How to correctly set exposure / ISO in Blackmagic iOS Camera

Hi,

I am very much a NOOB when it comes to shooting, and I was shooting with the iOS camera ap outdoors the other day, and I'm pretty sure I messed up the exposure.

Here is what I shot:


I believe I had the ISO set to 125.

I brought the footage into resolve, and here is what it looks like with a very basic color transform:

Input Color Space: Rec.2020
Input Gamma: Apple Log
Output Color Space: Rec.709
Output Gamma: Gamma 2.4

But with the scopes open, it looks like everything is very blown out.

2 basic questions:

1. How should I set the ISO before I begin shooting in this app to avoid this happening in the future (if I have shutter locked to 180°)?

2. Is there any way to "rescue" this shot and make it look decent?

Here is what my basic settings in the camera are looking like, btw:



Tx in advance for any help / tips.

The aperture is fixed and you want to shoot 180 degrees shutter, which is good for aesthetics.
So, what’s left to you in daylight is using ND filters, even the lowest ISO value might still overexpose.
Not much to be saved in the blown-out area, but you can try to use a curve on the highlights and may gain a bit.

When you can’t change the diameter of your lens opening, your only exposure controls are ISO and shutter speed. Your ISO was already low. If reducing it to 50 didn’t do the trick, your only option was to increase your shutter speed. That would mean abandoning the 180° shutter you adopted.

If you don’t want to increase your shutter speed, the work-around is to artificially reduce the amount of light entering your lens opening. This is where neutral density filters come in.

There’s a fair bit of discussion in the following thread about ND filters, and about the need in a given situation, or not, for a 180° shutter: viewtopic.php?f=2&t=191338

It's a pedantic point, but ISO is not an exposure control, just film speed.

It's a pedantic point, but ISO is not an exposure control, just film speed.

Yes, ISO is a measure of the sensitivity of the film or sensor. Consequently, one can object to calling it an exposure control on logic grounds. That said, if it’s good enough for Nikon, it's good enough for me From Nikon’s website at https://www.nikonusa.com/learn-and-expl ... so-control:

ISO Control

The ISO setting is one of three elements used to control exposure; the other two are f/stop and shutter speed.

...

So don't forget that along with f/stop and shutter speed, ISO is an important element of exposure control.

John Hess (Filmmaker IQ) is making a few good points why ISO is different and even why the exposure triangle is not very logical in his "6 Reasons Why We Should Ditch the Exposure Triangle".
As usual, quite scientific. Of course, you can still think of it as an "exposure rectangle" and add NDs.

But with the scopes open, it looks like everything is very blown out.

That doesn't mean a whole lot at this point, because the primary color wheels are all at their defaults. Viewing the waveform, there's no knowing how much of the shot is actually clipped and how much is recoverable when the levels are reduced (in Resolve). To the extent the data is actually there, you adjust the "exposure" in Resolve.

As for ISO, it doesn't have a fixed meaning for digital cameras, the way it does in the film realm, since it's implemented differently on different cameras. On BMD cameras shooting braw, the setting itself is not an exposure tool -- beyond the choice of the lower or higher ISO range. What ISO you expose *for* is what matters.

On BMD cameras shooting braw, the [ISO] setting itself is not an exposure tool -- beyond the choice of the lower or higher ISO range.

An iPhone is not a "BMD camera shooting braw”.

On a practical level, iPhone shutter speed and ISO control exposure, and suggesting otherwise to someone who says that he’s new to iPhone video is not helpful.

The Nikon website link above constitutes a clear, accurate statement of how iPhone exposure works, with the caveat that iPhone lenses have fixed apertures, making the use of ND filters and artificial lighting additional tools, when needed, to achieve the desired exposure.

John Hess...

In that six year old video, Hess also says that the world, having achieved 4K video, has “exhausted” the subject of resolution

Exposure is to light, as ISO is to signal amplification. They are distinct concepts.

Exposure is to light, as ISO is to signal amplification. They are distinct concepts.

You already said that you’re being “pedantic”, your own word

If Andrew wants to do some reading, there’s no shortage of discussions about what ISO is on the internet. He can also read about EI for good measure. Meanwhile, he needs to know how to set his iPhone's exposure.

An iPhone is not a "BMD camera shooting braw”.

On a practical level, iPhone shutter speed and ISO control exposure, and suggesting otherwise to someone who says that he’s new to iPhone video is not helpful.

