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Expert
Posts: 2,286
Registered: ‎11-23-2012
Message 41 of 92 (4,727 Views)

Re: Guide to Cine EI on the F5 and F55.

[ Edited ]

Doug J, With respect; Exposing for white probably explains why you find LUT's inconsistent, why you find the Sony ISO's to inconsistent. The system is not designed that way.

Of course as Denis points out you can choose to shoot however you wish, that is your choice and your light house footage shows that it works for you, but when your method does not match the way the system is designed to be used, don't be surprised to get results that differ from the designers.

Expert
Posts: 1,506
Registered: ‎11-20-2012
Message 42 of 92 (4,707 Views)

Re: Guide to Cine EI on the F5 and F55.

[ Edited ]

Nice try, Alister, but it's not operator error. You're still wrong.

 

But I'm willing to keep an open mind and do whatever test you want me to conduct that will prove your points for you.  And correct me if I'm wrong, but I think we disagree on two fundamental things:  1) That that ISO displayed on the side of the camera is ALWAYS correct and always accurately represents the actual sensitivy of the camera.  2)  That exposing for gray is correct, and exposing for white is not the correct method.  If I am wrong on either of those those points, please correct me now.

 


Okay, I've got my F55 and standard DSC ChromaduMonde chart all set up and ready to go.  I've got a Leader LV-5330 waveform monitor and a Sekonic L578 light meter.  If there is anything else I need, please let me know and I'll get it.

 

Tell me EXACTLY what menu settings for shutter speed, recording format, matrix, gamma, etc. to set on my camera.  You could even send me a Picture Profile or an All File if you want to help eliminate any chance of error on my part.  Anyone who is dumb enough to expose based on white probably can't be trusted to navigate the menus properly.

 

Next, tell me exactly how i should expose that DSC chart.  I will be using Litepanels daylight balanced 1x1 lights.  I mention that because i know you have stated earlier that we need to take into account the TYPE of lighting that is being used.

 

Next, tell me what criteria should I use to arrive at what YOU would say is a perfect exposure for the chart?  Should gray be at some particular level?  White at some level?  A combination of both?  You must have some definition of what defines the ideal exposure on a standard DSC chart using the menu settings on the camera that YOU have chosen.  I will follow your instructions to the letter. Let's leave nothing to chance and eliminate as many variable as possible.

 

Next, this final part is optional, but I'd appreciate it if you could tell me how I should bring that footage into Davinci Resolve Lite 10 -- and how I should grade it to get the final look that you yourself would call perfect and be proud to call your own.

 

Please post that information as soon as you can, and then I'll do the work of shooting the chart and grading the footage so you don't have to.  Once I've done that, it will be easier for me to show you how your theories don't hold up in the real world.

 

Expert
Posts: 1,723
Registered: ‎06-12-2013
Message 43 of 92 (4,682 Views)

Re: Guide to Cine EI on the F5 and F55.

Doug I dont see that Alister has disagreed with either of your points.. ? Its not that you are wrong,which seems to be the thorn in your side..  its plainly stated if it works for you its right.. and your work is roundly admired.. have a nice cup of tea sir..

Expert
Posts: 2,286
Registered: ‎11-23-2012
Message 44 of 92 (4,662 Views)

Re: Guide to Cine EI on the F5 and F55.

[ Edited ]

Doug. The DSC CDM charts background is not middle grey so you cannot use this, it's approx 25%. You can use a DSC Middle grey chart such as the SLog exposure chart or a Kodak 18% grey card. However if you are using a  Sekonic meter you need to use a 12.7% grey card as they calibrate their meters against 12.7% grey.  If using an 18% grey chart you have to deduct 1/2 a stop from your exposure, with the CDM charts the offset is a little over a stop.

 

 

Expert
Posts: 1,506
Registered: ‎11-20-2012
Message 45 of 92 (4,676 Views)

Re: Guide to Cine EI on the F5 and F55.

[ Edited ]

Hi Robbie, you seem to be coming into the middle of the conversation that goes beyond just this one thread.  It's more than just two different opinions here.  Both of use have stated what we believe are facts, and it's time to do a real test and find out who is correct.  For example, either ISO displayed by the camera is always correct or it is not.  That is not up to opinion, --so let's do a test and see.  Why not?

 

Also, in post #41 above Alister says I'm not setting exposure the way Sony intended, so my results will be different.  Okay, so I want him to show us exactly how it is supposed to be done so I can do a head-to-head analysis of the different results the two of us would get.  For example, if his method says f/2.8, and mine also says f/2.8, then there's no difference in metering from gray or white.  Only a test with very controlled and repeatable conditions will tell us anything of value. I hope other people decide to do their own testing once we get Alister's steps.

 

I'm sorry if you don't see the value in putting these matters to rest once and for all, but I certainly do.

Expert
Posts: 1,506
Registered: ‎11-20-2012
Message 46 of 92 (4,660 Views)

Re: Guide to Cine EI on the F5 and F55.

[ Edited ]

I have a Ko


alisterchapman wrote:

 . . . or a Kodak 18% grey card.  


I have several Kodak gray cards, so let's continue with that as our reference.

Expert
Posts: 2,286
Registered: ‎11-23-2012
Message 47 of 92 (4,633 Views)

Re: Guide to Cine EI on the F5 and F55.

