M9 intermediate ISO settings

[douglasf13]

Since the in-camera sensitivity amplification control is a firmware control function, it can be updated just as much as raw converters can update how they process the data. How much it is updated is the question mark ... The evidence isn't conclusive that it is substantively improved any more frequently with raw conversion sw than it is with firmware updates.

The analogue amp quality can't be improved by firmware, although I guess that if Leica did come up with an in-camera software solution that was better than their amps, they could bypass the analogue amps altogether and just use software amplification in future firmwares.

Either way, even if the camera firmware updates did compete with raw converter updates, you can't use the camera firmware to improve a picture that you've previously taken, which is what I meant by future proof.

I still contend that, in terms of image quality, using any ISO above base ISO isn't necessary, at least if you use LR4 (which is the only converter I've tested.) However, in terms of practicality, using higher ISOs may still be convenient and necessary.

As far as A mode, I find it half baked in the M9 and earlier M cameras. Not having an AEL button (I believe the Ikon has one,) along with having very center weighted metering, forces you to recompose and re-lock metering if you want to take two or more shots in a row in S mode. If the camera had an AEL button, you could lock the exposure, or, if the camera had matrix metering, you'd likely be fine without recomposing, but the combination of those two omissions keeps me using M mode, which I'm fine with, especially considering the "ISO-less" behavior of the camera.

 

[Godfrey]

If you consider ISO 160 to be the only true ISO setting on the camera, and you're going to use software scaling in raw processing to control ISO, how do you evaluate and set exposure when the exposure required runs out of range? If the camera were truly ISO-less, you would just set the aperture you wanted for the focus zone and the exposure time you wanted for stabilization and blur effect, then process the images out to the right density. But I know that doesn't lead to the best results ...

The only Ms that have had AE are the M7, MP, M8 and M9 (plus its variants). So there's not a long history of AE controls in the Leica M. And I'm not sure what's so half-baked about it. The shutter release acts as the temporary AE-Lock on the second detent. If you want to take several exposures at the same setting, it's pretty easy to note the shutter speed and set it on the dial.. I use that technique on all my cameras much more than any of their AE-Lock buttons, as it is much more likely I'll forget to UNlock the AE-Lock and get the wrong exposure on subsequent shots.

Or I meter, get the right setting, then frame and adjust the EV compensation until I get the right setting. Now the metering can float a little bit but with the desired offset, and I can get multiple exposures. A notice stays on in the viewfinder to tell me that the compensation is active as reminder to re-set it.

There are many ways to work the camera... this works for me. Manual metering works for me too, as does Auto ISO a good bit of the time.

G

 

[douglasf13]

...If the camera were truly ISO-less, you would just set the aperture you wanted for the focus zone and the exposure time you wanted for stabilization and blur effect, then process the images out to the right density. But I know that doesn't lead to the best results ...

Yep, that's exactly the way I think about it, and ISO 160 is the only true ISO setting of the M9. I know that the more light that hits the sensor, the better my SNR, but I have to make trade offs with depth of field and motion blur. Whether you use the camera's "ISO" gain or your raw converter's gain, you're still making your exposure first, and then applying the gain AFTER the fact. You're not actually changing your base ISO like with film, but the camera companies designed things to be easier to understand for film photographers, so they stuck with calling camera gain "ISO" and made it somewhat consistent with whole stops of light...although, as we know, all of the manufacturers tend to use different "ISO" values.

That's why I'm telling Edward that using ISO 1250 and boosting in LR4 vs. using ISO 1600 in-camera isn't really going to make much difference, and the ISO 1250 file boosted in post may actually be slightly cleaner. An ISO 640 file boosted might be even better, etc.

As for A mode on the M9, it certainly is usable for some. I still occasionally use it when I know that I won't be taking two pics in succession at any kind of pace, but Leica's implementation is a little odd in reference to all of the other cameras that I've used with A mode. If the M9 had an AE lock button, like the Ikon, I'd likely use A mode more often.


p.s. I want to reiterate that not all cameras are nearly "ISO-less," like Canon DSLRs. It depends on the sensor/ADC design.

