Native base ISO

[Gavin Cato]

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Hey guys,

 

Does anyone know on the SL2 is ISO 50 is the true native base of the sensor, or if it's a expanded iso range?

 

[SrMi]

5 hours ago, Gavin Cato said:

Hey guys,

 

Does anyone know on the SL2 is ISO 50 is the true native base of the sensor, or if it's a expanded iso range?

 

ISO50 is kind of native/base ISO :).

ISO 50 is not expanded or pulled ISO, but you need to underexpose a bit when shooting at ISO 50 (similar behavior as with Q2).

The DR at ISO 50 is about one stop higher than at ISO 100 (link).

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[Gavin Cato]

Thanks so much for that. I was noticing clipped highlights a bit sooner than I expected DR wise so that got me thinking about what the sensor would be best set at. 

I'll start using 50 more often!

cheers

[Photoworks]

I would stick with 100 ISO

50 ISO the hightlight recovery in much less then 100 ISO.

It must be the reason why the camera does not go to 50 ISO in auto

Edited August 23, 2020 by Photoworks

[helged]

10 hours ago, Photoworks said:

I would stick with 100 ISO

50 ISO the hightlight recovery in much less then 100 ISO.

It must be the reason why the camera does not go to 50 ISO in auto

Agree, highlight clipping is a problem at ISO50. Therefore I treat ISO100 as base ISO on the SL2. On SL, I avoided ISO100, so there I used ISO50 or ISO200... 

[SrMi]

I agree that ISO100 is the safest bet and has plenty of DR.

ISO 50 should be used when max. DR is needed and when exposure is done carefully to protect the highlights.

[Gavin Cato]

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No worries guys. So basically ;

- If you need max DR use 50 iso but make sure to underexpose a bit to avoid clipping any highlights then bring out the details/shadows in post.

- For general use 100 iso.

 

[helged]

5 hours ago, Gavin Cato said:

- If you need max DR use 50 iso but make sure to underexpose a bit to avoid clipping any highlights then bring out the details/shadows in post.

- For general use 100 iso.

 

And "underexpose a bit" is possibly 2/3 stop, implying you are essentially back to ISO100. 

[Slender]

The funny thing is then, why is the minimun we can go for in CINE mode is 400EI.... and then I see a noticeable noise decrease when I switch form EI1600 to EI3200? Plus on the Photons to photos website on the SL2 curves we can see a weirb bump downward in SNR curves at 400ISO.... are these tell-tale sign of a dual ISO architecture like on Panasonic cameras?

[Joakim]

7 hours ago, helged said:

And "underexpose a bit" is possibly 2/3 stop, implying you are essentially back to ISO100. 

Exactly why I think we’re missing something here, if you need to underexpose then that extra dynamic range has no value? I haven’t used ISO 50 much so I don’t have any real experience of it yet myself, maybe it’s time to change that

[BernardC]

3 hours ago, Slender said:

The funny thing is then, why is the minimun we can go for in CINE mode is 400EI.

Cine ISO is calculated differently. For video work, you want to have a tolerance for both under-exposure and over-exposure. As mentioned above, an ISO of 100 (or 50) leaves no margin on the overexposure side. That is arguably OK for a still image, but it can ruin a shot where people move, lights are turned on and off, etc. Also, cinema HDR (which is different from still HDR) means that you want to leave headroom for unusually bright areas within the frame.

In other words, cine 400 ISO and still 100 ISO are probably the exact same thing, as far as the sensor is concerned. The difference is that the cine version places middle grey 2 stops lower than the still version, in order to protect the highlights. The downside is that you can't "lift the shadows by 5 stops" in cine mode, but that kind of manipulation rarely looks good in moving images.

[Dr. G]

I have a question about this.  Should I basically be dialing back the exposure compensation until the blinking highlights go away and then underexpose by an additional 2/3 to 1 stop when using ISO 50?  It seems that when I just dial back compensation until nothing is blinking in the EVF and then I review the image, there are blinking highlights all over the image in playback.  

[SrMi]

10 hours ago, helged said:

And "underexpose a bit" is possibly 2/3 stop, implying you are essentially back to ISO100. 

No, DR is better at ISO50 by one stop. It is strange as the amount of light you feed to the sensor is almost the same.

Edited August 24, 2020 by SrMi

[helged]

22 minutes ago, SrMi said:

No, DR is better at ISO50 by one stop. It is strange as the amount of light you feed to the sensor is almost the same.

