Base or Pull

[jonoslack]

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Hi Jono,

 

Yes, the issue is rather academic.

 

Nevertheless, the base ISO is theoretically 100 because of what considerations?

 

dgktkr

 

Well, I'm not certain of the considerations, only the practicalities!

[pico]

Hi Jono,

 

Yes, the issue is rather academic.

 

Nevertheless, the base ISO is theoretically 100 because of what considerations?

 

dgktkr

Base ISO is where the manufacturer believes the sensor has the best balance of data vs noise - a careful compromise.

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[dgktkr]

Base ISO is where the manufacturer believes the sensor has the best balance of data vs noise - a careful compromise.

 

 

That's reasonable, if a bit vague. A little more specific might be the best combination of dynamic range and signal to noise.

 

So, at what ISO does the 601 sensor have the best combination of dynamic range and signal to noise? Doesn't DxOmark show that both are best at ISO 50: http://www.dxomark.com/Cameras/Leica/SL-Typ-601---Measurements? So why might one state that the base ISO is 100?

 

dgktkr

[pico]

The answer is to test it yourself. I understand that a hard metric would be useful, but only you, the photographer/artist can determine what is best. Look to Jono's response.

.

[jrp]

It may also vary with the firmware. Perhaps it was during my honeymoon period but I loved the (night) colours of the original 1.1 firmware. However, performance dipped at ISO 200 (ie, was better at ISO 400). That was corrected (perhaps reverted to the beta) in 1.2 and the colours no longer seem so special. Version 2 of the firmware makes no claims to image quality improvement.  

[steppenw0lf]

The answer is to test it yourself. I understand that a hard metric would be useful, but only you, the photographer/artist can determine what is best. Look to Jono's response.

.

 

 

If I can test it, then the producer can as well. And as this is a technical question I expect a clear answer from Leica.

What I do afterwards is my decision, but why would each one of us do this sh... measurement, if the camera costs so much. I expect this, exactlly as the consumption or mileage numbers for cars. And it is possible that we are told a complete lie, but I expect an answer.

This is a very small question to a big company. (Leica can answer, or the chip producer, or the designer, ...    but certainly not "it depends on each user." What a nonsense !!)

 

Again, it is not a very complicated or very important question, so why not give a clear answer and: That's it.

Edited April 22, 2016 by steppenw0lf

[349A]

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So why not ask Leica yourself? Then let us all know.

[pop]

If I can test it, then the producer can as well. And as this is a technical question I expect a clear answer from Leica.

What I do afterwards is my decision, but why would each one of us do this sh... measurement, if the camera costs so much. I expect this, exactlly as the consumption or mileage numbers for cars. And it is possible that we are told a complete lie, but I expect an answer.

This is a very small question to a big company. (Leica can answer, or the chip producer, or the designer, ...    but certainly not "it depends on each user." What a nonsense !!)

 

Again, it is not a very complicated or very important question, so why not give a clear answer and: That's it.

Ah, you seem to expect that the required ratio remains the same at all temperatures and exposure times. Have you  any particular reason for that expectation?

[pico]

If I can test it, then the producer can as well. And as this is a technical question I expect a clear answer from Leica.

 

ISO is self-reported, and Leica is just one in the crowd. There are many variables to interpret and there IS NO STANDARD. Live with it, learn-up or go away. You have eyes. Use them.

.

Edited April 22, 2016 by pico

[steppenw0lf]

Ah, you seem to expect that the required ratio remains the same at all temperatures and exposure times. Have you  any particular reason for that expectation?

 

Pop.

 

Any simple answer contains a certain amount of over-simplification or maybe even "uncorrectness". I do not really mind ...

There is an answer to this question for the Q. (With the same problems that you mentioned. How do you explain that there is this number ?)

Why not for the SL ?

But no, I do not want to know why. I simply want the number.

 

(And many tell that there is no difference, so how could I "see" it ?  Am I a magician, Pico ? )

 

 

To change it into a "practical" question: Is it optimal to set the minimum for autoISO range to 100 ? Or even to 200 ?  What about 400 ?

Normally I would set it simply to the base - so what do you recommend ?

If the numbers are all equal I could take the one that suits me best which is typically the highest.

Edited April 22, 2016 by steppenw0lf

[349A]

100. Or 50. Or 100. Who cares.

[steppenw0lf]

I know nothing, so I try to find anybody who knows more. Remember Socrates ? (No, he was not from Brazil.)   

What is the optimal/recommended "Minimum for the autoISO range" ?

Edited April 22, 2016 by steppenw0lf

[dgktkr]

ISO is self-reported, and Leica is just one in the crowd. There are many variables to interpret and there IS NO STANDARD. Live with it, learn-up or go away. You have eyes. Use them.

.

 

 

Do you mean "base ISO"? I agree that that term is self-reported and undefined. and therefore, not very useful.

