I have taken advantage of a much needed rain day here in Tasmania and explored my Canon R7 and ISO. As you say it is not ISO invariant and therefore I am better off using a higher ISO than the underexpose then push approach. I love how you can do this approach with a Fuji XT-5. If I didn’t already have Canon lenses I feel I would have preferred the Fuji XT-5, my favourite camera that I don’t own. Hopefully we will see more ISO invariant sensors in the future.
The article that @g-man linked was very informative and made me better understand the limits especially to dynamic range as you increase ISO. When possible 100 ISO would be best, but since much of my photography involves travel this is often not practical. The biggest killer of image quality on my R7 is underexposure so pushing the ISO is still the best option for that camera.
The take away for me is to when possible use the lowest ISO practical. I have taught that to my students for years and it clearly still holds true. Sometimes the lowest practical is 32000 ISO and so be it. We are not all photographing sunlight landscapes with a tripod.
I used to do Kart racing. I loved the rain because I gained such an advantage in the wet or should I say others loss their advantage in the wet. When it rained here on a weekend I would go to my local kart track and run laps on slick tyres just for the practice.
OOoh, nice!
I’ve only done indoor karting, with electric karts. Still fast, and it rewards skill, but not quite the same…
My main concern with the rally is just that it could be postponed, or worse, cancelled, but as it’s a round of the national ARC (Australian Rally Championship) I think it will have to be really wet for that to happen.
From a photographic perspective, I’m actually looking forward to a change from the hot, dry and dusty conditions of recent events.
Maybe. Are we talking about the same scene? The lux*s value changes, so then I guess not. In that case, if I understand correctly, the camera does not apply any analogue amplification, and less light clearly means lower values on the histogram, before ‘applying ISO’ via software.
Just wanted to share my simplistic view of the topic.
Know the constraints of your scene
available light
subject movement
photographer movement / focal length
Know your options
shutter time
aperture
base ISOs
Balance the tradeoffs and capture
My cam has two base ISOs (100 and 400) and it is easy to select the better one for the scene: "Do I have enough light => ISO 100, otherwise ISO 400… that’s it, basically …of course there are exceptions…
Using ISOs beyond 400 is just comfort, to get a brighter JPEG. This can also be done in post processing. I have shoot entire series which did look more or less black on the camera display but where fine after editing. Of course there will be noise in these pictures, but the reason is the low light, not the ISO setting.
I don’t understand that. What’s the definition for each of those? ‘lux’ is the unit of measurement of illuminance (flux per unit area, so like power per area, weighted according to the sensitivity of the eye). That, multiplied by time, gives energy. How could the same scene (given the same illumination, same aperture area and same exposure time) result in different illumination (lux*s) at the sensor?
I’m not sure I followed the whole discussion, but I think @xpatUSA was using lux-per-second? And adjusting exposure time to maintain the same overall exposure…
If it’s all gone over my head, sorry!
Yes. First and foremost, a lot of crop sensor cameras don’t go lower than ISO 200
I agree with everything though. I can easily deal with noise in software, and even ISO 1600 is acceptable in most post-2015 crop-sensor cameras. But motion blur from low shutter speed just kills the image in 99% of the cases.
As a side note, the kind of sensors we have these days are amazing when you think about it. I only used ISO 800 film once (I think it was Kodak Portra), and while some people like the washed-out colors, when it comes to grain (and thus effective resolution) even 1" sensor compacts do better these days. I can’t wait for dual gain sensors to trickle down to smaller micro 4/3 bodies.
No. If you want to suggest something, then suggest just over the dualgain cutin point of most modern cameras (or at least all Sonys less than a decade or so old, probably longer).
This cutin point varies from camera to camera. ISO400 is universally inferior to ISO100 for an ISO-invariant camera (nearly all modern cameras) unless the camera has dual conversion gain AND that ISO is above the cutin point. If a camera is ISO-invariant, there’s no noise benefit to shooting at ISO400 vs shooting ISO100 and pushing 2 stops in post for a given shutter+aperture combo. Shooting ISO400 will reduce your highlight headroom (and hence total dynamic range) by 2 stops though.
For the Sony A7M3 (and MANY other Sonys) you’re below the cut-in point. The A7M4 is one of the few with a cutin point of ISO400 or below: Photographic Dynamic Range versus ISO Setting
On an A7M3, ISO400 dynamic range will be LESS than ISO640 per the graphs linked above
A7M3 and A7M4 are effectively ISO-invariant, the read noise variation within a gain region are a fraction of a stop: Input-referred Read Noise versus ISO Setting - but the reduction in full well capacity reduces dynamic range much more than the negligible noise improvement
Unless you’re above the dualgain cutin point for a camera, all ISO400 buys you over ISO100 is blown highlights and maaaaybe 1/3 stop at most (less on most cameras)
It’s the stupid text editor … I should have typed “lux-sec”. It seems that a back-slash is necessary before the star on my computer … lx*s … a period works too … lx.s
I am saying that the light from the scene that is incident upon the camera lens does not change with the ISO setting but that the light incident upon the sensor does change with the ISO setting. In other words, 400 ISO causes 1/4 of the light on the sensor compared to 100 ISO.
This is more or less the opposite of Terry Pinfold’s “The problems with 100 ISO are many. The first is the risk of underexposure which tends to generate huge noise problems and loss of details in the shadows. Increasing the ISO to ensure good exposure would result in less noise and this is what so many people struggle to appreciate.”
I am not talking about Aptina-style sensors and neither am I talking about modern cameras with their complex ISO curves. I am talking about basic Exposure 101 as defined by the I.S.O.
Good point here. This, of course, assumes you change aperture/shutter to adjust for the increased ISO. Another thing I hinted at in my post and you also did:
With most modern cameras, the camera sensor itself is not the limiting factor as far as noise (with the exception of quantum efficiency, but there’s little evidence of any notable change in quantum efficiency for Bayer-on-silicon since the A7R2 in 2015 or so). Read noise is extremely low, and ADC resolution is high enough that under almost any scenario (even some EXTREME local underexposure, such as shadows on a dark object when metering for sunlight on white water), photon shot noise is the limiting factor. Shot noise is a statistical property of incoming light, and SNR for shot noise gets worse as signal decreases.
Yes, On my simple camera in Aperture Priority for example, the shutter period changes inversely with increasing ISO; the raw converter brightens the review image pro rata.
Really, what increased ISO does is to compel you to accept less energy on the sensor with the promise to turn up the gain on the other side. This promise makes you feel good about using that faster shutter speed to capture motion, at the expense of dynamic range.
I for one will continue to love my ISO 100 when I clamp the camera to the tripod staring down the dawn-lit face of Pikes Peak, or somesuch. Mostly though, I find myself in 1600-land, grab shots of restoration work in a dimly-lit workspace with horrid tent-filtered light. It all works, but one needs to understand the limitations…
(speaking as one from Louisiana)