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Old Feb 22, 2011, 2:06 PM   #1
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Default ISO vs Fast lenses- future considerations

I've wondered for quite awhile now...with camera technology improving by seeming leaps and bounds...will fast lenses...say for example...a 70-200 MM F 2.8...eventually, still fill a valuable niche for photographers ?

My new (in 2007) digital SLR was capable of 1600 ISO...which to me was astounding at the time.

In my early years of photography....400 ASA (now known as ISO) was a fast film. We shot 25, 65 ASA...personally I liked 100 ASA...sometimes used 200 ASA.

Graininess...or noise as it's known now, started to be an issue at 400.

Sometimes we 'pushed' film...say a 400 ASA to 800 ASA...to get the extra speed...to use in dimly lit, available light situations...but the trade off was not great....grain or noise as big as boulders.

Now 6400, 12,000 +....51 something...102,000 ISO is possible with some new DSLR's.

Every year we seem to have new higher ISO standards...the bar is constantly rising.

Noise at these higher ISO's is still an issue...but with some cameras I understand 3200, maybe 6400 ain't too bad.

I wonder within 5-10 years if ISO continues to go up and noise continues to go down...will we reach a point where a 70-200 or a 400...F 2.8....isn't worth it anymore ?

Will we be able to use a 400 F 5.6 , raise the ISO and get perfectly satisfactory pictures....with little noise...in dimly lit, indoor available light situations ?
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Old Feb 22, 2011, 2:57 PM   #2
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There are a few issues here:
First: higher ISO has no affect on DOF. This is both a pro and con. On the PRO side, higher ISOs allow you to "get the shot" with narrower aperture if you so choose. That's flexibility. BUT, on the CON side, if you want shallow DOF then higher ISO does nothing for you.

Second: focusing. Higher ISOs don't really impact focus ability. Wider apertures let more light in. So, other advancements beyond ISO noise performance will be needed for an f5.6 lens to focus with 4 times less light than an f2.8 lens requires. Or stated another way - independent of shutter speed - f5.6 lenses will struggle in lighting where f2.8 lenses focus fine in. And, heck,there are some environments where f2.8 focus performance is bad. So noise performance alone won't allow f5.6 lenses to operate in environments f2.8 lenses do today.
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Old Feb 22, 2011, 4:48 PM   #3
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Excellent points, John. DOF is a function of the lens, with no way around it, and the added light gathering of a fast lens should almost always make for better focusing ability.
I do have a question about high ISO and the contrast autofocus systems vs phase detect. If you have a DSLR with live view and high ISO capability, are you able to get better autofocus performance than you would using the optical viewfinder and phase detection under low light conditions? It seems to me that it should be that way, but I don't have both systems in one camera to try.

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Old Feb 23, 2011, 7:34 AM   #4
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Brian - honestly I've never used the liveview on my camera. Given it's age, I can't imagine it's a very good implementation - useful for tripod work but that's probably not the type of work we're talking about here anyway.
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Old Feb 23, 2011, 8:58 AM   #5
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This is photography. There is no substitute for light.

You will get less noise and greater dynamic range shooting at ISO 100 and f/2 than you will get at ISO 12800 and f/22.

And when you reduce the noise, you'll lose some detail, resulting in lower image quality.
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Old Feb 23, 2011, 2:59 PM   #6
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I've been experimenting a bit with live view vs. regular AF (I can't remember which is which at this point). In regular light it doesn't make a difference (as expected). However, in low light it does make a difference, where live view will be more accurate than regular auto focus methods. However, in really low light live view won't be able to focus at all, while the regular AF still indicates a focus lock (though it front focuses in really low light, it at least does focus). I found that my camera's live view magnification is good enough to manually focus, if there's enough light to see the subject.

I agree with John though - high ISO is nice and it will help in some situations where you want a big dof. However, there's no way you can replicate the dof at f2.8 with an f5.6 lens.

