"Sweet Spot" for ISO best sensor performance

[icqcq]

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I am, as we speak, working towards a new sort of metering system... the good news is that our exposure parameters are all based on halves/doubles, the only real problem is this range of units, another problem I'd love to solve, but then I'm attacking everything we've inherited.

 

But it may be time for revolution, rather than evolution.

[CheshireCat]

You shoot at 3200: you've pushed the sensor four stops: that information is buried, in the same way that shooting at 200 and underexposing by four stops would be buried. But because you've dialed in ISO3200, the software says, "Ah! I will now push the information up four stops, such that my master might chimp it!"

 

 

ISO is not just a number in a file. It controls the hardware gain (signal amplifier).

When using ISO, the data saved in the raw file are not underexposed.

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[icqcq]

That's more or less what I'm saying: the sensor has thirteen stops of latitude. Anything that falls within that range can not, by definition, be overexposed or underexposed: it is merely data that has been captured by the sensor. 

 

As for signal amplification, that's my reference to the software saying, "Ah! I will push this data up where Master might chimp it!" The raw data remains the same.

Edited March 13, 2016 by icqcq

[ECohen]

I do like the way this conversation is going.

 

But I think, until Leica changes the hardware and firmware...to accommodate me the sensor and a new metering system, 

I'm going to stick to ISO 200 as the base and a shooting style that mixes to old and new.........underexposing as needed for some shots...and using the camera as it was designed for most.......that seems like a comfortable plan

 

Unless you all have a better way to enjoy this 2016 version of the M240? I'm open to new ideas thats why I started looking for the sweet spot which is also a "sweet spot" in a shooting style as well.

 

Great conversation is Leica and other camera manufactures listening? Do you think the "photographers" shooting today be open to the change or a new way of working? 

 

......I would !  But I would also like a better Auto button on Camera Raw...as a starting point  ( not because I cant do it myself but because there will be to many photos to "fix")

and a nice Jpg, however the firmware chooses to process it,  for my cameras LCD ...I shot film too long to give up the preview feature that digital affords  me.

Edited March 13, 2016 by ECohen

[marchyman]

According to http://dpanswers.com/content/tech_iso.php 

 

The idea behind letting the photographer adjust ISO is mainly to ensure that the full input voltage range of the A/D Converter is utilised. This means that the full bit depth of the A/D Converter converter is used, so we get the maximum tonal range from the A/D Converter.

 

and

 

While setting a higher ISO speed on the camera does not change the base ISO of the sensor, doing so it still impacts on the RAW data emerging from the A/D converter. The exact behaviour varies from model to model, but in most cameras, raising the ISO will result in less noise and a greater dynamic range than shooting at base ISO and increasing the exposure by means of software.

 

That so far has been my experience at anything more than 2 stops.   Shooting 400 and pushing it two stops is about the same as shooting at 1600.   Shooting at 200 and pushing it 4 stops is worse than shooting at 3200.

[ECohen]

Am I the only one that thinks that shooting at 200 400 800 or1600  gives me a perfectly fine well exposed photo RAW or Jpg ...with little to no noise.

and little to no post processing ...unless I choose to "polish "something.

 

Granted there are many situations where underexposing or better said ,exposing for the highlights" and "fixing"the exposure, color and the shadows, in Camera RAW is a valuable technique in my tool box........but not necessary as an only and best way to work all the time.

 

Thoughts welcome ...I'm looking for the best way to work these days and open to new ideas

[icqcq]

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All I'm saying is that, although those woven sandals served you well all those years in Florida, now that you've moved to Saskatchewan, maybe you should think about buying a pair of winter boots.

[CheshireCat]

As for signal amplification, that's my reference to the software saying, "Ah! I will push this data up where Master might chimp it!" The raw data remains the same.

 

Let's just make it perfectly clear that when we use the correct ISO setting, the hardware is pushing the analog signals from the sensor. The software is not pushing the raw data, not even for chimping.

In other words, using the correct ISO setting, the signals are pushed by the hardware to the correctly exposed level before they are even converted to digital and subsequently stored to memory (or saved to a raw file).

Edited March 13, 2016 by CheshireCat

[CheshireCat]

The firmware could then show a well exposed jpeg image whilst the raw file data would stay underexposed if i follow you well, right?

 

 

Sorry for being finicky, but it is not correct to say that "the firmware shows a JPEG".

JPEG is a compression format only used to store data.