So take SLog2/Sgamut at 1250 ISO and evenly illuminate your chart. To ensure no frame rate/shutter confusion I suggest setting the camera to a 1/50th or 1/60th shutter and set the light meter to a non cine 1/50th or 1/60th shutter. Take a reading with the light meter. Match the cameras W/B to the light source, set the aperture according to the light meter subtracting 1/2 a stop (stop down) to compensate for the light meters 12% calibration and the chart should fall at 32%. The test would be more accurate with a tungsten light source if you have one to elimate any green spikes from the LED's effecting the green channel. Of course the test is only as accurate as the chart, if you have a couple take an average perhaps.

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Expert
Posts: 1,607
Registered: ‎11-19-2012
Message 48 of 92 (4,609 Views)

Re: Guide to Cine EI on the F5 and F55.

[ Edited ]

Sorry but this is not entirely accurate:

 

Any "cine" light meter by default works with a default of a 180 degree shutter which is why on a cine meter you only select the frame rate and not the shutter speed. So for 24fps 180 shutter angle the frame rate is 1/48th and of course your camera and meter should be set to using the same shutter speed/angle if you are rating the camera ISO. That is the whole point of determining the "working ISO" of the camera. DIP switches on the back of some light meters allow you to change the shutter angle incase you are working with a different shutter speed such as 90 or 270, etc... or you want to introduce your own exposure compensation for "advanced" use.

 

If your meter is not a "cine" meter then don't sweat it. Just set the shutter speed on the light meter to DOUBLE what the frame rate of the camera is (assuming that the camera default shutter is "on"). So if the camera is set to 24fps then you MUST set the shutter speed to 1/48 or 180 degree, or if you are in PAL land set the frame rate to 25fps and shutter to 1/50th. You woud not use 1/60th unless you were in 30fps mode on the camera. Again the shutter speed on your camera and light must match when rating your camera's ISO.

 

On the light meter itself make sure it is in incident measurement mode. To be in this mode the lumisphere must be raised. (white dome is up not recessed) and obviously to take a reading you hold the meter right in front of the grey card with the dome facing back to the camera and/or same lighting source used to illuminate the grey card.

 

Even though it is technically correct that a Kodak grey card is 18% and light meters are calibrated to 12%, initially I would not add any compensation to anything when performing the rating test because later you'll see why it does not become important. If you wish you can do as I do, and write down your settings on the camera, the light meter, what actual light you used, and even a measurement of the distance between the sensor plane of the camera and grey card. All this makes for great reference later.

 

Here's how I recommend you perform the test:

 

- Evenly light an 18% grey card. Set the camera to 24p, 1/48th (or 180 degree shutter), 0db gain. Pick a gamma curve and you must know it's middle grey placement on the gamma curve. I suggest slog2 since we know middle grey is mapped to 32%. Adjust your lens iris until you get 32% on a waveform monitor. You may want to play with your lighting intensity a little so that you can get your lens on an even stop value ie. f4 or f5.6, etc..

 

- On your light meter: if it is a cine meter select 24fps. If it is a regular light meter chose 1/48th shutter speed. Set the ISO to what the camera manufacturer rates the camera. On the F5 2000 ISO, on the F55 1250. Now take a light meter read. (make sure the lumishpere is up!). 

 

- Most meters let you hold down the mode1 button so that you can adjust the light meter ISO without losing the light reading you just took. Adjust the ISO on the light meter until the f-stop on the light meter matches what you set your taking lens to. 

 

- This new ISO value on your light meter is what you have rated the camera ISO as. 

 

As mentioned throughout our posts there are 100 reasons why film ISO will not match digital ISO and how errors can be introduced but the point of calibrating your light meter to what your camera sees as 18% grey and hence where middle grey gets mapped to is you can literaly light an entire scene with the light meter as your reference without the camera or waveform monitor, etc..  This is the value I get from working with it and how some of us like to work on more complex lighting setups, or where lighting is done in advance of shooting. After you gain enough experience you start to know what lights you can use just from the wattage and modifier, but still I trust my meter more than I trust myself at times.  Smiley Happy

 

Some people light by eye, some by WF, some by monitor, and some with light meters.

 

 

 

 

Expert
Posts: 1,506
Registered: ‎11-20-2012
Message 49 of 92 (4,559 Views)

Re: Guide to Cine EI on the F5 and F55.

I had a project drop in my lap this morning.  This will have to wait a few days.  Business first.

up4 Expert
Expert
Posts: 184
Registered: ‎03-24-2013
Message 50 of 92 (4,505 Views)

Re: Guide to Cine EI on the F5 and F55.

[ Edited ]

Hi Alister,

 

Thanks for the guide. I read all of it and maybe I missed something, but did you say that in the other thread that you were going to look into the significance (or not) of the absence noise reduction function in Cine-EI mode for pre-xavc encoding? Are you still planning to do that?

 

 

I do not have a way to capture uncompressed 422 10-bit 4K SDI signal myself but if I did (with something like the Blackmagic Ultrastudio 4K), I would compare PSNR and SSIM measurements for Cine-EI Slog3 and Custom Slog2 with noise reduction (but everything else set to off).


Right now, like I said, I remain on my (uncomfortable) position that the use of Cine-EI for XAVC recording is somewhat limited due to the absence of pre-encoding noise reduction. And I would like to know precisely just how much before I resolve myself to use it.

 

Or maybe you have heard that noise reduction will be enabled for Cine EI for XAVC at some point…

 

Thanks again.

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