iPhone 11 UWA Camera : Disturbing Discoveries

October 18, 2019 by

After just spending a day’s worth with the iPhone 11 Pro ultra wide angle camera, I’ve discovered a few things everyone should be aware of. I’m rather tired of Apple’s half-assed approach to everything photography related. This is not a whining of a 20-something reviewer. This is from someone who wasted months of his life to transform Apple’s incomplete, amateurish APIs to something suitable for professional photo apps, and wrote exposure calculation, image encoding/decoding/display and color space transformation code along the way.

To anyone reading this at Apple: I’m open to provide you with consultancy to help get your act together and make a truly pro-level camera device / API.

No RAW

Take a look on any JPG file from the ultra wide camera. You’ll see heavy smearing and exaggerated chromatic aberration as you approach the corners. These are telltale signs of distortion correction going on (I have quite a lot of experience in this since I wrote the world’s first wide angle converter real-time distortion correction code on iOS for the Mark II Artist’s Viewfinder six years ago).

Which means that the laws of physics still apply, and supports my suspicion that the ultra wide angle camera in fact has a pretty awful tiny lens, with huge amount of distortion. And Apple doesn’t want to advertise this, so rather turned RAW capture completely off for this camera. Why? Leica, Nikon, Panasonic all do software distortion correction for expensive lenses, and the photographer at least have the freedom to correct it or leave the distortion in place for artistic purposes. (That I would never buy a 5 grand lens that require distortion correction is a tale for another day.)

The professional approach would be to provide RAW capture, and include distortion correction data inside the DNG so that RAW converters could pick it up (with the WarpRectilinear opcode).

2-3 Stop Vignetting

iPhone 11 Pro Max ultra wide camera vignetting

Now seriously. When one does distortion correction, why vignetting correction isn’t in place is beyond me. The above shot is just a wall shot under daylight, and not something suitable for exact measurements. I might do it later on, but currently this is enough to illustrate how much vignetting the image suffers from.

Again, the professional approach would be to correct this in JPG images and live video stream (or even better, provide an API to be able to control the correction), and include the necessary correction data inside the DNG files (FixVignetteRadial opcode).

No Focusing

This camera has a fixed focus lens. Read: no focusing of any kind. With such an ultra wide lens, the lack of focusing ability is mostly disguised by huge depth of field. But don’t expect to use it for ultra wide closeups.

Conclusion

Anyone touting this camera as a professional grade, DSLR (or even medium format) contender must live in a reality distortion field, powered by a huge marketing budget. Over-processed Apple JPGs suck. They always sucked. Not having proper RAW capture on the ultra wide camera is a huge drawback of the iPhone 11 series, hindering their usability for professional image capture.

  ☕ ☕ ☕

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Kuuvik Capture 3.2 : The Dual Histogram

September 7, 2017 by

The very first Kuuvik Capture release introduced RAW histograms in an attempt to provide a tool for judging exposure more precisely than what regular histograms are capable of. I even wrote an article on the merits of having a RAW histogram. The conclusion of that article was that despite you have a RAW histogram, white balancing could clip channels in the converted image even if everything was fine with the RAW; so you need to see both the RAW and the processed histograms (preferably in your RAW converter) for the final decision on your exposure.

While my former article revolved around the white balance issue, other image processing parameters, like picture style and color space, also have heavy influence on histogram precision and usability. Making to see both histogram types a fundamental need. Not to mention that launching a RAW converter is not always convenient to do.

So version 3.2 sports a new Dual Histogram tool to show Kuuvik Capture’s RAW histogram along the usual one generated from processed data.

For images, the processed part is based on the JPG preview that every RAW image contains (this is what Kuuvik Capture displays, and this is the source of the histogram shown on the camera’s LCD). This represents how the image was processed by the camera. Your RAW converter will almost certainly convert it in a different way, so the final word on exposure still belongs to the converter. But the camera’s interpretation gives a solid starting point.

The processed histogram also indicates the image’s color space. Different color spaces have different clipping points – more on this later.

You can clearly see on the example how white balancing influenced things. You’d be in trouble having made a decision solely based on the RAW histogram in this case – the blue channel would be almost completely clipped. The example belongs to the original of the following photo (that is, before contrast stretching and other adjustments).

Ice Abstract

For live view and movie recording the camera always serves video frames in sRGB – even if you set your camera to Adobe RGB. But why is that important? Well, it’s time to talk about the effect of color space choice on histograms.

Color spaces vs. histograms

I made two photos of a regular ColorChecker chart. One with setting the camera to sRGB and another with setting it to Adobe RGB. Lighting and exposure were the same.

As you can see, there’s absolutely no clipping in the RAW data. And there’s no clipping when converted to Adobe RGB. But in sRGB both highlights and shadows are clipped! So live view (which is always in sRGB) may show some clipping while Adobe RGB not. And even a histogram from an Adobe RGB conversion might show clipping while there’s absolutely no clipping in the image when converted to ProPhoto RGB in Capture One.

