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09-02-2009, 03:09 PM   #76
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QuoteOriginally posted by Haakan Quote
This is exactly the type of comparison I was thinking of. So I looked at the D90 and D700 DxOMark curves (I wanted to take away other factors, and these cameras seemed to be very similar except for the sensor format). The difference in SNR curves shows about 1 EV benefit for the D700. But since the ISO for the 75mm f/2.8 would have to be 1 EV higher than for the 50mm f/2.0, the end result should be almost identical (again based on the DxO noise measurements)

Please do not think that I am trying to argue against your findings though, I am just following through on the logic of what I found when looking at these two specific cameras (D90 and D700)

Thanks, Haakan. I understand the math part. I think I do, anyway.

But I'm going to have to let this sit for a while.

I'm still trying to figure out what this means in practical terms. I have always known that, under many circumstances, an APS-C camera can take images that are the equal of the images in a full-frame camera - in sharpness, noise, and every other respect. I knew also (without thinking as hard about it as you have made me think today) that to get similar or identical results, I'd probably have to use different settings on my K20D than my full-frame friend would use. I would say also that I've always been under the impression that the "ISO advantage" of the full-frame cameras in real life was one to one and a half stops at best. One has to remember the ISO 25000 is only two stops better than ISO 6400. My impression is that Nikon photographers aren't using 25000 much more than I'm using 6400.

Perhaps I would give myself too much credit if I said that much has been obvious, so perhaps I should just say that I've always assumed this. I assumed it because most of the time, I think my photos are as good - at least technically - as the ones I see coming from the Canon and Nikon full-frame bodies.

I like to think that the built-in shake reduction of the Pentax bodies is a big deal, but in reality, most Nikon and Canon wedding pros (even those with D90's or Canon 50D's rather than full-frames) seem to be using stabilized lenses. They've paid a fortune for 'em, but hey, you do what you gotta do.

It's also been interesting here to think about noise as a function of lens size rather than sensor size.

Anyway, have to let this sit.

Thanks for starting the thread and I hope I haven't hijacked it or come across as too much of a pain.

Will

09-02-2009, 03:13 PM   #77
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QuoteOriginally posted by WMBP Quote
But the lenses? This Nikon 50 f/1.4 doesn't look any bigger than my Pentax 50 f/1.4:
It's not. But it's also not relevant. I assume you are using Nikon as an example FF system here, with Pentax the APS-C system. Fine. In which case, it's not the Nikon 50/1.4 you need to compare against the Pentax 50/1.4. It's a hypothetical 75/2 - because you need a 75mm lens on FF to give the same FOV as 50mm on APS-C. A 75/2 on FF would perform identically to a 50/1.4 on APS-C - same FOV, same DOF wide open, etc. And you'd get the same noise performance, because on the Pentax system you'd be shooting at half the ISO of the Nikon system. That's one of the main points of the "equivalence" article - that 50/1.4 on APS_C is the equivalent in all ways that matter to 75/2 on FF.

In order to get *better* performance on the Nikon, you'd need a 75/1.4. And that would indeed be a much larger lens than a 50/1.4, all else equal (ie, no fair considering the possibility of a "pancake" design for the 75 unless you also consider it for the the 50).

Of course, at these focal lengths, size isn't a huge issue. But get into longer telephoto focal lengths, and it's a much bigger concern.

QuoteQuote:
Is your point that this Nikon 70-200 f/2.8 is technically comparable to the Pentax 50-135 f/2.8, but that the Nikon WEIGHS 5 lbs while the Pentax weighs only 3 lbs?
No. These are *not* equivalent lenses when comparing FF to APS-C. A 70-200/2.8 is a larger diameter lens than a 50-135/2.8. As I said, you'd need a 50-135/2 on APS-C to yield the same diameter - and hence the same performance on APS-C - as the 70-200/2.8.

Now, since these are constant aperture zooms, they use some of the "optical trickery" I referred to earlier so their *actual* diameter is less than the effective diameter. Plus the specs give the diameter of the body of the lens, not of the glass in it, which adds a relatively constant fudge factor. That's why youire not seeing as big a difference between the 50/-135 and 70-200 as you might otherwise expect. But look at them in person - it's actually a very significant difference.