Another point - in general the faster the lens, the better glass and optics used. Shooting an f2.8 lens at f8 can often (but not always) give you a sharper, better picture than shooting an f5.6 lens at f8. There's always going to be a need for expensive, fast lenses (as I lust for a particular f1.8 lens).
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Old Feb 24, 2011, 4:15 AM   #7
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I agree no substitue for good glass. But I do see technology improving ISO quality at the higher end, to me that that just evolution very like fast computer chips keep coming out. As I said if you have good glass then that adds to the benifit, so you back to theres no substitute for good glass.
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Old Feb 24, 2011, 8:46 AM   #8
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Upping the maximum ISO setting on a new camera isn't rocket science. It depends on just how many bit shifts the manufacturer will permit. Every time you double the ISO setting, all you're doing is shifting the bits of every pixel in the digital image by one position.




Digital cameras capture image data in 12 bit, 14 bit, or even 16 bit registers, but just to make this simpler, I'll limit this to hypothetical 8 bit registers. In an 8 bit digital image:
  • 00000000 is Black
  • 11111111 is White
  • 01111111 is Gray
That gives you 8 bits of dynamic range, from 11111110 for the brightest white that wouldn't be the equivalent of a blown highlight, to 00000001 for the darkest gray that wouldn't be the equivalent of a lost shadow.

The way that digital cameras work is that photoreceptors count photons, and send an equivalent voltage to the A/D (Analog to Digital) Converter. If you want to increase the sensitivity of the image sensor by one ISO step, all the camera does is take that digital value that results from the A/D process of the voltage from the photoreceptor, and shifts the bits to the left, so that, for instance, 00111111 (Dark Gray) becomes 01111110 (Medium Gray.)

Keep in mind that I used 8 bit registers here to make this explanation simpler for me to write and for you to read. If these were 16 bit or even 32 bit registers, the process would be just as simple, but it would be more cumbersome for me to write and for you to read.

So the only thing keeping a manufacturer from having a maximum ISO setting of 6,553,600 is how large it wants to make those registers. So giving a new camera a higher ISO setting is nothing special.

And as for noise, I used to have a Konica Minolta 5D. It was a 6MP dSLR that was released in 2005. It could go as high as ISO 3200, but I wouldn't bother with anything over 800. I now have a Nikon D90, It's a 12MP dSLR that was released in 2008. It can go as high as 6400, but I wouldn't bother with anything over 1600. So I'm not really seeing any great advances in the handling of noise.
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Last edited by TCav; Feb 24, 2011 at 8:12 PM.
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Old Feb 24, 2011, 9:26 AM   #9
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Quote:
Originally Posted by TCav View Post
I now have a Nikon D90, It's a 12MP dSLR that was released in 2008. It can go as high as 6400, but I wouldn't bother with anything over 1600. So I'm not really seeing any great advances in the handling of noise.
Not all cameras and their implementations of a sensor and not all sensors are equally as effective in controlling noise. Nikon D3s and D700 produce very usable real-life photos at ISO 6400. Assuming the person behind the camera knows what they're doing with regards to high ISO photography. The D90 isn't the best representation of the advancements of high ISO implementation.
Here are some photos from another shooter using D700 and ISOs of 5600. Extremely usable photos. BUT, he's got great glass and he's a top notch shooter that knows how to shoot with high ISOs. I'm thinking these photos are quite a bit cleaner than what the old KM 700 could produce.
http://www.dgrin.com/showthread.php?t=153575

You can jump over to fred miranda forums and do some searches in their sports forum to see numerous d3s photos at 6400 and above that are quite usable.

When you think about it 1.5 - 2 stop advantage in ISO performance is HUGE. Not revolutionary, but still hugely beneficial.
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Old Feb 24, 2011, 9:38 AM   #10
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Or, a 5dII iso 12800 shot that was more than a stop underexposed. Sure noise reduction software has come a long way, but to have that kind of detail left in the hair at 12800 AND underexposed is extremely impressive:
http://forums.dpreview.com/forums/re...ssage=37602028
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