Why not ISO 50 and below?

Is it a crop sensor thing? Seems to be on the big girls but not on the 1.6 (unless the 7d has it?)

You can have 3200 and up, give me 50 instead!

There's a limit to how large a range the amplification can work with. Usually, the ISO 50 is just a mathematical construct anyway, something you can do in post processing with about the same result.

It's probably also a marketing descision, many more have problems with too little light than too much, and entry level cameras are more likely to use slower lenses.

When you say Big Girls, are you talking medium format or Canons 1Ds?

I'd like it even lower, say 25 ISO, but real, not just a "detuned" natural 100 or 200. The excessively high ISO rates being currently offered are of no interest to me.

Excessively high for your needs maybe, but there others who will really benefit.
I personally have little use for low ISOs, most everything is shot at 400 or higher

Lowner wrote in post #9085150
When you say Big Girls, are you talking medium format or Canons 1Ds?

I'd like it even lower, say 25 ISO, but real, not just a "detuned" natural 100 or 200. The excessively high ISO rates being currently offered are of no interest to me.

Exactly the same here. Whatever really re: the "big girls". I just want it on my 50D like the 5D2 and so on, and it seems that the xxD series misses out on 50 ISO.
I wouldn't care if it was any less noisy than 100 or whatever, I just want more ability to run longer shutters in certain circumstances without piling on the ND's etc.

apersson850 wrote in post #9085126
There's a limit to how large a range the amplification can work with. Usually, the ISO 50 is just a mathematical construct anyway, something you can do in post processing with about the same result.

unless you want some nice slow shutter speeds in bright sunlight of course. Are ISO settings not just gain control?

FretNoMore wrote in post #9085178
Excessively high for your needs maybe, but there others who will really benefit.
I personally have little use for low ISOs, most everything is shot at 400 or higher

That's why I said YOU can have 3200 and up. I'll trade you my 6400 for a 50 anyday, I'll even chuck in a completely useless 12800 (useless for me ) in the deal!

We get lots of sunny days down here you know!

Anders,

I don't critise your wish to shoot at 400 or above, but do understand that this photography game is a very broad church. While I do use 400 at times, it is extremely rare, 99% of the time I'm at 100 and would love a "clean" 25 ISO.

No criticism assumed.

BTW, I don't at all wish to shoot over ISO 400 - I have to.

Of course I wouldn't mind having a broader ISO range. There are many functions in my cameras that I never use but I'm not bothered by them. I think however there are technical considerations that have made Nikon use a base ISO of 200, and Canon ISO 100. I'm guessing like the other Anders above that there is a limited amplification range, and in that case I personally prefer higher ISOs. For my limited needs of slow shutter speeds I can always use a grey filter, but there is no way of increasing the ISO sensitivity in low light.

But that's why I'd like a real 25, I don't like putting extra filters onto glass that has cost me "a lot", certainly far more than the bodies I currently use. Even with the ND filters, the real ISO is still 100.

I'm guessing now, but maybe this has to do with noise. You'll always have noise in electronics, and if you make the sensor less sensitive you'll gather less light and thus get worse signal to noise performance. (Again, just guessing now). If the idea of having lower ISOs is better image quality as in the film days maybe this is not possible with digital, you'll get more noise instead.

Sadly I suspect you are right

pixelbasher wrote in post #9085120
Is it a crop sensor thing? Seems to be on the big girls but not on the 1.6 (unless the 7d has it?)

You can have 3200 and up, give me 50 instead!

The people who really do need less than 50 (or less than 100 on 1.6X) can usually manage with ND filters.

For technical reasons, going to even ISO 50 is an IQ degradation from ISO100, and offering up even lower values such as 25 or 12 might be nice from the standpoint of not needing ND filters but the lack of dynamic range might be too much to really fulfill expectations.

JeffreyG wrote in post #9085453
For technical reasons, going to even ISO 50 is an IQ degradation from ISO100, and offering up even lower values such as 25 or 12 might be nice from the standpoint of not needing ND filters but the lack of dynamic range might be too much to really fulfill expectations.

Is that right? I didn't realise the 50 in the cams that have them gave more noise than 100......interesting.

And yeah, I know a filter will cover most bases, it would be nice to simply dial down the ISO to less than 100 in quite a few circumstances. But if there are IQ issues with doing that, then I guess that's why mine doesn't have 50 or less. Having said that, the IQ degredation at figures below 100 can't possibly be worse than shooting at 12800!

JeffreyG wrote in post #9085453
The people who really do need less than 50 (or less than 100 on 1.6X) can usually manage with ND filters.

For technical reasons, going to even ISO 50 is an IQ degradation from ISO100, and offering up even lower values such as 25 or 12 might be nice from the standpoint of not needing ND filters but the lack of dynamic range might be too much to really fulfill expectations.

I'd like to see the science behind that statement. Not saying its wrong, just would like proof. Its the opposite of the film world.

Researched a little...
An ISO 50 image is captured at ISO 100 and processed in camera to lower the effective sensitivity.

Canon:
http://www.usa.canon.c​om …tArticleAct&art​icleID=268
(My summary: ISO 50 has about the same noise as ISO 100 but one stop less dynamic range)

Chuck Westfall:
http://www.digitaljour​nalist.org/issue0905/t​ech-tips.html
(My summary: ISO 100 has the best overall image quality in terms of noise and dynamic range)

So maybe there's is not much of a hit in terms of noise but rather in dynamic range, and that would at least be a bad thing for things like landscapes where you may have both strong highlights and dark shadows.