QuoteQuote:
I'm pretty sure I'd get better results from the Nikon lens mounted on a D3 than I get with the Pentax lens.
Right, because of exactly what I've been pointing out over and over and over: it's a larger diameter lens. If someone were to make a 50-135/2, that would be the same diameter, and would yield the same performance as the 70-200/2.8.

QuoteQuote:
It seems to me that the difference in the SIZE of the lenses is less of an issue if you tend to shoot things that are closer....
Well, let's say it's less of an issue at shorter focal lengths. Distance to subject isn't what matters. After all, landscapes are often shot with wide angle lenses focused close to infinity.
09-02-2009, 03:14 PM   #78
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QuoteOriginally posted by Marc Sabatella Quote
??? Which specific lens are you referring to? I was never considering a case where an FF user has something faster than f/2.8 available to even have the option of "stopping down" to f/2.8.


AAARRFFF. Sorry, simply a careless verbal mistake on my part. By "stop down" I meant, you know, bring the F-number down. In other words, I meant "open up" to f/2.8 from f/4 - assuming that the full-frame user had an f/2.8 lens. The Nikon 70-200 that I referred to already is, in fact, an f/2.8 lens.

Sorry to have confused things carelessly. They're confusing enough already!

Will
09-02-2009, 03:21 PM   #79
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QuoteOriginally posted by WMBP Quote
AAARRFFF. Sorry, simply a careless verbal mistake on my part. By "stop down" I meant, you know, bring the F-number down. In other words, I meant "open up" to f/2.8 from f/4 - assuming that the full-frame user had an f/2.8 lens. The Nikon 70-200 that I referred to already is, in fact, an f/2.8 lens.
Meaning it's much larger than the 50-135/2.8 (and it truly is). A 70-200/4 would be the same diameter and hence otherwise equivalent to a 50-135/2.8 when comparing FF to APS-C. You can't just compare any old lenses. You have to realize that to get the same results as a given APS-C lens, you need a lens that is 1.5X longer but a stop slower on FF. At that point, you;ll have the same FOV, same DOF, and same noise performance for a given shutter speed.

If you give yourself the luxury of buying the longer lens FF that is as fast in maximum f-stop as your APS-C lens (eg, f/2.8 in both cases), only then can you see an noise advantage, but the lens *will* be physically larger than the one you were using on APS-C, and DOF *will* be shallower. And *that's* how you'll be paying for your improvement in noise performance.

09-02-2009, 03:32 PM   #80
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QuoteOriginally posted by Marc Sabatella Quote
In order to get *better* performance on the Nikon, you'd need a 75/1.4. And that would indeed be a much larger lens than a 50/1.4, all else equal
Well, here's a Nikon 85mm f/1.4. Hardly huge. Very expensive. But I do understand that doubling the size of a lens that wasn't big to start with produces a lens that is still not too big, while doubling the size of a lens that is pretty big means you end up with a monster. Although the Pentax mount 'Bigma' deserves its name.

I also do understand the equivalence ratios. But I keep returning to the lenses that are actually available and you keep reminding me of the theory. I may have worn us both out. :-)


*

I've always understood - I think because I read it, but perhaps I made it up - that the noise advantage of full-frame cameras came from the fact that they could have larger photosites - larger light-collection buckets. In other words, it's not the simple dimensions of the sensor that matters. One of the supposed innovations or advantages of the K20D was that the sensor, while the same size as the K10D's, had bigger photosites and this in turn was supposed to mean less noise. Was I simply mistaken?

Could Olympus produce a 4/3 or micro 4/3 camera whose noise properties rival those of a Nikon D3X - simply by providing larger diameter lenses? Isn't there a reality ceiling here somewhere beyond which it's impossible to go technically?

Will
09-02-2009, 03:34 PM   #81
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QuoteOriginally posted by Marc Sabatella Quote
If you give yourself the luxury of buying the longer lens FF that is as fast in maximum f-stop as your APS-C lens (eg, f/2.8 in both cases), only then can you see an noise advantage, but the lens *will* be physically larger than the one you were using on APS-C, and DOF *will* be shallower. And *that's* how you'll be paying for your improvement in noise performance.
Well, that and MasterCard.

