Mark II Artist’s Viewfinder 5.0 Available

Version 5.0 of my Mark II Artist’s Viewfinder app is now available on the App Store. It took quite a bit longer than I first planned, but if you look at the sheer number of new stuff, you’ll understand why. More work went into this update than it took to develop the original version 1.

I wrote about the black & white mode and exposure compensation, and the question of RAW capture in former posts, now it’s time to reveal everything else. I’ll touch a few new things in this post, and highly recommend to take a look on the complete list in the release notes. And pay attention to the “Changes” section.

Quick Control Screen

The are a few subtle visual changes to make it less cluttered, and to make room for two new icons. The half dark/half light icon in the upper right toggles black & white mode. The 2x icon switches to the telephoto camera if you have an iPhone 7 Plus. The telephoto camera and wide converter use are mutually exclusive (as one would logically expect).

Icons for parallax correction/shift simulation and aspect ratio changing are now white when a non-default value is set for these (in the above example I set the 5DS R virtual camera to 16:9 aspect ratio).

Album -> Catalog

We had to rename the Album to Catalog to avoid a name clash with the thing that Apple calls an album in the Photos app. Now ours is named Catalog, since it would be extraordinarily hard to convince Apple that they should change…

And while we are talking about the Catalog, there are performance improvements here and there, meaning that an update may be required to the new format. The app automatically detects if this is the case, and will update the Catalog automatically.


This is a free update for existing Mark II Artist’s Viewfinder owners. New user can purchase the app from the App Store.

We offer upgrade bundles for former Viewfinder Basic/Pro/Cine edition owners, so they can upgrade for a reduced price.

The Viewfinder Handbook was also updated to cover all the new features.

Custom Wide Converters in Viewfinder 4.7

My Mark II Artist’s Viewfinder app has a unique feature from day one. Something that no competitor managed to copy: real-time distortion correction for wide converter lenses. In the past distortion correction was available through the profiles we made for all the wide converter and device combinations the app supports. Creating these profiles involves tedious measurements, and of course a purchase of each and every converter lens and iPhone/iPad we support.

The profile approach was good a few years ago with a limited set of converters on the market, but these days you can find at least a dozen different converter lenses at online retailers. This, together with the product lineup splits Apple already implemented with the Plus phones and Pro iPads, renders the previous modus operandi financially unsustainable.

So we decided to address this situation in a way that is beneficial for both our users as well ourselves: by allowing users to create a custom wide converter. And of course we do support simple distortion correction with this! Being a simple correction, it does not always produce the almost perfect results the profile-based approach is capable of, but as you’ll se in the examples later on, very capable nevertheless.

We’ll continue to support the profile-based approach for existing combinations, but will add new profiles only if:

  • we already have the converter and the device in the lab, or
  • we receive several customer requests to support a converter – as it was the case with the Moment Wide lens, or
  • we cooperate with the converter’s manufacturer.

OK, with all that said, let’s see how it works. Once you select Custom for the wide converter, a new menu item – Custom Converter Setup – will appear on the menu.

cwc-setupTapping it will bring up the converter setup screen that you can see on the left.

You can set the converter lens’ actual conversion factor with the first slider. Since this is almost always different from what the manufacturer says, you’ll definitely need to fine tune it for your actual phone (since the conversion factor also depends on the phone’s lens as well as the distortion correction amount – be prepared for a little trial and error). We support converters with factors between 0.45 and 0.7.

The second slider is used to specify how much distortion the converter lens has. It is an arbitrary scale from 0 to 30, zero meaning that you will not want to correct the distortion (suitable for well-corrected lenses such as the Moment Wide).

The setup procedure

Here’s how I recommend to do the setup. Set distortion correction first (if needed at all). I’d recommend 15 as the starting point for 0.65x-class lenses and 20 for 0.5x-class lenses. Check how the main screen looks, and watch for overcorrection in the corners. In case you still have barrel distortion, go back to the menu, and increase correction. If the corners are overcorrected, back off a little. A tiled wall, a window or a tall building are good test targets.

Once you’re happy with the correction, mount the phone steadily, turn off Wide Mode, and set the main screen so that you have some objects or markings at the edges of frame lines. Now turn on Wide Mode and check whether the objects/markings are still at the frame lines. Go into the menu and adjust the conversion factor if not. Repeat until you are satisfied with the result.

You can create only one custom wide converter, so it is advised to take note of the parameters in case you need to restore them later.