Rob, as much as you might want to restrict discussion here to matters you understand or youtubes you've watched lately, the meaning of ISO in the digital realm is quite plainly at issue above. That line of inquiry will not end, simply because you want it to. And when you state:

Yes, ISO is a measure of the sensitivity of the film or sensor.

you are not being helpful at all, because that statement is simply not true (or better said, is not a useful way to understand exposure) in the digital realm, because the implementation differs from camera to camera. What ISO means in the film realm has little useful application in digital. The analogy rarely works.

I can add also that ISO should be stitch as possible to native also on iPhone to reach the best of dynamic range of sensor for shadow but more for manage correctly the highlights.

Then we can only change shutter or Nd filter.
I remember that native iso for Gerald Undone seems more higher, and if we downsamolinga clipped signal, we cannot regain the highlights.

There is a great article on prolost website from stu about apple event shooter with iPhone 15, and all about their settings of light and shooting.
This man is the man behind Red Giant tools for color grading and more, ex ILM vfx artist and ex The orphanage founder. He know what he told.
There is also a great articles of video did only with iPhone 15 for vfx and why during another travel leave is mirrorless at home and gain great result with a phone.
He’s not an influencer or payed from anyone, he’s a great technical skilled Videomaker that analize the good and the worst of a tool.


Inviato dal mio iPhone utilizzando Tapatalk

Rob, as much as you might want to restrict discussion...

[ISO] implementation differs from camera to camera.

In fact, I have started discussions on this forum specifically about the iPhone 15, the Blackmagic app and ISO. There is a difference of opinion about optimal use of ISO and there are differences between apps on available ISO values. If you had read the relevant thread, you would know that I started those discussions and that there was a good deal of debate about both issues.

Andrew raised a practical question about exposure control on the iPhone 15 using the Blackmagic app. He wasn’t asking about some other camera or about some other app. Uli, who has used both, answered Andrew’s question. Having also used both, I also answered his question. You haven’t answered his question. As usual, you’re just here looking for an argument. You don’t even use an iPhone 15 and the Blackmagic app, do you.

I'm well aware, Rob, of all the "discussions" you've started here, hundreds of them. Add these tireless consumer preoccupations, wedded to a certain want of experience, and I wonder if you're the best police force for the forum, to set the beginning and end points.

And wouldn't that active policing policy of yours make you the one looking for the fight? Did I start by objecting to your posts?

As for the OP, it's remarkable that somebody as devoted to his interests as you are neglected to point out that he may not have actually lost much data -- that a passably good "exposure" may be right there in his footage, but he'll never know if he doesn't look. Perhaps you don't understand "exposure" in the digital realm as well as you think?

I can add also that ISO should be stitch as possible to native also on iPhone to reach the best of dynamic range of sensor for shadow but more for manage correctly the highlights.

Then we can only change shutter or Nd filter.
I remember that native iso for Gerald Undone seems more higher, and if we downsamolinga clipped signal, we cannot regain the highlights.

There is a great article on prolost website from stu about apple event shooter with iPhone 15, and all about their settings of light and shooting.
This man is the man behind Red Giant tools for color grading and more, ex ILM vfx artist and ex The orphanage founder. He know what he told.
There is also a great articles of video did only with iPhone 15 for vfx and why during another travel leave is mirrorless at home and gain great result with a phone.
He’s not an influencer or payed from anyone, he’s a great technical skilled Videomaker that analize the good and the worst of a tool.

It’s good that you've referred to the base ISO question because it’s an opportunity to address it.

Yes, the Gerald Undone/Patrick Tomasso video on YouTube is the source of a view that the iPhone’s base ISO is about 1250.

Stu Maschwitz wrote the post that you refer to, saying that Apple used ISO 55 for the Hallowe’en event that it shot with an iPhone 15. In the same post, he noted the Undone/Thomasso video, without expressing a view on ISO 1250. More recently, Maschwitz used an iPhone 15 to shoot a video in Taiwan. For that video, he adopted a conventional position on ISO.

Gerald Undone's position has not been adopted by Apple for its own iPhone 15 films, including its Chinese New Year film Little Garlic and its Super Bowl documentary Usher. Nor was it adopted by Claudio Miranda, A.S.C. for the short he made for Tilta, The X Gift. Miranda said that he was happy with ISO 200 and 400 and “mildly happy” with 500. See 14:30:

Indeed, I’m not aware of a single professional who has adopted Undone’s proposed base. I also think that Patrick Tomasso’s view, who actually carried out the Undone video tests, was less black and white than Undone characterised it.

