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.

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  1. I’m interested in getting an adaptor lens for my iPhone so I can simulate a 24mm lens on my Canon (full frame) using the Mark II viewfinder.
    Would I just need to buy the Schneider WA series II x.65 or do I need a whole set of lenses? My only interest is in 24mm / 28mm / 35mm / 50mm equivalent views (no telephoto).

  2. I’m looking into using your Artists Viewfinder app on an iPhone 5s. I need a recommendation for what current wide angle converter will best with your app to suit my needs.

    I will be using it as a hand-held viewfinder, for a 4×5 and a small range of semi-wide lenses. I may mount the phone on a tripod at times for ease of use, but will use an inexpensive quick release adapter for that, rather than something like the Alpa or Cambo mount. I will be using your app to help frame and record possible shots and scout locations. I would like to get the best quality recorded images as well.

    I am currently looking at using an Ebony RSW45 for the camera. The widest lens would be a Super Symmar 110mm XL, the longest a 150mm lens.

    From what I understand reading your documentation, it sounds like the latest versions of the Schneider 5s case and series 2 wide angle lens would be the best quality option for my 5s, as from my understanding a .5 converter lens would be too wide for my needs.

    I’ve read that you recommend the Alpa case and lens. I do prefer the simplicity of the Alpa case and the way the lens securely attaches. Is this as good or better an option with your app? For example, with the 5s display, is it possible to zoom in to use the frame lines I would need and still have a high quality view? Not really sure how this works in your app.

    Looks like you have a great app. Looking forward to using it. Thank you for any advice.

    • Laszlo Pusztai says:

      I assume you are using 4×5″ sheet film with the Ebony. The good news is that you don’t need a wide converter to simulate a 110mm 4×5 lens on an iPhone 5s – the frame lines are just a hair (1 or 2 pixels) outside of what a “naked” iPhone 5s can simulate. You just have to zoom out a little bit from the default to display the entire field the iPhone camera can see.

      So I would recommend to download the app, and configure it with no converter at all. And add converters later on as you need them. Quality-wise the ALPA and Schneider offerings are well above olloclips, but from the app’s perspective they are identical. Also both with the ALPA and the Schneider you buy one lens and just get new cases/clips for new devices, whereas you have to re-buy the entire olloclip thing for each new device.

      Personally I shoot ultra-wide, so I need a 0.5x converter lens. Having both the ALPA and the Schneider at hand I just prefer the ALPA for the reasons I mentioned in the post.

      Regarding zooming: yes, it’s possible to zoom in even if you have a wide converter attached. I would recommend to check out the Viewfinder Handbook ( which has extensive coverage on wide converters and on how to use them with the app.

  3. One other question. What is the differences between the Alpa eFinder and Artist Viewfinder apps? Will they both work as a viewfinder for 4×5 view cameras and various Schneider viewfinder lenses?

    • Laszlo Pusztai says:

      ALPA eFinder II is a subset of the Mark II Artist’s Viewfinder – it only supports ALPA cameras and the ALPA wide converter. But you can convert that into a full-featured Mark II via an in-app purchase.

  4. Hi Thank You… question….

    “wide Schneider exhibits only a small amount of barrel distortion – and this lens would be usable even without correction.


    The sharpest is the Schneider super wide.”

    HI; Please help; don’t understand your statement above. Which is the Sharpest lens… the Schneider “Wide” or “Super Wide”


    • Laszlo Pusztai says:

      The sharpest one is the super wide – at least before distortion correction. The correction takes away a large amount of corner sharpness (the center is mostly unaffected). So you may end up a sharper image _after correction_ with the wide (haven’t checked it yet). But the wide is only 0.65x, while the super wide is 0.5x. And I think that you should select a converter based on your conversion factor needs.

      • Great; Thank You… Is the “distortion correction” you mention inherent the iphone, or post in PS?

        • Laszlo Pusztai says:

          I mean distortion inherent in the wide converter lenses. The iPhone lens alone is just fine (I bet it’s corrected in the imaging pipeline). And by distortion correction I mean the correction in the Mark II Artist’s Viewfinder app. No PS involved. I think these converters are suitable only for viewfinder use, not for taking real photos 🙂

  5. Any chance that you would support the Moment Wide Lens as a wide converter? It seems to me to be a step up from the Olloclip, although probably not as good as the Schneider.

    • Laszlo Pusztai says:

      Yes, the upcoming version 4.3 will support the Moment Wide lens. Among the 0.65x class converters the Moment has the best image quality. But it’s still 0.65x, which may not be wide enough for some people (myself included).


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