“ISO is an almost meaningless sensitivity measure for a video camera” Alister Chapman

Categories: Miscellaneous 10 Comments

dB v ISO

As I reported back in October last year ISO is confusing and Alister Chapman has just verified this with a blog article on ISO.

For many years video camera operators only had a gain setting and due to relatively noisy cameras it was ingrained into you not to go above 0dB, so extra light was used indoors to achieve this goal.

People like to impress and think they are technically confident like a so called “Director” who told me to switch my Sony FS7 to Slog as thats the preferred setting…why…did he have a clue why he was asking me to do this…no, only that someone in his past had told him it was “better”.

So now we have a band of so called evangelist camera operators who talk about ISO rather than dBs because its “Cinematic speak”…”Oh I produce films not video”…sorry aren’t you using a video camera !!! I think the term “Digital Cinema” probably suits what we are trying to achieve these days…thank you David.

Remember when you use a film camera your ISO or ASA is fixed, usually at 125 ASA to give you less grain thats why in Cine EI mode on a Sony FS7 you can’t adjust the ISO when its in that mode. The Sony FS5 on the other hand has not got Cine EI, only Slog, but you can still play about with the ISO which you can’t do with a cine camera.

Unless your camera takes good old ASA speed rated film…you are still making a video. “Oh but its 24p”…hard cheese give me 50p anytime, in fact Nolab are just about to launch the digital film cartridge for all you film buffs.

Nolab-Digital-Cartridge-Brings-your-Super-8-Camera-to-Life-407757-3

Here we have the Nolab Super 8mm “film’ cartridge at the heart of the Nolab Digital Super 8 Cartridge is a tiny but powerful 5 megapixel image sensor similar to the one in your smartphone. Combined with a custom glass objective lens, the sensor focuses on a ground glass image plane pressed against the camera’s film gate. By using a 5 megapixel sensor we can capture 720p HD footage at the native Super 8 aspect ratio of 4:3.
Nolab-Digital-Cartridge-Brings-your-Super-8-Camera-to-Life-407757-2
Processors integrated into the image sensor are able to  process and encode the footage in real time to a removable SD card. Optionally the same processors can apply one of two predefined Film Look color correction filters to the footage.
That sounds simple enough, To allow the Nolab cartridge’s image sensor to synchronize with the camera’s shutter, a unique sensor had to be developed. It’s this design that allows the cartridge to work properly in any camera at any frame rate up to 60 fps.

Back to ISO…If you work mainly as I do with rec 709 stick to dB and you won’t go wrong, 0dB is the world standard setting for the best, quietest pictures your video, cinematic camera can produce.

“Oh but my Sony FS5 is not so good in low light” fine you have 3 options…

1. Boost the gain

2. Add extra light

3. Use a lens with better low light capabilities like an f1.8 constant aperture lens.

Unfortunately because some of the cinematic rantings get through we get a second set of guidelines called ISO which in the words of Alister Chapman is indeed meaningless, so like lemmings we all listen to those ranting on about cinematic this and “must have 24p” that, we have a legacy of two crafts joining forces and confusing the hell out of each other.

If you want the “film” look then use film and stop this utter nonsense of pretending a video camera will produce film when it can’t, it may produce a cinematic look but thats not film.

super8_press v2

 

Kodak are reintroducing Super 8mm film for all you film buffs the Kodak Super 8 Revival Initiative reaches far beyond the introduction of a new camera. The company has built a roadmap that includes a range of cameras, film development services, post production tools and more. “It is an ecosystem for film” said Jeff Clarke, Eastman Kodak Chief Executive Officer. “Following the 50th anniversary of Super 8, Kodak is providing new opportunities to enjoy and appreciate film as a medium.”

Film has generated huge buzz in Hollywood recently as the chosen medium for award-winning movie directors and blockbuster movies. Now the Kodak Super 8 Revival Initiative is being applauded by the industry’s top directors, many of whom got their start on Super 8 film.

super 8 canon

Kodak “Shooting Analogue has never been so easy. When you purchase film you will be buying the film, processing and digital transfer. The lab will send you your developed film back and email you a password to retrieve your digital scans from the cloud so you can edit and share in any way you choose.”