There is a great article on prolost website from stu about apple event shooter with iPhone 15, and all about their settings of light and shooting.
This man is the man behind Red Giant tools for color grading and more, ex ILM vfx artist and ex The orphanage founder. He know what he told.
There is also a great articles of video did only with iPhone 15 for vfx and why during another travel leave is mirrorless at home and gain great result with a phone.
He’s not an influencer or payed from anyone, he’s a great technical skilled Videomaker that analize the good and the worst of a tool.

Here is Stu Maschwitz's post about Apple’s Hallowe’en event that Carlo refers to above. It was published on November 7th, a week after the event: https://prolost.com/blog/scarybts This is Maschwitz’s bio: https://prolost.com/about The Maschwitz film that Carlo mentions is the Taiwan film that I refer to in the post just above.

Apparently Maschwitz also thinks it’s OK to talk about the iPhone’s exposure controls in plain English From his post:

They Shot at ISO 55: Matters to Apple’s Goal of Maximum Image Quality

Here’s where the level of professional control over the lighting starts to really matter: If Apple decided that they must shoot at ISO 55 (the lowest, although possibly not the native ISO of the 1x camera) for the highest image quality, and with a 180º shutter for the most pro-camera look, that means they have no other control over exposure. The iPhone 15 Pro 1x lens does not have a variable aperture, so shutter speed and ISO are your only exposure controls.

When shooting in uncontrolled environments, the typical method of limiting the amount of light entering the lens is via ND filters, sometimes variable ND filters. I don’t see any evidence that Apple used filters on this shoot, which would fit with their overall prioritization of image quality over all else. So this goes back to lighting — Apple’s team controlled that lighting perfectly, because they opted out of any exposure control they might have had in-camera.

I'm curious to learn more about this setting though. YouTubers Gerald Undone and Patrick Tomasso did some tests and found that the best dynamic range from the iPhone 15 Pro came from ISO 1100–1450, with 1250 being their recommended sweet spot. Did Apple prioritize low noise over dynamic range?

I’ll keep that in mind as I have a photo shoot next weekend for which I plan on using the iPhone 14 Pro in a theatrical setting so usually lighting is manageable.

I had my doubts about that 1,250 ISO from the start, having experimented with Apple’s highlight extension. Further experience tells me that Claudio Miranda’s values are much more realistic.
That whole story shows that ‘native’ ISO is not easily defined in digital.
OTOH, neither was ISO carved in stone with optochemical.

I had my doubts about that 1,250 ISO from the start, having experimented with Apple’s highlight extension. Further experience tells me that Claudio Miranda’s values are much more realistic.
That whole story shows that ‘native’ ISO is not easily defined in digital.
OTOH, neither was ISO carved in stone with optochemical.

People have been deviating from official film ISO, and from official sensor native ISO, forever. In still photography forums, the debates on this subject go on for pages. So do the debates about a related subject, the Zone System. If you feel the need for a refresher, pop over to Photrio or The Large Format Photography Forum

I don’t know anybody with a good amount of film or digital experience who claims that one must treat an ISO number as sacred. For example, all of my acquaintances with an interest in images, when speaking about film emulsions, are likely to use the term box speed. The whole purpose of that term is to recognise that many people use a different speed from the stated ISO.

The original question, from someone who says he’s completely new to this, was about the mechanics of setting exposure. I think that there’s plenty of time to get into these kinds of nuances.

i'm with the Stu thinking, Apple priorize low noise over DR be cause they do it live, and work and a perfectly controlled environment. Jerald seems a guy that do ever is exercise and Him also had a strong knowledge on sensors and cameras.

Like told from Robertedge, and like we learn from DR spreadsheet along Blackmagic manuals about Iso and different stop avaible, i'm agree that nothing is stone sculpted, it's a matter of choise and what we need in a different situation.

If we see default Iphone app working, it use shutter to change exposure, to keep more consistent the contrast of picture.

People who are interested in the iPhone 15 Pro's dynamic range, which is the principal subject of the Gerald Undone/Patrick Tomasso video, are likely to find Strada’s new video highly informative:

Measuring the Dynamic Range of an iPhone

Some may be interested in following up by watching professionally shot iPhone 6 footage. Austin Reza used an iPhone 5S and a 6 for his Intelligent Details films:

Intelligent Details (iPhone 5S)

Intelligent Details: The Bespoke Driving Jacket (iPhone 6)

Reza also made behind the scenes films for these.