 

[Godfrey]

Hmm.

It's going to take some to convince me that there's much benefit to be had from externalizing the ISO adjustment, even if it is entirely software. It seems a theoretical nuance at best, and makes processing more difficult since you're always going to be punching the ends of the image processing tools' range.

Setting ISO in the camera also sets up an appropriate dynamic range that's easy to learn and understand. I suppose you can develop that information through experience in external pushing, but I'm unconvinced it's worth the effort.

 

[douglasf13]

The beauty of not raising the internal ISO (when using the cameras in question) is that you actually maximize your dynamic range without the risk of blowing out highlights. That is the main advantage. Also, like WB, it allows you one less adjustment on the fly when shooting raw, since you can just adjust it after the fact.

As I've mentioned, I do use an ISO above base ISO when shooting in lower light, but only when I want a usable jpeg review on the camera's lcd. There really isn't any technical reason to raise ISO outside of that, for me.

Various cameras work very differently in this regard. Some cameras use analogue gain to a certain ISO, and then switch to digital gain (like Canons,) some cameras use analogue gain to a certain ISO, and then just flag the converter to push the raw exposure after that point (like the Fuji X100,) some cameras don't actually raise ISO at all and just flag the raw converter to push exposure under the hood at all ISOs above base (like some MFDBs,) etc.

A telltale sign that a camera is more or less "ISO-less" is to look at their dynamic range plot. If it is a flat, linear line, the camera is likely close to being "ISO-less."

I may not be the best at explaining this, so here are 3 links with good leads about it:

Re: Please allow me to show my ignorance.: Open Talk Forum: Digital Photography Review (the green text in this post explains it well)

About ISOless: Sony Cyber-shot Talk Forum: Digital Photography Review

Google Translate

 

[Godfrey]

I'll do my own tests and see if its worth the trouble to figure out an entirely different way of operating both the camera and the image processing workflow. I'm as yet unconvinced.

G

 

[ghoonk]

Yep, that's exactly the way I think about it, and ISO 160 is the only true ISO setting of the M9. I know that the more light that hits the sensor, the better my SNR, but I have to make trade offs with depth of field and motion blur. Whether you use the camera's "ISO" gain or your raw converter's gain, you're still making your exposure first, and then applying the gain AFTER the fact. You're not actually changing your base ISO like with film, but the camera companies designed things to be easier to understand for film photographers, so they stuck with calling camera gain "ISO" and made it somewhat consistent with whole stops of light...although, as we know, all of the manufacturers tend to use different "ISO" values.

That's why I'm telling Edward that using ISO 1250 and boosting in LR4 vs. using ISO 1600 in-camera isn't really going to make much difference, and the ISO 1250 file boosted in post may actually be slightly cleaner. An ISO 640 file boosted might be even better, etc.

As for A mode on the M9, it certainly is usable for some. I still occasionally use it when I know that I won't be taking two pics in succession at any kind of pace, but Leica's implementation is a little odd in reference to all of the other cameras that I've used with A mode. If the M9 had an AE lock button, like the Ikon, I'd likely use A mode more often.


p.s. I want to reiterate that not all cameras are nearly "ISO-less," like Canon DSLRs. It depends on the sensor/ADC design.

That's an interesting view - based on what's been discussed so far, I'm getting the impression that outdoors, I could technically shoot at ISO160, f8, 1/400s and not worry too much about actual underexposure since I can push exposure to recover the image (except blown highlights and lost shadows)?

 

[edwardkaraa]

Thank you Douglas for the very interesting information.

I personally am still keen to know to which category the M9 belongs, but there doesn't seem to be any research done on this subject, so I guess we will never know.

On the practical side, it is quite reassuring for me that I can save underexposed files without quality loss (and even some quality gain ) so that I can only concentrate on not loosing the highlights. Chimping is an essential part of digital photography, so at least for me, I would still want to see well exposed shots on my LCD, so I don't think that I will apply the method in question. But it's good to know nonetheless

 

[Godfrey]

"Chimping is an essential part...?" Um. No. I use review when needed, but I often look only after I'm done shooting.

