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09-05-2009, 02:21 PM   #136
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QuoteOriginally posted by Haakan Quote

5. Thus one conclusion is that the only factor that really gives you better noise performance is having a bigger front lens (or more exactly larger aperture in absolute number) (it was falconeye who pointed this out)

6. In addition, also for lens combinations where you have same f values on both the FF and APS-C. e.g. 85mm f/1.4 and 55mm f/1.4, any time you use the lens at less than max aperture (e.g. you go to 2.8 on your 85mm to gain DOF) you can get exactly the same image in terms of FOV, DOF, shutter speed, having equal amount of noise, on your APS-C (using an aperture of 2.0 on the 55mm lens). I.e. a FF will not give you a benefit in lower noise unless you shoot all full aperture.

This is really the reason for the thread. I had always thought that FF gives you 1 EV lower noise, thinking that this would be seen across all high ISO images if you compared the two formats, even for images not shot at max aperture. This thread has made me realize that for me, in practice there would be very few situations where the FF would give me a less noisy image.

I do not know if that helped as summary, there is a lot more details in the thread though.

Haakan
Sure did, that was enlightening, especially since we all don't want to live with maximum aperture all the time with little DOF, so practically FF and smaller sizes noise won't have much difference from each other.

Thanks much.

09-05-2009, 02:28 PM   #137
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QuoteOriginally posted by Marc Sabatella Quote
If you literally use the same lens and same aperture, you get two very different pictures, due to the crop factor. Why would you want to compare noise in two very different pictures? That's why we've been focusing on making sure to use lenses and apertures that yield the same picture, and comparing the noise that way. Hence the notion of "equivalence" - the idea of figuring out what lenses and settings on one camera will yield the same *results* are on another, rather than blindly using the same lenses and settings regardless of results.
Yeah, I had a hard time mixing electronics and final image results, that's why the thread was all confusing for me. Point taken now, thanks.
09-05-2009, 09:43 PM   #138
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Thanks to Haakan, the OP, and other posters on this thread (such as Marc, Will, Falconeye.. more) for enlightening me and helping me understanding the true benefit of FF vs APS-C sensor format instead of just following what most people who "claimed" to know better said.

I had a discussion with friends who recently bought the 5D MK II and another one who is waiting to buy for the next D700 FF body. They both claimed that all professionals use FF format, and there is definitely a big advantage with low noise in high ISO because they read anything on the Internet about this, I must be wrong and I should not waste money on Pentax and APS-C body. What do I know, they must have learned all these "facts" from the Canikon camp not independent reviews. I am not going to argue about that... Now, I read this thread (every poster's contribution) and feel that my choice to stay on APS-C is not bad at all (my next upgrade would be K-7); with my setup of DA* 50-135mm f2.8, I would be no worse than 5D MK II 24-105mm L f4 which by the way will cost me twice as much.

Thanks again to all posters on this thread.
Alfred
09-05-2009, 10:36 PM   #139
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guys...screw all these calculations, a well-made sensor is a well-made sensor.

09-05-2009, 10:46 PM   #140
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QuoteOriginally posted by PNTXFTW12 Quote
guys...screw all these calculations, a well-made sensor is a well-made sensor.
what are you suggesting? care to elaborate?
09-05-2009, 11:44 PM   #141
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There are situations where an FF sensor would be definitely better than APS-C - when either the subject is stationary (so you can use a slightly slower shuter speed to retain the ISO advantage, while stopped down to obtain the same DOF), or far away (so you can use a larger aperture because the DOF wouldn't make a large difference). In either situation the ISO does not need to be increased, thus you'll get the FF noise advantage.

Also for WA, FF doesn't need an extreme focal length which often proves to be problematic at the edges. But again, in some situations you can stitch APS-C shots to obtain the same results.

A lens need not resolve many MP, so a cheaper lens on FF can be comparable to the best lens on APS-C (this is given the same total MP only!)