My experience is that highlight clipping is more likely to happen at 50 vs 100 ISO. Yes, the measure response curves show a 1 stop DR advantages at 50 ISO. But still, I prefer ISO 100. Counterintuitive, I know.

Questions (since I don't know): Are we sure that DR and highlight clipping can be understood similarly, or that a sensor's response depends linearely (or whatever releationship) on the photons hitting the sensor? What about the colour filtering, the sensor wells, sensor coverage/micro lenses, you name it?

Irrespective of the counterintuitivness, I remain an 100 ISO shooter until others - and my own experience - tells me something else...

In the mean time - happy shooting to us all 😉! 

[SrMi]

1 hour ago, helged said:

My experience is that highlight clipping is more likely to happen at 50 vs 100 ISO. Yes, the measure response curves show a 1 stop DR advantages at 50 ISO. But still, I prefer ISO 100. Counterintuitive, I know.

Questions (since I don't know): Are we sure that DR and highlight clipping can be understood similarly, or that a sensor's response depends linearely (or whatever releationship) on the photons hitting the sensor? What about the colour filtering, the sensor wells, sensor coverage/micro lenses, you name it?

Irrespective of the counterintuitivness, I remain an 100 ISO shooter until others - and my own experience - tells me something else...

In the mean time - happy shooting to us all 😉! 

Makes sense, ISO 100 is simpler, especially with automatic exposures.

If I do not have time I use Auto ISO, which uses ISO 100 as lowest ISO. For most of my good images, ISO100 has more than plenty of DR.

If I have time, I expose manually, ETTR at ISO 50 (using histogram & blinkies).

Happy shooting :)!

 

[Dr. G]

48 minutes ago, SrMi said:

Makes sense, ISO 100 is simpler, especially with automatic exposures.

If I do not have time I use Auto ISO, which uses ISO 100 as lowest ISO. For most of my good images, ISO100 has more than plenty of DR.

If I have time, I expose manually, ETTR at ISO 50 (using histogram & blinkies).

Happy shooting :)!

 

I still would like to know if you use the histogram and blinkies to ETTR and expose as not to see any blinking highlights - and then when reviewing the image in camera find the image has blinking highlights everywhere.  I don't understand how I could expose "properly" in the EVF with the exposure aids and then have overexposed portions of my image when reviewing.

[helged]

45 minutes ago, Dr. G said:

I don't understand how I could expose "properly" in the EVF with the exposure aids and then have overexposed portions of my image when reviewing.

Good point! I cant talk for others, but I usually ensure that there is no clipping (based on histogram and blinkies, as you say 😉) during capture. The image in LR, without any modifications, typically show now clipping either. Fine. But a tiny pp may easily/quicly end up with either clipping, or harsh, bad-looking graduation into the highlights. I highly dislike this (similarly to pink snow or sand beaches, tilted horizons, etc.). M10-R and S3 are less prone to highlights falling apart, which is a big plus in my book (keeping finances out of the equation, obviously...).

[SrMi]

27 minutes ago, Dr. G said:

I still would like to know if you use the histogram and blinkies to ETTR and expose as not to see any blinking highlights - and then when reviewing the image in camera find the image has blinking highlights everywhere.  I don't understand how I could expose "properly" in the EVF with the exposure aids and then have overexposed portions of my image when reviewing.

Thank you for that question!

I assume you are talking about the discrepancy of live-view vs. image-review at ISO50. 
I use the live-view histogram/blinkies to adjust the exposure. The histogram/blinkies of the image-review at ISO50 cannot be trusted unless you are shooting JPEGs (in which case you cannot trust live-view).
Test: DNG image shot with ISO100 and ISO50, with one-stop difference in shutter speed and same aperture; DNGs have the same histogram in LrC, but in image review, SL2 shows an overexposed image. 
Note that the JPEG image will be overexposed at ISO50, while DNG is exposed correctly.
This is another reason for using ISO100 instead of ISO50 :). I would not use ISO50 when shooting JPEGs (which I don't).

[northernlights]

With firmware 6.00 and highlight-priority metering that was not available at the time of this discussion almost 3.5 years ago, ISO50 is great!

Edited March 7 by northernlights

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[Filip Baraka]

4 hours ago, northernlights said:

With firmware 6.00 and highlight-priority metering that was not available at the time of this discussion almost 3.5 years ago, ISO50 is great!

Is there a noticeable difference between files at 50 and 100?