Will

(trying to lighten things up before I collapse)
09-02-2009, 03:46 PM   #82
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QuoteOriginally posted by WMBP Quote
Well, here's a Nikon 85mm f/1.4. Hardly huge.
Filter size 77mm as opposed to 49mm for the Pentax 50/1.4. That's pretty much exactly the sort of increase in diameter one should expect. But indeed, not a huge issue at this focal length.

QuoteQuote:
I've always understood - I think because I read it, but perhaps I made it up - that the noise advantage of full-frame cameras came from the fact that they could have larger photosites - larger light-collection buckets. In other words, it's not the simple dimensions of the sensor that matters.
I've heard this too, many times, but now understand it to be, at best, misleading. Because reducing the pixel count on a smaller sensor doesn't make it do as well. The high resolution FF cameras of today have smaller pixel sites than the low resolution APS-C cameras of yesterday.

QuoteQuote:
Could Olympus produce a 4/3 or micro 4/3 camera whose noise properties rival those of a Nikon D3X - simply by providing larger diameter lenses? Isn't there a reality ceiling here somewhere beyond which it's impossible to go technically?
Undoubtedly. Olympus is the only company to offer a constant aperture f/2 zoom as it is, which is good for them, because that's needed just to compete with the f/2.8 zooms on APS-C. But given that there are practical as well as theoretical limits on how wide an effective aperture can be, you *won't* be seeing P*S cameras with their tiny sensors ever making up for it with larger and larger lenses, even if such a thing (tiny camera, huge lens) would be marketable.
09-02-2009, 04:04 PM   #83
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I guess the difficulty I'm seeing with the comparison is that you can't actually make an apples to apples comparison when you're trying to compare the attributes of an orange to a watermelon.

Based on what I'm seeing, to get the same noise, FOV and DOF, you're using faster, wider glass on the APS-C camera and shooting at a lower ISO. To me, there is no comparison because no matter what you do, you will never have an even playing field as they're different formats, with different attributes. You have to handicap the strengths of one format to equal the other.

I don't see the purpose as whether you have an APS-C or FF camera, you're going to compose and execute a photograph based on the camera and lens you have, not the camera and lens you don't have (or aren't using at the moment).

09-02-2009, 04:30 PM   #84
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While I appreciate the general point being made about FF and APS-C equivalences, it is worth noting that noise performance, and some other IQ issues such as dynamic range, are still going to be impacted by sensor quality/efficiency/sensitivity/technology, no matter what is going on in front of the sensor. This applies to APS-C, FF and also the comparisons between them.
09-02-2009, 04:30 PM   #85
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QuoteOriginally posted by Andrew Faires Quote
I guess the difficulty I'm seeing with the comparison is that you can't actually make an apples to apples comparison when you're trying to compare the attributes of an orange to a watermelon.

Based on what I'm seeing, to get the same noise, FOV and DOF, you're using faster, wider glass on the APS-C camera and shooting at a lower ISO. To me, there is no comparison because no matter what you do, you will never have an even playing field as they're different formats, with different attributes. You have to handicap the strengths of one format to equal the other.

I don't see the purpose as whether you have an APS-C or FF camera, you're going to compose and execute a photograph based on the camera and lens you have, not the camera and lens you don't have (or aren't using at the moment).

In general, Andrew, you've summed up what I've tried to say in, um, my last 37 tiresome posts.

However, there may be a practical point here, at least for some of us. I think all the time about buying a full-frame camera. Unless I win the lottery, I wouldn't abandon my Pentax cameras. Actually, even if I WON the lottery, I wouldn't give up on APS-C. But if I don't, I'm certainly not going to be shooting weddings with a couple of full-frame cameras around my neck. However, what I do think about - and what would be practical for me - is the purchase of one full-frame camera, with perhaps just one good lens in the 50-150 (35mm equivalency) range. I'd use it in church instead of my Pentax 50-135 f/2.8. It's possible to get a used Canon 5D these days at a pretty good price. And Sony now has a very attractive looking full-frame camera for less that $2K.

But this thread may lead me to conclude that full-frame is even less useful to me than I thought.