APS-C is definitely better than FF in some situations when bright light is available, for example your subject will fill the frame more fully in those tele shots with enough resolution to show the details, or in macro shots, where you'll never get enough magnification or enough DOF.
09-06-2009, 12:00 AM   #142
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QuoteOriginally posted by wolfier Quote
There are situations where an FF sensor would be definitely better than APS-C - when either the subject is stationary (so you can use a slightly slower shuter speed to retain the ISO advantage, while stopped down to obtain the same DOF), or far away (so you can use a larger aperture because the DOF wouldn't make a large difference). In either situation the ISO does not need to be increased, thus you'll get the FF noise advantage.

Also for WA, FF doesn't need an extreme focal length which often proves to be problematic at the edges. But again, in some situations you can stitch APS-C shots to obtain the same results.

A lens need not resolve many MP, so a cheaper lens on FF can be comparable to the best lens on APS-C (this is given the same total MP only!)

APS-C is definitely better than FF in some situations when bright light is available, for example your subject will fill the frame more fully in those tele shots with enough resolution to show the details, or in macro shots, where you'll never get enough magnification or enough DOF.
thus by saying that, there is no perfect or better sensor over the other.
09-06-2009, 12:26 AM   #143
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Original Poster
QuoteOriginally posted by wolfier Quote
There are situations where an FF sensor would be definitely better than APS-C - when either the subject is stationary (so you can use a slightly slower shuter speed to retain the ISO advantage, while stopped down to obtain the same DOF), or far away (so you can use a larger aperture because the DOF wouldn't make a large difference). In either situation the ISO does not need to be increased, thus you'll get the FF noise advantage.

Also for WA, FF doesn't need an extreme focal length which often proves to be problematic at the edges. But again, in some situations you can stitch APS-C shots to obtain the same results.

A lens need not resolve many MP, so a cheaper lens on FF can be comparable to the best lens on APS-C (this is given the same total MP only!)

APS-C is definitely better than FF in some situations when bright light is available, for example your subject will fill the frame more fully in those tele shots with enough resolution to show the details, or in macro shots, where you'll never get enough magnification or enough DOF.
Hi wolfier,
I agree that FF in some cases have an advantage (and as you pointed out there are also the opposite cases). But you first example is where it actually in real life does not have a noise advantage.

If you can increase the shutter time for FF, you can of course to the same for the APS-C, again giving the same noise performance. As discussed in the thread, when aperture is stepped down in order to gain DOF, you will not have any noise advantage with FF.

Best regards,
Haakan

09-06-2009, 06:52 AM   #144
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QuoteOriginally posted by wolfier Quote
There are situations where an FF sensor would be definitely better than APS-C - when either the subject is stationary (so you can use a slightly slower shuter speed to retain the ISO advantage, while stopped down to obtain the same DOF), or far away (so you can use a larger aperture because the DOF wouldn't make a large difference). In either situation the ISO does not need to be increased, thus you'll get the FF noise advantage.
Yes, but if you then add SR into the equation, you gain 3 stops for the stabilised system. Hence, buying stabilised lenses or cameras is more relevant than larger formats for stationary subjects.

QuoteQuote:
Also for WA, FF doesn't need an extreme focal length which often proves to be problematic at the edges. But again, in some situations you can stitch APS-C shots to obtain the same results.
A 17mm lens on APS and a 24mm lens on FF will have very similar distortion and edge performance issues. Compare the Pentax 17-70 F4 with the Canon 24-105 F4. The Canon lens actually has a lot more distortion, vignetting, corner softness, etc. etc. Yes, it has shallower DOF wide open....
QuoteQuote:
A lens need not resolve many MP, so a cheaper lens on FF can be comparable to the best lens on APS-C (this is given the same total MP only!)
Generally this is only true in the centre of the frame or stopped down. Cheap lenses on FF will have lousy edge performance, worse CA, worse vignetting......all of these faults are reduced when you crop the image.
QuoteQuote:

APS-C is definitely better than FF in some situations when bright light is available, for example your subject will fill the frame more fully in those tele shots with enough resolution to show the details, or in macro shots, where you'll never get enough magnification or enough DOF.
IMO, neither is "better" than the other, each has pros and cons. However, to exploit the advantages of FF you generally require higher expenditure on glass.

