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Author Topic: Best ISO for IQ280  (Read 53459 times)

gagemanning

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Best ISO for IQ280
« on: July 04, 2015, 11:41:37 am »

I was just wondering what base ISO most use for there IQ280 (even the IQ260).  I've always been use to shooting at ISO 100 but I now the IQ280 goes to ISO 35.  Do you lose any dynamic range when you get that low (I know with the Leica systems you can if you shoot below there "normal" ISO).

gage
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voidshatter

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Re: Best ISO for IQ280
« Reply #1 on: July 04, 2015, 11:55:28 am »

For IQ280, if you shoot at the same aperture and shutter speed, then ISO 35 gives you identical exposure and image quality as ISO 100. ISO 35 is just an extended ISO affecting the calculations of metering forcing you to do ETTR. It is more about marketing. Nikon D810 can shoot at ISO 32.
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gagemanning

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Best ISO for IQ280
« Reply #2 on: July 04, 2015, 08:52:17 pm »

Thanks voidshatter!


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sbernthal

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Re: Best ISO for IQ280
« Reply #3 on: July 05, 2015, 02:52:47 pm »

ISO 35 is not identical to ISO 100 and it's not just marketing.

ISO 35 when underexposed is pushed much better than ISO 100 with the same underexposure.
When pushing overexposure, ISO 100 is better.
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voidshatter

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Re: Best ISO for IQ280
« Reply #4 on: July 05, 2015, 03:10:31 pm »

ISO 35 is not identical to ISO 100 and it's not just marketing.

ISO 35 when underexposed is pushed much better than ISO 100 with the same underexposure.
When pushing overexposure, ISO 100 is better.
Then please supply evidence by means of raw files. Shoot at ISO 35 and ISO 100 for the same aperture and shutter speed.
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sbernthal

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Re: Best ISO for IQ280
« Reply #5 on: July 05, 2015, 03:27:33 pm »

I don't need to shoot it, because I already have.
I would never have made such a bold statement without testing it myself first.
I did this test when I got my camera, but that was a few years ago, and when I saw your statement today I though maybe I don't remember correctly, so I did it again.
These are Credo files, but it's the same as IQ.


« Last Edit: July 06, 2015, 02:03:33 am by sbernthal »
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Don Libby

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Re: Best ISO for IQ280
« Reply #6 on: July 05, 2015, 04:11:08 pm »

I have a 180.  That said while shooting landscape I always try and shoot using the lowest ISO I can which normally 35.

voidshatter

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Re: Best ISO for IQ280
« Reply #7 on: July 05, 2015, 09:20:53 pm »

I don't need to shoot it, because I already have.
I would never have made such a bold statement without testing it myself first.
I did this test when I got my camera, but that was a few years ago, and when I saw your statement today I though maybe I don't remember correctly, so I did it again.
These are Credo files, but it's the same as IQ.

http://www.shlomi.net/ftp/T35404.IIQ
http://www.shlomi.net/ftp/T35410.IIQ


Your RAW files don't add up the math. For the same aperture and shutter speed, if the manufacturer's ISO settings were to be trusted, then ISO 100 is supposed to be 1.5EV brighter than ISO 35, but in your RAW files ISO 100 is 1.5EV darker than ISO 35. Clearly something is wrong there:

a) Credo 80 is cheating - they have reversed the ISO settings between 35 and 100;
b) There's a firmware bug;
c) Someone has manipulated the metadata using a hex editor.

« Last Edit: July 05, 2015, 10:38:09 pm by voidshatter »
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sbernthal

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Re: Best ISO for IQ280
« Reply #8 on: July 06, 2015, 12:38:02 am »

It's not the same amount of light.
You adapt the lighting so that the histograms of the unpushed files are equal, and then you push them the same amount.
They have identical brightness unpushed and pushed, but not the same noise and detail pushed.

You don't own a Credo/IQ?
Then why did you offer advice to the OP?
Analyzing other people's files doesn't give you the same amount and quality of information as performing tests on your own.
There are plenty of owners here and I believe this is the advice he was soliciting.
« Last Edit: July 06, 2015, 12:42:17 am by sbernthal »
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Wayne Fox

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Re: Best ISO for IQ280
« Reply #9 on: July 06, 2015, 01:08:37 am »

Native ISO of the IQ180/280 is 35.  Any other setting is simply a metadata change ( the camera is basically ISO less). Here is a sample from a couple of years ago when this was discussed extensively over at getDPI.com.

So why use higher ISOís?  It makes the workflow easier.  If you canít get the desired exposure at 35, rather than shooting an image that looks extremely underexposed, using 100 will get you to an acceptable starting point.

The higher the ISO the more grain, because  you are underexposing.