 

[douglasf13]

That's an interesting view - based on what's been discussed so far, I'm getting the impression that outdoors, I could technically shoot at ISO160, f8, 1/400s and not worry too much about actual underexposure since I can push exposure to recover the image (except blown highlights and lost shadows)?

The overall point is that shooting at ISO 160 and boosting in LR should be as good or better than shooting at a higher ISO in-camera, in terms of IQ, and you don't risk blowing highlights.

I should also mention that this assumes that you shoot uncompressed raw. I've seen evidence that it still might work ok with compressed raw, but I'm not sure, and I'd imagine that bringing up the shadows wouldn't work as well with compressed raw.

 

[edwardkaraa]

"Chimping is an essential part...?" Um. No. I use review when needed, but I often look only after I'm done shooting.

Well, I use the LCD review the same way I used Polaroid test shots in film days. Chimping is essential to verify exposure and composition, IMHO.

 

[douglasf13]

Thank you Douglas for the very interesting information.

I personally am still keen to know to which category the M9 belongs, but there doesn't seem to be any research done on this subject, so I guess we will never know.

On the practical side, it is quite reassuring for me that I can save underexposed files without quality loss (and even some quality gain ) so that I can only concentrate on not loosing the highlights. Chimping is an essential part of digital photography, so at least for me, I would still want to see well exposed shots on my LCD, so I don't think that I will apply the method in question. But it's good to know nonetheless

I certainly don't mean to imply that I think you (or Godfrey) should overhaul your enitre method of working. I was just trying to give a little insight on how the camera works, so you can make small adjustments if you feel like it.

Even if you do decide to explore these ideas, you don't have to take it to the extreme, because it could still help you with small ISO jumps. Since you were interested in the difference between ISO 1250 and ISO 1600, you could just leave the camera at ISO 1250 and boost a little in LR. You'd still have a usable image to chimp, and you won't risk blowing your highlights. That's all that I was trying to get at, originally, since most wouldn't find it practical to shoot ISO 160 all of the time, for various reasons.

As for your original question about intermediate ISO settings, you're right that it is tough to find a definite answer. To be honest, judging by the camera's performance data, and the design of the relatively outdated sensor that is similar to some MFDB chips, I wouldn't be surprised if every in-camera ISO used interpolation, rather than analog gain, but I'm not sure.

I did find another forum topic about the intermediate ISOs on RFF: Native ISO's on M9? - Rangefinderforum.com

p.s. The M9 does apparently use NR on raw files, and it gets stronger as the in-camera ISO raises. I wonder if the relatively small jump in SNR from ISO 1250 to ISO 1600 is because that is the point where Leica ramps up the NR a bit more? That would be my guess.

 

[edwardkaraa]

Understood, Douglas. I have to say the idea itself is very appealing, but not easy to use in practice, especially for someone who uses the LCD review often. But as I said, it is very reassuring to know that it is possible to save severely underexposed shots with little IQ loss.

Like you, I also suspect the M9 to use interpolation all the way due to the smooth transitions in the graph that I linked to.

 

[douglasf13]

You know, I may have to take back the comment about the M9 using interpolation the whole way. The "ISO Sensitivity" chart on DXO Mark would have likely been different, like the P45+, if the camera didn't use some kind of analogue ISO gain. I think the M9 might use analogue gain for ISO, but that still doesn't answer the question about intermediate ISOs.

 

[douglasf13]

Understood, Douglas. I have to say the idea itself is very appealing, but not easy to use in practice, especially for someone who uses the LCD review often. But as I said, it is very reassuring to know that it is possible to save severely underexposed shots with little IQ loss.

I would say that slightly underexposed shots is where the technique becomes really handy.

For example, lets say I have the camera set to ISO 640, f2, 1/30, and my meter is telling me that I'm about a stop underexposed. I can't open my lens any more, and I don't want to slow my shutter, so the usual coarse of attack would be to raise the ISO to 1250...or, with this new concept, I can just leave everything as is and fire away, since I can boost the exposure later in LR4. At just a stop underexposed in camera, the LCD review is still quite usable, and I didn't risk accidentally adding too much gain and blowing highlights.