I’d recommend to treat these processed histogram clipping warnings as different levels. The sRGB warning in live view goes off first, this should ring a bell in your head to watch more closely after taking the image, as there may be a problem. After taking a picture, if Adobe RGB shows clipping, then it’s time to either check it in your RAW converter or back off a little bit.

But RAW histogram clipping warnings are always hard facts: indicating unrecoverable data loss.

The above example explains why I recommend to set your camera to Adobe RGB: to prevent premature clipping in histograms displayed on the camera’s LCD.

A few words on JPG support

JPG files slowly become a first-class citizen in Kuuvik Capture. The JPG processing engine in version 3.2 is up to 5x faster than previous releases. This speedup is what allows efficient histogram generation and made Dual Histograms possible. JPG histogram display was also a requirement for a JPG-only workflow, which was high on our feature request list. And now it’s fully supported as you’ll see in my upcoming post.

Kuuvik Capture 3.2 is available on the Mac App Store. It is a free update for existing Kuuvik Capture 2.x and 3.x users.

Filed Under: Image Processing, My Apps, Photo Software, Photo Technique Tagged With: , , , , , ,

Dual Pixel RAW and Kuuvik Capture

August 30, 2016 by

Dual Pixel RAW is Canon’s new invention that will see its first release with the EOS 5D Mark IV. There’s some vague marketing info floating around, but haven’t seen a concise description of these files yet. So while updating Kuuvik Capture’s (website, my posts) RAW decoder to support the 5D Mark IV, I had a chance to dig deeper into Dual Pixel RAWs.

To understand the following discussion, you need to know how Canon’s Dual Pixel AF works, especially how these Dual Pixels are divided into two separate photodiodes. This article by Dave Etchells gives you a thorough explanation.

What is a Dual Pixel RAW file?

Normal CR2 files contain the following sections:

  • Metadata
  • Previews
  • RAW data

The DPRAW file is a CR2 file that contains one more additional section:

  • Metadata
  • Previews
  • RAW data
  • DPRAW data

This organization have a very important implication. Any RAW processing software that does support the normal 5D Mark IV files will be able to open DPRAWs. If the app is unable to interpret the DPRAW data part, it will simply ignore it and will work with the file as a normal RAW. There’s no risk or penalty in taking DPRAWs (besides the huge buffer drop from 21 to 7 frames).

The DPRAW file contains the normal RAW data section to make this compatibility possible, plus one side of each pixel in the DPRAW data section.

The RAW data section contains pixel values with the sum left and right sides of the photodiode, while the DPRAW section contains pixel values from just one side of each photodiode.

The RAW data section contains pixel values with the sum of left and right side photodiodes, while the DPRAW section contains pixel values from just one photodiode of the two.

But how do we get the other side of each pixel to let Dual Pixel aware processing apps do their tricks? It’s easy: since the RAW pixel value is the sum of left and right pixel sides, just subtract the DPRAW pixel value from the RAW pixel value.

This is an unusually clever implementation from Canon, where I’m used to see all kinds of inflexible hacks that look like as if they were designed in the 1980s.

Size-wise, DPRAW files are slightly less than double the size of normal RAWs (since metadata and preview images are stored only once).

How will Kuuvik Capture 2.5 handle DPRAWs?

Not being a RAW converter, Kuuvik Capture needs the RAW data for two purposes: the RAW histogram as well as shadow/highlight warnings (the image displayed on the screen comes from the preview embedded in each CR2 file). For these the RAW data section is totally sufficient, and the app will ignore the DPRAW data section if present in a CR2 file.

The app will display normal RAW and DPRAW files equally fast, but downloading DPRAW files from the camera will take almost twice as much time as normal RAW (because of their larger size).

I assume that there will be a possibility to switch the camera into DPRAW mode remotely (I can’t be sure until my rental unit arrives). If that is the case, then a new preference will let you specify whether you’d like to shoot RAWs or DPRAWs.

Filed Under: My Apps, Photo Software, Photo Technique Tagged With: , , , , , ,

Shooting a Waterfall in the Rain

August 24, 2016 by

One of the things I had learned during the last decade is that image making is a pursuit that involves a healthy amount of plastic bags and gaffer tape to solve various problems.

Let’s take the following image for example.

Smooth and Rough

Smooth and Rough

There was a light rain when we arrived, not to mention the water droplets from the waterfall that the wind slammed in our face. It was a blessing to walk the scene with the Mark II Artist’s Viewfinder with no need to open the backpack and soak several lenses just to find a composition.

In my favorite composition (of the several I tried in just a few minutes) I wanted to emphasize the clash of dark rough rocks and light smooth water. So I needed a long exposure to smooth out the water flow. Unlike the 5DS R, none of my Zeiss lenses are weather sealed. And water accumulating on the LEE Big Stopper is also problematic. Since I don’t carry an umbrella (which would be the trivial solution), I used the largest water-resistant thing in my bag: the Shadepirate flag in the plastic bag I used to carry it in.

Shadepirate flag functioning as an umbrella

Shadepirate flag functioning as an umbrella

Some extra light also came from the direction of rain/water so the flag actually served double-duty. The setup worked quite well, and had to wipe just a small amount of water from the filter between exposures.