(Iíll try to get the full size originals to replace these, but both shots were exposed 1 sec at f/11.  the left shot the back was set to ISO 35, the right it was set to ISO 200. simply making an exposure adjustment in Capture One yielded the corrected ISO 35 image.
« Last Edit: July 06, 2015, 01:21:21 am by Wayne Fox »
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ErikKaffehr

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Re: Best ISO for IQ280
« Reply #10 on: July 06, 2015, 01:10:20 am »

Hi,

I would have expected the same exposure. If exposure is increased, the noise will be less. What I guess "Voidshatter" means is that if you have same exposure, that is combination of light, aperture and exposure time, identical results would be gained at different ISO settings.

When you talk about the histogram, which one do you mean? Histogram on the back or histogram in Capture One?

Best regards
Erik

It's not the same amount of light.
You adapt the lighting so that the histograms of the unpushed files are equal, and then you push them the same amount.
They have identical brightness unpushed and pushed, but not the same noise and detail pushed.

You don't own a Credo/IQ?
Then why did you offer advice to the OP?
Analyzing other people's files doesn't give you the same amount and quality of information as performing tests on your own.
There are plenty of owners here and I believe this is the advice he was soliciting.
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Erik Kaffehr
 

voidshatter

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Re: Best ISO for IQ280
« Reply #11 on: July 06, 2015, 01:11:49 am »

It's not the same amount of light.
You adapt the lighting so that the histograms of the unpushed files are equal, and then you push them the same amount.
They have identical brightness unpushed and pushed, but not the same noise and detail pushed.

You don't own a Credo/IQ?
Then why did you offer advice to the OP?
Analyzing other people's files doesn't give you the same amount and quality of information as performing tests on your own.
There are plenty of owners here and I believe this is the advice he was soliciting.

You are not testing it correctly. You need to apply the same lightning. If you really want to learn then you should disable flash to simplify things. Credo or IQ isn't that expensive. There are so many superstitions that people just won't admit.
« Last Edit: July 06, 2015, 01:15:24 am by voidshatter »
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voidshatter

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Re: Best ISO for IQ280
« Reply #12 on: July 06, 2015, 01:14:03 am »

Native ISO of the IQ180/280 is 35.  Any other setting is simply a metadata change ( the camera is basically ISO less). Here is a simple from a couple of years ago when this was discussed extensively over at getDPI.com.

So why use higher ISOís?  It makes the workflow easier.  If you canít get the desired exposure at 35, rather than shooting an image that looks extremely underexposed, using 100 will get you to an acceptable starting point.

The higher the ISO the more grain, because  you are underexposing.





(Iíll try to get the full size originals to replace these, but both shots were exposed 1 sec at f/11.  the left shot the back was set to ISO 35, the right it was set to ISO 200. Smiley making an exposure adjustment in Capture One yielded the corrected ISO 35 image.

Hi, please compare ISO 35 against ISO 100 for the same aperture and shutter speed by means of RAW files for download. ISO 35 and ISO 100 are the same, but ISO 100 is better than ISO 200.
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sbernthal

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Re: Best ISO for IQ280
« Reply #13 on: July 06, 2015, 01:17:09 am »

You want to compare ISO 35 and ISO 100 with the same amount of light?
That makes no sense.
The 35 will be darker.
To get similar results you will need to push the 35 and not push the 100 - so what are you comparing?
Of course 100 unpushed will be cleaner than 35 pushed.
Pushing before encoding will be cleaner than pushing after encoding.

For me the question was should I be using ISO 35 or ISO 100 for studio, and then adapt the lights for good exposure.
With ISO 35 the lights need to work harder. Not every light can do it.
Is there a reason to do it?
I think there is.

If you are outside then you use the lowest ISO the light allows you with the parameters you need.
I would not compromise my parameters just to get to ISO 35, of course ISO 100 is good enough in Credo/IQ (not in all Aptus models).
I would use ISO 35 only when there is no sacrifice in the parameters, and the only sacrifice is the longevity and cost of my light.
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voidshatter

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Re: Best ISO for IQ280
« Reply #14 on: July 06, 2015, 01:22:46 am »

You want to compare ISO 35 and ISO 100 with the same amount of light?
That makes no sense.
The 35 will be darker.

In such case, ISO 35 will only appear darker in Capture One or ACR or similar software. You will see that they are identical in RawDigger. If you push the ISO 35 image by 1.5EV in Capture One or ACR then you get exactly the same brightness (and same quality) as of the ISO 100 image.

To get similar results you will need to push the 35 and not push the 100 - so what are you comparing?
Of course 100 unpushed will be cleaner than 35 pushed.
Pushing before encoding will be cleaner than pushing after encoding.