APSC is a very VERY good as a value for money format which for any photographer shooting regular stuff and printing up to A3 will likely meet all their needs. For anyone with $10k burning a hole in their pocket, you can eke out some advantages from FF, but its a myth to think you can somehow exploit cheap lenses on FF and match APSC on a low budget.

If there is anything to be learned from this thread its that buying good glass for your APSC camera is a good investment and will be on the whole a better solution than using average glass on a FF camera. Plus, the cheaper body means you can upgrade more frequently.
09-06-2009, 08:03 AM   #145
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To add something new to the discussion, I decided to check the low ISO ranges for various formats, possibly ignoring the marketing spec (using DxO sensitivity measuremetn instead):

FourThirds:
Olympus E-3: ISO 118
Panasonic G1: ISO 129

APS-C:
Pentax K20D: ISO 87
Pentax K-m: ISO 98
Nikon D300: ISO 145
./.
(yes, the K20D has a better SNR than D300 at lowest ISO, but not a better DR ...
for D300, SNR (11.72Bit) and DR (11.59Bit) are equal; not so for K20D, SNR (12.19Bit) and DR (10.61Bit) differ -- the explaination lies in the non linear full SNR log log plots ... K20D is less linear and better at brighter luminances, D300 better at darker ones )
./.
Nikon D90: ISO 145
Canon 50D: ISO 157
Canon 500D: ISO 92
Sony 380: ISO 87

FF:
Canon 1DsmkIII: ISO 73
Canon 5DmkII: ISO 73
(would have stellar dynamic range if not flattening out below ISO 800 )
Nikon D3X: ISO 78
Nikon D3: ISO 161
Nikon D700: ISO 162
Sony 850: ISO 101 (DxO mark out already!)
Sony 900: ISO 119


Conclusion:
Currently, the low ISO boundary is more vendor-specific than dependent on APS-C vs. FF.

Pentax, Canon, and Sony seem to offer true ISO 100 where Nikon does it only for the D3X.


The low ISO boundary is determined by two factors: "full well capacity" (a CMOS process parameter -- the better the lower the low ISO boundary) and "quantum efficiency" (another CMOS/microlens process parameter -- the better the higher the low ISO boundary).


If I think about it again, the maximum number of possible photons (before overexposure) hitting a square millimeter should be independent of sensor size. Therefore, the low ISO limit should be independent as well, giving the larger sensor a possible advantage for dynamic range (allowing longer exposure at the same physical aperture or a wider physical aperture (same f-stop), so that more photons overall can be collected before the sensor is "full"). This is confirmed by looking at some P&S: Nikon P6000 (ISO 94, marketing: 64) and Leica/Pansonic LX3 (ISO 53, marketing: 80).

BTW, a curiosity are the Hasselblads which stay at ISO 47 whatever ISO setting you use

Last edited by falconeye; 09-06-2009 at 08:52 AM.
09-06-2009, 11:12 AM   #146
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I don't know about much, but I would echo what Steve said. A lot of cheaper lenses look halfway decent on APS-C, because their corners are cropped out. Lenses like the limiteds of course, would be very strong on either format, but their price tag also bears that out. Wide angles and teles are expensive in either format as well.
09-06-2009, 10:01 PM   #147
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QuoteOriginally posted by *isteve Quote
Yes, but if you then add SR into the equation, you gain 3 stops for the stabilised system. Hence, buying stabilised lenses or cameras is more relevant than larger formats for stationary subjects.
Completely agree, that for stationary objects, with SR or a tripod, as long as you can get the same DOF, the sensor size doesn't matter anymore. Sloppiness on my logic.

QuoteOriginally posted by *isteve Quote
A 17mm lens on APS and a 24mm lens on FF will have very similar distortion and edge performance issues. Compare the Pentax 17-70 F4 with the Canon 24-105 F4. The Canon lens actually has a lot more distortion, vignetting, corner softness, etc. etc. Yes, it has shallower DOF wide open....
But when we stop the FF lens down from f/4 to f/5.6 for an equivalent DOF, would things improve? Also...when I'm talking about WA, it's 11mm on APS-C vs 17mm on 135 - from the limited examples I've seen, the 11mm lens does considerably worse at the corners - and then 9mm rectilinear lenses don't really exist to get the same FOV as a 14mm 135 lens.