Kodak film 2

Now we shall see the men from the boys, ASA ratings input into a light meter, no image stabilisation and about 3 minutes of film per cartridge and no sound track. The cost of buying and getting your Super 8mm film cartridge processed is expected to be between $50 to $75 US.

I have been fortunate to see and test over 25 camcorders over the last few years and have come to realise that sensor size dictates to a greater degree how noisy a camera will be so going by my rule of thumb…

3 Chip 1/3″ camcorders use NR circuits to try and mask chip noise, 1″ single chip camcorders are less noisy at 0dB and give a better shallow depth of field, 3 chip 2/3″ perform a lot better than 1/3″ and tend to be better in low light and super 35mm sensors tend to be able to boost the gain way beyond the smaller sensor cameras and have exceptional depth of field properties. The one thing that is the same with all these cameras is 0dB the same cannot be said about ISO ratings.

For more information on the new Kodak film service: http://www.kodak.com/ek/us/en/Consumer/Products/Super8/default.htm?CID=go&idhbx=super8

More reading from Alister Chapman go here : http://www.xdcam-user.com/2016/01/iso-fiasco/http://www.xdcam-user.com/2016/01/iso-fiasco/

For all your video production needs in Scotland, get in touch with Small Video Productions

10 comments on this post

  1. MARK says:

    irrelevant is this discussion , talking about video cameras. what’s relevant is the intentional processing that the manufacturers apply depending on the cost of the model. And it has very little to do with the noise and “sensitivity”, the aperture, the shutter speed : sensors are intentionally processed to produce darker footage if the marketing and cost goes to the lower end. Don’t believe me? compare the PMW-400 to the X70 , same aperture, same ISO/ASA or whatever, same shutter speed. See? here we go. It’s not some ASA/ISO useless discussions : it’s marketing and the intentional limitations to the processing of the sensor.

  2. David Heath says:

    Hmmm. I see where you’re coming from, but does “0dB” really tell you any more than ISO…?

    The point about an ISO rating is that if you measure the light, then for a given shutter speed, you know what to set the iris to for correct exposure.

    But “0dB” for a given camera only tells you that it’s the gain level that the designers think will give you optimum results. And expressed as ISO it will vary from camera to camera. The equivalent ISO is needed to calculate exposure for a given measured lighting level.

    With previous generations of camera such may only have mattered on a big job with a big lighting rig. The lighting director would know that he had to light evenly to a given level – and may have done such the day before any camera arrived!

    On smaller jobs, less of a problem, and we may have got used to setting camera to it’s 0dB, then adjusting ND/iris to get correct exposure according to zebras or whatever. So who does need ISO?

    The trouble is that with factors such as s-log etc you can’t really do that anymore. The whole point is that with such it’s increasingly difficult to set correct (or at least, optimal) exposure that way. Far better to measure the light level and use that to set f stop….. but then, of course, you MUST use ISO values!

    I’m with Alister in that the subject has created a vast level of misunderstanding, and will agree with you that s-log is not always the best way to go. But I think it’s then a stretch to dismiss ISO terminology usage as just “evangelist camera operators who talk about ISO rather than dBs because its “Cinematic speak”…”Oh I produce films not video”…”. There is a place for ISO usage.

  3. Mike says:

    If ISO is so meaningless why does the FS5 say “ISO/Gain” on the button. Obviously Sony thought it was important enough to include as an option.
    How about everyone just uses whatever they are most comfortable with? There is no “right” and “wrong” in the world of video production.

  4. MARK says:

    About time we had this topic finally revealed. I said it before and I’ll say it again: thanks to Philip for bringing this up again!. Low light performance has no standards in video. It does with stills but for video there is only marketing and intentional limitations (darker processing depending on the price). 0db should mean 0db and a standard luminosity (period). The manufacturers had complete carte blanc until now. To be clear the better low light performance has been a formidable tool to sell the better performing cameras at stratospheric prices (darkening all the others intentionally). We know that, don’t we? and it’s all (90%) in the processing. Now we finally talk about the limitations (intentional) and the complete lack of standards. I’ll say that the only standard in video regarding the low light performance is the cost of the camera.