Will
09-02-2009, 04:36 PM   #86
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QuoteOriginally posted by Torphoto Quote
what am I doing worng here?
Torphoto, you repeat your question here. May I invite you to read again my response #17?
09-02-2009, 04:38 PM   #87
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QuoteQuote:
And finally, a good photographer with a K20D will outshoot Uncle Larry the camera collector with his D3X every day of the week, in any kind of light
QuoteQuote:
.
QuoteOriginally posted by stanleyk Quote
Thank you!!
Yup, that old horse gets trotted out of the stable at least once per thread when the going gets tough.
09-02-2009, 04:48 PM   #88
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QuoteOriginally posted by WMBP Quote
In general, Andrew, you've summed up what I've tried to say in, um, my last 37 tiresome posts.

However, there may be a practical point here, at least for some of us. I think all the time about buying a full-frame camera. Unless I win the lottery, I wouldn't abandon my Pentax cameras. Actually, even if I WON the lottery, I wouldn't give up on APS-C. But if I don't, I'm certainly not going to be shooting weddings with a couple of full-frame cameras around my neck. However, what I do think about - and what would be practical for me - is the purchase of one full-frame camera, with perhaps just one good lens in the 50-150 (35mm equivalency) range. I'd use it in church instead of my Pentax 50-135 f/2.8. It's possible to get a used Canon 5D these days at a pretty good price. And Sony now has a very attractive looking full-frame camera for less that $2K.

But this thread may lead me to conclude that full-frame is even less useful to me than I thought.

Will
The reality is that in theory you can compare apples to apples, but as has been pointed out, there are some apples you just can't buy.

I'm planning to keep a Pentax as a hi-quality street cam. Ideally, sell the K20d, buy the K7 and slap my 43/1.9 on the front, bringing along the 50-135* when I want something longer. The FF is for when I need a higher quality file or if I know I'm going to be in really low light (and sometimes they coincide). For an important shoot, I can have both FF and APS as the backup instead of my last situation where my backup was my DLux4 and the images were only good for small web display. Thankfully the K20d/31/77 combo did ok, but I know I can get something better. And since selling the 31 and 77, I'm part of the way there towards getting it
09-02-2009, 04:49 PM   #89
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QuoteOriginally posted by rawr Quote
While I appreciate the general point being made about FF and APS-C equivalences, it is worth noting that noise performance, and some other IQ issues such as dynamic range, are still going to be impacted by sensor quality/efficiency/sensitivity/technology, no matter what is going on in front of the sensor. This applies to APS-C, FF and also the comparisons between them.
Right. This is something that's been on my mind throughout this thread. The Nikon D90 - like the K20D, an APS-C camera - is supposed to have better high-iso, low-light performance than the Pentax K-7 or K20D and I assume it's not because everybody with a D90 is using lenses with bigger diameters. I assume it has to do with the processing engine, precise design (not size, but design) of the sensor, and other technical wizardry that I don't really understand (or need to understand).

What I have wanted to do throughout this thread is get a friend with a D3 to come over to my house and do some real-life comparison shooting with me. Unfortunately, I don't have a friend with a D3 handy here in east Dallas.

Years ago - in the early or mid-1990s - BYTE magazine (then the greatest of the geek magazines) devoted an issue to the RISC processor that was being used in Apple's new computers. The experts, talking theory mainly, agreed that the RISC chip was capable of speed that the CISC chips produced by Intel could not match and it was just a matter of time before RISC ruled the world. Well, Intel got more out of CISC than anybody thought possible and continues to do so, in part because Intel had so much more money to spend than Motorola and IBM and the other folks working on RISC designs. So the expert prognosticators in BYTE were right in theory - but wrong in fact.

Here, too, the theory may be correct, but the realities belie the theory. That is, when you're shooting in low-light, you might get an APS-C camera to produce results with noise no worse than those produced by a full-frame camera, simply by using a bigger lens. In theory. In practice, with real rather than abstract cameras, things seem a bit less certain to me. The Canon 5D, now long in the tooth, doesn't seem that much better than a K20D. The newer Nikon full-frame cameras, on the other hand, which have the same sized sensor, clearly produce cleaner images at the same settings than the Canon 5D.

But on the other hand, I'm hopeful that the large number of APS-C cameras being sold will result in more R&D being done on the APS-C so that before long we can get great results at ISO 6400 from a future Pentax K-3...

Will
09-02-2009, 04:50 PM   #90
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QuoteOriginally posted by Wheatfield Quote
Yup, that old horse gets trotted out of the stable at least once per thread when the going gets tough.
Such a cynic.

Will
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