Filed Under: My Photos, Photo Technique Tagged With: , , ,

Focus Stacking with the Otus 1.4/28

March 2, 2016 by

Last weekend I had a little time to play with the Otus 1.4/28. I was at Lake Tisza, but the light was suboptimal to put it mildly. So I decided to make a test shot to check how focus stacking will work with the Otus 28.

Why would you need focus stacking in the first place with such a wide angle? Well, if you have a brutal 50 megapixel sensor, with a lens that’s sharper in the corners than most lenses in the center, you don’t want to throw that resolution away by stopping down below the diffraction limit.

For this test I ended up using f/6.3 and taking 6 slices.

Early Spring Pier, Lake Tisza

Early Spring Pier, Lake Tisza

It was a quite a bit windy, and I wanted to smooth out the waves using the 10-stop LEE Big Stopper. I had to realize that I ran out of gaffer tape (unfortunately the Big Stopper on the Otus 28 leaves quite a gap at the sides), so I used my heavy cotton dark cloth to keep unwanted light from hitting the front element.

The dark cloth covered the entire camera, but it was quite easy to focus on the 11″ screen of my MacBook Air using Kuuvik Capture. The images were focus stacked in Photoshop CC.

And the result? Perfect front-to-back, corner-to-corner sharpness. It’s simply amazing.

Filed Under: My Photos, Photo Technique Tagged With: , , , , , ,

Photographing Grebes with the 5DS R

September 20, 2015 by

The 5DS R became my main camera the instant I got my hands on it. Honestly, I thought that it will somehow augment either the 7D Mark II or the 5D Mark III as a high-res landscape camera, while one of those will remain my wildlife camera. I was wrong.

The 5DS R has so many seductive qualities that I tend to forget all its shortcomings and difficulties (more on those later).

Colors are bold and thanks to the anti-aliasing cancellation filter it can produce lovely crisp images. Such as the following one.

aaa

A moment before diving

It was taken in early morning light with the Canon 500/4 IS II lens and the 1.4x III teleconverter. It’s a moderate crop of about 26 megapixels – still enough for a 40×60 cm print. Yes, you can crop the hell out of these files, and still retain a huge amount of details due to the lack of AA filtering.

Some of my former grebe images are 6-8 megapixels from the 1D Mark II… So its a huge increase in usage flexibility.

Of course those huge files have a few consequences you have to live with. First, the 5DS R feels like a medium format camera. From the sound of the mirror to the time it needs to display an image on the LCD. It feels like you travel a decade back in time… Press the play button and wait… Also I haven’t experienced buffer full issues since the 1D Mark II – but run into that quite a lot even using 1066x Lexar CF cards.

You also need more time to cull a shoot. Fortunately I have an app for that: with Kuuvik Capture 2 I can sift the daily crop of 1500-2000 images pretty quickly. An old friend of mine was sitting besides me last morning and was surprised how fast the app deals with 50 MP files (and this was on a 1.4GHz 11″ MacBook Air I use as a field computer).

The next one is cropped from the sides for the rectangular composition. Same lens and converter combo. I stop down to f/6.3 with this combination, which is a bit below the f/6.7 diffraction limit of the camera. So unlike landscapes, one doesn’t have to deal with the depth of field versus diffraction issues here.

bbb

Curious visitor

Surprisingly, I found ISO 800 images a bit sharper than ISO 400 ones, so all of these were made on 800. I’ll have to investigate this further before I can draw serious conclusions. But until then, ISO 800 seems to be perfectly usable with no need for extra noise reduction.

The images in this post are the tranquil ones (the action shots are saved for another post). The 5 fps maximum speed turned out to be usable with a little anticipation of what’s going to happen (which also helps your photographs and in the understanding of the behavior of the species you are photographing). But for fast paced action I still reach for the 7D Mark II.

I tend to like to include a bit of the bird’s habitat in my images (maybe I should call them birdscapes), for which the full frame sensor is a real boon. And I can crop the surroundings away if a tight composition is what I’m after.

ccc

Breakfast for the nestlings

AF is superb. The best I’ve ever found on a Canon camera (excluding the 1D X, because of it’s faster focus driving speed). The only thing I miss is the AF mode selection lever of the 7D Mark II. I find myself reaching for the lever and cursing who’s responsible for this omission quite often.

A hot topic is the dynamic range of current Canon sensors. Well, while sometimes I would need more (maybe a handful of times during the last 12 years), what the 5DS R offers usually pretty much enough. Especially that I print my images where I have just 6 or 7 stops, and usually expose my images properly with no need to recover from the shadows. Also I like to utilize clipped highlights and shadows as artistic tools… So I’m not complaining on this front.

ddd

Good night!

As you may already think, I really like the 5DS R. It’s not the absolute fastest and the most suitable camera for bird photography, but those limitations are igniting my creativity and are not in the way of image making. It’s an exceptional tool for making the kind of photographs I have in mind.

Filed Under: My Photos, Photo Equipment, Photo Technique Tagged With: , , , , ,
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