Correction examples

Walked up to Hallgrímskirja in Reykjavík to make some examples with my iPhone 6s Plus and two olloclip converters. Here is how the 4-IN-1 Wide lens looks with no correction.

olloclip 4-IN-1 Wide on iPhone 6s Plus - No Distortion Correction

olloclip 4-IN-1 Wide on iPhone 6s Plus – No distortion correction

As you can see below, this lens has a simple spherical distortion, which can be corrected almost perfectly with the custom converter setup. My experience is that most 0.65x lenses behave the same way and would only marginally benefit from a profile. Note that I set the conversion factor ad-hoc in these examples, so you may see some discrepancy in frame line positions.

olloclip 4-IN-1 Wide on iPhone 6s Plus - Custom wide converter with distortion setting 13

olloclip 4-IN-1 Wide on iPhone 6s Plus – Custom wide converter with distortion setting 13

Now to the olloclip Ultra Wide. Distortion is huge, and without correction renders the lens pretty much unusable for viewfinder purposes.

olloclip Active Ultra Wide on iPhone 6s Plus - No distortion correction

olloclip Active Ultra Wide on iPhone 6s Plus – No distortion correction

And this is how it looks with the custom wide converter’s correction. You see some mustache-like corners as the simple correction is not able to eliminate complex distortions (which profiles can do), but the lens becomes usable.

olloclip Active Ultra Wide on iPhone 6s Plus - Custom wide converter with distortion setting 22

olloclip Active Ultra Wide on iPhone 6s Plus – Custom wide converter with distortion setting 22

Just like with profiles, the simple distortion correction works only with wide and ultra wide lenses – not with fisheyes.

When will this be available? The feature is currently in testing in version 4.7, and is planned to be released later this summer. In the meantime, comments are welcome.

The updated app is now available for download.

Thoughts on iDevice Wide Converters

Last week I added support for a bunch of iPhone/iPod wide converter lenses to the upcoming release of our Mark II Artist’s Viewfinder app. They were Schneider’s Series 2 super wide and wide iPro lenses as well as the wide lens in olloclip’s 4-in-1 offering. The picture below shows them: Schneiders on the left, olloclips on the right, and the ALPA ACAM in the middle. They are shown without their mounting cases (except for the olloclips).

A bunch of wide converters

A bunch of wide converters

While they are all suitable for viewfinder use, you can’t expect good optical performance from such lenses, period. Their manufacturers like to advertise them as “high quality”, “precision”, etc. Well, they might be high quality for someone who lo-fi filters the crap out of their smartphone images, but in my book they are not usable for real photography – even on smartphones.

They are all priced in the same range ($65-$100) with mounting hardware included. Schneiders usually occupying the higher end of this range.

Conversion factor and distortion

The bad news: advertised conversion factors can’t be used to compare these lenses. All super wide converters we measured exhibit huge (10% or more) barrel distortion. What gets in the marketing material is the magnification ratio with no distortion correction applied. That is, they count in the extreme edges, which will result in smaller factors.

But when distortion is removed, those extreme edges go away (as you can see in the first illustration in my previous post). The result: Schneider’s super wide lens that’s advertised as having a 0.45x conversion factor is a 0.5x lens is reality. ALPA’s lens, which is advertised as 0.5x (because I told them to) is a bit wider in reality than Schneider’s 0.45x.

The conversion factor also changes from device to device – and all the adapters I measured go wider when they are used on a device having a wider native field of view. For example, the ALPA is a 0.5x on an iPhone 4, but a 0.48x on an iPhone 5S.

ALPA ACAM mounted for measurement

ALPA ACAM mounted for measurement

If you look at conversion factors you’ll find out that there are two distinct classes: 0.5x and 0.65x. The Schneider super wide and the ALPA wide belongs to the first, and the Schneider wide and the olloclip belongs to the second. Is it important to note that the wide Schneider exhibits only a small amount of barrel distortion – and this lens would be usable even without correction. The olloclip is not, it has the same huge distortion as super-wides.


The sharpest is the Schneider super wide. The least sharp is the iPhone 4/4S variant of the olloclip – so much that I struggled for hours to find the checkerboard corners in the sea of blur and chromatic aberration.

Other aberrations

Schneiders are almost free of chromatic aberration. All others exhibit a huge amount of it in the corners. Centering is bad on all converters. The Schneider super wide also exhibits hard to correct mustache-like distortion. On the iPhone 5 for example this – together with bad centering – causes residual pincushion distortion on one side of the image after the barrel has been removed.


Olloclips tend to slip off easily – except when you use it on an iPod, where a rubber inserts keeps the lens in place. Converters with cases are all solid, although I found Schneider’s iPhone 4/4S case too tight and hard to remove.

Mounting on the top of the camera (in the hot shoe for example) is another story. If you want to use the converter lens to compose stitched panoramas with the Mark II, you’ll need a holder that keeps the phone’s lens centered with the camera’s. This is to avoid parallax as much as possible. This is where things start to cost more. ALPA makes a holder that ships with the super wide converter lens and two cases. Other manufacturers, such as Cambo, also make holders (the Cambo includes a converter lens that the Mark II does not support yet). But be prepared to spend $800-$900 on these.

My favorites

I’m not a big fan of the Schneiders. I was confused about which case is compatible with which series lenses, and their site offers little help. Now I know that the series 1 cases can hold series 2 lenses, but not vice versa.

Actually I have two favorites. The ALPA rig (holder and such) is what I use. It offers the widest view, it’s easy to mount on my camera, has the sturdiest lens mount, and so on. All in all, highly recommended.

The other, the olloclip 4-in-1 on an iPod touch 5, was a surprise for me. I never thought how usable this combo could be. It’s lightweight, fast, and the rubber insert keeps the lens from falling. It can simulate lenses down to about 24mm (on full frame 35mm cameras). Not to mention that it’s the cheapest way to get into the wide converter world of the Mark II.