Quite a feat at the time!
And even in 2011 Park Chan-wook and Park Chan-kyong from South Korea shot the fantasy/horror „Night Fishing“, even with an iPhone 4 and won the "Golden Bear" at Berlinale for the best short.
Proving that it's all about content, not technical quality of the phone:

There’s discussion earlier in this thread about Apple’s decision to shoot its Hallowe’en event on iPhone.

Last frames of Apple’s iPad event today, at which it announced a new iPad Pro, version 2 of Final Cut for iPad and a stand alone Final Cut Camera app:

apple credit.jpg (54.9 KiB) Viewed 832 times

And even in 2011 Park Chan-wook and Park Chan-kyong from South Korea shot the fantasy/horror „Night Fishing“, even with an iPhone 4 and won the "Golden Bear" at Berlinale for the best short.
Proving that it's all about content, not technical quality of the phone

True enough, but there's no question the short looks like what it is --a program shot with a poor quality camera. That look may actually be to good effect for the material, but that's saying something other than the "camera doesn't matter". Look at Park's recent "Decision to Leave". No iphone there. And you wouldn't want one.

The joke is, if you have money, sure, you can shoot on a iphone even though somebody with money never would. It'll look a bit plastic, but if the production values are great, it'll pass as oh wow professional among consumer iphone buyers. That's plainly evident here. But without money and resources what will it look like..... Need one say more?

Seconded. The professional shoots are made to convince amateurs that they'll be just as good as the pros if they only buy that phone. Which, of course, is not true.

Quite a feat at the time!
And even in 2011 Park Chan-wook and Park Chan-kyong from South Korea shot the fantasy/horror „Night Fishing“, even with an iPhone 4...

Yes, Austin Reza (https://www.reza.la) talks in the video below about how the Intelligent Design/Bentley Motors films were made. They used Vadym Chalenko’s first Beastgrip cage, which he’d spent a year developing. This is Chalenko’s 2013 Kickstarter application: https://www.kickstarter.com/projects/10 ... t-camera-p. Reza also says that they used Freefly Systems’s MŌVI, launched in 2013 as the first handheld electronic camera stabiliser.

The Strada film emphasises the technical advances in digital image-making since about 2010, and suggests that Apple is on a road that will surprise us. I think that is consistent with what Apple has been doing with its imaging products since it released the iPhone 15 in September. Peter McKinnon says that the iPhone 15 reminds him of the beginning of the "DSLR revolution”.

The professional shoots are made to convince amateurs that they'll be just as good as the pros if they only buy that phone. Which, of course, is not true.

The Strada video has a completely different take on what’s happening. The statement quoted above is just a bald assertion. There are no facts offered to back it up because there aren’t any.

Exactly what I wrote in my review last year. If you look around in the digital village, there are supposed "game changers" every hour, which are more like Ephemeroptera ( fly living for about one day).
But the iPhone 15 might be rightfully regarded that way, one day in retrospect, just like the Canon 5D mark II. Other than that, you can even use it for a phone call. But don't forget to switch that off when shooting

The professional shoots are made to convince amateurs that they'll be just as good as the pros if they only buy that phone. Which, of course, is not true.

The Strada video has a completely different take on what’s happening. The statement above is just a bald assertion. There are no facts offered to back it up because there aren’t any.

Oh, it's only my conspiracy theory, dear Rob.
But the brothers from Korea got money from Apple to do it. I didn't speak with any of the others.

BTW, why are you shooting against me, when I have just agreed with you in two points (for a change)?

Exactly what I wrote in my review last year...

But the iPhone 15 might be rightfully regarded that way, one day in retrospect, just like the Canon 5D mark II.

Are the above references to McKinnon’s analogy, or something else?

McKinnon's, of course.

Here is my original text from last year:
"Apple hat beim iPhone 15 Pro einen erstaunlichen Spagat hinbekommen: 99 Prozent oder mehr unter den Nutzern bekommen ohne große Sachkenntnis nette Bilder geliefert und Profis bekommen eine Kamera, die mit der richtigen App weit mehr als ein konventionelles Smartphone kann. Die Sau namens „Game Changer“ wird ja fast täglich durch’s digitale Dorf getrieben – meist sind es eher Ephemeroptera (Eintagsfliegen). Aber die Pro-Modelle des iPhone 15 könnten tatsächlich einen Paradigmenwechsel signalisieren, ähnlich wie vor 15 Jahren die Canon 5D Mark II. So wie jene den Beginn der hybriden Foto/Filmkameras markiert, ist das iPhone nun ein Arbeitsgerät für Profis."
(Sent to the publisher on 12/6/2023 at 12:17. Please use DeepL for translation.)

