IQ3 100 VS Arri Alexa Dynamic Range

Questions, comments and suggestions regarding Phase One IQ4, IQ3, IQ2 and IQ1 series digital camera backs.

IQ3 100 VS Arri Alexa Dynamic Range

Postby NNN635934946108963955 » Tue Apr 14, 2020 6:52 pm

Hi there,

Im a cinematographer and I'm searching a long time for a good still photography camera to jump from analog to digital but I'm just disappointed. What is your experience?
I made a practical Dynamic Range test with the best digital cameras available. Please judge by yourself and tell me if Im wrong. But the Phase One IQ3 100 has never ever 15 stops of dynamic range.

Please Download the images for viewing. they are very big.

Cameras:

PHASE ONE IQ3 100 (2017)
- 35.000€
- 8984x 6732
- 15 Stops
- IIQ 16 Bit Compressed RAW / around 120MB

VS

Arri Alexa LF ( Sensor technology age 2008)
- 30.000 € - 90.000 €
- 4448 x 3096
- 14 Stops +
- Uncompressed 12 Bit / ARRI RAW / 20,9 MB Per Frame


Pictures are shown in an logarithmic Curve ( Log C) instead of linear, so we can see what informations are stored in the frames.

IQ3100 VS ALEXA -6 to +/-0
Image


IQ3100 VS ALEXA +1 to +9
Image


As you can see, with the PHASE ONE IQ3100 you already lose information when you just overexpose the image by 2 stops. Thats insane no? I thought that's best photo camera? Ok there is now the IQ4 150 but I doubt that the dynamic range improved.

My thoughts on that: I don't need 100MP if I can't overexpose by two stops or lets say it like that: anything what has 18% grey can't be over exposed by 2 Stops.

By the way, film holds up to +9, not losing any information.
and by the way my P65+ has exactly the same dynamic range as the IQ3100
I'm open for discussions :))

thanks
NNN635934946108963955
 
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Re: IQ3 100 VS Arri Alexa Dynamic Range

Postby Ulf » Wed Apr 15, 2020 11:11 am

HI

We would be really happy to check your claims but there is so much more to this.
This might be done in away to create a desired result.

Images you have attached are not very useful as you have to work from RAW data and not processed data.

There is a massive difference in a Phase One back between overexposed data and clipped data.
Also dynamic range is the total dynamic range, both over and under. Not only over.
Secondly: the Arri has about 1/8th of the resolution. So did you just scale up the Arri so you compared them 1:1?
Or was the Phase One file downscaled in order to favour the Arri?

Lastly is you pricing as far as I can see the pricing for an Arri LF (Launched in 2018) this starts around 78k for a usable solution.

But this is in the end all irrelevant as it is comparing pears and apples.

I would invite you to contact us @ http://support.phaseone.com and we would be happy to help you in your analysis.
Ulf
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Re: IQ3 100 VS Arri Alexa Dynamic Range

Postby NNN635934946108963955 » Wed Apr 15, 2020 2:07 pm

Hi Ulf,

thank you very much for your answer and time for reading my post.

I'm not trying to be negative or something. its just an observation that I made and I try to understand the difference between digital motion picture Cameras and digital still cameras. I own a P65+ and would like to upgrade.

Its not really comparing pine and apples.it is comparing recorded values. But you are right, the tech behind is different but a sensor records what he can record and collected data is not different from each other.

I worked off the raw files and there is not much to recover from the highlights. I can provide the files.
what I did:

1.)
I took both cameras and took the same focal length (80mm for the Phase one, 85mm for the Fullframe Alexa LF) and photographed the chart from the same distance. (Sensor base) So the charts are somehow the same size on 100% zoom. But anyway dynamic range does not depend on the resolution right?

2.) I photographed a series, always with a stop difference. I took my light meter and I have measured the light that hit the chart. I don't know why this should be speculative. I'm comparing collected data from the sensor F-stop by F-stop at base ISO of each sensor. The series goes from -6 to + 9. So each frame that is further overexposed shows me what I can recover at the previous frame. I understand that there is data in the underexposed areas of the frame. I come to that soon.

3.) The Alexa LF came out 2018 but the sensor is from 2007/2008 and came out with the ARRI ALEXA Classic. It is a S35 size sensor (APSC more or less) with much less resolution but same dynamic range. the pixel density did not change since that.The Sensor in the LF just got bigger. Same as in the Alexa 65 (65mm Format)

4.) Dynamic range:

What I have learned as a cinematographer with film and digital. A sensor can just collect a certain amount of information, we are all calling that dynamic range.

lets take Kodak and analog film. if its written the film stock has 200 ASA, I know that my 18% Grey will be exposed as 18% also on film when I expose the film with the right settings. But what I also know is that my Dynamic range goes from -6 to +9 stops. (of course there are variations in the film stocks) the noise is given by the grain size.

the Arri Alexa is not different: its basically the same as analog film. the Base ISO is 800 and my 18% Grey is 18% Grey at 800 Iso with the correct settings according to the light meter. but I know that my 18% grey in the dynamic range of the Alexa is set quite in the middle of the range at base iso. and I have always 14+ stops no matter what ISO I choose I just shift the 18% Grey. So I can better light a scene.
please se the image:
Image

the thing is, the base ISO should have a good Noise / ISO ratio to each other. and everybody wants low noise.
But ARRI made it very clear and I have full control and knowledge about what the sensor does and what data is collected.

for example, when I photograph a frame indoor and my brightest spot outside of a window is 8,5 stops over my base F-Stop (@800 ISO I have 7+ stops up), I can push the ISO from 800 to 1600 and I can shift my 18%grey one stop down of the dynamic range Scala by closing my lens by one stop, so I get all my information outside and a correct preview. I don't win a stop but I know where my borders are. in this example, I underexpose my Sensor by one stop and push it again by one stop to get a normal looking image.

So when there is more data in the IQ3 100 in the underexposed areas and the Back captures the 15+ Stops, the 18% grey is not set in the middle of the whole range right? is there such a exposer index table?
With that experience I made now with the IQ3 100 I would under expose a lot to get as much information in the highlights as possible. but the preview images would be all dark. So I guess that's not the intended way right?

I just trie to get to it and dive deep. because for me it seams there are two worlds of digital photography ( motion and Still)

thanks
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Re: IQ3 100 VS Arri Alexa Dynamic Range

Postby Ulf » Wed Apr 15, 2020 2:47 pm

Hi

I would invite you to contact us @ http://support.phaseone.com and we would be happy to help you in your analysis.
Ulf
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Re: IQ3 100 VS Arri Alexa Dynamic Range

Postby NNN635934946108963955 » Wed Apr 15, 2020 3:42 pm

Hi,

Yes I will do it.

Thank you
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Posts: 18
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Re: IQ3 100 VS Arri Alexa Dynamic Range

Postby Mexecutioner » Thu Apr 16, 2020 2:00 am

What a waste of time. If you think there is abetter still camera than a Phase one DB, just go ahead and buy it.
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Re: IQ3 100 VS Arri Alexa Dynamic Range

Postby NNN635934946108963955 » Thu Apr 16, 2020 8:40 am

of course there is no better camera.

but its also not a waste of time to do test.
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