The firmware simply shows the image developed using the internal software (think about a mini-Lightroom app inside your camera).

 

Since the displayed image is always going through this mini-Lightroom app (including EVF Live View), icqcq's idea is to just disable the analog gain in the hardware, and only use the ISO setting as a software input to the app, so the underexposed raw data would be displayed correctly.

And we are trying to find out if and when this idea makes sense.

[Exodies]

Looking at the ISO menu, it says pull 100, just the numbers from 200 to 3200, then push 4000 to 6400.

I presume this means 100 is halved after digitisation, the analogue signal is amplified after 200 and from 4000 on, amplified and then multiplied after digitisation. 

 

It isn't clear that amplification is more accurate than digital multiplying but presumably it is in the range it is offered. So, we shouldn't give up this choice - how much amplification we want between 200 and 3200 - as this is not reproducible digitally.

[pgk]

Granted there are many situations where underexposing or better said ,exposing for the highlights" and "fixing"the exposure, color and the shadows, in Camera RAW is a valuable technique in my tool box........but not necessary as an only and best way to work all the time.

 

As with everything, one 'rule' does not fit every situation. I vary my technique (though I really can't remember changing from base ISO) depending on subject and subject contrast. In my very high contrast example in post 50, its obvious that using any fixed ISO will result is substantial underexposure of the shadows but boosting ISO will simply mean that in order to retain highlights, the shadows will already have received some 'amplification' (albeit 'in camera') meaning that at higher than base ISO I would have underexposed the image even more to retain highlights. In this case I see nothing to be gained by boosting ISO and something to be lost. But for lower contrast images exposure will be different. I've tried the ETTR route on lower contrast images but not always found it to be optimal. Placing the mid tone centrally on the histogram works best for me in such situations with contrast adjustments used in post processing to retain the best 'quality' (least noise). So I would not advocate one exposure system for all situations. I prefer to fit the way I expose to the situation I am facing and accept that there will be times when there are trade offs such as increased noise in some images. This does not bother me if the image itself can overcome such features which often it can.

 

But back to ISO. In film days ISO had a different definition to digital ISO as it was based on a film's characteristic curve and obviously sensors do not inherently have a film type sensitivity curve. IMO using an 'ISO number', even if based on a different, digital definition, is where things fall down. It confuses sensitivity explanations of two very different technologies because it utilises the same descriptor. I'm sure it does so because continuity was seen as a 'good thing' by camera manufacturers when digital started to impact on consumers, but has left a legacy in terms of film and sensor sensitivity thinking which is difficult to change and which leads to the adoption of old ways rather than a potential progression towards newer ways. Just MO of course.

Edited March 13, 2016 by pgk

[ECohen]

All I'm saying is that, although those woven sandals served you well all those years in Florida, now that you've moved to Saskatchewan, maybe you should think about buying a pair of winter boots.

 

 

Point taken .......

 

Your l issue should be with camera manufactures for the hybrid camera we are all now using today.

 

I am simply  wondering how this group uses their camera/makes photos? Many of us use Leica because it's set up like the analog cameras we love ... it has a rangefinder and a simple menu with only the features I need.

 

As for buying a new pair of boots.......of course. Its photography ever changing. I used to "expose for the shadows and develop for the highlights"  

Now because of my new boots I "expose for the highlights and develop for for the shadows"   ......and other techniques using Photoshop

 

But because of how my hybrid camera is designed I don't "expose for the highlights and develop for for the shadows"  all the time. Because  the LCD works /Live View works/and the industry for whatever reason, developed no noise at 200 400 800 &1600......so I use them.....in many of my shooting situations.

 

Just like when I was shooting professionally I didn't use the Zone system on every job, but it was in my mind every time I choose where to meter the scene. The same today, I think about the sensor every time I set the camera. And a step furtherer I also thought about CCD sensor differently than the CMOS.

 

I applaud your simple explanation of how and why you always "expose for the highlights and develop for for the shadows" . I think what bugs me is that, you do it as if we don't understand the difference between digital and analog photography.

 

I like change.......even though I use a rangefinder   I also think you are 100% correct its time cameras changed, meters, firmware etc. 

 

A cameras purpose is to capture an "accurate" image and supply me with a file that I can manipulate to my personal vision........ I also want an LCD 

 

I say we put you on the Leica design team and please keep me in mind for your beta tester.