 

[edwardkaraa]

You know, I may have to take back the comment about the M9 using interpolation the whole way. The "ISO Sensitivity" chart on DXO Mark would have likely been different, like the P45+, if the camera didn't use some kind of analogue ISO gain. I think the M9 might use analogue gain for ISO, but that still doesn't answer the question about intermediate ISOs.

I wonder if Leica would be willing to disclose this info if we ask them, but probably not.

 

[douglasf13]

I wonder if Leica would be willing to disclose this info if we ask them, but probably not.

Yeah, I wonder.

 

[Godfrey]

I certainly don't mean to imply that I think you (or Godfrey) should overhaul your enitre method of working. I was just trying to give a little insight on how the camera works, so you can make small adjustments if you feel like it. ...

I've decided to simply ignore it, thanks anyway. I've developed my technique for getting what I want out of the M9, which is based on learning what the different ISO settings do with respect to dynamic range, how the meter is calibrated, and how to get the best exposure for my photos. What I'm finding is that 95% of the time, my raw files process through Lr 4.2, with my customized defaults, and are done right there ... little need to do any additional adjustment other than the superfluous but pretty effects (a little added vignetting and a pleasant border for digital framing).

Whether it perform a miniscule bit better at some specific ISO settings than others ... eh? The differences are simply not apparent enough to care overmuch. For me, anyway.

Life is short. I'd rather be making photographs and letting the equipment do its thing without consuming my time.. ;-)

 

[douglasf13]

I've decided to simply ignore it, thanks anyway. I've developed my technique for getting what I want out of the M9, which is based on learning what the different ISO settings do with respect to dynamic range, how the meter is calibrated, and how to get the best exposure for my photos. What I'm finding is that 95% of the time, my raw files process through Lr 4.2, with my customized defaults, and are done right there ... little need to do any additional adjustment other than the superfluous but pretty effects (a little added vignetting and a pleasant border for digital framing).

Whether it perform a miniscule bit better at some specific ISO settings than others ... eh? The differences are simply not apparent enough to care overmuch. For me, anyway.

Life is short. I'd rather be making photographs and letting the equipment do its thing without consuming my time.. ;-)

No problemo, but I would contend that changing ISO less often will save you time during the capture process. We're only talking about moving a single slider in post, so it doesn't exactly add a lot of time to each picture, just like adjusting your WB. What you're currently doing, by using the camera ISO to add gain to your exposure, is allowing the equipment to take up more of your time on the front end, where saving time usually matters.

Raising ISO in-camera isn't really much different than adjusting your WB for every single frame at the capture stage, rather than using a single WB (or even autoWB) and adjusting to taste in post. It is necessary when shooting jpeg, but not so much for raw.

Ultimately, like with using a single WB, using only one (or a few) ISOs reminds of shooting a few speeds of film, where I would just push the film after the fact, if necessary. It's no biggie, really.

As for dynamic range, the methods I describe are all about maximizing dynamic range, so, while other techniques are valid, none would provide more usable dynamic range, due to the design of the camera. If you were shooting a Canon DSLR, or, say, a Nikon D3/D700/D3s, it would be an entirely different story, but not so with the M9.

 

[douglasf13]

Ha! Oddly enough, I just started reading today's article on Steve Huff, and, coincidentally, Ofri Wolfus briefly mentions how sensors have a single ISO, and gain is added after the fact:

I Shoot Digital Film by Ofri Wolfus | STEVE HUFF PHOTOS


"...Another little known fact is that a digital sensor has a single sensitivity to light. Increasing the ISO in the camera simply increases the amount of analog signal amplification, but the sensor’s sensitivity to light remains unchanged.

At this point lets stop for a second and look back at what we have. Surprisingly, this mechanism is extremely similar to how we work with film. First, we expose the film to light. Then we develop the film, at which point we can push process it, effectively increasing its ISO and adding “noise”..."