7 replies to this topic

[NickOn]

Can anyone explain, in simple terms, what is meant when the term native ISO is used, please?

[ScottinPollock]

https://www.bhphotov...derstanding-iso

[NickOn]

Thanks for the reply and link ScottinPollock.

 

Checking out your link, native seems to me to be the ISO which (paraphrasing) "does not get amplified or simulated"?  On my D300 that would be ISO 200 to 3200.  Either side of this I am into the Lo and Hi settings, which presumably are false settings created by the camera's software and are probably more prone to creating noise?  

 

Other internet research I've done has defined it as the lowest end of a range so it would be ISO 200 for my D300. There appear to be two different views on what native is?

 

I've also picked up this term "base ISO" which wasn't in the article in the link.  Is this the lower end of the ISO range of a sensor?

 

Any further thoughts or information would be appreciated.

[Merco_61]

The native ISO is the same as base ISO, which for the D300 is 200 as that is what the sensor puts out without any amplification at all. The extended ISO (Lo and Hi) are settings that aren't fully linear in response and therefore don't fulfill the standard set in the ISO requirements.

[NickOn]

Thanks for the reply Merco_61.  In between the Hi and Lo settings, I have a range of ISO 200-3200 on my D300.  Is this the range where I would expect to find ISO values that can be assumed to work without amplification?  With no amplification, they should give me images with least or acceptable noise?  I find that my D300 does not perform brilliantly with regards noise, beyond ISO 800. 

 

In another thread, I've got some useful comment on the wisdom or otherwise of moving to a D610 full-frame.  However, it's range is only ISO 100 to 6400, which to my inexperienced eye doesn't seem to be a lot more!

 

Am I also missing the relevance of the pixel count on the two cameras here?!

[Merco_61]

The only ISO that isn't amplified at all in the D300 is ISO 200. I don't remember how high it uses voltage overdrive to increase analog gain and where it switches over to digital amplification because a higher analog gain would affect the SNR too much. I don't hesitate to use ISO 1600 and reducing noise with dFine as I will not lose much detail yet. 3200 is another matter... I have shot with 3200 quite a bit, but then I make a thing of the noise and use it for ambience.

 

The D300 has a SNR of about 28@ISO 1600 when reduced to the 8 MP needed for a good 20x30 print. The D610 has 28@6400, which is a two step advantage. When it comes to DR, it works similarly. The D300 goes below the DR of a good, slow slide film @ISO 3200, the D610 not until @ISO 12800. The tonal range and colour sensitivity follows the same pattern with the D610 sensor getting to the same level 2 steps higher in ISO.

[ScottinPollock]

native seems to me to be the ISO which (paraphrasing) "does not get amplified or simulated"? On my D300 that would be ISO 200 to 3200.

Not quite... anything above native (or base) requires additional gain. In the case of the D300 that would be all ISOs above 200.

Hi and Lo settings use means other than traditional gain changes (algorithmical processing).

[NickOn]

Many thanks for the replies Merco_61 and ScottinPollock, they are both very helpful.

 

I'm reading from this that the superior dynamic range and more favourable signal to noise ratio of the D610 make it a significantly better tool than he D300 when it comes to working in challenging low light conditions?  I'm not decrying the D300, which I've used for some years and will keep doing so!  What I will get from the D610, with regards exposure, is two additional and usable exposure values.

 

The D610 is probably the furthest that I will get into the full-frame stable as D750 prices are beyond my budget!

 

Thanks for the clarification of terms such as native and base.  This all helps my understanding.