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"Sweet Spot" for ISO best sensor performance


ECohen

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I just wrote in a post  that I use ISO 200 and my "sweet spot" for best sensor performance...that got me thinking.

 

When I got my M I ran a few tests, nothing scientific and went with the conclusion that 200 ISO  gives me the best overall performance. Don't get me wrong I use the entire camera often smoothing grain  at 3200. And inside shooting at 1600, 3200 and rarely 64000.

.....I never use 100 ...it dosn't look right to me?

 

The more I think of it .....Am I looking at this as film? (I am an old film guy) Or more accurately am I still looking at the M like my old digital  cameras? Nikon's /Early Imacon's  that had seriously ISO flaws and the sweet spot was important. Leica and other manufactures have caught up with the tech curve and perhaps my sweet spot thinking is out dated? 

 

You guys are far more scientific and well as art people. What conclusions have you come up with? 

How do you think about your ISO in relation best quality file on the M240?

 

Thanks as always for your incite.
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You can maximize your dynamic range with (as far as I know ALL) digital sensors by shooting at base (200 in this case) ISO.  For most uses this is appropriate, assuming shutter speed and aperture selected are what is needed for the particular subject.

Edited by Schrödinger's cat
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Any other speed than "base" ISO is faked anyway. The sensor captures the light at its base ISO (presumably found  and set by the manufacturer after tests) and other ISO settings are extrapolated from that by amplifying the output signal of the sensor.

It's like having a 160 ISO film and effectively under exposing it by metering at ISO 640 and then developing it for more time. Only really possible in single sheets on Large Format... until the Digital camera meant you can do it frame by frame at the touch of a button.

 

John

Edited by jpattison
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Any other speed than "base" ISO is faked anyway. The sensor captures the light at its base ISO (presumably found  and set by the manufacturer after tests) and other ISO settings are extrapolated from that by amplifying the output signal of the sensor.

It's like having a 160 ISO film and over exposing it at 640 and then developing it for less time. Only really possible in single sheets on Large Format... until the Digital camera meant you can do it frame by frame at the touch of a button.

 

John

 

 

Thats my thinking ...Is it written by Leica that the Ms "base" is 200?

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Sorry, please ignore the bit you have quoted, I've correctly modified it to "effectively under expose the film by setting the ISO at 640 and dev for more time"

 

The M9 base is 160, Monochrom (Mk 1) is 320

I'm not sure about the M and Monochrom (Mk2)

 

John

Edited by jpattison
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The longer I used digital, the more I think that ISO in digital sensors is just a reference for us old guys who used film for years.  The base sensitivity of the sensor IS the sweet spot, and changing it to anything higher is just really a metering crutch for those of us who need it and still think in "stops of ISO."    The bottom line is that you can under expose by several stops and still recover light values in post processing when shooting at the sensor's native ISO.  

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hepcat raises an interesting idea: that our use of ISO is a concession to the previous way of thinking, in the same way that our computer interface still uses 'folders' as a system of organization, because that's the closest analogue: evolution overriding revolution. The conclusion is that the camera always shoots at one value, and extrapolates data from there... my furthering of that thought is that ISO is not unlike the gearbox in your car: the engine can only turn between a limited range of cycles, and the gearbox extrapolates that into usable power, allowing a greater range of speeds. Similarly, ISO allows our camera to extrapolate beyond the range that our aperture/shutter speed combinations can manage.

 

ps

the best part of the original post has been overlooked: the use of 'incite' - as in, 'to provoke violent response' - in place of 'insight' - as in, 'your understanding from experience.'

Remember: Never Read The Bottom Half Of The Internet.

Edited by icqcq
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to quote: icqcq......."the best part of the original post has been overlooked: the use of 'incite' - as in, 'to provoke violent response' - in place of 'insight' - as in, 'your understanding from experience.'

 

So I made a mistake ...get a grip and get back to the issue at hand 

Edited by ECohen
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to quote: icqcq......."the best part of the original post has been overlooked: the use of 'incite' - as in, 'to provoke violent response' - in place of 'insight' - as in, 'your understanding from experience.'