For me the question was should I be using ISO 35 or ISO 100 for studio, and then adapt the lights for good exposure.
With ISO 35 the lights need to work harder. Not every light can do it.
Is there a reason to do it?
I think there is.

If you are outside then you use the lowest ISO the light allows you with the parameters you need.
I would not compromise my parameters just to get to ISO 35, of course ISO 100 is good enough in Credo/IQ (not in all Aptus models).
I would use ISO 35 only when there is no sacrifice in the parameters, and the only sacrifice is the longevity and cost of my light.

As I said in my first reply to this thread, ISO 35 is just a means to affect the metering and force ETTR. If you measure the light and set the parameters with ISO 35 (and fix the lighting), then before you press the shutter, if you now set ISO to 100, then in the final image you would have got the same quality RAW file (same shadow SNR and same highlight) as if you shot with ISO 35. There is no benefit of using ISO 35 other than forcing you ETTR.
« Last Edit: July 06, 2015, 01:30:52 am by voidshatter »
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sbernthal

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Re: Best ISO for IQ280
« Reply #15 on: July 06, 2015, 01:24:03 am »

I would have expected the same exposure. If exposure is increased, the noise will be less.

ISO 35 is for studio.
When you are using ISO 35 in studio, you need to use much more light to get to the same result.
The question is: is there any point to make the effort of extra light just to be using ISO 35, or should I be using ISO 100 and shock my subjects less.

Another pertinent comparison would be long exposures.
I believe ISO 35 would be less noisy, but I haven't tried it as it's not relevant for what I do.

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voidshatter

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Re: Best ISO for IQ280
« Reply #16 on: July 06, 2015, 01:28:18 am »

ISO 35 is for studio.
When you are using ISO 35 in studio, you need to use much more light to get to the same result.
The question is: is there any point to make the effort of extra light just to be using ISO 35, or should I be using ISO 100 and shock my subjects less.

Another pertinent comparison would be long exposures.
I believe ISO 35 would be less noisy, but I haven't tried it as it's not relevant for what I do.



Then ISO 35 is just forcing you to give more light. If you give the same amount of light for ISO 100 (and same aperture + same shutter speed) you still get the same image. This is also true for ISO 32 on the Nikon D810. It's just extended ISO. Phase One does not explicitly label it in the specifications. This is just marketing.
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sbernthal

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Re: Best ISO for IQ280
« Reply #17 on: July 06, 2015, 01:31:11 am »

It forces you to give more light, and then you get a file that is DIFFERENT! That's the point.


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voidshatter

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Re: Best ISO for IQ280
« Reply #18 on: July 06, 2015, 01:33:18 am »

It forces you to give more light, and then you get a file that is DIFFERENT! That's the point.




You can always ignore the ISO 35 setting and deliberately give more light for ISO 100. ISO 35 will not give you better image quality. Without ISO 35 you can still achieve as good image quality if you shoot at ISO 100 and give the same light.

For your use case in the studio, the ISO 35 setting is merely a "+1.5EV exposure compensation for flash" for people like you who have no clue about what is called native ISO. You can dial +1.5EV exposure compensation for your flash and use ISO 100 without relying on ISO 35.

Common superstitions for MFDB:

a) ISO 35 is great;
b) Fullframe CCD has great dynamic range and latitude;
c) 16-bit is awesome.

None of these three is true. It cost me a fortune to realize these.
« Last Edit: July 06, 2015, 01:42:33 am by voidshatter »
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ErikKaffehr

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Re: Best ISO for IQ280
« Reply #19 on: July 06, 2015, 01:56:50 am »

Hi,

- I would say that base ISO seems to be around 35 for the 80 MP backs.

- I don't know if full frame CCD has great dynamic range, that may depend on definition of both great and dynamic range. What I may see is that MFD systems tend to underexpose and thereby protect highlights. For instance, the default film curve in Capture One makes image very bright.

- Readout noise is higher on CCD, so the darks are noisy.

- Yes 16 bit is indeed awesome, but so is 14 bits and even 12 bits.

For the kind of work I am doing my P45+ is mostly quite OK, there are exceptions, however.

Best regards
Erik



You can always ignore the ISO 35 setting and deliberately give more light for ISO 100. ISO 35 will not give you better image quality. Without ISO 35 you can still achieve as good image quality if you shoot at ISO 100 and give the same light.

For your use case in the studio, the ISO 35 setting is merely a "+1.5EV exposure compensation for flash" for people like you who have no clue about what is called native ISO. You can dial +1.5EV exposure compensation for your flash and use ISO 100 without relying on ISO 35.

Common superstitions for MFDB:

a) ISO 35 is great;
b) Fullframe CCD has great dynamic range and latitude;
c) 16-bit is awesome.

None of these three is true. It cost me a fortune to realize these.
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Erik Kaffehr
 
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