  5. David Doré says:

    Thanks for this interesting rant Phil. I should just like to say, in my defence, that I have always hated the word video. I think there is a legitimate use for the term ‘digital cinema.’ Would you call the Arri Alexa a video camera? As to the ISO/0db argument I confess to being agnostic. I have been using DSLRs for some time now and thus I am stuck with ISO anyway! As an old film man at least it sounds familiar (we used to call it Weston). Finally let me say that Wolff Hall, shot an Alexa and at times only lit by candles, was one of the most impressive productions I have ever seen. It certainly didn’t look like video!

    HDW : Yes David point taken but even the Alexa is a video camera with a cinematic look.

  6. Ron Evans says:

    Well to support Mark and Philip I think both the use of iso and db are marketing driven. If the manufacturer wants the camera to appeal to the film group then put iso on the controls. If one wants to make the camera look good in low light set the 0db position to support this. However if one uses RAW then most of the manufacturers controls are removed so one then needs to work with the base technology of the sensor. Needs more skill to set exposure, just like dealing with film. I shot film in the 60’s and I am so pleased I now shoot video at 60P !!!

    Ron Evans

  7. mark says:

    David Doré : I’m sorry but I disagree. I assume that you are talking about movies (with a budget, actors and crew). 2K is already in the same league of 35mm film. Again for movies you rent Arri because it’s there and comes with all the rest, but in terms of performance any GH3 will produce 2K the same. If I take the latest star wars (shot on film) I can easily assume that maybe digital would’ve been better. The next one will be shot on alexa 6K. Then there is the GH4 , 4K, that surpasses film in any aspect. The only difference between Alexa and GH4 is the rolling shutter and the blur panning, but that’s because of the intentional limitations they put on the consumer GH4 (slow processing, intentional of course). But in here we talk more about regular video cameras (not really for movies, but with a lanc, a zoom and a decent low light), more for events/sports (where we make money) and the discussion about the low light performance becomes ridiculous : it’s all marketing. For example the x70 is laughable if compared to the PMW-400 in low light. It’s evident and clear to me that it’s all intentional . How can I say it better? They intentionally darken the processing, better now?

  8. David Doré says:

    Mark: I think you’ll find that Star Wars VII was shot on 65mm Eastman negative, not 35mm. As to your comparison between the GH4 and the Alexa, I can only say that, while the GH4 is an excellent camera, I don’t think you could have shot the candle-lit scenes without very significant noise. So no… I don’t think it is quite reduced to marketing decisions…. maybe I’m wrong.

  9. Mark says:

    David Dore’ : I never said that star wars was shot on 35mm , I said that right now digital is in the same league of 35mm film. Please read again, words are important. Regarding the low light performance I know that the alexa 2K is comparable to the GH2 , but not even close to the GH4. alexa 2K vs. GH2 gives the advantage of a flatten processing (not really DR advantage): just a better processing but only for the colorists. And I also remember that the guys (in Germany) with the Alexa 2K project said that 2K was more than enough and ARRI wasn’t even considering going beyond that. Last famous words. LOL . The interview was official, on the ARRI’s website. Not long ago. Regarding the marketing tricks you are completely wrong: it is ALL about marketing with digital, from the intentional lack of servo zooms for DSLR to the 29min max , to the locked aperture, to the slow processing, to the darken (intentionally) processing, to the proprietary media, and the list could go on and on and on. Take this discussion for example: camcorders never had any open verification of the 0db standards , EVER. Even now we have to repeat it over and over and still many don’t get it: the main reason why we had to spend 10-20K (US) more for a decent low light camera was because the affordable ones were intentionally made darker. In the end you are wrong with both the star wars reference and the low light linked to marketing. But I appreciate your contribution that gave me one more chance to reveal the tricks they use to sell to us.

  10. David Doré says:

    I retire defeated… how did I ever get involved in this rant?

    A final thought… ‘Chopsticks’ probably sounds as good on the old pub piano as it does on a Bosendorfer grand, but I doubt whether Beethoven’s Piano Concerto 5 does!

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