is the same FOR THE SAME EMULSION and ISO. So you need a larger negative to get more information if you want to stick with Velvia for instance.

And as to simplistic mantras such as "size always matters" its not particularly helpful. It may "matter" but sometimes smaller is better and sometimes bigger is better depending on what you want to do with it. How would the infantry fare if instead of an M16 they were all armed with a heavy machine gun shooting .50 calibre rounds of belt ammo?

01-23-2009, 10:23 AM   #39
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Your question:
QuoteOriginally posted by *isteve Quote
but if it can resolve 100MP at F4 on a FF sensor, then I could resolve 50MP on APSC at F4, yes?
My response:
QuoteOriginally posted by falconeye Quote
So, an even shorter summary:
The possible DSLR resolution is independent of sensor size today, but will become dependent at some moment in future.
QuoteOriginally posted by *isteve Quote
OK, fine but what about the breeze and the smell of fresh Alpine meadows....oh oh there I go.... [...]
Alpine meadows are what I smell at my office space (Aying) anyway ... typically crowded by horses rather than cows though

For the unfortunate more far away, I fear that no model by Pentax will fix it
01-23-2009, 10:42 AM   #40
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QuoteOriginally posted by falconeye Quote
Alpine meadows are what I smell at my office space (Aying) anyway ... typically crowded by horses rather than cows though

For the unfortunate more far away, I fear that no model by Pentax will fix it
You are a lucky man! I lived in Montreux for a while (working on an IT contract for Nestle) and used to take the Golden Pass railway to Gruyere and spend the days walking in the hills. Heaven, even with the cow bells!
01-23-2009, 10:47 AM   #41
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QuoteOriginally posted by *isteve Quote
working on an IT contract for Nestle
The Suisse seem to pay good Franks for IT work. Some of my friends left Munich for Zürich ...
01-23-2009, 12:04 PM   #42
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QuoteOriginally posted by falconeye Quote
The Suisse seem to pay good Franks for IT work. Some of my friends left Munich for Zürich ...
Yes I have some friends there as well! Hope they are being paid in Franks and not Pounds!!
01-23-2009, 01:09 PM   #43
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QuoteOriginally posted by *isteve Quote
I said, grain size is the same FOR THE SAME EMULSION and ISO. So you need a larger negative to get more information if you want to stick with Velvia for instance.

And as to simplistic mantras such as "size always matters" its not particularly helpful. It may "matter" but sometimes smaller is better and sometimes bigger is better depending on what you want to do with it. How would the infantry fare if instead of an M16 they were all armed with a heavy machine gun shooting .50 calibre rounds of belt ammo?
Mea Culpa, Mea Culpa. Maybe next time I will actually read what is posted.
01-23-2009, 01:35 PM   #44
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QuoteOriginally posted by *isteve Quote
By your own admission, he used the better lens (85 and F6.3) on the D700, and on the D300 he used an F stop where diffraction effects are already occuring (F8).
Actually, I had no idea which was the better lens, but was assuming it was the 50. So if the 85 is indeed the better lens, I agree it would seem to provide a counterexample to my argument. Although I can easily believe these lenses are in that class where they are so both so good that they are not having much of a limiting effect on resolution, as you have been saying.

QuoteQuote:
Now I said all along that cheap lenses would show more of a difference, but DX lenses claw back some advantage. Using your own test, check the resolution (on a D200) of Nikons cheapest zooms, the 55-200 DX and the 70-300 D.
Yeah, that's something I have considered as well.

At this point, I would say you have convinced me - despite the reasons why lens resolution issues *could* favor larger sensors in theory, it remains the case that most of the time, there is not going to a difference worth talking about in practice. Which is good, because it gives me one less reason to lust after FF :-)

FWIW, none of this would have occurred to me were it not for an off-hand comment - I think by Marc Langille - a few weeks ago. Something to the effect of, "a 200mm lens on APS-C may have the field of view of a 300mm lens on FF, but it won't have the resolution of the 300mm lens". I didn't ask for explanation of this, but instead starting thinking about it. Dangerous, I know :-), but the whole line of reasoning I have been putting forth came from this.

QuoteQuote:
I hope they dont try and make a 24MP APS sensor.
Ditto.
01-23-2009, 03:16 PM   #45
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QuoteOriginally posted by Marc Sabatella Quote
FWIW, none of this would have occurred to me were it not for an off-hand comment - I think by Marc Langille - a few weeks ago. Something to the effect of, "a 200mm lens on APS-C may have the field of view of a 300mm lens on FF, but it won't have the resolution of the 300mm lens". I didn't ask for explanation of this, but instead starting thinking about it. Dangerous, I know :-), but the whole line of reasoning I have been putting forth came from this.
Well, he had the right idea (although actually the lens had the same resolution but the sensor itself had more) but did not necessarily come to the right conclusion about whether it would matter or not....
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