McKinnon's, of course.

Here is my original [review] text from last year... Please use DeepL for translation.)

From DeepL:

"With the iPhone 15 Pro, Apple has managed an amazing balancing act: 99 per cent or more of users get nice pictures without much expertise and professionals get a camera that, with the right app, can do far more than a conventional smartphone. The pig called "game changer" is driven through the digital village almost every day - mostly ephemeroptera (mayflies). But the Pro models of the iPhone 15 could actually signal a paradigm shift, similar to the Canon 5D Mark II 15 years ago. Just as that marked the beginning of hybrid photo/film cameras, the iPhone is now a working tool for professionals.”

McKinnon and you were on the same wavelength. He doesn’t say where he shot this, but it’s Banff National Park. My brother was there at the same time, sending me photos of an unusually early October snowstorm

Thanks for the translation, Rob.
Unfortunately, AI still doesn't get specific phrases or local color (Bavarian here) very well, so for clarification:
"eine Sau durch's Dorf treiben" translates like "to make a big fuss about something" and "Eintagsfliege" is a short-lived news. It was figurative, since a "Sau" is a pretty large and heavy animal and that fly is really tiny

To get back to the subject of this thread: I was a bit surprised how clean his Xyla recordings look. We made such measurements in late 2011 with the classic Arri Alexa, the Sony PMW-F3, and the Red Epic, using a Xyla 21. The Alexa came out on top, but I counted 14.5 Stops of DR. After all, DR is the number of the gaps, not the highs. Maybe we were not staring at the low end long enough to see more.
Without HDRx, the Red showed 11.5 stops of DR, the last one pretty much buried in the deeper noise floor.
We made our tests in a black studio with no other light than the Xyla, it was pitch black to the eye. Our lenses were Arri primes (actually Zeiss). Nevertheless, we saw a lot of light scattered in the lens around the highlight fields above the noise, which I would count as expected behaviour under such extreme conditions. Unfortunately, we don't have a Xyla any more, but I don't doubt the relative DR of the iPhone anyway.
This is how the classic Alexa looked like OOC:

Xyla_Arri.png (261.47 KiB) Viewed 527 times

And then, the explanation of log is a nice one for beginners, but somewhat incorrect. You could also record linear in 16 bit, but log is simply much more efficient. The true reason is re-distribution of bits from where humans don't perceive small differences anyway into the more critical, darker range, saving storage that way:

Log.jpg (37.61 KiB) Viewed 522 times

I really like one of his closing remarks: "Talent lives at the heart of any production, and iPhone 15 captures it with enough quality to respect the effort of a talented crew." Nothing to add.

Unfortunately, we don't have a Xyla any more, but I don't doubt the relative DR of the iPhone anyway.

As has been pointed out elsewhere, and as I'm sure you know, a whole lot of noise reduction goes a long way to explaining those DR results. The more meaningful measure -- latitude in stops -- is much more what one would expect. Not bad, but it's still a phone.

I wonder if another "DSLR revolution" is all that desirable -- it produced what cinematic masterpieces, forgetting a number of out-of-focus no-budget features? -- but the only real revolution here would seem to be one of marketing. Just look how personal it's become for iphone owners, with mortal offense taken at any suggestion that his, her or their iphone may not be the last cinema camera anyone ever needs for all the movies which will never get shot.

What I'm waiting for, passionately, is an Alexa with a dial-tone. Any day now?

You're right, there's always something more to say, and we have to interpret those DR values with care.
The iPhone is doing massive NR, even when shooting log, and being fast enough to be done while shooting, it will inevitably kill some detail. It may still take a few years until such a good algorithm as UltraNR can run in a phone in realtime.
What is rarely mentioned, also neither by Undone and Tommaso, nor by McKinnon, is the EDR extension done in the iPhone. You can easily miss that if you let shutter and ISO run freely, but if your exposure time is getting too long, you will get a sudden drop in DR. If you get below about 1/70 of a second (at 50 fps), the highlight extension is getting lost. If you have 1/96 or shorter times, it extends, since the phone is getting enough time between the frames to compute that.
Might be useful for Andrew Kortina too.

Just look how personal it's become for iphone owners, with mortal offense taken at any suggestion that his, her or their iphone may not be the last cinema camera anyone ever needs for all the movies which will never get shot.

Don’t let anything get in the way of looking down on other people. If you don’t have any facts, just make them up