(to be clear this statement is not sarcasm I sincerely applaud you vision and passion)

 

 

And back to my original question how does the majority of this group use the hybrid Leica we have in our hands today?

Although Im starting to think Leica is with you because they are coming out with digital cameras that don't have an LCD? ....which I think is nuts.

 

Edited March 13, 2016 by ECohen

[marchyman]

I don't know what the majority does.  My M doesn't have live view or an EVF (M 262 owner).  I mostly use auto ISO capped at 1600 and try to pay attention where the camera is pointing when I lock exposure with a half press.   Interesting enough I do pretty much the same thing when using my Q with live view and an EVF.

 

Once in a while I'll lock in a specific ISO, mostly when I'm OK with slower shutter speeds and don't want the camera boosting the ISO to keep the shutter speed up.  If shooting with a tripod I'll most likely pick a specific ISO.

[icqcq]

This minority is just learning of all this magical/whimsical thinking on the part of the designers and programmers of our cameras....

 

So, up til now, I had just gone along on the ride: dial in a nice, comfy ISO, season with aperture and shutter speed to suit, and mangle the results in LightRoom. 

 

But I'm a changed man, now. Changed, I tell you.

Edited March 13, 2016 by icqcq

[lct]

[...] And back to my original question how does the majority of this group use the hybrid Leica we have in our hands today?

 

I can't speak for the majority but i use digital the same way as i did with transparencies basically i.e. exposing for the highlights mostly. What is new is auto iso mode that i find quite usefull actually, provided i can set the maximum sensitivity though. How would i do this if our briliiant collegues suceeded in getting isos replaced by something else? I have not the least idea but why doing simple when one can complicate? Just kidding folks.

[ECohen]

This minority is just learning of all this magical/whimsical thinking on the part of the designers and programmers of our cameras....

 

So, up til now, I had just gone along on the ride: dial in a nice, comfy ISO, season with aperture and shutter speed to suit, and mangle the results in LightRoom. 

 

But I'm a changed man, now. Changed, I tell you.

 

 

Your OK with me.  I'll be thinking of you every time I  "expose for the highlights and develop for for the shadows"  and when camera manufactures catch up with your thinking

 

 

​Please stay on this forum and keep us abreast as to how you modify you work style. 

Edited March 13, 2016 by ECohen

[AlanG]

If you have 13 stops of range, they will represent 8192 shades of grey. If you underexpose by one stop you will only have 4096 shades to work with.  By the time you underexpose by 5 stops there will only be 256 shades of grey to represent your entire scene. Since every reduction of a stop cuts in half the remaining shades, at 5 stops underexposure, your shadow details will have very few shades left to work with.  E.g. if you cut out 5 stops, you have 8 stops of range left to work with. The shading within those ranges will be more rough the darker the tone. Between stop 8 and 7 you have 128 shades of tones. Between 7 and 6 64.. Between 6 and 5 32. Between 5 and 4 16 tones... etc.

[pico]

While we're at it, I'd like to propose a new nomenclature for apertures, based on percentages

Percentage of what, please? Where would zero be?

 

Excuse this old analog film guy. When I look at exposure response curves I know I am looking at log.

[icqcq]

An f1.0 lens has a front element:focal length ratio of 1:1. That's the starting point: f1.0 then becomes Ø100. The aperture currently known as f1.4 allows half the light through that an f1 does, so it becomes Ø50, f2 becomes Ø25, f2.8:Ø12.5, f4:Ø6, f5.6:Ø3, f8:Ø1.5, f11:Ø.75....

 

This at least gives the user a logical progression; since shutter speed is fractions, going with percentages differentiates, while also providing a similar sequence that doesn't require a savant or chart to follow.

 

As for the beloved Nocti, there's no reason it can't be an Ø105.

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Hallo,

Look here: Interesting Leica gear

[CheshireCat]

Percentage of what, please? Where would zero be?

 

 

I think he just does not like the logaritmic stuff, and wants to linearize the aperture (i.e. make it proportional to light flow).

Something like new l-stop concept:

f/1 = l/1

f/1.4 = l/2

f/2 = l/4

f/2.8 = l/8

et cetera. This makes it clear that a f/2.8 lens needs 8 times the exposure of a f/1 lens.

 

Now, while we are at it, let's change other stupid units and make 10 seconds in a minute, 10 minutes in a hour, 10 hours in a day, 10 days in a week, 10 weeks in a month, and 10 months in a year. Thank you