QuoteOriginally posted by *isteve Quote
Generally this is only true in the centre of the frame or stopped down. Cheap lenses on FF will have lousy edge performance, worse CA, worse vignetting......all of these faults are reduced when you crop the image.
Point taken. The curiosity now lies in the question whether things will improve when the 135 lens is stopped down by 1 stop...

QuoteOriginally posted by *isteve Quote
Plus, the cheaper body means you can upgrade more frequently.
This one about frequent body upgrades, I have to disagree. The money would be better spent on lenses regardless of sensor size, especially given how quickly Pentax bodies depreciate - look up on Craigslist and you'll be surprised to find the used price of a D70 to be about the same as that of a K10D. Lenses, on the other hand, always give you better results when you own it, and always sells for better prices than bodies - if you buy them used, you may even make a profit when you resell them.
09-07-2009, 12:51 AM   #148
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QuoteOriginally posted by wolfier Quote
Completely agree, that for stationary objects, with SR or a tripod, as long as you can get the same DOF, the sensor size doesn't matter anymore. Sloppiness on my logic.

But when we stop the FF lens down from f/4 to f/5.6 for an equivalent DOF, would things improve?
Actually, I get a faster shutter speed for the same DOF on the APSC camera. The FF camera is only "better" if I want "less" DOF, not if I want more, and only if I have a lens of equivalent speed at the longer focal length. If I have a 200mm F2.8 lens on the APSC camera and a 300mm F4 lens on the FF camera (about the same size, weight and cost) there is no real advantage to the FF camera. I would need a 300mm F2.8 lens and they are a lot bigger and more expensive.

QuoteQuote:
Also...when I'm talking about WA, it's 11mm on APS-C vs 17mm on 135 - from the limited examples I've seen, the 11mm lens does considerably worse at the corners - and then 9mm rectilinear lenses don't really exist to get the same FOV as a 14mm 135 lens.
Sadly I would have to disagree.
Canon 10-22mm on APSC
Canon EF-S 10-22mm f/3.5-4.5 USM - Retest @ 15MP / Review
Canon 17-40mm on FF
Canon EF 17-40mm f/4 USM L (full format) - Test Report / Review

If you want a 9mm rectilinear lens, well OK, but thats generally quite a rare and exotic bit of glass. I have never had much use for any rectilinear lens much wider than 12mm because the perspective distortion and flare makes them hard to find a use for. The Nikon 14-24 FF lens is excellent, but IMO too fragile and vulnerable in the field.

QuoteQuote:
Point taken. The curiosity now lies in the question whether things will improve when the 135 lens is stopped down by 1 stop...
It will do nothing to aid distortion. As to other issues, check the reviews above.

QuoteQuote:
This one about frequent body upgrades, I have to disagree. The money would be better spent on lenses regardless of sensor size, especially given how quickly Pentax bodies depreciate - look up on Craigslist and you'll be surprised to find the used price of a D70 to be about the same as that of a K10D. Lenses, on the other hand, always give you better results when you own it, and always sells for better prices than bodies - if you buy them used, you may even make a profit when you resell them.
Still cheaper for APSC than for FF.
09-07-2009, 03:39 AM   #149
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My post #145 was too long to have been noticed. Let me repeat the relevant sentence:

The larger sensor has an advantage for low ISO dynamic range.

(allowing longer exposure at the same physical aperture or a wider physical aperture (same f-stop), so that more photons overall can be collected before the sensor is "full").


We all have been looking at the wrong end of the ISO range:
  • At the high ISO end, the advantage entirely comes from the bigger lenses able to collect more photons (this thread).
  • But at the low ISO end, the advantage entirely comes from the bigger sensor which is able to collect more photons before overflow.
09-07-2009, 05:10 AM   #150
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QuoteOriginally posted by falconeye Quote

The larger sensor has an advantage for low ISO dynamic range.

We all have been looking at the wrong end of the ISO range:
Now that's out of the box... on the other end
Thanks for the insight, all!
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