Let's get something straight

Isn’t Twitter amazing? If you’ve not yet embraced the power of this social networking tool I’m going to give you a very good reason to do so. Especially if you’re into photography, because you’ll find yourself bumping into people willing to share tips and expertise that could save you a lot of time. And money.

When people ask me to describe Twitter, I say it’s like a water cooler. A giant, global water cooler (office kitchen, coffee lounge, whatever your cultural tastes lean to) where people bump into one another and share information. Pointless gossip. Pointed attempts at humour. Unsolicited opinion. Solicited opinion. Best of all, though, is the exchange of useful information, and here’s a really good example of why photographers should be using Twitter.

I follow an amazing US photographer called Michael James, whose Twitter name is HDRphotography and has a blog about HDR. If those three letters mean something to you, it’ll be because you know something about High Dynamic Range imaging.

If you don’t, I won’t get bogged down with explaining HDR other than to say it’s a software-based procedure solving a problem that has vexed photographers since the invention of photography. Namely, the challenge of accurately recording detail in both shadow and highlight portions of an image. If HDR is a mystery to you, let me know in MacTheForum and I’ll blog a HDR primer. Or have a look at Mr James’s HDR blog.

Now, the thing about HDR is that like so many other software tools available to photographers, there’s plenty of room for abuse. Indeed, hunt around the web and you’ll see plenty of good examples. I’ve even heard it described as the “21st century version of the velvet Elvis poster”. Ouch.

However, Mr James’s work doesn’t suffer the excesses that are so easily attained when using HDR. Rather, as an architectural photographer specialising in shooting homes for the high-end real estate market, he uses HDR as a means to an end, which is to show a home in its very best light. And he does an amazing job of it.

If you were thinking this is leading to some amazing revelation about HDR software, then sorry because it’s not. All of that was for context. The introduction to Michael James was due because it was he who — as is so often the case on Twitter — generously shared some really great info, namely a link to a software developer who produces a terrific little app for correcting lens distortion. The app is called PTLens. It costs $US25. For your registration fee you get a standalone 64-bit app, a Lightroom and an Aperture plug-in, a Photoshop plug-in and a Photoshop action for use with shift lenses. Just one of those software gems would be good value for the asking price.

So ... what’s it for? Fixing lens distortion.

Even top-quality lenses exhibit some form of distortion as one of the problems inherent to bending light to your will. Chromatic aberration and the twin bedfellows of pincushion and barrel distortion are common ones to deal with but the particular type of distortion that I’ve been looking for a quick fix for is what I call the “falling-over” effect. This happens when you use a wide angle lens and point it up at a building, which causes the verticals of the building to converge and makes it look like it’s falling over backwards, away from the viewer. Yes, falling over can be “arty”. But buildings not falling over is good, too. Their architects appreciate it.

Yes, there are fixes for the falling-over effect. Different point of view (not always accessible), use of a shift lens (OK if you can afford one), use of a longer lens from further back (again, not always possible) and, of course, the choice of elite architectural shooters, the monorail camera with its range of lens and film plane movements that can overcome all sorts of perspective problems. But they cost a squillion.

And for software solutions, there’s Photoshop, right? Well, yes. If you have it. If not, and you’re an Aperture or even a Lightroom user, an Aperture plug-in is a way cheaper option. Better yet, PTLens is much faster than Photoshop. Or at least it is in comparisons I’ve made with Photoshop CS4. CS5’s 64-bit goodness may address the speed issue.

One thing to bear in mind with using PTLens as a plug-in for Aperture is that it won’t handle RAW files. You must first convert a RAW file to TIFF before exporting it for use in the standalone app, which can be done manually (export TIFF from Aperture, open with PTLens) or you can set PTLens as your external editor and specify TIFF as your editing format in Aperture’s preferences. If you’re using the plug-in, the conversion is handled automatically. You can also batch-process images, which will come in useful if you've shot bracketed exposures for a HDR workflow.

It's not all about fixing converging verticals. If you’ve never used lens correction software, prepare to be amazed at what happens when PTLens leverages image metadata to load a lens profile and apply it to an image to correct for pincushion, barrel or other distortion. The image magically looks crisper, better focused, more "real".

To see what I mean, and get a closer look at what PTLens can do — not only for architectural images but all of your work — download the installer and use it in demo mode on ten images before getting the “buy me” nag.

I’m pretty sure you won’t be disappointed. If you have more money to burn, have a look at www.dxo.com where you’ll find some top-shelf lens correction and RAW conversion software starting at $US99.

Had I not complimented Michael James on how he managed to keep his verticals vertical and consequently received a reply pointing me at PTLens, I probably would have bought the DXO package. Great software, for sure, but more than I wanted to spend. And if PTLens is good enough for Mr James, I reckon it has to be more than adequate for most of us.

Discuss this with me on MacTheForum!

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