 

You probably already know this, but there is a standard for determining digital camera speed ratings: ISO 12232:2006. It's copyrighted by ISO: http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=37777, and it costs CHF88 to get the 17 page PDF file.

 

dgktkr

[pop]

Any simple answer contains a certain amount of over-simplification or maybe even "uncorrectness". I do not really mind ...

Well, if you really don't mind: my Simple Answer is 100. You're perfectly aware, of course, that this answer contains a certain amount of over-simplification or, perhaps, a bit of "uncorrectness", but in this case it's better than - say - 42.

[jonoslack]

 

To change it into a "practical" question: Is it optimal to set the minimum for autoISO range to 100 ? Or even to 200 ?  What about 400 ?

Normally I would set it simply to the base - so what do you recommend ?

If the numbers are all equal I could take the one that suits me best which is typically the highest.

 

As far as I understand this - and I have discussed it at length:

 

The optimal ISO minimum is 50 ISO - which is why Leica defaulted it to that

the technical base ISO is apparently 100 - but neither their tests, nor mine FWIW could find any difference between the two.

 

Will that do? 

[steppenw0lf]

Summary: I understand that several ISO levels produce about equal technical quality (50, 100, 200).

Because I tend to photograph in bad light I would like to have a camera that avoids very small ISOs, so I can (without remorse) choose a higher minimum for the autoISO range, e.g. 200. The result will be that many more photos will be taken at ISO200, compared to right now, when the camera takes most photos at ISO50.

As this will result in 4 times smaller length of exposure, there will be less jitter (my biggest enemy). Goal accomplished.

 

That's good enough for me. Thanks.

 

Stephan

[Jared]

Base ISO is theoretically determined by the combination of quantum efficiency, pixel size, read noise characteristics, and full well capacity. Basically, it's the amount of gain at which you get the best dynamic range. It's generally inherent in the sensor, but your implementation can make a small impact as well.

 

With a "pull" ISO you are allowing the pixels to saturate (hit the anti-blooming gate cutoff) by allowing in "too much" light for a correct exposure then pulling the exposure back down to its "correct" value during amplification. You lose some dynamic range in the highlights.

 

I know that Leica's product management says that ISO 50 is technicall a pull, but testing by DXO and others has shown no loss in dynamic range--even a slight gain at ISO 50 vs the base ISO of 100, so I wouldn't worry about using it at 50 or allowing the auto ISO to use 50 as the base. You can confirm this yourself easily enough by taking pictures at various exposures, measuring and picking an arbitrary noise floor, and then seeing how many EV you've got before you start to clip the highlights. In my own testing, I got about ⅓ EV of additional dynamic range at ISO 50, but that's easily within experimental error. Any differences between 50 and 100 are purely academic.

 

- Jared

[ramarren]

It may also vary with the firmware. Perhaps it was during my honeymoon period but I loved the (night) colours of the original 1.1 firmware. However, performance dipped at ISO 200 (ie, was better at ISO 400). That was corrected (perhaps reverted to the beta) in 1.2 and the colours no longer seem so special. Version 2 of the firmware makes no claims to image quality improvement.  

 

 

Actually, v2 firmware does have image quality improvements in it, in the JPEG engine. For my shooting using mostly raw files, I've seen little if any change at all from v1.1 to v1.2 to v2.0. 

 

I'm a little perplexed as to why this was such a big deal to you, Stefan. If the difference between ISO 50 and 100 was not instantly apparent to you, what does it matter? 

 

Since the Auto ISO low limit setting causes some exposure issues for me, I just leave my camera set to 50 to 125000 with 1/2f limit or lock it to ISO 400. These settings produce the right results for me, which I learned from studying the results I get. 

Edited April 25, 2016 by ramarren

[steppenw0lf]

Since the Auto ISO low limit setting causes some exposure issues for me, I just leave my camera set to 50 to 125000 with 1/2f limit or lock it to ISO 400. These settings produce the right results for me, which I learned from studying the results I get. 

 

 

The camera takes many shots at ISO50, but I would like my camera to prefer 100 or even 200, because that gives me shorter exposure times and less shaky pictures. This should be no problem as everybody agrees that there is no quality loss.

But currently I have to leave autoISO range untouched, because of the problems mentioned.

 

Stephan

Edited April 25, 2016 by steppenw0lf

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[ramarren]

The camera takes many shots at ISO50, but I would like my camera to prefer 100 or even 200, because that gives me shorter exposure times and less shaky pictures. This should be no problem as everybody agrees that there is no quality loss.

But currently I have to leave autoISO range untouched, because of the problems mentioned.

 

Stephan

 

 

But aren't these completely different issues compared to the question of whether the camera's base ISO is 50 or 100? 

 

The Auto ISO bottom limit issues are why all my setups default to ISO 400. I only set Auto ISO when I know that it behaves consistently for what I'm shooting. Whether the base ISO is 50, 100, or 200 is inconsequential to me because I can't see enough difference to be of significance.