Using a smartphone as a loupe

Part of my work as a prepress operator requires looking at printed material under magnification, usually a loupe. This is done for a variety of reasons, such as:

  • Determining if a previous print was printed in full colour process or spot colour;
  • Assessing the effectiveness of trapping;
  • Checking if print is aligned in register;
  • Determining the dot structure of a printed product (was it stochastic or halftone; and if it was halftone, was the dot shape round, Euclidean or other);
  • Attempting to determine the value of a colour breakdown;
  • Confirming that barcode width reduction appropriately compensates for ink gain on a printed barcode.

In previous posts on Colecandoo, I’ve shown several photos taken using my digital microscope, such as this image that was used to illustrate the misregistration of a varnish compared to the ink underneath.

The digital microscope is certainly useful for checking details not immediately obvious with a loupe such as the barcode example, but for most magnifying tasks, a loupe works just fine.

Isn’t there a smartphone app for this?  

Yes and no. There are specific smartphone apps I will use for prepress work, such as:

  • What the Font – great for identifying fonts when I’m far away from my laptop;
  • Measure – when a tape measure is unavailable and centimetre precision will do;
  • Adobe Scan – when I need to take in typeset material when I’m not near my flatbed scanner; or if a customer’s original can’t be taken apart to fit on a flatbed scanner.
  • Touch Portal – when I need extra buttons for my laptop – an equivalent would be elgato’ streamdeck.

Many smartphones now feature macro lenses that have comparable zoom to a loupe, but require the phone to be held the correct distance away from the subject and to have a steady hand or a rig established for the purpose.

Enter smartphone lenses

I’ve recently invested in a macro lens for my smartphone. Since using it at work, it has been quite useful – to the point where it inspired this article.

To demonstrate the difference of the smartphone macro lens to the default macro lens and the digital microscope, here is a comparison on a printed image.

For me at least, I can now safely stash my old loupe in the desk drawer and begin to use the macro lens as an alternative. Here are some reasons that I’ve made this decision:

It has several advantages over a conventional loupe:

  • Virtually no chromatic aberration
  • Others can see the image without me needing to share the loupe
  • Can share the footage live using screen sharing software so that the image isn’t just on the phone screen, but on a larger display; or take a photo and email to the client or file for later use.

There are also several advantages of this lens over iphone’s macro lens:

  • Higher magnification;
  • Stable to hold as the diffusion filter also acts as a rest;
  • As any Sandmarc lens is shipped with a case or clip to allow the lens to be mounted, it also provides the ability to change out lenses for other purposes

This also has advantage over the digital microscope

  • No wires;
  • Requires no additional power;
  • No additional “unitasker” software (serves one purpose alone)

However, the macro lens isn’t without it’s disadvantages:

  • Needs good lighting – a backlight would help tremendously;
  • Requires a case or clamp to fasten the lens, though with the Sandmarc lens that I purchased, this was provided upon purchase;
  • Requires additional software to access the individual lenses as the iphone’s default camera app will not allow this flexibility – software such as Adobe Lightroom is what I use, but this was on my phone anyway;
  • Not portable enough to become part of my everyday carryables such as car keys, phone, wallet etc. Is small enough to fit in a tiny bag that sits on my desk.

So while I now have a new tool in my prepress arsenal, I’d like to know what other apps or tools that people are using to assist them in their design or prepress tasks – feel free to comment below.

Finally, as a matter of full disclosure, this article is NOT sponsored by Adobe, Sandmarc, Apple or any other company mentioned in the article. If they would like to sponsor Colecandoo in the future, that may be something to explore, but this article is my own thoughts and opinions and the macro lens I purchased.

About colmin8r
A prepress operator and graphic designer for a South Australian commercial printer, with close to 20 years of experience in the trade. He is also a regular contributor to this site and InDesign Magazine, and hosts his own prepress blog "Colecandoo".

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