 

So I made a mistake ...get a grip and get back to the issue at hand 

 

Most of my internet posting is on dprview, where the atmosphere is a bit different.  Being accustom to their prevailing standard for internet behavior, it never actually occurred to me that a mistake had occurred :)

 

Liked your website Evan. :)

Edited by Schrödinger's cat
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Most of my internet posting is on dprview, where the atmosphere is a bit different.  Being accustom to their prevailing standard for internet behavior, it never actually occurred to me that a mistake had occurred :)

 

Liked your website Evan. :)

 

 

Thank You I appreciate that...really.  

I'm new to posting .....for the most part you are a very friendly bunch.  

Thats an old website pre Leica 

Edited by ECohen
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to quote: icqcq......."the best part of the original post has been overlooked: the use of 'incite' - as in, 'to provoke violent response' - in place of 'insight' - as in, 'your understanding from experience.'

 

So I made a mistake ...get a grip and get back to the issue at hand 

 

To the contrary: I assumed it was intentional, and a gentle poke at what often results from the simplest, least provocative inquiry.

 

And I did get to the issue at hand, but prior to this observation... next time I'll try the humor first, then my inciteful response.

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If you think about it, shooting any higher than base ISO is just telling the camera to apply gain, or increase amplification, to the information that the sensor delivers to the camera (I'm assuming that we are talking about RAW files in this context). I feel that doing this is actually limiting as it 'fixes' the data to an ISO reference point and whilst this may be beneficial currently, as RAW file processing software evolves we may be able to reinterpret RAW files far better in future - I can now produce far better files from RAW files than I could when I shot some 10 years ago.

 

So I've been shooting at base ISO for several years and relying on Photoshop to adjust for underexposure. I would say though that my experience of Leica files is that they often show significant noise but are less likely to show bad banding than many others that I've tried. Whilst noise can be tolerated, I find banding far less acceptable.

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pgk & CheshireCat:

 

OK, so if the M240 is ISOless, 'pushing' the ISO is detrimental to the image... so how does one go about shooting in low-light situations? Or 'exposure' is now irrelevant, because all of the data to retrieve is in the file just waiting for post-processing? In which case, what we're saying is that the effective latitude of the CMOS is outrageous, and aperture & shutter speed are only used for 'effect': depth of field and motion, respectively. So what I should be doing is shooting at 200 ("sweetspot") ISO, at whatever shutter speed & aperture give me the 'effect' I want, and handle actual 'exposure' in pp... I suppose the variable not considered is the use of ND filters in bright situations, but that's less the issue than working in low-light situations, when we'd want to 'push' the ISO up the scale.

 

Is this where we're heading with this conversation?

Edited by icqcq
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Is this where we're heading with this conversation?

 

In a way. Its easy enough to try - just shoot a series of shots with increasing underexposure and pull them back in post and compare them. Photography is a practical process ;) .

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That actually isn't what I meant ...By "sweet spot" I meant that was my starting point that I would like to use.... only if it makes sense. Like choosing Plus X/FP4 or choosing Portra 160, because I like the balance of grain to color/tone.....I would only choose Tri X or push to 1600 as a last resort ....or for an effect. I treat digital 3200 and 6400 the same as a last resort or for an effect.

 
I look at digital and  the sweet spot being 200 the same way ....if it that works for my exposure combination, great if not I adjust, being concerned when inside at around 1600, past that the quality is not to my liking.
 
I would never intentionally under expose just to use ISO200 and fix in photoshop because that adds new undesirable variables....more undesirable (to me ) than using the camera between 200 to 800 ...1600 is OK but I prefer the look of lower ISO. 
 
 I was wondering how you all decide where to start as far as ISO.  How do you think of ISO on the M as it factors into the creative process of making your exposure choices.
 
Thanks to all for your replies it is truly helping me grow as a digital photographer learning to see digitally 
 
And as an aside:
How do you all see ISO 100 ? 
Edited by ECohen
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I was wondering how you all decide where to start as far as ISO.  How do you think of ISO on the M as it factors into the creative process of making your exposure choices.

 
[...]
 
How do you all see ISO 100 ? 

 

 

I use ISO, and just try to stay at the minimum ISO possible for the exposure I need as a function of the "artistic parameters": speed and aperture.

 

ISO 100 is fake. The camera uses ISO 200, and then scales the levels in software. I never use it.

 

What I really miss is 1/8000s shutter speed in the M. But after all, only professional cameras have it ;)

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